Author: "Amram, N." - Searchworks@Jio Institute Digital Library Search Results

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4,993 results on '"Amram, N."'

201. Search for Higgs boson pair production in the bb¯bb¯ final state from pp collisions at s=8 TeVwith the ATLAS detector

Author: Aad, G, Abbott, B, Abdallah, J, Abdinov, O, Aben, R, Abolins, M, AbouZeid, OS, Abramowicz, H, Abreu, H, Abreu, R, Abulaiti, Y, Acharya, BS, Adamczyk, L, Adams, DL, Adelman, J, Adomeit, S, Adye, T, Affolder, AA, Agatonovic-Jovin, T, Aguilar-Saavedra, JA, Ahlen, SP, Ahmadov, F, Aielli, G, Akerstedt, H, Åkesson, TPA, Akimoto, G, Akimov, AV, Alberghi, GL, Albert, J, Albrand, S, Alconada Verzini, MJ, Aleksa, M, Aleksandrov, IN, Alexa, C, Alexander, G, Alexopoulos, T, Alhroob, M, Alimonti, G, Alio, L, Alison, J, Alkire, SP, Allbrooke, BMM, Allport, PP, Aloisio, A, Alonso, A, Alonso, F, Alpigiani, C, Altheimer, A, Alvarez Gonzalez, B, Álvarez Piqueras, D, Alviggi, MG, Amadio, BT, Amako, K, Amaral Coutinho, Y, Amelung, C, Amidei, D, Amor Dos Santos, SP, Amorim, A, Amoroso, S, Amram, N, Amundsen, G, Anastopoulos, C, Ancu, LS, Andari, N, Andeen, T, Anders, CF, Anders, G, Anders, JK, Anderson, KJ, Andreazza, A, Andrei, V, Angelidakis, S, Angelozzi, I, Anger, P, Angerami, A, Anghinolfi, F, Anisenkov, AV, Anjos, N, Annovi, A, Antonelli, M, Antonov, A, Antos, J, Anulli, F, Aoki, M, Aperio Bella, L, Arabidze, G, Arai, Y, Araque, JP, Arce, ATH, Arduh, FA, Arguin, J-F, Argyropoulos, S, Arik, M, Armbruster, AJ, Arnaez, O, Arnal, V, Arnold, H, Arratia, M, Arslan, O, and Artamonov, A
Subjects: Nuclear and Plasma Physics, Particle and High Energy Physics, Physical Sciences, ATLAS Collaboration, hep-ex, Atomic, Molecular, Nuclear, Particle and Plasma Physics, Quantum Physics, Nuclear & Particles Physics, Astronomical sciences, Atomic, molecular and optical physics, Particle and high energy physics
Abstract: A search for Higgs boson pair production [Formula: see text] is performed with 19.5 fb[Formula: see text] of proton-proton collision data at [Formula: see text] TeV, which were recorded by the ATLAS detector at the Large Hadron Collider in 2012. The decay products of each Higgs boson are reconstructed as a high-momentum [Formula: see text] system with either a pair of small-radius jets or a single large-radius jet, the latter exploiting jet substructure techniques and associated b-tagged track-jets. No evidence for resonant or non-resonant Higgs boson pair production is observed. The data are interpreted in the context of the Randall-Sundrum model with a warped extra dimension as well as the two-Higgs-doublet model. An upper limit on the cross-section for [Formula: see text] of 3.2 (2.3) fb is set for a Kaluza-Klein graviton [Formula: see text] mass of 1.0 (1.5) TeV, at the 95 % confidence level. The search for non-resonant Standard Model hh production sets an observed 95 % confidence level upper limit on the production cross-section [Formula: see text] of 202 fb, compared to a Standard Model prediction of [Formula: see text] fb.
Published: 2015

202. Erratum to: Measurement of the inclusive jet cross-section in proton-proton collisions at s=7 TeV using 4.5 fb−1 of data with the ATLAS detector

Author: The ATLAS collaboration, Aad, G, Abbott, B, Abdallah, J, Abdel Khalek, S, Abdinov, O, Aben, R, Abi, B, Abolins, M, AbouZeid, OS, Abramowicz, H, Abreu, H, Abreu, R, Abulaiti, Y, Acharya, BS, Adamczyk, L, Adams, DL, Adelman, J, Adomeit, S, Adye, T, Agatonovic-Jovin, T, Aguilar-Saavedra, JA, Agustoni, M, Ahlen, SP, Ahmadov, F, Aielli, G, Akerstedt, H, Åkesson, TPA, Akimoto, G, Akimov, AV, Alberghi, GL, Albert, J, Albrand, S, Alconada Verzini, MJ, Aleksa, M, Aleksandrov, IN, Alexa, C, Alexander, G, Alexandre, G, Alexopoulos, T, Alhroob, M, Alimonti, G, Alio, L, Alison, J, Allbrooke, BMM, Allison, LJ, Allport, PP, Almond, J, Aloisio, A, Alonso, A, Alonso, F, Alpigiani, C, Altheimer, A, Alvarez Gonzalez, B, Alviggi, MG, Amako, K, Amaral Coutinho, Y, Amelung, C, Amidei, D, Amor Dos Santos, SP, Amorim, A, Amoroso, S, Amram, N, Amundsen, G, Anastopoulos, C, Ancu, LS, Andari, N, Andeen, T, Anders, CF, Anders, G, Anderson, KJ, Andreazza, A, Andrei, V, Anduaga, XS, Angelidakis, S, Angelozzi, I, Anger, P, Angerami, A, Anghinolfi, F, Anisenkov, AV, Anjos, N, Annovi, A, Antonaki, A, Antonelli, M, Antonov, A, Antos, J, Anulli, F, Aoki, M, Aperio Bella, L, Apolle, R, Arabidze, G, Aracena, I, Arai, Y, Araque, JP, Arce, ATH, Arguin, J-F, Argyropoulos, S, Arik, M, Armbruster, AJ, and Arnaez, O
Subjects: Nuclear and Plasma Physics, Particle and High Energy Physics, Physical Sciences, Mathematical Physics, Atomic, Molecular, Nuclear, Particle and Plasma Physics, Quantum Physics, Nuclear & Particles Physics, Mathematical physics, Nuclear and plasma physics, Particle and high energy physics
Abstract: Abstract: It was found that the non-perturbative corrections calculated using Pythia with the Perugia 2011 tune did not include the effect of the underlying event. The affected correction factors were recomputed using the Pythia 6.427 generator. These corrections are applied as baseline to the NLO pQCD calculations and thus the central values of the theoretical predictions have changed by a few percent with the new corrections. This has a minor impact on the agreement between the data and the theoretical predictions. Figures 2 and 6 to 13, and all the tables have been updated with the new values. A few sentences in the discussion in sections 5.2 and 9 were altered or removed.[Figure not available: see fulltext.]
Published: 2015

203. Measurement of the forward-backward asymmetry of electron and muon pair-production in pp collisions at s=7 TeV with the ATLAS detector

Author: The ATLAS collaboration, Aad, G, Abbott, B, Abdallah, J, Abdel Khalek, S, Abdinov, O, Aben, R, Abi, B, Abolins, M, AbouZeid, OS, Abramowicz, H, Abreu, H, Abreu, R, Abulaiti, Y, Acharya, BS, Adamczyk, L, Adams, DL, Adelman, J, Adomeit, S, Adye, T, Agatonovic-Jovin, T, Aguilar-Saavedra, JA, Agustoni, M, Ahlen, SP, Ahmadov, F, Aielli, G, Akerstedt, H, Åkesson, TPA, Akimoto, G, Akimov, AV, Alberghi, GL, Albert, J, Albrand, S, Alconada Verzini, MJ, Aleksa, M, Aleksandrov, IN, Alexa, C, Alexander, G, Alexandre, G, Alexopoulos, T, Alhroob, M, Alimonti, G, Alio, L, Alison, J, Allbrooke, BMM, Allison, LJ, Allport, PP, Almond, J, Aloisio, A, Alonso, A, Alonso, F, Alpigiani, C, Altheimer, A, Alvarez Gonzalez, B, Alviggi, MG, Amako, K, Amaral Coutinho, Y, Amelung, C, Amidei, D, Amor Dos Santos, SP, Amorim, A, Amoroso, S, Amram, N, Amundsen, G, Anastopoulos, C, Ancu, LS, Andari, N, Andeen, T, Anders, CF, Anders, G, Anderson, KJ, Andreazza, A, Andrei, V, Anduaga, XS, Angelidakis, S, Angelozzi, I, Anger, P, Angerami, A, Anghinolfi, F, Anisenkov, AV, Anjos, N, Annovi, A, Antonaki, A, Antonelli, M, Antonov, A, Antos, J, Anulli, F, Aoki, M, Aperio Bella, L, Apolle, R, Arabidze, G, Aracena, I, Arai, Y, Araque, JP, Arce, ATH, Arguin, J-F, Argyropoulos, S, Arik, M, Armbruster, AJ, and Arnaez, O
Subjects: Nuclear and Plasma Physics, Particle and High Energy Physics, Physical Sciences, Hadron-Hadron Scattering, hep-ex, Mathematical Physics, Atomic, Molecular, Nuclear, Particle and Plasma Physics, Quantum Physics, Nuclear & Particles Physics, Mathematical physics, Nuclear and plasma physics, Particle and high energy physics
Abstract: This paper presents measurements from the ATLAS experiment of the forward-backward asymmetry in the reaction pp → Z/γ* → l+l−, with l being electrons or muons, and the extraction of the effective weak mixing angle. The results are based on the full set of data collected in 2011 in pp collisions at the LHC at (Formula presented.), corresponding to an integrated luminosity of 4.8 fb−1. The measured asymmetry values are found to be in agreement with the corresponding Standard Model predictions. The combination of the muon and electron channels yields a value of the effective weak mixing angle of sin2θefflept = 0.2308 ± 0.0005(stat.) ± 0.0006(syst.) ± 0.0009(PDF), where the first uncertainty corresponds to data statistics, the second to systematic effects and the third to knowledge of the parton density functions. This result agrees with the current world average from the Particle Data Group fit.
Published: 2015

204. Measurement of charged-particle spectra in Pb+Pb collisions at sNN=2.76 TeV with the ATLAS detector at the LHC

Author: The ATLAS collaboration, Aad, G, Abbott, B, Abdallah, J, Abdel Khalek, S, Abdinov, O, Aben, R, Abi, B, Abolins, M, AbouZeid, OS, Abramowicz, H, Abreu, H, Abreu, R, Abulaiti, Y, Acharya, BS, Adamczyk, L, Adams, DL, Adelman, J, Adomeit, S, Adye, T, Agatonovic-Jovin, T, Aguilar-Saavedra, JA, Agustoni, M, Ahlen, SP, Ahmadov, F, Aielli, G, Akerstedt, H, Åkesson, TPA, Akimoto, G, Akimov, AV, Alberghi, GL, Albert, J, Albrand, S, Alconada Verzini, MJ, Aleksa, M, Aleksandrov, IN, Alexa, C, Alexander, G, Alexandre, G, Alexopoulos, T, Alhroob, M, Alimonti, G, Alio, L, Alison, J, Allbrooke, BMM, Allison, LJ, Allport, PP, Aloisio, A, Alonso, A, Alonso, F, Alpigiani, C, Altheimer, A, Alvarez Gonzalez, B, Alviggi, MG, Amako, K, Amaral Coutinho, Y, Amelung, C, Amidei, D, Amor Dos Santos, SP, Amorim, A, Amoroso, S, Amram, N, Amundsen, G, Anastopoulos, C, Ancu, LS, Andari, N, Andeen, T, Anders, CF, Anders, G, Anderson, KJ, Andreazza, A, Andrei, V, Anduaga, XS, Angelidakis, S, Angelozzi, I, Anger, P, Angerami, A, Anghinolfi, F, Anisenkov, AV, Anjos, N, Annovi, A, Antonelli, M, Antonov, A, Antos, J, Anulli, F, Aoki, M, Aperio Bella, L, Arabidze, G, Arai, Y, Araque, JP, Arce, ATH, Arduh, FA, Arguin, J-F, Argyropoulos, S, Arik, M, Armbruster, AJ, Arnaez, O, Arnal, V, Arnold, H, and Arratia, M
Subjects: Nuclear and Plasma Physics, Particle and High Energy Physics, Physical Sciences, QCD, Heavy Ions, hep-ex, nucl-ex, Mathematical Physics, Atomic, Molecular, Nuclear, Particle and Plasma Physics, Quantum Physics, Nuclear & Particles Physics, Mathematical physics, Nuclear and plasma physics, Particle and high energy physics
Abstract: Charged-particle spectra obtained in Pb+Pb interactions at (Formula presented.) and pp interactions at (Formula presented.) with the ATLAS detector at the LHC are presented, using data with integrated luminosities of 0.15 nb−1 and 4.2 pb−1, respectively, in a wide transverse momentum (0.5 < pT< 150 GeV) and pseudorapidity (|η| < 2) range. For Pb+Pb collisions, the spectra are presented as a function of collision centrality, which is determined by the response of the forward calorimeters located on both sides of the interaction point. The nuclear modification factors RAA and RCP are presented in detail as a function of centrality, pT and η. They show a distinct pT-dependence with a pronounced minimum at about 7 GeV. Above 60 GeV, RAA is consistent with a plateau at a centrality-dependent value, within the uncertainties. The value is 0.55 ± 0.01(stat.) ± 0.04(syst.) in the most central collisions. The RAA distribution is consistent with flat |η| dependence over the whole transverse momentum range in all centrality classes.
Published: 2015

205. Search for heavy lepton resonances decaying to a Z boson and a lepton in pp collisions at s=8 TeV with the ATLAS detector

Author: The ATLAS collaboration, Aad, G, Abbott, B, Abdallah, J, Abdinov, O, Aben, R, Abolins, M, AbouZeid, OS, Abramowicz, H, Abreu, H, Abreu, R, Abulaiti, Y, Acharya, BS, Adamczyk, L, Adams, DL, Adelman, J, Adomeit, S, Adye, T, Affolder, AA, Agatonovic-Jovin, T, Aguilar-Saavedra, JA, Ahlen, SP, Ahmadov, F, Aielli, G, Akerstedt, H, Åkesson, TPA, Akimoto, G, Akimov, AV, Alberghi, GL, Albert, J, Albrand, S, Alconada Verzini, MJ, Aleksa, M, Aleksandrov, IN, Alexa, C, Alexander, G, Alexopoulos, T, Alhroob, M, Alimonti, G, Alio, L, Alison, J, Alkire, SP, Allbrooke, BMM, Allport, PP, Aloisio, A, Alonso, A, Alonso, F, Alpigiani, C, Altheimer, A, Alvarez Gonzalez, B, Álvarez Piqueras, D, Alviggi, MG, Amadio, BT, Amako, K, Amaral Coutinho, Y, Amelung, C, Amidei, D, Amor Dos Santos, SP, Amorim, A, Amoroso, S, Amram, N, Amundsen, G, Anastopoulos, C, Ancu, LS, Andari, N, Andeen, T, Anders, CF, Anders, G, Anders, JK, Anderson, KJ, Andreazza, A, Andrei, V, Angelidakis, S, Angelozzi, I, Anger, P, Angerami, A, Anghinolfi, F, Anisenkov, AV, Anjos, N, Annovi, A, Antonelli, M, Antonov, A, Antos, J, Anulli, F, Aoki, M, Aperio Bella, L, Arabidze, G, Arai, Y, Araque, JP, Arce, ATH, Arduh, FA, Arguin, J-F, Argyropoulos, S, Arik, M, Armbruster, AJ, Arnaez, O, Arnal, V, Arnold, H, Arratia, M, and Arslan, O
Subjects: Nuclear and Plasma Physics, Particle and High Energy Physics, Physical Sciences, Hadron-Hadron Scattering, hep-ex, Mathematical Physics, Atomic, Molecular, Nuclear, Particle and Plasma Physics, Quantum Physics, Nuclear & Particles Physics, Mathematical physics, Nuclear and plasma physics, Particle and high energy physics
Abstract: A search for heavy leptons decaying to a Z boson and an electron or a muon is presented. The search is based on pp collision data taken at (Formula presented.) = 8 TeV by the ATLAS experiment at the CERN Large Hadron Collider, corresponding to an integrated luminosity of 20.3 fb−1. Three high-transverse-momentum electrons or muons are selected, with two of them required to be consistent with originating from a Z boson decay. No significant excess above Standard Model background predictions is observed, and 95% confidence level limits on the production cross section of high-mass trilepton resonances are derived. The results are interpreted in the context of vector-like lepton and type-III seesaw models. For the vector-like lepton model, most heavy lepton mass values in the range 114–176 GeV are excluded. For the type-III seesaw model, most mass values in the range 100–468 GeV are excluded.
Published: 2015

206. Search for metastable heavy charged particles with large ionisation energy loss in pp collisions at s=8 TeV using the ATLAS experiment

Author: ATLAS Collaboration, Aad, G, Abbott, B, Abdallah, J, Abdinov, O, Aben, R, Abolins, M, AbouZeid, OS, Abramowicz, H, Abreu, H, Abreu, R, Abulaiti, Y, Acharya, BS, Adamczyk, L, Adams, DL, Adelman, J, Adomeit, S, Adye, T, Affolder, AA, Agatonovic-Jovin, T, Agricola, J, Aguilar-Saavedra, JA, Ahlen, SP, Ahmadov, F, Aielli, G, Akerstedt, H, Åkesson, TPA, Akimov, AV, Alberghi, GL, Albert, J, Albrand, S, Alconada Verzini, MJ, Aleksa, M, Aleksandrov, IN, Alexa, C, Alexander, G, Alexopoulos, T, Alhroob, M, Alimonti, G, Alio, L, Alison, J, Alkire, SP, Allbrooke, BMM, Allport, PP, Aloisio, A, Alonso, A, Alonso, F, Alpigiani, C, Altheimer, A, Alvarez Gonzalez, B, Álvarez Piqueras, D, Alviggi, MG, Amadio, BT, Amako, K, Amaral Coutinho, Y, Amelung, C, Amidei, D, Amor Dos Santos, SP, Amorim, A, Amoroso, S, Amram, N, Amundsen, G, Anastopoulos, C, Ancu, LS, Andari, N, Andeen, T, Anders, CF, Anders, G, Anders, JK, Anderson, KJ, Andreazza, A, Andrei, V, Angelidakis, S, Angelozzi, I, Anger, P, Angerami, A, Anghinolfi, F, Anisenkov, AV, Anjos, N, Annovi, A, Antonelli, M, Antonov, A, Antos, J, Anulli, F, Aoki, M, Aperio Bella, L, Arabidze, G, Arai, Y, Araque, JP, Arce, ATH, Arduh, FA, Arguin, J-F, Argyropoulos, S, Arik, M, Armbruster, AJ, Arnaez, O, Arnal, V, Arnold, H, Arratia, M, and Arslan, O
Subjects: Nuclear and Plasma Physics, Particle and High Energy Physics, Physical Sciences, ATLAS Collaboration, hep-ex, Atomic, Molecular, Nuclear, Particle and Plasma Physics, Quantum Physics, Nuclear & Particles Physics, Astronomical sciences, Atomic, molecular and optical physics, Particle and high energy physics
Abstract: Many extensions of the Standard Model predict the existence of charged heavy long-lived particles, such as R-hadrons or charginos. These particles, if produced at the Large Hadron Collider, should be moving non-relativistically and are therefore identifiable through the measurement of an anomalously large specific energy loss in the ATLAS pixel detector. Measuring heavy long-lived particles through their track parameters in the vicinity of the interaction vertex provides sensitivity to metastable particles with lifetimes from 0.6 ns to 30 ns. A search for such particles with the ATLAS detector at the Large Hadron Collider is presented, based on a data sample corresponding to an integrated luminosity of [Formula: see text] fb[Formula: see text] of pp collisions at [Formula: see text] TeV. No significant deviation from the Standard Model background expectation is observed, and lifetime-dependent upper limits on R-hadrons and chargino production are set. Gluino R-hadrons with 10 ns lifetime and masses up to 1185 GeV are excluded at 95 [Formula: see text] confidence level, and so are charginos with 15 ns lifetime and masses up to 482 GeV.
Published: 2015

207. Search for production of vector-like quark pairs and of four top quarks in the lepton-plus-jets final state in pp collisions at √s = 8 TeV with the ATLAS detector

Author: The ATLAS collaboration, Aad, G, Abbott, B, Abdallah, J, Abdinov, O, Aben, R, Abolins, M, AbouZeid, OS, Abramowicz, H, Abreu, H, Abreu, R, Abulaiti, Y, Acharya, BS, Adamczyk, L, Adams, DL, Adelman, J, Adomeit, S, Adye, T, Affolder, AA, Agatonovic-Jovin, T, Aguilar-Saavedra, JA, Ahlen, SP, Ahmadov, F, Aielli, G, Akerstedt, H, Åkesson, TPA, Akimoto, G, Akimov, AV, Alberghi, GL, Albert, J, Albrand, S, Alconada Verzini, MJ, Aleksa, M, Aleksandrov, IN, Alexa, C, Alexander, G, Alexopoulos, T, Alhroob, M, Alimonti, G, Alio, L, Alison, J, Alkire, SP, Allbrooke, BMM, Allport, PP, Aloisio, A, Alonso, A, Alonso, F, Alpigiani, C, Altheimer, A, Alvarez Gonzalez, B, Álvarez Piqueras, D, Alviggi, MG, Amadio, BT, Amako, K, Amaral Coutinho, Y, Amelung, C, Amidei, D, Amor Dos Santos, SP, Amorim, A, Amoroso, S, Amram, N, Amundsen, G, Anastopoulos, C, Ancu, LS, Andari, N, Andeen, T, Anders, CF, Anders, G, Anders, JK, Anderson, KJ, Andreazza, A, Andrei, V, Angelidakis, S, Angelozzi, I, Anger, P, Angerami, A, Anghinolfi, F, Anisenkov, AV, Anjos, N, Annovi, A, Antonelli, M, Antonov, A, Antos, J, Anulli, F, Aoki, M, Aperio Bella, L, Arabidze, G, Arai, Y, Araque, JP, Arce, ATH, Arduh, FA, Arguin, JF, Argyropoulos, S, Arik, M, Armbruster, AJ, Arnaez, O, Arnal, V, Arnold, H, Arratia, M, and Arslan, O
Subjects: Hadron-Hadron Scattering, hep-ex, Nuclear & Particles Physics, Mathematical Physics, Atomic, Molecular, Nuclear, Particle and Plasma Physics, Quantum Physics
Abstract: A search for pair production of vector-like quarks, both up-type (T) and down-type (B), as well as for four-top-quark production, is presented. The search is based on pp collisions at (Formula presented.) TeV recorded in 2012 with the ATLAS detector at the CERN Large Hadron Collider and corresponding to an integrated luminosity of 20.3 fb−1. Data are analysed in the lepton-plus-jets final state, characterised by an isolated electron or muon with high transverse momentum, large missing transverse momentum and multiple jets. Dedicated analyses are performed targeting three cases: a T quark with significant branching ratio to a W boson and a b-quark (TT¯→Wb+X), and both a T quark and a B quark with significant branching ratio to a Higgs boson and a third-generation quark (TT¯→Ht+XandBB¯→Hb+X respectively). No significant excess of events above the Standard Model expectation is observed, and 95% CL lower limits are derived on the masses of the vector-like T and B quarks under several branching ratio hypotheses assuming contributions from T → Wb, Zt, Ht and B → Wt, Zb, Hb decays. The 95% CL observed lower limits on the T quark mass range between 715 GeV and 950 GeV for all possible values of the branching ratios into the three decay modes, and are the most stringent constraints to date. Additionally, the most restrictive upper bounds on four-top-quark production are set in a number of new physics scenarios.
Published: 2015

208. Measurements of the Total and Differential Higgs Boson Production Cross Sections Combining the H→γγ and H→ZZ*→4ℓ Decay Channels at s=8 TeV with the ATLAS Detector

Author: Aad, G, Abbott, B, Abdallah, J, Abdinov, O, Aben, R, Abolins, M, AbouZeid, OS, Abramowicz, H, Abreu, H, Abreu, R, Abulaiti, Y, Acharya, BS, Adamczyk, L, Adams, DL, Adelman, J, Adomeit, S, Adye, T, Affolder, AA, Agatonovic-Jovin, T, Aguilar-Saavedra, JA, Agustoni, M, Ahlen, SP, Ahmadov, F, Aielli, G, Akerstedt, H, Åkesson, TPA, Akimoto, G, Akimov, AV, Alberghi, GL, Albert, J, Albrand, S, Verzini, MJ Alconada, Aleksa, M, Aleksandrov, IN, Alexa, C, Alexander, G, Alexopoulos, T, Alhroob, M, Alimonti, G, Alio, L, Alison, J, Alkire, SP, Allbrooke, BMM, Allport, PP, Aloisio, A, Alonso, A, Alonso, F, Alpigiani, C, Altheimer, A, Gonzalez, B Alvarez, Piqueras, D Álvarez, Alviggi, MG, Amako, K, Coutinho, Y Amaral, Amelung, C, Amidei, D, Dos Santos, SP Amor, Amorim, A, Amoroso, S, Amram, N, Amundsen, G, Anastopoulos, C, Ancu, LS, Andari, N, Andeen, T, Anders, CF, Anders, G, Anderson, KJ, Andreazza, A, Andrei, V, Angelidakis, S, Angelozzi, I, Anger, P, Angerami, A, Anghinolfi, F, Anisenkov, AV, Anjos, N, Annovi, A, Antonelli, M, Antonov, A, Antos, J, Anulli, F, Aoki, M, Bella, L Aperio, Arabidze, G, Arai, Y, Araque, JP, Arce, ATH, Arduh, FA, Arguin, J-F, Argyropoulos, S, Arik, M, Armbruster, AJ, Arnaez, O, Arnal, V, Arnold, H, Arratia, M, Arslan, O, Artamonov, A, and Artoni, G
Subjects: Nuclear and Plasma Physics, Particle and High Energy Physics, Physical Sciences, ATLAS Collaboration, hep-ex, Mathematical Sciences, Engineering, General Physics, Mathematical sciences, Physical sciences
Abstract: Measurements of the total and differential cross sections of Higgs boson production are performed using 20.3 fb^{-1} of pp collisions produced by the Large Hadron Collider at a center-of-mass energy of sqrt[s]=8 TeV and recorded by the ATLAS detector. Cross sections are obtained from measured H→γγ and H→ZZ^{*}→4ℓ event yields, which are combined accounting for detector efficiencies, fiducial acceptances, and branching fractions. Differential cross sections are reported as a function of Higgs boson transverse momentum, Higgs boson rapidity, number of jets in the event, and transverse momentum of the leading jet. The total production cross section is determined to be σ_{pp→H}=33.0±5.3 (stat)±1.6 (syst) pb. The measurements are compared to state-of-the-art predictions.
Published: 2015

209. Search for high-mass diphoton resonances in pp collisions at s =8 TeV with the ATLAS detector

Author: Aad, G, Abbott, B, Abdallah, J, Abdel Khalek, S, Abdinov, O, Aben, R, Abi, B, Abolins, M, Abouzeid, OS, Abramowicz, H, Abreu, H, Abreu, R, Abulaiti, Y, Acharya, BS, Adamczyk, L, Adams, DL, Adelman, J, Adomeit, S, Adye, T, Agatonovic-Jovin, T, Aguilar-Saavedra, JA, Agustoni, M, Ahlen, SP, Ahmadov, F, Aielli, G, Akerstedt, H, Åkesson, TPA, Akimoto, G, Akimov, AV, Alberghi, GL, Albert, J, Albrand, S, Alconada Verzini, MJ, Aleksa, M, Aleksandrov, IN, Alexa, C, Alexander, G, Alexandre, G, Alexopoulos, T, Alhroob, M, Alimonti, G, Alio, L, Alison, J, Allbrooke, BMM, Allison, LJ, Allport, PP, Aloisio, A, Alonso, A, Alonso, F, Alpigiani, C, Altheimer, A, Alvarez Gonzalez, B, Alviggi, MG, Amako, K, Amaral Coutinho, Y, Amelung, C, Amidei, D, Amor Dos Santos, SP, Amorim, A, Amoroso, S, Amram, N, Amundsen, G, Anastopoulos, C, Ancu, LS, Andari, N, Andeen, T, Anders, CF, Anders, G, Anderson, KJ, Andreazza, A, Andrei, V, Anduaga, XS, Angelidakis, S, Angelozzi, I, Anger, P, Angerami, A, Anghinolfi, F, Anisenkov, AV, Anjos, N, Annovi, A, Antonelli, M, Antonov, A, Antos, J, Anulli, F, Aoki, M, Aperio Bella, L, Arabidze, G, Arai, Y, Araque, JP, Arce, ATH, Arduh, FA, Arguin, JF, Argyropoulos, S, Arik, M, Armbruster, AJ, Arnaez, O, Arnal, V, Arnold, H, Arratia, M, and Arslan, O
Subjects: hep-ex, Nuclear & Particles Physics, Astronomical and Space Sciences, Atomic, Molecular, Nuclear, Particle and Plasma Physics, Quantum Physics, Atomic, Molecular, Nuclear, Particle and Plasma Physics
Abstract: This article describes a search for high-mass resonances decaying to a pair of photons using a sample of 20.3 fb-1 of pp collisions at s=8 TeV recorded with the ATLAS detector at the Large Hadron Collider. The data are found to be in agreement with the Standard Model prediction, and limits are reported in the framework of the Randall-Sundrum model. This theory leads to the prediction of graviton states, the lightest of which could be observed at the Large Hadron Collider. A lower limit of 2.66 (1.41) TeV at 95% confidence level is set on the mass of the lightest graviton for couplings of k/M¯Pl=0.1 (0.01).
Published: 2015

210. Study of (W/Z)H production and Higgs boson couplings using H→ W W∗ decays with the ATLAS detector

Author: The ATLAS collaboration, Aad, G, Abbott, B, Abdallah, J, Abdinov, O, Aben, R, Abolins, M, AbouZeid, OS, Abramowicz, H, Abreu, H, Abreu, R, Abulaiti, Y, Acharya, BS, Adamczyk, L, Adams, DL, Adelman, J, Adomeit, S, Adye, T, Affolder, AA, Agatonovic-Jovin, T, Aguilar-Saavedra, JA, Ahlen, SP, Ahmadov, F, Aielli, G, Akerstedt, H, Åkesson, TPA, Akimoto, G, Akimov, AV, Alberghi, GL, Albert, J, Albrand, S, Alconada Verzini, MJ, Aleksa, M, Aleksandrov, IN, Alexa, C, Alexander, G, Alexopoulos, T, Alhroob, M, Alimonti, G, Alio, L, Alison, J, Alkire, SP, Allbrooke, BMM, Allport, PP, Aloisio, A, Alonso, A, Alonso, F, Alpigiani, C, Altheimer, A, Alvarez Gonzalez, B, Álvarez Piqueras, D, Alviggi, MG, Amadio, BT, Amako, K, Amaral Coutinho, Y, Amelung, C, Amidei, D, Amor Dos Santos, SP, Amorim, A, Amoroso, S, Amram, N, Amundsen, G, Anastopoulos, C, Ancu, LS, Andari, N, Andeen, T, Anders, CF, Anders, G, Anders, JK, Anderson, KJ, Andreazza, A, Andrei, V, Angelidakis, S, Angelozzi, I, Anger, P, Angerami, A, Anghinolfi, F, Anisenkov, AV, Anjos, N, Annovi, A, Antonelli, M, Antonov, A, Antos, J, Anulli, F, Aoki, M, Aperio Bella, L, Arabidze, G, Arai, Y, Araque, JP, Arce, ATH, Arduh, FA, Arguin, JF, Argyropoulos, S, Arik, M, Armbruster, AJ, Arnaez, O, Arnal, V, Arnold, H, Arratia, M, and Arslan, O
Subjects: Hadron-Hadron Scattering, Higgs physics, hep-ex, Nuclear & Particles Physics, Mathematical Physics, Atomic, Molecular, Nuclear, Particle and Plasma Physics, Quantum Physics
Abstract: Abstract: A search for Higgs boson production in association with a W or Z boson, in the H→ W W∗ decay channel, is performed with a data sample collected with the ATLAS detector at the LHC in proton-proton collisions at centre-of-mass energies √s=7$$ \sqrt{s}=7 $$ TeV and 8 TeV, corresponding to integrated luminosities of 4.5 fb−1 and 20.3 fb−1, respectively. The WH production mode is studied in two-lepton and three-lepton final states, while two- lepton and four-lepton final states are used to search for the ZH production mode. The observed significance, for the combined W H and ZH production, is 2.5 standard deviations while a significance of 0.9 standard deviations is expected in the Standard Model Higgs boson hypothesis. The ratio of the combined W H and ZH signal yield to the Standard Model expectation, μV H , is found to be μV H = 3.0− 1.1+ 1.3(stat.)− 0.7+ 1.0(sys.) for the Higgs boson mass of 125.36 GeV. The W H and ZH production modes are also combined with the gluon fusion and vector boson fusion production modes studied in the H → W W∗ → ℓνℓν decay channel, resulting in an overall observed significance of 6.5 standard deviations and μggF + VBF + VH = 1. 16− 0.15+ 0.16(stat.)− 0.15+ 0.18(sys.). The results are interpreted in terms of scaling factors of the Higgs boson couplings to vector bosons (κV ) and fermions (κF ); the combined results are: |κV| = 1.06− 0.10+ 0.10, |κF| = 0. 85− 0.20+ 0.26.[Figure not available: see fulltext.]
Published: 2015

211. Search for new phenomena in events with three or more charged leptons in pp collisions at √s=8 TeV with the ATLAS detector

Author: The ATLAS collaboration, Aad, G, Abbott, B, Abdallah, J, Abdel Khalek, S, Abdinov, O, Aben, R, Abi, B, Abolins, M, AbouZeid, OS, Abramowicz, H, Abreu, H, Abreu, R, Abulaiti, Y, Acharya, BS, Adamczyk, L, Adams, DL, Adelman, J, Adomeit, S, Adye, T, Agatonovic-Jovin, T, Aguilar-Saavedra, JA, Agustoni, M, Ahlen, SP, Ahmadov, F, Aielli, G, Akerstedt, H, Åkesson, TPA, Akimoto, G, Akimov, AV, Alberghi, GL, Albert, J, Albrand, S, Alconada Verzini, MJ, Aleksa, M, Aleksandrov, IN, Alexa, C, Alexander, G, Alexandre, G, Alexopoulos, T, Alhroob, M, Alimonti, G, Alio, L, Alison, J, Allbrooke, BMM, Allison, LJ, Allport, PP, Aloisio, A, Alonso, A, Alonso, F, Alpigiani, C, Altheimer, A, Alvarez Gonzalez, B, Alviggi, MG, Amako, K, Amaral Coutinho, Y, Amelung, C, Amidei, D, Amor Dos Santos, SP, Amorim, A, Amoroso, S, Amram, N, Amundsen, G, Anastopoulos, C, Ancu, LS, Andari, N, Andeen, T, Anders, CF, Anders, G, Anderson, KJ, Andreazza, A, Andrei, V, Anduaga, XS, Angelidakis, S, Angelozzi, I, Anger, P, Angerami, A, Anghinolfi, F, Anisenkov, AV, Anjos, N, Annovi, A, Antonelli, M, Antonov, A, Antos, J, Anulli, F, Aoki, M, Aperio Bella, L, Arabidze, G, Arai, Y, Araque, JP, Arce, ATH, Arduh, FA, Arguin, JF, Argyropoulos, S, Arik, M, Armbruster, AJ, Arnaez, O, Arnal, V, Arnold, H, and Arratia, M
Subjects: Hadron-Hadron Scattering, hep-ex, Nuclear & Particles Physics, Mathematical Physics, Atomic, Molecular, Nuclear, Particle and Plasma Physics, Quantum Physics
Abstract: Abstract: A generic search for anomalous production of events with at least three charged leptons is presented. The data sample consists of pp collisions at √s=8 TeV collected in 2012 by the ATLAS experiment at the CERN Large Hadron Collider, and corresponds to an integrated luminosity of 20.3 fb−1. Events are required to have at least three selected lepton candidates, at least two of which must be electrons or muons, while the third may be a hadronically decaying tau. Selected events are categorized based on their lepton flavour content and signal regions are constructed using several kinematic variables of interest. No significant deviations from Standard Model predictions are observed. Model-independent upper limits on contributions from beyond the Standard Model phenomena are provided for each signal region, along with prescription to re-interpret the limits for any model. Constraints are also placed on models predicting doubly charged Higgs bosons and excited leptons. For doubly charged Higgs bosons decaying to eτ or μτ, lower limits on the mass are set at 400 GeV at 95% confidence level. For excited leptons, constraints are provided as functions of both the mass of the excited state and the compositeness scale Λ, with the strongest mass constraints arising in regions where the mass equals Λ. In such scenarios, lower mass limits are set at 3.0 TeV for excited electrons and muons, 2.5 TeV for excited taus, and 1.6 TeV for every excited-neutrino flavour.
Published: 2015

212. A search for tt resonances using lepton-plus-jets events in proton-proton collisions at √s=8 TeV with the ATLAS detector

Author: The ATLAS collaboration, Aad, G, Abbott, B, Abdallah, J, Abdinov, O, Aben, R, Abolins, M, AbouZeid, OS, Abramowicz, H, Abreu, H, Abreu, R, Abulaiti, Y, Acharya, BS, Adamczyk, L, Adams, DL, Adelman, J, Adomeit, S, Adye, T, Affolder, AA, Agatonovic-Jovin, T, Aguilar-Saavedra, JA, Ahlen, SP, Ahmadov, F, Aielli, G, Akerstedt, H, Åkesson, TPA, Akimoto, G, Akimov, AV, Alberghi, GL, Albert, J, Albrand, S, Alconada Verzini, MJ, Aleksa, M, Aleksandrov, IN, Alexa, C, Alexander, G, Alexopoulos, T, Alhroob, M, Alimonti, G, Alio, L, Alison, J, Alkire, SP, Allbrooke, BMM, Allport, PP, Aloisio, A, Alonso, A, Alonso, F, Alpigiani, C, Altheimer, A, Alvarez Gonzalez, B, Álvarez Piqueras, D, Alviggi, MG, Amadio, BT, Amako, K, Amaral Coutinho, Y, Amelung, C, Amidei, D, Amor Dos Santos, SP, Amorim, A, Amoroso, S, Amram, N, Amundsen, G, Anastopoulos, C, Ancu, LS, Andari, N, Andeen, T, Anders, CF, Anders, G, Anders, JK, Anderson, KJ, Andreazza, A, Andrei, V, Angelidakis, S, Angelozzi, I, Anger, P, Angerami, A, Anghinolfi, F, Anisenkov, AV, Anjos, N, Annovi, A, Antonelli, M, Antonov, A, Antos, J, Anulli, F, Aoki, M, Aperio Bella, L, Arabidze, G, Arai, Y, Araque, JP, Arce, ATH, Arduh, FA, Arguin, JF, Argyropoulos, S, Arik, M, Armbruster, AJ, Arnaez, O, Arnal, V, Arnold, H, Arratia, M, and Arslan, O
Subjects: Exotics, Hadron-Hadron Scattering, Top physics, hep-ex, Nuclear & Particles Physics, Mathematical Physics, Atomic, Molecular, Nuclear, Particle and Plasma Physics, Quantum Physics
Abstract: Abstract: A search for new particles that decay into top quark pairs is reported. The search is performed with the ATLAS experiment at the LHC using an integrated luminosity of 20.3 fb−1 of proton-proton collision data collected at a centre-of-mass energy of √s=8 TeV. The lepton-plus-jets final state is used, where the top pair decays to W+bW−b¯, with one W boson decaying leptonically and the other hadronically. The invariant mass spectrum of top quark pairs is examined for local excesses or deficits that are inconsistent with the Standard Model predictions. No evidence for a top quark pair resonance is found, and 95% confidence-level limits on the production rate are determined for massive states in benchmark models. The upper limits on the cross-section times branching ratio of a narrow Z′ boson decaying to top pairs range from 4.2 pb to 0.03 pb for resonance masses from 0.4 TeV to 3.0 TeV. A narrow leptophobic topcolour Z′ boson with mass below 1.8 TeV is excluded. Upper limits are set on the cross-section times branching ratio for a broad colour-octet resonance with Γ/m = 15% decaying to tt¯. These range from 4.8 pb to 0.03 pb for masses from 0.4 TeV to 3.0 TeV. A Kaluza-Klein excitation of the gluon in a Randall-Sundrum model is excluded for masses below 2.2 TeV.
Published: 2015

213. Search for type-III seesaw heavy leptons in pp collisions at s =8 TeV with the ATLAS detector

Author: Aad, G, Abbott, B, Abdallah, J, Abdinov, O, Aben, R, Abolins, M, Abouzeid, OS, Abramowicz, H, Abreu, H, Abreu, R, Abulaiti, Y, Acharya, BS, Adamczyk, L, Adams, DL, Adelman, J, Adomeit, S, Adye, T, Affolder, AA, Agatonovic-Jovin, T, Aguilar-Saavedra, JA, Ahlen, SP, Ahmadov, F, Aielli, G, Akerstedt, H, Åkesson, TPA, Akimoto, G, Akimov, AV, Alberghi, GL, Albert, J, Albrand, S, Alconada Verzini, MJ, Aleksa, M, Aleksandrov, IN, Alexa, C, Alexander, G, Alexopoulos, T, Alhroob, M, Alimonti, G, Alio, L, Alison, J, Alkire, SP, Allbrooke, BMM, Allport, PP, Aloisio, A, Alonso, A, Alonso, F, Alpigiani, C, Altheimer, A, Alvarez Gonzalez, B, Álvarez Piqueras, D, Alviggi, MG, Amadio, BT, Amako, K, Amaral Coutinho, Y, Amelung, C, Amidei, D, Amor Dos Santos, SP, Amorim, A, Amoroso, S, Amram, N, Amundsen, G, Anastopoulos, C, Ancu, LS, Andari, N, Andeen, T, Anders, CF, Anders, G, Anders, JK, Anderson, KJ, Andreazza, A, Andrei, V, Angelidakis, S, Angelozzi, I, Anger, P, Angerami, A, Anghinolfi, F, Anisenkov, AV, Anjos, N, Annovi, A, Antonelli, M, Antonov, A, Antos, J, Anulli, F, Aoki, M, Aperio Bella, L, Arabidze, G, Arai, Y, Araque, JP, Arce, ATH, Arduh, FA, Arguin, JF, Argyropoulos, S, Arik, M, Armbruster, AJ, Arnaez, O, Arnal, V, Arnold, H, Arratia, M, Arslan, O, and Artamonov, A
Subjects: hep-ex, Nuclear & Particles Physics, Astronomical and Space Sciences, Atomic, Molecular, Nuclear, Particle and Plasma Physics, Quantum Physics, Atomic, Molecular, Nuclear, Particle and Plasma Physics
Abstract: A search for the pair production of heavy leptons (N0,L±) predicted by the type-III seesaw theory formulated to explain the origin of small neutrino masses is presented. The decay channels N0→W±l (=e,μ,τ) and L±→W±ν (ν=νe,νμ,ντ) are considered. The analysis is performed using the final state that contains two leptons (electrons or muons), two jets from a hadronically decaying W boson and large missing transverse momentum. The data used in the measurement correspond to an integrated luminosity of 20.3 fb-1 of pp collisions at s=8 TeV collected by the ATLAS detector at the LHC. No evidence of heavy lepton pair production is observed. Heavy leptons with masses below 325-540 GeV are excluded at the 95% confidence level, depending on the theoretical scenario considered.
Published: 2015

214. Erratum to: Search for production of WW / WZ resonances decaying to a lepton, neutrino and jets in pp collisions at s=8 TeV with the ATLAS detector

Author: ATLAS Collaboration, Aad, G, Abbott, B, Abdallah, J, Abdel Khalek, S, Abdinov, O, Aben, R, Abi, B, Abolins, M, AbouZeid, OS, Abramowicz, H, Abreu, H, Abreu, R, Abulaiti, Y, Acharya, BS, Adamczyk, L, Adams, DL, Adelman, J, Adomeit, S, Adye, T, Agatonovic-Jovin, T, Aguilar-Saavedra, JA, Agustoni, M, Ahlen, SP, Ahmadov, F, Aielli, G, Akerstedt, H, Åkesson, TPA, Akimoto, G, Akimov, AV, Alberghi, GL, Albert, J, Albrand, S, Alconada Verzini, MJ, Aleksa, M, Aleksandrov, IN, Alexa, C, Alexander, G, Alexandre, G, Alexopoulos, T, Alhroob, M, Alimonti, G, Alio, L, Alison, J, Allbrooke, BMM, Allison, LJ, Allport, PP, Aloisio, A, Alonso, A, Alonso, F, Alpigiani, C, Altheimer, A, Alvarez Gonzalez, B, Alviggi, MG, Amako, K, Amaral Coutinho, Y, Amelung, C, Amidei, D, Amor Dos Santos, SP, Amorim, A, Amoroso, S, Amram, N, Amundsen, G, Anastopoulos, C, Ancu, LS, Andari, N, Andeen, T, Anders, CF, Anders, G, Anderson, KJ, Andreazza, A, Andrei, V, Anduaga, XS, Angelidakis, S, Angelozzi, I, Anger, P, Angerami, A, Anghinolfi, F, Anisenkov, AV, Anjos, N, Annovi, A, Antonelli, M, Antonov, A, Antos, J, Anulli, F, Aoki, M, Aperio Bella, L, Arabidze, G, Arai, Y, Araque, JP, Arce, ATH, Arduh, FA, Arguin, J-F, Argyropoulos, S, Arik, M, Armbruster, AJ, Arnaez, O, Arnal, V, Arnold, H, and Arratia, M
Subjects: Nuclear and Plasma Physics, Particle and High Energy Physics, Physical Sciences, Atomic, Molecular, Nuclear, Particle and Plasma Physics, Quantum Physics, Nuclear & Particles Physics, Astronomical sciences, Atomic, molecular and optical physics, Particle and high energy physics
Published: 2015

215. Search for type-III seesaw heavy leptons in pp collisions at s=8 TeV with the ATLAS detector

Author: Aad, G, Abbott, B, Abdallah, J, Abdinov, O, Aben, R, Abolins, M, AbouZeid, OS, Abramowicz, H, Abreu, H, Abreu, R, Abulaiti, Y, Acharya, BS, Adamczyk, L, Adams, DL, Adelman, J, Adomeit, S, Adye, T, Affolder, AA, Agatonovic-Jovin, T, Aguilar-Saavedra, JA, Ahlen, SP, Ahmadov, F, Aielli, G, Akerstedt, H, Åkesson, TPA, Akimoto, G, Akimov, AV, Alberghi, GL, Albert, J, Albrand, S, Verzini, MJ Alconada, Aleksa, M, Aleksandrov, IN, Alexa, C, Alexander, G, Alexopoulos, T, Alhroob, M, Alimonti, G, Alio, L, Alison, J, Alkire, SP, Allbrooke, BMM, Allport, PP, Aloisio, A, Alonso, A, Alonso, F, Alpigiani, C, Altheimer, A, Gonzalez, B Alvarez, Piqueras, D Álvarez, Alviggi, MG, Amadio, BT, Amako, K, Coutinho, Y Amaral, Amelung, C, Amidei, D, Dos Santos, SP Amor, Amorim, A, Amoroso, S, Amram, N, Amundsen, G, Anastopoulos, C, Ancu, LS, Andari, N, Andeen, T, Anders, CF, Anders, G, Anders, JK, Anderson, KJ, Andreazza, A, Andrei, V, Angelidakis, S, Angelozzi, I, Anger, P, Angerami, A, Anghinolfi, F, Anisenkov, AV, Anjos, N, Annovi, A, Antonelli, M, Antonov, A, Antos, J, Anulli, F, Aoki, M, Bella, L Aperio, Arabidze, G, Arai, Y, Araque, JP, Arce, ATH, Arduh, FA, Arguin, J-F, Argyropoulos, S, Arik, M, Armbruster, AJ, Arnaez, O, Arnal, V, Arnold, H, Arratia, M, Arslan, O, and Artamonov, A
Subjects: Nuclear and Plasma Physics, Particle and High Energy Physics, Physical Sciences, hep-ex
Abstract: A search for the pair production of heavy leptons (N0,L±) predicted by the type-III seesaw theory formulated to explain the origin of small neutrino masses is presented. The decay channels N0→W±l (=e,μ,τ) and L±→W±ν (ν=νe,νμ,ντ) are considered. The analysis is performed using the final state that contains two leptons (electrons or muons), two jets from a hadronically decaying W boson and large missing transverse momentum. The data used in the measurement correspond to an integrated luminosity of 20.3 fb-1 of pp collisions at s=8 TeV collected by the ATLAS detector at the LHC. No evidence of heavy lepton pair production is observed. Heavy leptons with masses below 325-540 GeV are excluded at the 95% confidence level, depending on the theoretical scenario considered.
Published: 2015

216. Search for high-mass diphoton resonances in pp collisions at s=8 TeV with the ATLAS detector

Author: Aad, G, Abbott, B, Abdallah, J, Khalek, S Abdel, Abdinov, O, Aben, R, Abi, B, Abolins, M, AbouZeid, OS, Abramowicz, H, Abreu, H, Abreu, R, Abulaiti, Y, Acharya, BS, Adamczyk, L, Adams, DL, Adelman, J, Adomeit, S, Adye, T, Agatonovic-Jovin, T, Aguilar-Saavedra, JA, Agustoni, M, Ahlen, SP, Ahmadov, F, Aielli, G, Akerstedt, H, Åkesson, TPA, Akimoto, G, Akimov, AV, Alberghi, GL, Albert, J, Albrand, S, Verzini, MJ Alconada, Aleksa, M, Aleksandrov, IN, Alexa, C, Alexander, G, Alexandre, G, Alexopoulos, T, Alhroob, M, Alimonti, G, Alio, L, Alison, J, Allbrooke, BMM, Allison, LJ, Allport, PP, Aloisio, A, Alonso, A, Alonso, F, Alpigiani, C, Altheimer, A, Gonzalez, B Alvarez, Alviggi, MG, Amako, K, Coutinho, Y Amaral, Amelung, C, Amidei, D, Dos Santos, SP Amor, Amorim, A, Amoroso, S, Amram, N, Amundsen, G, Anastopoulos, C, Ancu, LS, Andari, N, Andeen, T, Anders, CF, Anders, G, Anderson, KJ, Andreazza, A, Andrei, V, Anduaga, XS, Angelidakis, S, Angelozzi, I, Anger, P, Angerami, A, Anghinolfi, F, Anisenkov, AV, Anjos, N, Annovi, A, Antonelli, M, Antonov, A, Antos, J, Anulli, F, Aoki, M, Bella, L Aperio, Arabidze, G, Arai, Y, Araque, JP, Arce, ATH, Arduh, FA, Arguin, J-F, Argyropoulos, S, Arik, M, Armbruster, AJ, Arnaez, O, Arnal, V, Arnold, H, Arratia, M, and Arslan, O
Subjects: Nuclear and Plasma Physics, Particle and High Energy Physics, Physical Sciences, hep-ex
Abstract: This article describes a search for high-mass resonances decaying to a pair of photons using a sample of 20.3 fb-1 of pp collisions at s=8 TeV recorded with the ATLAS detector at the Large Hadron Collider. The data are found to be in agreement with the Standard Model prediction, and limits are reported in the framework of the Randall-Sundrum model. This theory leads to the prediction of graviton states, the lightest of which could be observed at the Large Hadron Collider. A lower limit of 2.66 (1.41) TeV at 95% confidence level is set on the mass of the lightest graviton for couplings of k/M¯Pl=0.1 (0.01).
Published: 2015

217. A search for tt¯ resonances using lepton-plus-jets events in proton-proton collisions at s=8 TeV with the ATLAS detector

Author: The ATLAS collaboration, Aad, G, Abbott, B, Abdallah, J, Abdinov, O, Aben, R, Abolins, M, AbouZeid, OS, Abramowicz, H, Abreu, H, Abreu, R, Abulaiti, Y, Acharya, BS, Adamczyk, L, Adams, DL, Adelman, J, Adomeit, S, Adye, T, Affolder, AA, Agatonovic-Jovin, T, Aguilar-Saavedra, JA, Ahlen, SP, Ahmadov, F, Aielli, G, Akerstedt, H, Åkesson, TPA, Akimoto, G, Akimov, AV, Alberghi, GL, Albert, J, Albrand, S, Alconada Verzini, MJ, Aleksa, M, Aleksandrov, IN, Alexa, C, Alexander, G, Alexopoulos, T, Alhroob, M, Alimonti, G, Alio, L, Alison, J, Alkire, SP, Allbrooke, BMM, Allport, PP, Aloisio, A, Alonso, A, Alonso, F, Alpigiani, C, Altheimer, A, Alvarez Gonzalez, B, Álvarez Piqueras, D, Alviggi, MG, Amadio, BT, Amako, K, Amaral Coutinho, Y, Amelung, C, Amidei, D, Amor Dos Santos, SP, Amorim, A, Amoroso, S, Amram, N, Amundsen, G, Anastopoulos, C, Ancu, LS, Andari, N, Andeen, T, Anders, CF, Anders, G, Anders, JK, Anderson, KJ, Andreazza, A, Andrei, V, Angelidakis, S, Angelozzi, I, Anger, P, Angerami, A, Anghinolfi, F, Anisenkov, AV, Anjos, N, Annovi, A, Antonelli, M, Antonov, A, Antos, J, Anulli, F, Aoki, M, Aperio Bella, L, Arabidze, G, Arai, Y, Araque, JP, Arce, ATH, Arduh, FA, Arguin, J-F, Argyropoulos, S, Arik, M, Armbruster, AJ, Arnaez, O, Arnal, V, Arnold, H, Arratia, M, and Arslan, O
Subjects: Nuclear and Plasma Physics, Particle and High Energy Physics, Mathematical Physics, Mathematical Sciences, Physical Sciences, Exotics, Hadron-Hadron Scattering, Top physics, hep-ex, Atomic, Molecular, Nuclear, Particle and Plasma Physics, Quantum Physics, Nuclear & Particles Physics, Mathematical physics, Nuclear and plasma physics, Particle and high energy physics
Abstract: Abstract: A search for new particles that decay into top quark pairs is reported. The search is performed with the ATLAS experiment at the LHC using an integrated luminosity of 20.3 fb−1 of proton-proton collision data collected at a centre-of-mass energy of √s=8 TeV. The lepton-plus-jets final state is used, where the top pair decays to W+bW−b¯, with one W boson decaying leptonically and the other hadronically. The invariant mass spectrum of top quark pairs is examined for local excesses or deficits that are inconsistent with the Standard Model predictions. No evidence for a top quark pair resonance is found, and 95% confidence-level limits on the production rate are determined for massive states in benchmark models. The upper limits on the cross-section times branching ratio of a narrow Z′ boson decaying to top pairs range from 4.2 pb to 0.03 pb for resonance masses from 0.4 TeV to 3.0 TeV. A narrow leptophobic topcolour Z′ boson with mass below 1.8 TeV is excluded. Upper limits are set on the cross-section times branching ratio for a broad colour-octet resonance with Γ/m = 15% decaying to tt¯. These range from 4.8 pb to 0.03 pb for masses from 0.4 TeV to 3.0 TeV. A Kaluza-Klein excitation of the gluon in a Randall-Sundrum model is excluded for masses below 2.2 TeV.
Published: 2015

218. Search for new phenomena in events with three or more charged leptons in pp collisions at s=8 TeV with the ATLAS detector

Author: The ATLAS collaboration, Aad, G, Abbott, B, Abdallah, J, Abdel Khalek, S, Abdinov, O, Aben, R, Abi, B, Abolins, M, AbouZeid, OS, Abramowicz, H, Abreu, H, Abreu, R, Abulaiti, Y, Acharya, BS, Adamczyk, L, Adams, DL, Adelman, J, Adomeit, S, Adye, T, Agatonovic-Jovin, T, Aguilar-Saavedra, JA, Agustoni, M, Ahlen, SP, Ahmadov, F, Aielli, G, Akerstedt, H, Åkesson, TPA, Akimoto, G, Akimov, AV, Alberghi, GL, Albert, J, Albrand, S, Alconada Verzini, MJ, Aleksa, M, Aleksandrov, IN, Alexa, C, Alexander, G, Alexandre, G, Alexopoulos, T, Alhroob, M, Alimonti, G, Alio, L, Alison, J, Allbrooke, BMM, Allison, LJ, Allport, PP, Aloisio, A, Alonso, A, Alonso, F, Alpigiani, C, Altheimer, A, Alvarez Gonzalez, B, Alviggi, MG, Amako, K, Amaral Coutinho, Y, Amelung, C, Amidei, D, Amor Dos Santos, SP, Amorim, A, Amoroso, S, Amram, N, Amundsen, G, Anastopoulos, C, Ancu, LS, Andari, N, Andeen, T, Anders, CF, Anders, G, Anderson, KJ, Andreazza, A, Andrei, V, Anduaga, XS, Angelidakis, S, Angelozzi, I, Anger, P, Angerami, A, Anghinolfi, F, Anisenkov, AV, Anjos, N, Annovi, A, Antonelli, M, Antonov, A, Antos, J, Anulli, F, Aoki, M, Aperio Bella, L, Arabidze, G, Arai, Y, Araque, JP, Arce, ATH, Arduh, FA, Arguin, J-F, Argyropoulos, S, Arik, M, Armbruster, AJ, Arnaez, O, Arnal, V, Arnold, H, and Arratia, M
Subjects: Nuclear and Plasma Physics, Particle and High Energy Physics, Physical Sciences, Hadron-Hadron Scattering, hep-ex, Mathematical Physics, Atomic, Molecular, Nuclear, Particle and Plasma Physics, Quantum Physics, Nuclear & Particles Physics, Mathematical physics, Nuclear and plasma physics, Particle and high energy physics
Abstract: Abstract: A generic search for anomalous production of events with at least three charged leptons is presented. The data sample consists of pp collisions at √s=8 TeV collected in 2012 by the ATLAS experiment at the CERN Large Hadron Collider, and corresponds to an integrated luminosity of 20.3 fb−1. Events are required to have at least three selected lepton candidates, at least two of which must be electrons or muons, while the third may be a hadronically decaying tau. Selected events are categorized based on their lepton flavour content and signal regions are constructed using several kinematic variables of interest. No significant deviations from Standard Model predictions are observed. Model-independent upper limits on contributions from beyond the Standard Model phenomena are provided for each signal region, along with prescription to re-interpret the limits for any model. Constraints are also placed on models predicting doubly charged Higgs bosons and excited leptons. For doubly charged Higgs bosons decaying to eτ or μτ, lower limits on the mass are set at 400 GeV at 95% confidence level. For excited leptons, constraints are provided as functions of both the mass of the excited state and the compositeness scale Λ, with the strongest mass constraints arising in regions where the mass equals Λ. In such scenarios, lower mass limits are set at 3.0 TeV for excited electrons and muons, 2.5 TeV for excited taus, and 1.6 TeV for every excited-neutrino flavour.
Published: 2015

219. Search for production of vector-like quark pairs and of four top quarks in the lepton-plus-jets final state in pp collisions at s=8 TeV with the ATLAS detector

Author: The ATLAS collaboration, Aad, G, Abbott, B, Abdallah, J, Abdinov, O, Aben, R, Abolins, M, AbouZeid, OS, Abramowicz, H, Abreu, H, Abreu, R, Abulaiti, Y, Acharya, BS, Adamczyk, L, Adams, DL, Adelman, J, Adomeit, S, Adye, T, Affolder, AA, Agatonovic-Jovin, T, Aguilar-Saavedra, JA, Ahlen, SP, Ahmadov, F, Aielli, G, Akerstedt, H, Åkesson, TPA, Akimoto, G, Akimov, AV, Alberghi, GL, Albert, J, Albrand, S, Alconada Verzini, MJ, Aleksa, M, Aleksandrov, IN, Alexa, C, Alexander, G, Alexopoulos, T, Alhroob, M, Alimonti, G, Alio, L, Alison, J, Alkire, SP, Allbrooke, BMM, Allport, PP, Aloisio, A, Alonso, A, Alonso, F, Alpigiani, C, Altheimer, A, Alvarez Gonzalez, B, Álvarez Piqueras, D, Alviggi, MG, Amadio, BT, Amako, K, Amaral Coutinho, Y, Amelung, C, Amidei, D, Amor Dos Santos, SP, Amorim, A, Amoroso, S, Amram, N, Amundsen, G, Anastopoulos, C, Ancu, LS, Andari, N, Andeen, T, Anders, CF, Anders, G, Anders, JK, Anderson, KJ, Andreazza, A, Andrei, V, Angelidakis, S, Angelozzi, I, Anger, P, Angerami, A, Anghinolfi, F, Anisenkov, AV, Anjos, N, Annovi, A, Antonelli, M, Antonov, A, Antos, J, Anulli, F, Aoki, M, Aperio Bella, L, Arabidze, G, Arai, Y, Araque, JP, Arce, ATH, Arduh, FA, Arguin, J-F, Argyropoulos, S, Arik, M, Armbruster, AJ, Arnaez, O, Arnal, V, Arnold, H, Arratia, M, and Arslan, O
Subjects: Nuclear and Plasma Physics, Particle and High Energy Physics, Physical Sciences, Hadron-Hadron Scattering, hep-ex, Mathematical Physics, Atomic, Molecular, Nuclear, Particle and Plasma Physics, Quantum Physics, Nuclear & Particles Physics, Mathematical physics, Nuclear and plasma physics, Particle and high energy physics
Abstract: A search for pair production of vector-like quarks, both up-type (T) and down-type (B), as well as for four-top-quark production, is presented. The search is based on pp collisions at (Formula presented.) TeV recorded in 2012 with the ATLAS detector at the CERN Large Hadron Collider and corresponding to an integrated luminosity of 20.3 fb−1. Data are analysed in the lepton-plus-jets final state, characterised by an isolated electron or muon with high transverse momentum, large missing transverse momentum and multiple jets. Dedicated analyses are performed targeting three cases: a T quark with significant branching ratio to a W boson and a b-quark (TT¯→Wb+X), and both a T quark and a B quark with significant branching ratio to a Higgs boson and a third-generation quark (TT¯→Ht+XandBB¯→Hb+X respectively). No significant excess of events above the Standard Model expectation is observed, and 95% CL lower limits are derived on the masses of the vector-like T and B quarks under several branching ratio hypotheses assuming contributions from T → Wb, Zt, Ht and B → Wt, Zb, Hb decays. The 95% CL observed lower limits on the T quark mass range between 715 GeV and 950 GeV for all possible values of the branching ratios into the three decay modes, and are the most stringent constraints to date. Additionally, the most restrictive upper bounds on four-top-quark production are set in a number of new physics scenarios.
Published: 2015

220. Search for low-scale gravity signatures in multi-jet final states with the ATLAS detector at √s = 8TeV

Author: The ATLAS collaboration, Aad, G, Abbott, B, Abdallah, J, Abdinov, O, Aben, R, Abolins, M, AbouZeid, OS, Abramowicz, H, Abreu, H, Abreu, R, Abulaiti, Y, Acharya, BS, Adamczyk, L, Adams, DL, Adelman, J, Adomeit, S, Adye, T, Affolder, AA, Agatonovic-Jovin, T, Aguilar-Saavedra, JA, Ahlen, SP, Ahmadov, F, Aielli, G, Akerstedt, H, Åkesson, TPA, Akimoto, G, Akimov, AV, Alberghi, GL, Albert, J, Albrand, S, Alconada Verzini, MJ, Aleksa, M, Aleksandrov, IN, Alexa, C, Alexander, G, Alexopoulos, T, Alhroob, M, Alimonti, G, Alio, L, Alison, J, Alkire, SP, Allbrooke, BMM, Allport, PP, Aloisio, A, Alonso, A, Alonso, F, Alpigiani, C, Altheimer, A, Alvarez Gonzalez, B, Álvarez Piqueras, D, Alviggi, MG, Amadio, BT, Amako, K, Amaral Coutinho, Y, Amelung, C, Amidei, D, Amor Dos Santos, SP, Amorim, A, Amoroso, S, Amram, N, Amundsen, G, Anastopoulos, C, Ancu, LS, Andari, N, Andeen, T, Anders, CF, Anders, G, Anders, JK, Anderson, KJ, Andreazza, A, Andrei, V, Angelidakis, S, Angelozzi, I, Anger, P, Angerami, A, Anghinolfi, F, Anisenkov, AV, Anjos, N, Annovi, A, Antonelli, M, Antonov, A, Antos, J, Anulli, F, Aoki, M, Aperio Bella, L, Arabidze, G, Arai, Y, Araque, JP, Arce, ATH, Arduh, FA, Arguin, JF, Argyropoulos, S, Arik, M, Armbruster, AJ, Arnaez, O, Arnal, V, Arnold, H, Arratia, M, and Arslan, O
Subjects: Exotics, Hadron-Hadron Scattering, hep-ex, Nuclear & Particles Physics, Mathematical Physics, Atomic, Molecular, Nuclear, Particle and Plasma Physics, Quantum Physics
Abstract: A search for evidence of physics beyond the Standard Model in final states with multiple high-transverse-momentum jets is performed using 20.3 fb−1 of proton-proton collision data at (Formula presented.) = 8 TeV recorded by the ATLAS detector at the LHC. No significant excess of events beyond Standard Model expectations is observed, and upper limits on the visible cross sections for non-Standard Model production of multi-jet final states are set. A wide variety of models for black hole and string ball production and decay are considered, and the upper limit on the cross section times acceptance is as low as 0.16 fb at the 95% confidence level. For these models, excluded regions are also given as function of the main model parameters.
Published: 2015

221. Search for long-lived, weakly interacting particles that decay to displaced hadronic jets in proton-proton collisions at s =8 TeV with the ATLAS detector

Author: Aad, G, Abbott, B, Abdallah, J, Abdinov, O, Aben, R, Abolins, M, Abouzeid, OS, Abramowicz, H, Abreu, H, Abreu, R, Abulaiti, Y, Acharya, BS, Adamczyk, L, Adams, DL, Adelman, J, Adomeit, S, Adye, T, Affolder, AA, Agatonovic-Jovin, T, Aguilar-Saavedra, JA, Ahlen, SP, Ahmadov, F, Aielli, G, Akerstedt, H, Åkesson, TPA, Akimoto, G, Akimov, AV, Alberghi, GL, Albert, J, Albrand, S, Alconada Verzini, MJ, Aleksa, M, Aleksandrov, IN, Alexa, C, Alexander, G, Alexopoulos, T, Alhroob, M, Alimonti, G, Alio, L, Alison, J, Alkire, SP, Allbrooke, BMM, Allport, PP, Aloisio, A, Alonso, A, Alonso, F, Alpigiani, C, Altheimer, A, Alvarez Gonzalez, B, Álvarez Piqueras, D, Alviggi, MG, Amadio, BT, Amako, K, Amaral Coutinho, Y, Amelung, C, Amidei, D, Amor Dos Santos, SP, Amorim, A, Amoroso, S, Amram, N, Amundsen, G, Anastopoulos, C, Ancu, LS, Andari, N, Andeen, T, Anders, CF, Anders, G, Anders, JK, Anderson, KJ, Andreazza, A, Andrei, V, Angelidakis, S, Angelozzi, I, Anger, P, Angerami, A, Anghinolfi, F, Anisenkov, AV, Anjos, N, Annovi, A, Antonelli, M, Antonov, A, Antos, J, Anulli, F, Aoki, M, Aperio Bella, L, Arabidze, G, Arai, Y, Araque, JP, Arce, ATH, Arduh, FA, Arguin, JF, Argyropoulos, S, Arik, M, Armbruster, AJ, Arnaez, O, Arnal, V, Arnold, H, Arratia, M, Arslan, O, and Artamonov, A
Subjects: hep-ex, Nuclear & Particles Physics, Astronomical and Space Sciences, Atomic, Molecular, Nuclear, Particle and Plasma Physics, Quantum Physics, Atomic, Molecular, Nuclear, Particle and Plasma Physics
Abstract: A search for the decay of neutral, weakly interacting, long-lived particles using data collected by the ATLAS detector at the LHC is presented. This analysis uses the full data set recorded in 2012: 20.3 fb-1 of proton-proton collision data at s=8 TeV. The search employs techniques for reconstructing decay vertices of long-lived particles decaying to jets in the inner tracking detector and muon spectrometer. Signal events require at least two reconstructed vertices. No significant excess of events over the expected background is found, and limits as a function of proper lifetime are reported for the decay of the Higgs boson and other scalar bosons to long-lived particles and for Hidden Valley Z′ and Stealth SUSY benchmark models. The first search results for displaced decays in Z′ and Stealth SUSY models are presented. The upper bounds of the excluded proper lifetimes are the most stringent to date.
Published: 2015

222. Evidence of Wγγ Production in pp Collisions at s=8 TeV and Limits on Anomalous Quartic Gauge Couplings with the ATLAS Detector

Author: Aad, G, Abbott, B, Abdallah, J, Khalek, S Abdel, Abdinov, O, Aben, R, Abi, B, Abolins, M, AbouZeid, OS, Abramowicz, H, Abreu, H, Abreu, R, Abulaiti, Y, Acharya, BS, Adamczyk, L, Adams, DL, Adelman, J, Adomeit, S, Adye, T, Agatonovic-Jovin, T, Aguilar-Saavedra, JA, Agustoni, M, Ahlen, SP, Ahmadov, F, Aielli, G, Akerstedt, H, Åkesson, TPA, Akimoto, G, Akimov, AV, Alberghi, GL, Albert, J, Albrand, S, Verzini, MJ Alconada, Aleksa, M, Aleksandrov, IN, Alexa, C, Alexander, G, Alexandre, G, Alexopoulos, T, Alhroob, M, Alimonti, G, Alio, L, Alison, J, Allbrooke, BMM, Allison, LJ, Allport, PP, Aloisio, A, Alonso, A, Alonso, F, Alpigiani, C, Altheimer, A, Gonzalez, B Alvarez, Alviggi, MG, Amako, K, Coutinho, Y Amaral, Amelung, C, Amidei, D, Dos Santos, SP Amor, Amorim, A, Amoroso, S, Amram, N, Amundsen, G, Anastopoulos, C, Ancu, LS, Andari, N, Andeen, T, Anders, CF, Anders, G, Anderson, KJ, Andreazza, A, Andrei, V, Anduaga, XS, Angelidakis, S, Angelozzi, I, Anger, P, Angerami, A, Anghinolfi, F, Anisenkov, AV, Anjos, N, Annovi, A, Antonelli, M, Antonov, A, Antos, J, Anulli, F, Aoki, M, Bella, L Aperio, Arabidze, G, Arai, Y, Araque, JP, Arce, ATH, Arduh, FA, Arguin, J-F, Argyropoulos, S, Arik, M, Armbruster, AJ, Arnaez, O, Arnal, V, Arnold, H, Arratia, M, and Arslan, O
Subjects: Nuclear and Plasma Physics, Particle and High Energy Physics, Physical Sciences, ATLAS Collaboration, hep-ex, Mathematical Sciences, Engineering, General Physics, Mathematical sciences, Physical sciences
Abstract: This Letter reports evidence of triple gauge boson production pp→W(ℓν)γγ+X, which is accessible for the first time with the 8 TeV LHC data set. The fiducial cross section for this process is measured in a data sample corresponding to an integrated luminosity of 20.3 fb^{-1}, collected by the ATLAS detector in 2012. Events are selected using the W boson decay to eν or μν as well as requiring two isolated photons. The measured cross section is used to set limits on anomalous quartic gauge couplings in the high diphoton mass region.
Published: 2015

223. Search for a Heavy Neutral Particle Decaying to eμ, eτ, or μτ in pp Collisions at s=8 TeV with the ATLAS Detector

Author: Aad, G, Abbott, B, Abdallah, J, Abdinov, O, Aben, R, Abolins, M, AbouZeid, OS, Abramowicz, H, Abreu, H, Abreu, R, Abulaiti, Y, Acharya, BS, Adamczyk, L, Adams, DL, Adelman, J, Adomeit, S, Adye, T, Affolder, AA, Agatonovic-Jovin, T, Aguilar-Saavedra, JA, Agustoni, M, Ahlen, SP, Ahmadov, F, Aielli, G, Akerstedt, H, Åkesson, TPA, Akimoto, G, Akimov, AV, Alberghi, GL, Albert, J, Albrand, S, Verzini, MJ Alconada, Aleksa, M, Aleksandrov, IN, Alexa, C, Alexander, G, Alexopoulos, T, Alhroob, M, Alimonti, G, Alio, L, Alison, J, Alkire, SP, Allbrooke, BMM, Allport, PP, Aloisio, A, Alonso, A, Alonso, F, Alpigiani, C, Altheimer, A, Gonzalez, B Alvarez, Alviggi, MG, Amako, K, Coutinho, Y Amaral, Amelung, C, Amidei, D, Dos Santos, SP Amor, Amorim, A, Amoroso, S, Amram, N, Amundsen, G, Anastopoulos, C, Ancu, LS, Andari, N, Andeen, T, Anders, CF, Anders, G, Anderson, KJ, Andreazza, A, Andrei, V, Angelidakis, S, Angelozzi, I, Anger, P, Angerami, A, Anghinolfi, F, Anisenkov, AV, Anjos, N, Annovi, A, Antonelli, M, Antonov, A, Antos, J, Anulli, F, Aoki, M, Bella, L Aperio, Arabidze, G, Arai, Y, Araque, JP, Arce, ATH, Arduh, FA, Arguin, J-F, Argyropoulos, S, Arik, M, Armbruster, AJ, Arnaez, O, Arnal, V, Arnold, H, Arratia, M, Arslan, O, Artamonov, A, Artoni, G, and Asai, S
Subjects: Nuclear and Plasma Physics, Particle and High Energy Physics, Physical Sciences, ATLAS Collaboration, hep-ex, Mathematical Sciences, Engineering, General Physics, Mathematical sciences, Physical sciences
Abstract: This Letter presents a search for a heavy neutral particle decaying into an opposite-sign different-flavor dilepton pair, e^{±}μ^{∓}, e^{±}τ^{∓}, or μ^{±}τ^{∓} using 20.3 fb^{-1} of pp collision data at sqrt[s]=8 TeV collected by the ATLAS detector at the LHC. The numbers of observed candidate events are compatible with the standard model expectations. Limits are set on the cross section of new phenomena in two scenarios: the production of ν[over ˜]_{τ} in R-parity-violating supersymmetric models and the production of a lepton-flavor-violating Z^{'} vector boson.
Published: 2015

224. Observation and measurement of Higgs boson decays to WW∗with the ATLAS detector

Author: Aad, G, Abbott, B, Abdallah, J, Abdel Khalek, S, Abdinov, O, Aben, R, Abi, B, Abolins, M, Abou Zeid, OS, Abramowicz, H, Abreu, H, Abreu, R, Abulaiti, Y, Acharya, BS, Adamczyk, L, Adams, DL, Adelman, J, Adomeit, S, Adye, T, Agatonovic-Jovin, T, Aguilar-Saavedra, JA, Agustoni, M, Ahlen, SP, Ahmadov, F, Aielli, G, Akerstedt, H, Åkesson, TPA, Akimoto, G, Akimov, AV, Alberghi, GL, Albert, J, Albrand, S, Alconada Verzini, MJ, Aleksa, M, Aleksandrov, IN, Alexa, C, Alexander, G, Alexandre, G, Alexopoulos, T, Alhroob, M, Alimonti, G, Alio, L, Alison, J, Allbrooke, BMM, Allison, LJ, Allport, PP, Aloisio, A, Alonso, A, Alonso, F, Alpigiani, C, Altheimer, A, Alvarez Gonzalez, B, Alviggi, MG, Amako, K, Amaral Coutinho, Y, Amelung, C, Amidei, D, Amor Dos Santos, SP, Amorim, A, Amoroso, S, Amram, N, Amundsen, G, Anastopoulos, C, Ancu, LS, Andari, N, Andeen, T, Anders, CF, Anders, G, Anderson, KJ, Andreazza, A, Andrei, V, Anduaga, XS, Angelidakis, S, Angelozzi, I, Anger, P, Angerami, A, Anghinolfi, F, Anisenkov, AV, Anjos, N, Annovi, A, Antonelli, M, Antonov, A, Antos, J, Anulli, F, Aoki, M, Aperio Bella, L, Arabidze, G, Arai, Y, Araque, JP, Arce, ATH, Arduh, FA, Arguin, JF, Argyropoulos, S, Arik, M, Armbruster, AJ, Arnaez, O, Arnal, V, Arnold, H, Arratia, M, and Arslan, O
Subjects: hep-ex, Nuclear & Particles Physics, Astronomical and Space Sciences, Atomic, Molecular, Nuclear, Particle and Plasma Physics, Quantum Physics, Atomic, Molecular, Nuclear, Particle and Plasma Physics
Abstract: We report the observation of Higgs boson decays to WW∗based on an excess over background of 6.1 standard deviations in the dilepton final state, where the Standard Model expectation is 5.8 standard deviations. Evidence for the vector-boson fusion (VBF) production process is obtained with a significance of 3.2 standard deviations. The results are obtained from a data sample corresponding to an integrated luminosity of 25 fb-1from √s = 7 and 8 TeV pp collisions recorded by the ATLAS detector at the LHC. For a Higgs boson mass of 125.36 GeV, the ratio of the measured value to the expected value of the total production cross section times branching fraction is 1.09+0.16-0.15(stat)+0.17-0.14(syst). The corresponding ratios for the gluon fusion and vector-boson fusion production mechanisms are 1.02 ± 0.19(stat)+0.22-0.18(syst) and 1.27+0.44-0.40(stat)+0.30-0.21(syst), respectively. At √s = 8 TeV, the total production cross sections are measured to be σ(gg→H→WW∗)=4.6±0.9(stat)+0.8-0.7(syst) pb and σ(VBF H → WW∗)=0.51+0.17-0.15(stat)+0.13-0.08(syst)pb. The fiducial cross section is determined for the gluon-fusion process in exclusive final states with zero or one associated jet.
Published: 2015

225. A search for high-mass resonances decaying to τ+τ− in pp collisions at √s =8 TeV with the ATLAS detector

Author: The ATLAS collaboration, Aad, G, Abbott, B, Abdallah, J, Abdel Khalek, S, Abdinov, O, Aben, R, Abi, B, Abolins, M, AbouZeid, OS, Abramowicz, H, Abreu, H, Abreu, R, Abulaiti, Y, Acharya, BS, Adamczyk, L, Adams, DL, Adelman, J, Adomeit, S, Adye, T, Agatonovic-Jovin, T, Aguilar-Saavedra, JA, Agustoni, M, Ahlen, SP, Ahmadov, F, Aielli, G, Akerstedt, H, Åkesson, TPA, Akimoto, G, Akimov, AV, Alberghi, GL, Albert, J, Albrand, S, Alconada Verzini, MJ, Aleksa, M, Aleksandrov, IN, Alexa, C, Alexander, G, Alexandre, G, Alexopoulos, T, Alhroob, M, Alimonti, G, Alio, L, Alison, J, Allbrooke, BMM, Allison, LJ, Allport, PP, Aloisio, A, Alonso, A, Alonso, F, Alpigiani, C, Altheimer, A, Alvarez Gonzalez, B, Alviggi, MG, Amako, K, Amaral Coutinho, Y, Amelung, C, Amidei, D, Amor Dos Santos, SP, Amorim, A, Amoroso, S, Amram, N, Amundsen, G, Anastopoulos, C, Ancu, LS, Andari, N, Andeen, T, Anders, CF, Anders, G, Anderson, KJ, Andreazza, A, Andrei, V, Anduaga, XS, Angelidakis, S, Angelozzi, I, Anger, P, Angerami, A, Anghinolfi, F, Anisenkov, AV, Anjos, N, Annovi, A, Antonelli, M, Antonov, A, Antos, J, Anulli, F, Aoki, M, Aperio Bella, L, Arabidze, G, Arai, Y, Araque, JP, Arce, ATH, Arduh, FA, Arguin, JF, Argyropoulos, S, Arik, M, Armbruster, AJ, Arnaez, O, Arnal, V, Arnold, H, and Arratia, M
Subjects: Hadron-Hadron Scattering, hep-ex, Nuclear & Particles Physics, Mathematical Physics, Atomic, Molecular, Nuclear, Particle and Plasma Physics, Quantum Physics
Abstract: Abstract: A search for high-mass resonances decaying into τ+τ− final states using proton-proton collisions at s=8$$ \sqrt{s}=8 $$ TeV produced by the Large Hadron Collider is presented. The data were recorded with the ATLAS detector and correspond to an integrated luminosity of 19.5–20.3 fb−1. No statistically significant excess above the Standard Model expectation is observed; 95% credibility upper limits are set on the cross section times branching fraction of Z′ resonances decaying into τ+τ− pairs as a function of the resonance mass. As a result, Z′ bosons of the Sequential Standard Model with masses less than 2.02 TeV are excluded at 95% credibility. The impact of the fermionic couplings on the Z′ acceptance is investigated and limits are also placed on a Z′ model that exhibits enhanced couplings to third-generation fermions.[Figure not available: see fulltext.]
Published: 2015

226. Search for heavy Majorana neutrinos with the ATLAS detector in pp collisions at √s = 8 TeV

Author: The ATLAS collaboration, Aad, G, Abbott, B, Abdallah, J, Abdel Khalek, S, Abdinov, O, Aben, R, Abi, B, Abolins, M, AbouZeid, OS, Abramowicz, H, Abreu, H, Abreu, R, Abulaiti, Y, Acharya, BS, Adamczyk, L, Adams, DL, Adelman, J, Adomeit, S, Adye, T, Agatonovic-Jovin, T, Aguilar-Saavedra, JA, Agustoni, M, Ahlen, SP, Ahmadov, F, Aielli, G, Akerstedt, H, Åkesson, TPA, Akimoto, G, Akimov, AV, Alberghi, GL, Albert, J, Albrand, S, Alconada Verzini, MJ, Aleksa, M, Aleksandrov, IN, Alexa, C, Alexander, G, Alexandre, G, Alexopoulos, T, Alhroob, M, Alimonti, G, Alio, L, Alison, J, Allbrooke, BMM, Allison, LJ, Allport, PP, Almond, J, Aloisio, A, Alonso, A, Alonso, F, Alpigiani, C, Altheimer, A, Alvarez Gonzalez, B, Alviggi, MG, Amako, K, Amaral Coutinho, Y, Amelung, C, Amidei, D, Amor Dos Santos, SP, Amorim, A, Amoroso, S, Amram, N, Amundsen, G, Anastopoulos, C, Ancu, LS, Andari, N, Andeen, T, Anders, CF, Anders, G, Anderson, KJ, Andreazza, A, Andrei, V, Anduaga, XS, Angelidakis, S, Angelozzi, I, Anger, P, Angerami, A, Anghinolfi, F, Anisenkov, AV, Anjos, N, Annovi, A, Antonelli, M, Antonov, A, Antos, J, Anulli, F, Aoki, M, Aperio Bella, L, Arabidze, G, Arai, Y, Araque, JP, Arce, ATH, Arduh, FA, Arguin, JF, Argyropoulos, S, Arik, M, Armbruster, AJ, Arnaez, O, Arnal, V, and Arnold, H
Subjects: Hadron-Hadron Scattering, hep-ex, Nuclear & Particles Physics, Mathematical Physics, Atomic, Molecular, Nuclear, Particle and Plasma Physics, Quantum Physics
Abstract: Abstract: A search for heavy Majorana neutrinos in events containing a pair of high-pT leptons of the same charge and high-pT jets is presented. The search uses 20.3 fb−1 of pp collision data collected with the ATLAS detector at the CERN Large Hadron Collider with a centre-of-mass energy of 221as = 8 TeV. The data are found to be consistent with the background-only hypothesis based on the Standard Model expectation. In the context of a Type-I seesaw mechanism, limits are set on the production cross-section times branching ratio for production of heavy Majorana neutrinos in the mass range between 100 and 500 GeV. The limits are subsequently interpreted as limits on the mixing between the heavy Majorana neutrinos and the Standard Model neutrinos. In the context of a left-right symmetric model, limits on the production cross-section times branching ratio are set with respect to the masses of heavy Majorana neutrinos and heavy gauge bosons WR and Z′.[Figure not available: see fulltext.]
Published: 2015

227. Search for the Standard Model Higgs boson produced in association with top quarks and decaying into bb¯ in pp collisions at s=8TeV with the ATLAS detector

Author: Aad, G, Abbott, B, Abdallah, J, Abdinov, O, Aben, R, Abolins, M, AbouZeid, OS, Abramowicz, H, Abreu, H, Abreu, R, Abulaiti, Y, Acharya, BS, Adamczyk, L, Adams, DL, Adelman, J, Adomeit, S, Adye, T, Affolder, AA, Agatonovic-Jovin, T, Aguilar-Saavedra, JA, Agustoni, M, Ahlen, SP, Ahmadov, F, Aielli, G, Akerstedt, H, Åkesson, TPA, Akimoto, G, Akimov, AV, Alberghi, GL, Albert, J, Albrand, S, Alconada Verzini, MJ, Aleksa, M, Aleksandrov, IN, Alexa, C, Alexander, G, Alexopoulos, T, Alhroob, M, Alimonti, G, Alio, L, Alison, J, Alkire, SP, Allbrooke, BMM, Allport, PP, Aloisio, A, Alonso, A, Alonso, F, Alpigiani, C, Altheimer, A, Alvarez Gonzalez, B, Piqueras, D Álvarez, Alviggi, MG, Amako, K, Amaral Coutinho, Y, Amelung, C, Amidei, D, Amor Dos Santos, SP, Amorim, A, Amoroso, S, Amram, N, Amundsen, G, Anastopoulos, C, Ancu, LS, Andari, N, Andeen, T, Anders, CF, Anders, G, Anderson, KJ, Andreazza, A, Andrei, V, Angelidakis, S, Angelozzi, I, Anger, P, Angerami, A, Anghinolfi, F, Anisenkov, AV, Anjos, N, Annovi, A, Antonelli, M, Antonov, A, Antos, J, Anulli, F, Aoki, M, Aperio Bella, L, Arabidze, G, Arai, Y, Araque, JP, Arce, ATH, Arduh, FA, Arguin, J-F, Argyropoulos, S, Arik, M, Armbruster, AJ, Arnaez, O, Arnal, V, Arnold, H, Arratia, M, Arslan, O, Artamonov, A, and Artoni, G
Subjects: Nuclear and Plasma Physics, Particle and High Energy Physics, Physical Sciences, ATLAS Publications, hep-ex, Atomic, Molecular, Nuclear, Particle and Plasma Physics, Quantum Physics, Nuclear & Particles Physics, Astronomical sciences, Atomic, molecular and optical physics, Particle and high energy physics
Abstract: A search for the Standard Model Higgs boson produced in association with a top-quark pair, [Formula: see text], is presented. The analysis uses 20.3 fb-1 of pp collision data at [Formula: see text], collected with the ATLAS detector at the Large Hadron Collider during 2012. The search is designed for the [Formula: see text] decay mode and uses events containing one or two electrons or muons. In order to improve the sensitivity of the search, events are categorised according to their jet and b-tagged jet multiplicities. A neural network is used to discriminate between signal and background events, the latter being dominated by [Formula: see text]+jets production. In the single-lepton channel, variables calculated using a matrix element method are included as inputs to the neural network to improve discrimination of the irreducible [Formula: see text] background. No significant excess of events above the background expectation is found and an observed (expected) limit of 3.4 (2.2) times the Standard Model cross section is obtained at 95 % confidence level. The ratio of the measured [Formula: see text] signal cross section to the Standard Model expectation is found to be [Formula: see text] assuming a Higgs boson mass of 125[Formula: see text].
Published: 2015

228. Observation and measurement of Higgs boson decays to WW* with the ATLAS detector

Author: Aad, G, Abbott, B, Abdallah, J, Khalek, S Abdel, Abdinov, O, Aben, R, Abi, B, Abolins, M, AbouZeid, OS, Abramowicz, H, Abreu, H, Abreu, R, Abulaiti, Y, Acharya, BS, Adamczyk, L, Adams, DL, Adelman, J, Adomeit, S, Adye, T, Agatonovic-Jovin, T, Aguilar-Saavedra, JA, Agustoni, M, Ahlen, SP, Ahmadov, F, Aielli, G, Akerstedt, H, Åkesson, TPA, Akimoto, G, Akimov, AV, Alberghi, GL, Albert, J, Albrand, S, Verzini, MJ Alconada, Aleksa, M, Aleksandrov, IN, Alexa, C, Alexander, G, Alexandre, G, Alexopoulos, T, Alhroob, M, Alimonti, G, Alio, L, Alison, J, Allbrooke, BMM, Allison, LJ, Allport, PP, Aloisio, A, Alonso, A, Alonso, F, Alpigiani, C, Altheimer, A, Gonzalez, B Alvarez, Alviggi, MG, Amako, K, Coutinho, Y Amaral, Amelung, C, Amidei, D, Dos Santos, SP Amor, Amorim, A, Amoroso, S, Amram, N, Amundsen, G, Anastopoulos, C, Ancu, LS, Andari, N, Andeen, T, Anders, CF, Anders, G, Anderson, KJ, Andreazza, A, Andrei, V, Anduaga, XS, Angelidakis, S, Angelozzi, I, Anger, P, Angerami, A, Anghinolfi, F, Anisenkov, AV, Anjos, N, Annovi, A, Antonelli, M, Antonov, A, Antos, J, Anulli, F, Aoki, M, Bella, L Aperio, Arabidze, G, Arai, Y, Araque, JP, Arce, ATH, Arduh, FA, Arguin, J-F, Argyropoulos, S, Arik, M, Armbruster, AJ, Arnaez, O, Arnal, V, Arnold, H, Arratia, M, and Arslan, O
Subjects: Nuclear and Plasma Physics, Particle and High Energy Physics, Physical Sciences, hep-ex
Abstract: We report the observation of Higgs boson decays to WW∗based on an excess over background of 6.1 standard deviations in the dilepton final state, where the Standard Model expectation is 5.8 standard deviations. Evidence for the vector-boson fusion (VBF) production process is obtained with a significance of 3.2 standard deviations. The results are obtained from a data sample corresponding to an integrated luminosity of 25 fb-1from √s = 7 and 8 TeV pp collisions recorded by the ATLAS detector at the LHC. For a Higgs boson mass of 125.36 GeV, the ratio of the measured value to the expected value of the total production cross section times branching fraction is 1.09+0.16-0.15(stat)+0.17-0.14(syst). The corresponding ratios for the gluon fusion and vector-boson fusion production mechanisms are 1.02 ± 0.19(stat)+0.22-0.18(syst) and 1.27+0.44-0.40(stat)+0.30-0.21(syst), respectively. At √s = 8 TeV, the total production cross sections are measured to be σ(gg→H→WW∗)=4.6±0.9(stat)+0.8-0.7(syst) pb and σ(VBF H → WW∗)=0.51+0.17-0.15(stat)+0.13-0.08(syst)pb. The fiducial cross section is determined for the gluon-fusion process in exclusive final states with zero or one associated jet.
Published: 2015

229. Search for long-lived, weakly interacting particles that decay to displaced hadronic jets in proton-proton collisions at s=8 TeV with the ATLAS detector

Author: Aad, G, Abbott, B, Abdallah, J, Abdinov, O, Aben, R, Abolins, M, AbouZeid, OS, Abramowicz, H, Abreu, H, Abreu, R, Abulaiti, Y, Acharya, BS, Adamczyk, L, Adams, DL, Adelman, J, Adomeit, S, Adye, T, Affolder, AA, Agatonovic-Jovin, T, Aguilar-Saavedra, JA, Ahlen, SP, Ahmadov, F, Aielli, G, Akerstedt, H, Åkesson, TPA, Akimoto, G, Akimov, AV, Alberghi, GL, Albert, J, Albrand, S, Verzini, MJ Alconada, Aleksa, M, Aleksandrov, IN, Alexa, C, Alexander, G, Alexopoulos, T, Alhroob, M, Alimonti, G, Alio, L, Alison, J, Alkire, SP, Allbrooke, BMM, Allport, PP, Aloisio, A, Alonso, A, Alonso, F, Alpigiani, C, Altheimer, A, Gonzalez, B Alvarez, Piqueras, D Álvarez, Alviggi, MG, Amadio, BT, Amako, K, Coutinho, Y Amaral, Amelung, C, Amidei, D, Dos Santos, SP Amor, Amorim, A, Amoroso, S, Amram, N, Amundsen, G, Anastopoulos, C, Ancu, LS, Andari, N, Andeen, T, Anders, CF, Anders, G, Anders, JK, Anderson, KJ, Andreazza, A, Andrei, V, Angelidakis, S, Angelozzi, I, Anger, P, Angerami, A, Anghinolfi, F, Anisenkov, AV, Anjos, N, Annovi, A, Antonelli, M, Antonov, A, Antos, J, Anulli, F, Aoki, M, Bella, L Aperio, Arabidze, G, Arai, Y, Araque, JP, Arce, ATH, Arduh, FA, Arguin, J-F, Argyropoulos, S, Arik, M, Armbruster, AJ, Arnaez, O, Arnal, V, Arnold, H, Arratia, M, Arslan, O, and Artamonov, A
Subjects: Nuclear and Plasma Physics, Particle and High Energy Physics, Physical Sciences, hep-ex
Abstract: A search for the decay of neutral, weakly interacting, long-lived particles using data collected by the ATLAS detector at the LHC is presented. This analysis uses the full data set recorded in 2012: 20.3 fb-1 of proton-proton collision data at s=8 TeV. The search employs techniques for reconstructing decay vertices of long-lived particles decaying to jets in the inner tracking detector and muon spectrometer. Signal events require at least two reconstructed vertices. No significant excess of events over the expected background is found, and limits as a function of proper lifetime are reported for the decay of the Higgs boson and other scalar bosons to long-lived particles and for Hidden Valley Z′ and Stealth SUSY benchmark models. The first search results for displaced decays in Z′ and Stealth SUSY models are presented. The upper bounds of the excluded proper lifetimes are the most stringent to date.
Published: 2015

230. Search for invisible decays of the Higgs boson produced in association with a hadronically decaying vector boson in pp collisions at s=8 TeV with the ATLAS detector

Author: Aad, G, Abbott, B, Abdallah, J, Abdinov, O, Aben, R, Abolins, M, AbouZeid, OS, Abramowicz, H, Abreu, H, Abreu, R, Abulaiti, Y, Acharya, BS, Adamczyk, L, Adams, DL, Adelman, J, Adomeit, S, Adye, T, Affolder, AA, Agatonovic-Jovin, T, Aguilar-Saavedra, JA, Ahlen, SP, Ahmadov, F, Aielli, G, Akerstedt, H, Åkesson, TPA, Akimoto, G, Akimov, AV, Alberghi, GL, Albert, J, Albrand, S, Alconada Verzini, MJ, Aleksa, M, Aleksandrov, IN, Alexa, C, Alexander, G, Alexopoulos, T, Alhroob, M, Alimonti, G, Alio, L, Alison, J, Alkire, SP, Allbrooke, BMM, Allport, PP, Aloisio, A, Alonso, A, Alonso, F, Alpigiani, C, Altheimer, A, Alvarez Gonzalez, B, Álvarez Piqueras, D, Alviggi, MG, Amadio, BT, Amako, K, Amaral Coutinho, Y, Amelung, C, Amidei, D, Amor Dos Santos, SP, Amorim, A, Amoroso, S, Amram, N, Amundsen, G, Anastopoulos, C, Ancu, LS, Andari, N, Andeen, T, Anders, CF, Anders, G, Anders, JK, Anderson, KJ, Andreazza, A, Andrei, V, Angelidakis, S, Angelozzi, I, Anger, P, Angerami, A, Anghinolfi, F, Anisenkov, AV, Anjos, N, Annovi, A, Antonelli, M, Antonov, A, Antos, J, Anulli, F, Aoki, M, Aperio Bella, L, Arabidze, G, Arai, Y, Araque, JP, Arce, ATH, Arduh, FA, Arguin, J-F, Argyropoulos, S, Arik, M, Armbruster, AJ, Arnaez, O, Arnal, V, Arnold, H, Arratia, M, Arslan, O, and Artamonov, A
Subjects: Nuclear and Plasma Physics, Particle and High Energy Physics, Physical Sciences, ATLAS collaboration, hep-ex, Atomic, Molecular, Nuclear, Particle and Plasma Physics, Quantum Physics, Nuclear & Particles Physics, Astronomical sciences, Atomic, molecular and optical physics, Particle and high energy physics
Abstract: A search for Higgs boson decays to invisible particles is performed using 20.3 [Formula: see text] of pp collision data at a centre-of-mass energy of 8 TeV recorded by the ATLAS detector at the Large Hadron Collider. The process considered is Higgs boson production in association with a vector boson ([Formula: see text] or Z) that decays hadronically, resulting in events with two or more jets and large missing transverse momentum. No excess of candidates is observed in the data over the background expectation. The results are used to constrain VH production followed by H decaying to invisible particles for the Higgs boson mass range [Formula: see text] GeV. The 95 % confidence-level observed upper limit on [Formula: see text] varies from 1.6 pb at 115 GeV to 0.13 pb at 300 GeV. Assuming Standard Model production and including the [Formula: see text] contribution as signal, the results also lead to an observed upper limit of 78 % at 95 % confidence level on the branching ratio of Higgs bosons decays to invisible particles at a mass of 125 GeV.
Published: 2015

231. Search for heavy Majorana neutrinos with the ATLAS detector in pp collisions at s=8 TeV

Author: The ATLAS collaboration, Aad, G, Abbott, B, Abdallah, J, Abdel Khalek, S, Abdinov, O, Aben, R, Abi, B, Abolins, M, AbouZeid, OS, Abramowicz, H, Abreu, H, Abreu, R, Abulaiti, Y, Acharya, BS, Adamczyk, L, Adams, DL, Adelman, J, Adomeit, S, Adye, T, Agatonovic-Jovin, T, Aguilar-Saavedra, JA, Agustoni, M, Ahlen, SP, Ahmadov, F, Aielli, G, Akerstedt, H, Åkesson, TPA, Akimoto, G, Akimov, AV, Alberghi, GL, Albert, J, Albrand, S, Alconada Verzini, MJ, Aleksa, M, Aleksandrov, IN, Alexa, C, Alexander, G, Alexandre, G, Alexopoulos, T, Alhroob, M, Alimonti, G, Alio, L, Alison, J, Allbrooke, BMM, Allison, LJ, Allport, PP, Almond, J, Aloisio, A, Alonso, A, Alonso, F, Alpigiani, C, Altheimer, A, Alvarez Gonzalez, B, Alviggi, MG, Amako, K, Amaral Coutinho, Y, Amelung, C, Amidei, D, Amor Dos Santos, SP, Amorim, A, Amoroso, S, Amram, N, Amundsen, G, Anastopoulos, C, Ancu, LS, Andari, N, Andeen, T, Anders, CF, Anders, G, Anderson, KJ, Andreazza, A, Andrei, V, Anduaga, XS, Angelidakis, S, Angelozzi, I, Anger, P, Angerami, A, Anghinolfi, F, Anisenkov, AV, Anjos, N, Annovi, A, Antonelli, M, Antonov, A, Antos, J, Anulli, F, Aoki, M, Aperio Bella, L, Arabidze, G, Arai, Y, Araque, JP, Arce, ATH, Arduh, FA, Arguin, J-F, Argyropoulos, S, Arik, M, Armbruster, AJ, Arnaez, O, Arnal, V, and Arnold, H
Subjects: Nuclear and Plasma Physics, Particle and High Energy Physics, Physical Sciences, Hadron-Hadron Scattering, hep-ex, Mathematical Physics, Atomic, Molecular, Nuclear, Particle and Plasma Physics, Quantum Physics, Nuclear & Particles Physics, Mathematical physics, Nuclear and plasma physics, Particle and high energy physics
Abstract: Abstract: A search for heavy Majorana neutrinos in events containing a pair of high-pT leptons of the same charge and high-pT jets is presented. The search uses 20.3 fb−1 of pp collision data collected with the ATLAS detector at the CERN Large Hadron Collider with a centre-of-mass energy of 221as = 8 TeV. The data are found to be consistent with the background-only hypothesis based on the Standard Model expectation. In the context of a Type-I seesaw mechanism, limits are set on the production cross-section times branching ratio for production of heavy Majorana neutrinos in the mass range between 100 and 500 GeV. The limits are subsequently interpreted as limits on the mixing between the heavy Majorana neutrinos and the Standard Model neutrinos. In the context of a left-right symmetric model, limits on the production cross-section times branching ratio are set with respect to the masses of heavy Majorana neutrinos and heavy gauge bosons WR and Z′.[Figure not available: see fulltext.]
Published: 2015

232. Search for supersymmetry in events containing a same-flavour opposite-sign dilepton pair, jets, and large missing transverse momentum in s=8 TeV pp collisions with the ATLAS detector

Author: Aad, G, Abbott, B, Abdallah, J, Abdinov, O, Aben, R, Abolins, M, AbouZeid, OS, Abramowicz, H, Abreu, H, Abreu, R, Abulaiti, Y, Acharya, BS, Adamczyk, L, Adams, DL, Adelman, J, Adomeit, S, Adye, T, Affolder, AA, Agatonovic-Jovin, T, Aguilar-Saavedra, JA, Agustoni, M, Ahlen, SP, Ahmadov, F, Aielli, G, Akerstedt, H, Åkesson, TPA, Akimoto, G, Akimov, AV, Alberghi, GL, Albert, J, Albrand, S, Verzini, MJ Alconada, Aleksa, M, Aleksandrov, IN, Alexa, C, Alexander, G, Alexopoulos, T, Alhroob, M, Alimonti, G, Alio, L, Alison, J, Alkire, SP, Allbrooke, BMM, Allport, PP, Aloisio, A, Alonso, A, Alonso, F, Alpigiani, C, Altheimer, A, Gonzalez, B Alvarez, Piqueras, D Álvarez, Alviggi, MG, Amako, K, Coutinho, Y Amaral, Amelung, C, Amidei, D, Dos Santos, SP Amor, Amorim, A, Amoroso, S, Amram, N, Amundsen, G, Anastopoulos, C, Ancu, LS, Andari, N, Andeen, T, Anders, CF, Anders, G, Anderson, KJ, Andreazza, A, Andrei, V, Angelidakis, S, Angelozzi, I, Anger, P, Angerami, A, Anghinolfi, F, Anisenkov, AV, Anjos, N, Annovi, A, Antonelli, M, Antonov, A, Antos, J, Anulli, F, Aoki, M, Bella, L Aperio, Arabidze, G, Arai, Y, Araque, JP, Arce, ATH, Arduh, FA, Arguin, J-F, Argyropoulos, S, Arik, M, Armbruster, AJ, Arnaez, O, Arnal, V, Arnold, H, Arratia, M, Arslan, O, Artamonov, A, and Artoni, G
Subjects: Nuclear and Plasma Physics, Particle and High Energy Physics, Physical Sciences, ATLAS Publications, hep-ex, Atomic, Molecular, Nuclear, Particle and Plasma Physics, Quantum Physics, Nuclear & Particles Physics, Astronomical sciences, Atomic, molecular and optical physics, Particle and high energy physics
Abstract: Two searches for supersymmetric particles in final states containing a same-flavour opposite-sign lepton pair, jets and large missing transverse momentum are presented. The proton-proton collision data used in these searches were collected at a centre-of-mass energy [Formula: see text] TeV by the ATLAS detector at the Large Hadron Collider and corresponds to an integrated luminosity of 20.3 fb[Formula: see text]. Two leptonic production mechanisms are considered: decays of squarks and gluinos with Z bosons in the final state, resulting in a peak in the dilepton invariant mass distribution around the Z-boson mass; and decays of neutralinos (e.g. [Formula: see text]), resulting in a kinematic endpoint in the dilepton invariant mass distribution. For the former, an excess of events above the expected Standard Model background is observed, with a significance of three standard deviations. In the latter case, the data are well-described by the expected Standard Model background. The results from each channel are interpreted in the context of several supersymmetric models involving the production of squarks and gluinos.
Published: 2015

233. A search for high-mass resonances decaying to τ+τ− in pp collisions at s=8 TeV with the ATLAS detector

Author: The ATLAS collaboration, Aad, G, Abbott, B, Abdallah, J, Abdel Khalek, S, Abdinov, O, Aben, R, Abi, B, Abolins, M, AbouZeid, OS, Abramowicz, H, Abreu, H, Abreu, R, Abulaiti, Y, Acharya, BS, Adamczyk, L, Adams, DL, Adelman, J, Adomeit, S, Adye, T, Agatonovic-Jovin, T, Aguilar-Saavedra, JA, Agustoni, M, Ahlen, SP, Ahmadov, F, Aielli, G, Akerstedt, H, Åkesson, TPA, Akimoto, G, Akimov, AV, Alberghi, GL, Albert, J, Albrand, S, Alconada Verzini, MJ, Aleksa, M, Aleksandrov, IN, Alexa, C, Alexander, G, Alexandre, G, Alexopoulos, T, Alhroob, M, Alimonti, G, Alio, L, Alison, J, Allbrooke, BMM, Allison, LJ, Allport, PP, Aloisio, A, Alonso, A, Alonso, F, Alpigiani, C, Altheimer, A, Alvarez Gonzalez, B, Alviggi, MG, Amako, K, Amaral Coutinho, Y, Amelung, C, Amidei, D, Amor Dos Santos, SP, Amorim, A, Amoroso, S, Amram, N, Amundsen, G, Anastopoulos, C, Ancu, LS, Andari, N, Andeen, T, Anders, CF, Anders, G, Anderson, KJ, Andreazza, A, Andrei, V, Anduaga, XS, Angelidakis, S, Angelozzi, I, Anger, P, Angerami, A, Anghinolfi, F, Anisenkov, AV, Anjos, N, Annovi, A, Antonelli, M, Antonov, A, Antos, J, Anulli, F, Aoki, M, Aperio Bella, L, Arabidze, G, Arai, Y, Araque, JP, Arce, ATH, Arduh, FA, Arguin, J-F, Argyropoulos, S, Arik, M, Armbruster, AJ, Arnaez, O, Arnal, V, Arnold, H, and Arratia, M
Subjects: Nuclear and Plasma Physics, Particle and High Energy Physics, Physical Sciences, Hadron-Hadron Scattering, hep-ex, Mathematical Physics, Atomic, Molecular, Nuclear, Particle and Plasma Physics, Quantum Physics, Nuclear & Particles Physics, Mathematical physics, Nuclear and plasma physics, Particle and high energy physics
Abstract: Abstract: A search for high-mass resonances decaying into τ+τ− final states using proton-proton collisions at s=8$$ \sqrt{s}=8 $$ TeV produced by the Large Hadron Collider is presented. The data were recorded with the ATLAS detector and correspond to an integrated luminosity of 19.5–20.3 fb−1. No statistically significant excess above the Standard Model expectation is observed; 95% credibility upper limits are set on the cross section times branching fraction of Z′ resonances decaying into τ+τ− pairs as a function of the resonance mass. As a result, Z′ bosons of the Sequential Standard Model with masses less than 2.02 TeV are excluded at 95% credibility. The impact of the fermionic couplings on the Z′ acceptance is investigated and limits are also placed on a Z′ model that exhibits enhanced couplings to third-generation fermions.[Figure not available: see fulltext.]
Published: 2015

234. Search for low-scale gravity signatures in multi-jet final states with the ATLAS detector at s=8 TeV

Author: The ATLAS collaboration, Aad, G, Abbott, B, Abdallah, J, Abdinov, O, Aben, R, Abolins, M, AbouZeid, OS, Abramowicz, H, Abreu, H, Abreu, R, Abulaiti, Y, Acharya, BS, Adamczyk, L, Adams, DL, Adelman, J, Adomeit, S, Adye, T, Affolder, AA, Agatonovic-Jovin, T, Aguilar-Saavedra, JA, Ahlen, SP, Ahmadov, F, Aielli, G, Akerstedt, H, Åkesson, TPA, Akimoto, G, Akimov, AV, Alberghi, GL, Albert, J, Albrand, S, Alconada Verzini, MJ, Aleksa, M, Aleksandrov, IN, Alexa, C, Alexander, G, Alexopoulos, T, Alhroob, M, Alimonti, G, Alio, L, Alison, J, Alkire, SP, Allbrooke, BMM, Allport, PP, Aloisio, A, Alonso, A, Alonso, F, Alpigiani, C, Altheimer, A, Alvarez Gonzalez, B, Álvarez Piqueras, D, Alviggi, MG, Amadio, BT, Amako, K, Amaral Coutinho, Y, Amelung, C, Amidei, D, Amor Dos Santos, SP, Amorim, A, Amoroso, S, Amram, N, Amundsen, G, Anastopoulos, C, Ancu, LS, Andari, N, Andeen, T, Anders, CF, Anders, G, Anders, JK, Anderson, KJ, Andreazza, A, Andrei, V, Angelidakis, S, Angelozzi, I, Anger, P, Angerami, A, Anghinolfi, F, Anisenkov, AV, Anjos, N, Annovi, A, Antonelli, M, Antonov, A, Antos, J, Anulli, F, Aoki, M, Aperio Bella, L, Arabidze, G, Arai, Y, Araque, JP, Arce, ATH, Arduh, FA, Arguin, J-F, Argyropoulos, S, Arik, M, Armbruster, AJ, Arnaez, O, Arnal, V, Arnold, H, Arratia, M, and Arslan, O
Subjects: Nuclear and Plasma Physics, Particle and High Energy Physics, Mathematical Physics, Mathematical Sciences, Physical Sciences, Exotics, Hadron-Hadron Scattering, hep-ex, Atomic, Molecular, Nuclear, Particle and Plasma Physics, Quantum Physics, Nuclear & Particles Physics, Mathematical physics, Nuclear and plasma physics, Particle and high energy physics
Abstract: A search for evidence of physics beyond the Standard Model in final states with multiple high-transverse-momentum jets is performed using 20.3 fb−1 of proton-proton collision data at (Formula presented.) = 8 TeV recorded by the ATLAS detector at the LHC. No significant excess of events beyond Standard Model expectations is observed, and upper limits on the visible cross sections for non-Standard Model production of multi-jet final states are set. A wide variety of models for black hole and string ball production and decay are considered, and the upper limit on the cross section times acceptance is as low as 0.16 fb at the 95% confidence level. For these models, excluded regions are also given as function of the main model parameters.
Published: 2015

235. Measurement of the top quark mass in the tt¯→lepton+jets and tt¯→dilepton channels using s=7 TeV ATLAS data

Author: Aad, G, Abbott, B, Abdallah, J, Abdinov, O, Aben, R, Abolins, M, AbouZeid, OS, Abramowicz, H, Abreu, H, Abreu, R, Abulaiti, Y, Acharya, BS, Adamczyk, L, Adams, DL, Adelman, J, Adomeit, S, Adye, T, Affolder, AA, Agatonovic-Jovin, T, Aguilar-Saavedra, JA, Ahlen, SP, Ahmadov, F, Aielli, G, Akerstedt, H, Åkesson, TPA, Akimoto, G, Akimov, AV, Alberghi, GL, Albert, J, Albrand, S, Alconada Verzini, MJ, Aleksa, M, Aleksandrov, IN, Alexa, C, Alexander, G, Alexopoulos, T, Alhroob, M, Alimonti, G, Alio, L, Alison, J, Alkire, SP, Allbrooke, BMM, Allport, PP, Aloisio, A, Alonso, A, Alonso, F, Alpigiani, C, Altheimer, A, Alvarez Gonzalez, B, Álvarez Piqueras, D, Alviggi, MG, Amadio, BT, Amako, K, Amaral Coutinho, Y, Amelung, C, Amidei, D, Amor Dos Santos, SP, Amorim, A, Amoroso, S, Amram, N, Amundsen, G, Anastopoulos, C, Ancu, LS, Andari, N, Andeen, T, Anders, CF, Anders, G, Anders, JK, Anderson, KJ, Andreazza, A, Andrei, V, Angelidakis, S, Angelozzi, I, Anger, P, Angerami, A, Anghinolfi, F, Anisenkov, AV, Anjos, N, Annovi, A, Antonelli, M, Antonov, A, Antos, J, Anulli, F, Aoki, M, Aperio Bella, L, Arabidze, G, Arai, Y, Araque, JP, Arce, ATH, Arduh, FA, Arguin, J-F, Argyropoulos, S, Arik, M, Armbruster, AJ, Arnaez, O, Arnal, V, Arnold, H, Arratia, M, Arslan, O, and Artamonov, A
Subjects: Nuclear and Plasma Physics, Particle and High Energy Physics, Physical Sciences, ATLAS Collaboration, hep-ex, Atomic, Molecular, Nuclear, Particle and Plasma Physics, Quantum Physics, Nuclear & Particles Physics, Astronomical sciences, Atomic, molecular and optical physics, Particle and high energy physics
Abstract: The top quark mass was measured in the channels tt → lepton+jets and tt → dilepton (lepton = e, μ) based on ATLAS data recorded in 2011. The data were taken at the LHC with a proton–proton centre-of-mass energy of √s = 7 TeV and correspond to an integrated luminosity of 4.6 fb−1. The tt → lepton+jets analysis uses a three-dimensional template technique which determines the top quark mass together with a global jet energy scale factor (JSF), and a relative b-to-light-jet energy scale factor (bJSF), where the terms b-jets and light-jets refer to jets originating from b-quarks and u, d, c, s-quarks or gluons, respectively. The analysis of the tt → dilepton channel exploits a one-dimensional template method using the mℓb observable, defined as the average invariant mass of the two lepton+b-jet pairs in each event. The top quark mass is measured to be 172.33 ± 0.75(stat + JSF + bJSF) ± 1.02(syst) GeV, and 173.79 ± 0.54(stat) ± 1.30(syst) GeV in the tt → lepton+jets and tt → dilepton channels, respectively. The combination of the two results yields mtop = 172.99 ± 0.48(stat) ± 0.78(syst) GeV, with a total uncertainty of 0.91 GeV.
Published: 2015

236. Constraints on the off-shell Higgs boson signal strength in the high-mass ZZ and WW final states with the ATLAS detector

Author: ATLAS Collaboration, Aad, G, Abbott, B, Abdallah, J, Abdinov, O, Aben, R, Abolins, M, AbouZeid, OS, Abramowicz, H, Abreu, H, Abreu, R, Abulaiti, Y, Acharya, BS, Adamczyk, L, Adams, DL, Adelman, J, Adomeit, S, Adye, T, Affolder, AA, Agatonovic-Jovin, T, Aguilar-Saavedra, JA, Agustoni, M, Ahlen, SP, Ahmadov, F, Aielli, G, Akerstedt, H, Åkesson, TPA, Akimoto, G, Akimov, AV, Alberghi, GL, Albert, J, Albrand, S, Alconada Verzini, MJ, Aleksa, M, Aleksandrov, IN, Alexa, C, Alexander, G, Alexopoulos, T, Alhroob, M, Alimonti, G, Alio, L, Alison, J, Alkire, SP, Allbrooke, BMM, Allport, PP, Aloisio, A, Alonso, A, Alonso, F, Alpigiani, C, Altheimer, A, Alvarez Gonzalez, B, Piqueras, D Álvarez, Alviggi, MG, Amako, K, Amaral Coutinho, Y, Amelung, C, Amidei, D, Amor Dos Santos, SP, Amorim, A, Amoroso, S, Amram, N, Amundsen, G, Anastopoulos, C, Ancu, LS, Andari, N, Andeen, T, Anders, CF, Anders, G, Anderson, KJ, Andreazza, A, Andrei, V, Angelidakis, S, Angelozzi, I, Anger, P, Angerami, A, Anghinolfi, F, Anisenkov, AV, Anjos, N, Annovi, A, Antonelli, M, Antonov, A, Antos, J, Anulli, F, Aoki, M, Aperio Bella, L, Arabidze, G, Arai, Y, Araque, JP, Arce, ATH, Arduh, FA, Arguin, J-F, Argyropoulos, S, Arik, M, Armbruster, AJ, Arnaez, O, Arnal, V, Arnold, H, Arratia, M, Arslan, O, and Artamonov, A
Subjects: Nuclear and Plasma Physics, Particle and High Energy Physics, Physical Sciences, Affordable and Clean Energy, ATLAS Collaboration, hep-ex, Atomic, Molecular, Nuclear, Particle and Plasma Physics, Quantum Physics, Nuclear & Particles Physics, Astronomical sciences, Atomic, molecular and optical physics, Particle and high energy physics
Abstract: Measurements of the ZZ and WW final states in the mass range above the [Formula: see text] and [Formula: see text] thresholds provide a unique opportunity to measure the off-shell coupling strength of the Higgs boson. This paper presents constraints on the off-shell Higgs boson event yields normalised to the Standard Model prediction (signal strength) in the [Formula: see text], [Formula: see text] and [Formula: see text] final states. The result is based on pp collision data collected by the ATLAS experiment at the LHC, corresponding to an integrated luminosity of 20.3 fb[Formula: see text] at a collision energy of [Formula: see text] TeV. Using the [Formula: see text] method, the observed 95 [Formula: see text] confidence level (CL) upper limit on the off-shell signal strength is in the range 5.1-8.6, with an expected range of 6.7-11.0. In each case the range is determined by varying the unknown [Formula: see text] and [Formula: see text] background K-factor from higher-order quantum chromodynamics corrections between half and twice the value of the known signal K-factor. Assuming the relevant Higgs boson couplings are independent of the energy scale of the Higgs boson production, a combination with the on-shell measurements yields an observed (expected) 95 [Formula: see text] CL upper limit on [Formula: see text] in the range 4.5-7.5 (6.5-11.2) using the same variations of the background K-factor. Assuming that the unknown [Formula: see text] background K-factor is equal to the signal K-factor, this translates into an observed (expected) 95 [Formula: see text] CL upper limit on the Higgs boson total width of 22.7 (33.0) MeV.
Published: 2015

237. Identification and energy calibration of hadronically decaying tau leptons with the ATLAS experiment in pp collisions at s=8TeV

Author: Aad, G, Abbott, B, Abdallah, J, Abdel Khalek, S, Abdinov, O, Aben, R, Abi, B, Abolins, M, AbouZeid, OS, Abramowicz, H, Abreu, H, Abreu, R, Abulaiti, Y, Acharya, BS, Adamczyk, L, Adams, DL, Adelman, J, Adomeit, S, Adye, T, Agatonovic-Jovin, T, Aguilar-Saavedra, JA, Agustoni, M, Ahlen, SP, Ahmadov, F, Aielli, G, Akerstedt, H, Åkesson, TPA, Akimoto, G, Akimov, AV, Alberghi, GL, Albert, J, Albrand, S, Alconada Verzini, MJ, Aleksa, M, Aleksandrov, IN, Alexa, C, Alexander, G, Alexandre, G, Alexopoulos, T, Alhroob, M, Alimonti, G, Alio, L, Alison, J, Allbrooke, BMM, Allison, LJ, Allport, PP, Aloisio, A, Alonso, A, Alonso, F, Alpigiani, C, Altheimer, A, Alvarez Gonzalez, B, Alviggi, MG, Amako, K, Amaral Coutinho, Y, Amelung, C, Amidei, D, Amor Dos Santos, SP, Amorim, A, Amoroso, S, Amram, N, Amundsen, G, Anastopoulos, C, Ancu, LS, Andari, N, Andeen, T, Anders, CF, Anders, G, Anderson, KJ, Andreazza, A, Andrei, V, Anduaga, XS, Angelidakis, S, Angelozzi, I, Anger, P, Angerami, A, Anghinolfi, F, Anisenkov, AV, Anjos, N, Annovi, A, Antonaki, A, Antonelli, M, Antonov, A, Antos, J, Anulli, F, Aoki, M, Aperio Bella, L, Apolle, R, Arabidze, G, Aracena, I, Arai, Y, Araque, JP, Arce, ATH, Arduh, FA, Arguin, J-F, Argyropoulos, S, Arik, M, Armbruster, AJ, Arnaez, O, and Arnal, V
Subjects: Nuclear and Plasma Physics, Particle and High Energy Physics, Physical Sciences, Affordable and Clean Energy, Atlas Collaboration, hep-ex, Atomic, Molecular, Nuclear, Particle and Plasma Physics, Quantum Physics, Nuclear & Particles Physics, Astronomical sciences, Atomic, molecular and optical physics, Particle and high energy physics
Abstract: This paper describes the trigger and offline reconstruction, identification and energy calibration algorithms for hadronic decays of tau leptons employed for the data collected from pp collisions in 2012 with the ATLAS detector at the LHC center-of-mass energy [Formula: see text] [Formula: see text]. The performance of these algorithms is measured in most cases with [Formula: see text] decays to tau leptons using the full 2012 dataset, corresponding to an integrated luminosity of 20.3 fb[Formula: see text]. An uncertainty on the offline reconstructed tau energy scale of 2-4 %, depending on transverse energy and pseudorapidity, is achieved using two independent methods. The offline tau identification efficiency is measured with a precision of 2.5 % for hadronically decaying tau leptons with one associated track, and of 4 % for the case of three associated tracks, inclusive in pseudorapidity and for a visible transverse energy greater than 20 [Formula: see text]. For hadronic tau lepton decays selected by offline algorithms, the tau trigger identification efficiency is measured with a precision of 2-8 %, depending on the transverse energy. The performance of the tau algorithms, both offline and at the trigger level, is found to be stable with respect to the number of concurrent proton-proton interactions and has supported a variety of physics results using hadronically decaying tau leptons at ATLAS.
Published: 2015

238. Search for new phenomena in final states with an energetic jet and large missing transverse momentum in pp collisions at s=8TeV with the ATLAS detector

Author: Aad, G, Abbott, B, Abdallah, J, Abdel Khalek, S, Abdinov, O, Aben, R, Abi, B, Abolins, M, AbouZeid, OS, Abramowicz, H, Abreu, H, Abreu, R, Abulaiti, Y, Acharya, BS, Adamczyk, L, Adams, DL, Adelman, J, Adomeit, S, Adye, T, Agatonovic-Jovin, T, Aguilar-Saavedra, JA, Agustoni, M, Ahlen, SP, Ahmadov, F, Aielli, G, Akerstedt, H, Åkesson, TPA, Akimoto, G, Akimov, AV, Alberghi, GL, Albert, J, Albrand, S, Alconada Verzini, MJ, Aleksa, M, Aleksandrov, IN, Alexa, C, Alexander, G, Alexandre, G, Alexopoulos, T, Alhroob, M, Alimonti, G, Alio, L, Alison, J, Allbrooke, BMM, Allison, LJ, Allport, PP, Aloisio, A, Alonso, A, Alonso, F, Alpigiani, C, Altheimer, A, Alvarez Gonzalez, B, Alviggi, MG, Amako, K, Amaral Coutinho, Y, Amelung, C, Amidei, D, Amor Dos Santos, SP, Amorim, A, Amoroso, S, Amram, N, Amundsen, G, Anastopoulos, C, Ancu, LS, Andari, N, Andeen, T, Anders, CF, Anders, G, Anderson, KJ, Andreazza, A, Andrei, V, Anduaga, XS, Angelidakis, S, Angelozzi, I, Anger, P, Angerami, A, Anghinolfi, F, Anisenkov, AV, Anjos, N, Annovi, A, Antonelli, M, Antonov, A, Antos, J, Anulli, F, Aoki, M, Aperio Bella, L, Arabidze, G, Arai, Y, Araque, JP, Arce, ATH, Arduh, FA, Arguin, J-F, Argyropoulos, S, Arik, M, Armbruster, AJ, Arnaez, O, Arnal, V, Arnold, H, Arratia, M, and Arslan, O
Subjects: Nuclear and Plasma Physics, Particle and High Energy Physics, Physical Sciences, ATLAS Collaboration, hep-ex, Atomic, Molecular, Nuclear, Particle and Plasma Physics, Quantum Physics, Nuclear & Particles Physics, Astronomical sciences, Atomic, molecular and optical physics, Particle and high energy physics
Abstract: Results of a search for new phenomena in final states with an energetic jet and large missing transverse momentum are reported. The search uses 20.3 fb[Formula: see text] of [Formula: see text] TeV data collected in 2012 with the ATLAS detector at the LHC. Events are required to have at least one jet with [Formula: see text] GeV and no leptons. Nine signal regions are considered with increasing missing transverse momentum requirements between [Formula: see text] GeV and [Formula: see text] GeV. Good agreement is observed between the number of events in data and Standard Model expectations. The results are translated into exclusion limits on models with either large extra spatial dimensions, pair production of weakly interacting dark matter candidates, or production of very light gravitinos in a gauge-mediated supersymmetric model. In addition, limits on the production of an invisibly decaying Higgs-like boson leading to similar topologies in the final state are presented.
Published: 2015

239. Differential top-antitop cross-section measurements as a function of observables constructed from final-state particles using pp collisions at √s = 7 TeV in the ATLAS detector

Author: The ATLAS collaboration, Aad, G, Abbott, B, Abdallah, J, Abdel Khalek, S, Abdinov, O, Aben, R, Abi, B, Abolins, M, AbouZeid, OS, Abramowicz, H, Abreu, H, Abreu, R, Abulaiti, Y, Acharya, BS, Adamczyk, L, Adams, DL, Adelman, J, Adomeit, S, Adye, T, Agatonovic-Jovin, T, Aguilar-Saavedra, JA, Agustoni, M, Ahlen, SP, Ahmadov, F, Aielli, G, Akerstedt, H, Åkesson, TPA, Akimoto, G, Akimov, AV, Alberghi, GL, Albert, J, Albrand, S, Alconada Verzini, MJ, Aleksa, M, Aleksandrov, IN, Alexa, C, Alexander, G, Alexandre, G, Alexopoulos, T, Alhroob, M, Alimonti, G, Alio, L, Alison, J, Allbrooke, BMM, Allison, LJ, Allport, PP, Aloisio, A, Alonso, A, Alonso, F, Alpigiani, C, Altheimer, A, Alvarez Gonzalez, B, Alviggi, MG, Amako, K, Amaral Coutinho, Y, Amelung, C, Amidei, D, Amor Dos Santos, SP, Amorim, A, Amoroso, S, Amram, N, Amundsen, G, Anastopoulos, C, Ancu, LS, Andari, N, Andeen, T, Anders, CF, Anders, G, Anderson, KJ, Andreazza, A, Andrei, V, Anduaga, XS, Angelidakis, S, Angelozzi, I, Anger, P, Angerami, A, Anghinolfi, F, Anisenkov, AV, Anjos, N, Annovi, A, Antonelli, M, Antonov, A, Antos, J, Anulli, F, Aoki, M, Aperio Bella, L, Arabidze, G, Arai, Y, Araque, JP, Arce, ATH, Arduh, FA, Arguin, JF, Argyropoulos, S, Arik, M, Armbruster, AJ, Arnaez, O, Arnal, V, Arnold, H, and Arratia, M
Subjects: Hadron-Hadron Scattering, Top physics, Bioengineering, hep-ex, Nuclear & Particles Physics, Mathematical Physics, Atomic, Molecular, Nuclear, Particle and Plasma Physics, Quantum Physics
Abstract: Abstract: Various differential cross-sections are measured in top-quark pair (tt) events produced in proton-proton collisions at a centre-of-mass energy of √s = 7 TeV at the LHC with the ATLAS detector. These differential cross-sections are presented in a data set corresponding to an integrated luminosity of 4.6 fb−1. The differential cross-sections are presented in terms of kinematic variables, such as momentum, rapidity and invariant mass, of a top-quark proxy referred to as the pseudo-top-quark as well as the pseudo-top-quark pair system. The dependence of the measurement on theoretical models is minimal. The measurements are performed on tt events in the lepton+jets channel, requiring exactly one charged lepton and at least four jets with at least two of them tagged as originating from a b-quark. The hadronic and leptonic pseudo-top-quarks are defined via the leptonic or hadronic decay mode of the W boson produced by the top-quark decay in events with a single charged lepton. Differential cross-section measurements of the pseudo-top-quark variables are compared with several Monte Carlo models that implement next-to-leading order or leading-order multi-leg matrix-element calculations.
Published: 2015

240. Measurement of the top pair production cross section in 8 TeV proton-proton collisions using kinematic information in the lepton + jets final state with ATLAS

Author: Aad, G, Abbott, B, Abdallah, J, Abdel Khalek, S, Abdinov, O, Aben, R, Abi, B, Abolins, M, Abouzeid, OS, Abramowicz, H, Abreu, H, Abreu, R, Abulaiti, Y, Acharya, BS, Adamczyk, L, Adams, DL, Adelman, J, Adomeit, S, Adye, T, Agatonovic-Jovin, T, Aguilar-Saavedra, JA, Agustoni, M, Ahlen, SP, Ahmadov, F, Aielli, G, Akerstedt, H, Åkesson, TPA, Akimoto, G, Akimov, AV, Alberghi, GL, Albert, J, Albrand, S, Alconada Verzini, MJ, Aleksa, M, Aleksandrov, IN, Alexa, C, Alexander, G, Alexandre, G, Alexopoulos, T, Alhroob, M, Alimonti, G, Alio, L, Alison, J, Allbrooke, BMM, Allison, LJ, Allport, PP, Aloisio, A, Alonso, A, Alonso, F, Alpigiani, C, Altheimer, A, Alvarez Gonzalez, B, Alviggi, MG, Amako, K, Amaral Coutinho, Y, Amelung, C, Amidei, D, Amor Dos Santos, SP, Amorim, A, Amoroso, S, Amram, N, Amundsen, G, Anastopoulos, C, Ancu, LS, Andari, N, Andeen, T, Anders, CF, Anders, G, Anderson, KJ, Andreazza, A, Andrei, V, Anduaga, XS, Angelidakis, S, Angelozzi, I, Anger, P, Angerami, A, Anghinolfi, F, Anisenkov, AV, Anjos, N, Annovi, A, Antonelli, M, Antonov, A, Antos, J, Anulli, F, Aoki, M, Aperio Bella, L, Arabidze, G, Arai, Y, Araque, JP, Arce, ATH, Arduh, FA, Arguin, JF, Argyropoulos, S, Arik, M, Armbruster, AJ, Arnaez, O, Arnal, V, Arnold, H, Arratia, M, and Arslan, O
Subjects: hep-ex, Nuclear & Particles Physics, Astronomical and Space Sciences, Atomic, Molecular, Nuclear, Particle and Plasma Physics, Quantum Physics, Atomic, Molecular, Nuclear, Particle and Plasma Physics
Abstract: A measurement is presented of the (formula presented) inclusive production cross section in pp collisions at a center-of-mass energy of (formula presented) using data collected by the ATLAS detector at the CERN Large Hadron pffiffi Collider. The measurement was performed in the lepton + jets final state using a data set corresponding to an integrated luminosity of 20.3 fb-1. The cross section was obtained using a likelihood discriminant fit and b-jet identification was used to improve the signal-to-background ratio. The inclusive tt production cross section was measured to be (formula presented) pb assuming a top-quark mass of 172.5 GeV, in good agreement with the theoretical prediction of (formula presented) pb. The (formula presented) production cross section in the fiducial region determined by the detector acceptance is also reported.
Published: 2015

241. Search for vectorlike B quarks in events with one isolated lepton, missing transverse momentum, and jets at s =8 TeV with the ATLAS detector

Author: Aad, G, Abbott, B, Abdallah, J, Abdinov, O, Aben, R, Abolins, M, Abouzeid, OS, Abramowicz, H, Abreu, H, Abreu, R, Abulaiti, Y, Acharya, BS, Adamczyk, L, Adams, DL, Adelman, J, Adomeit, S, Adye, T, Affolder, AA, Agatonovic-Jovin, T, Aguilar-Saavedra, JA, Agustoni, M, Ahlen, SP, Ahmadov, F, Aielli, G, Akerstedt, H, Åkesson, TPA, Akimoto, G, Akimov, AV, Alberghi, GL, Albert, J, Albrand, S, Alconada Verzini, MJ, Aleksa, M, Aleksandrov, IN, Alexa, C, Alexander, G, Alexopoulos, T, Alhroob, M, Alimonti, G, Alio, L, Alison, J, Alkire, SP, Allbrooke, BMM, Allport, PP, Aloisio, A, Alonso, A, Alonso, F, Alpigiani, C, Altheimer, A, Alvarez Gonzalez, B, Álvarez Piqueras, D, Alviggi, MG, Amako, K, Amaral Coutinho, Y, Amelung, C, Amidei, D, Amor Dos Santos, SP, Amorim, A, Amoroso, S, Amram, N, Amundsen, G, Anastopoulos, C, Ancu, LS, Andari, N, Andeen, T, Anders, CF, Anders, G, Anderson, KJ, Andreazza, A, Andrei, V, Angelidakis, S, Angelozzi, I, Anger, P, Angerami, A, Anghinolfi, F, Anisenkov, AV, Anjos, N, Annovi, A, Antonelli, M, Antonov, A, Antos, J, Anulli, F, Aoki, M, Aperio Bella, L, Arabidze, G, Arai, Y, Araque, JP, Arce, ATH, Arduh, FA, Arguin, JF, Argyropoulos, S, Arik, M, Armbruster, AJ, Arnaez, O, Arnal, V, Arnold, H, Arratia, M, Arslan, O, Artamonov, A, and Artoni, G
Subjects: hep-ex, Nuclear & Particles Physics, Astronomical and Space Sciences, Atomic, Molecular, Nuclear, Particle and Plasma Physics, Quantum Physics, Atomic, Molecular, Nuclear, Particle and Plasma Physics
Abstract: A search has been performed for pair production of heavy vectorlike down-type (B) quarks. The analysis explores the lepton-plus-jets final state, characterized by events with one isolated charged lepton (electron or muon), significant missing transverse momentum, and multiple jets. One or more jets are required to be tagged as arising from b quarks, and at least one pair of jets must be tagged as arising from the hadronic decay of an electroweak boson. The analysis uses the full data sample of pp collisions recorded in 2012 by the ATLAS detector at the LHC, operating at a center-of-mass energy of 8 TeV, corresponding to an integrated luminosity of 20.3 fb-1. No significant excess of events is observed above the expected background. Limits are set on vectorlike B production, as a function of the B branching ratios, assuming the allowable decay modes are B→Wt/Zb/Hb. In the chiral limit with a branching ratio of 100% for the decay B→Wt, the observed (expected) 95% C.L. lower limit on the vectorlike B mass is 810 GeV (760 GeV). In the case where the vectorlike B quark has branching ratio values corresponding to those of an SU(2) singlet state, the observed (expected) 95% C.L. lower limit on the vectorlike B mass is 640 GeV (505 GeV). The same analysis, when used to investigate pair production of a colored, charge 5/3 exotic fermion T5/3, with subsequent decay T5/3→Wt, sets an observed (expected) 95% C.L. lower limit on the T5/3 mass of 840 GeV (780 GeV).
Published: 2015

242. Search for a Charged Higgs Boson Produced in the Vector-Boson Fusion Mode with Decay H±→W±Z using pp Collisions at s=8 TeV with the ATLAS Experiment

Author: Aad, G, Abbott, B, Abdallah, J, Abdinov, O, Aben, R, Abolins, M, AbouZeid, OS, Abramowicz, H, Abreu, H, Abreu, R, Abulaiti, Y, Acharya, BS, Adamczyk, L, Adams, DL, Adelman, J, Adomeit, S, Adye, T, Affolder, AA, Agatonovic-Jovin, T, Aguilar-Saavedra, JA, Ahlen, SP, Ahmadov, F, Aielli, G, Akerstedt, H, Åkesson, TPA, Akimoto, G, Akimov, AV, Alberghi, GL, Albert, J, Albrand, S, Verzini, MJ Alconada, Aleksa, M, Aleksandrov, IN, Alexa, C, Alexander, G, Alexopoulos, T, Alhroob, M, Alimonti, G, Alio, L, Alison, J, Alkire, SP, Allbrooke, BMM, Allport, PP, Aloisio, A, Alonso, A, Alonso, F, Alpigiani, C, Altheimer, A, Gonzalez, B Alvarez, Piqueras, D Álvarez, Alviggi, MG, Amadio, BT, Amako, K, Coutinho, Y Amaral, Amelung, C, Amidei, D, Dos Santos, SP Amor, Amorim, A, Amoroso, S, Amram, N, Amundsen, G, Anastopoulos, C, Ancu, LS, Andari, N, Andeen, T, Anders, CF, Anders, G, Anders, JK, Anderson, KJ, Andreazza, A, Andrei, V, Angelidakis, S, Angelozzi, I, Anger, P, Angerami, A, Anghinolfi, F, Anisenkov, AV, Anjos, N, Annovi, A, Antonelli, M, Antonov, A, Antos, J, Anulli, F, Aoki, M, Bella, L Aperio, Arabidze, G, Arai, Y, Araque, JP, Arce, ATH, Arduh, FA, Arguin, J-F, Argyropoulos, S, Arik, M, Armbruster, AJ, Arnaez, O, Arnal, V, Arnold, H, Arratia, M, Arslan, O, and Artamonov, A
Subjects: Nuclear and Plasma Physics, Particle and High Energy Physics, Physical Sciences, ATLAS Collaboration, hep-ex, Mathematical Sciences, Engineering, General Physics, Mathematical sciences, Physical sciences
Abstract: A search for a charged Higgs boson, H(±), decaying to a W(±) boson and a Z boson is presented. The search is based on 20.3 fb(-1) of proton-proton collision data at a center-of-mass energy of 8 TeV recorded with the ATLAS detector at the LHC. The H(±) boson is assumed to be produced via vector-boson fusion and the decays W(±)→qq' and Z→e(+)e(-)/μ(+)μ(-) are considered. The search is performed in a range of charged Higgs boson masses from 200 to 1000 GeV. No evidence for the production of an H(±) boson is observed. Upper limits of 31-1020 fb at 95% C.L. are placed on the cross section for vector-boson fusion production of an H(±) boson times its branching fraction to W(±)Z. The limits are compared with predictions from the Georgi-Machacek Higgs triplet model.
Published: 2015

243. Search for a Charged Higgs Boson Produced in the Vector-Boson Fusion Mode with Decay H(±)→W(±)Z using pp Collisions at √s=8 TeV with the ATLAS Experiment.

Author: Aad, G, Abbott, B, Abdallah, J, Abdinov, O, Aben, R, Abolins, M, AbouZeid, OS, Abramowicz, H, Abreu, H, Abreu, R, Abulaiti, Y, Acharya, BS, Adamczyk, L, Adams, DL, Adelman, J, Adomeit, S, Adye, T, Affolder, AA, Agatonovic-Jovin, T, Aguilar-Saavedra, JA, Ahlen, SP, Ahmadov, F, Aielli, G, Akerstedt, H, Åkesson, TPA, Akimoto, G, Akimov, AV, Alberghi, GL, Albert, J, Albrand, S, Alconada Verzini, MJ, Aleksa, M, Aleksandrov, IN, Alexa, C, Alexander, G, Alexopoulos, T, Alhroob, M, Alimonti, G, Alio, L, Alison, J, Alkire, SP, Allbrooke, BMM, Allport, PP, Aloisio, A, Alonso, A, Alonso, F, Alpigiani, C, Altheimer, A, Alvarez Gonzalez, B, Álvarez Piqueras, D, Alviggi, MG, Amadio, BT, Amako, K, Amaral Coutinho, Y, Amelung, C, Amidei, D, Amor Dos Santos, SP, Amorim, A, Amoroso, S, Amram, N, Amundsen, G, Anastopoulos, C, Ancu, LS, Andari, N, Andeen, T, Anders, CF, Anders, G, Anders, JK, Anderson, KJ, Andreazza, A, Andrei, V, Angelidakis, S, Angelozzi, I, Anger, P, Angerami, A, Anghinolfi, F, Anisenkov, AV, Anjos, N, Annovi, A, Antonelli, M, Antonov, A, Antos, J, Anulli, F, Aoki, M, Aperio Bella, L, Arabidze, G, Arai, Y, Araque, JP, Arce, ATH, Arduh, FA, Arguin, J-F, Argyropoulos, S, Arik, M, Armbruster, AJ, Arnaez, O, Arnal, V, Arnold, H, Arratia, M, Arslan, O, and Artamonov, A
Subjects: ATLAS Collaboration, hep-ex, General Physics, Mathematical Sciences, Physical Sciences, Engineering
Abstract: A search for a charged Higgs boson, H(±), decaying to a W(±) boson and a Z boson is presented. The search is based on 20.3 fb(-1) of proton-proton collision data at a center-of-mass energy of 8 TeV recorded with the ATLAS detector at the LHC. The H(±) boson is assumed to be produced via vector-boson fusion and the decays W(±)→qq' and Z→e(+)e(-)/μ(+)μ(-) are considered. The search is performed in a range of charged Higgs boson masses from 200 to 1000 GeV. No evidence for the production of an H(±) boson is observed. Upper limits of 31-1020 fb at 95% C.L. are placed on the cross section for vector-boson fusion production of an H(±) boson times its branching fraction to W(±)Z. The limits are compared with predictions from the Georgi-Machacek Higgs triplet model.
Published: 2015

244. Search for New Phenomena in Dijet Angular Distributions in Proton-Proton Collisions at s=8 TeV Measured with the ATLAS Detector

Author: Aad, G, Abbott, B, Abdallah, J, Abdinov, O, Aben, R, Abolins, M, AbouZeid, OS, Abramowicz, H, Abreu, H, Abreu, R, Abulaiti, Y, Acharya, BS, Adamczyk, L, Adams, DL, Adelman, J, Adomeit, S, Adye, T, Affolder, AA, Agatonovic-Jovin, T, Aguilar-Saavedra, JA, Ahlen, SP, Ahmadov, F, Aielli, G, Akerstedt, H, Åkesson, TPA, Akimoto, G, Akimov, AV, Alberghi, GL, Albert, J, Albrand, S, Verzini, MJ Alconada, Aleksa, M, Aleksandrov, IN, Alexa, C, Alexander, G, Alexopoulos, T, Alhroob, M, Alimonti, G, Alio, L, Alison, J, Alkire, SP, Allbrooke, BMM, Allport, PP, Aloisio, A, Alonso, A, Alonso, F, Alpigiani, C, Altheimer, A, Gonzalez, B Alvarez, Piqueras, D Álvarez, Alviggi, MG, Amadio, BT, Amako, K, Coutinho, Y Amaral, Amelung, C, Amidei, D, Dos Santos, SP Amor, Amorim, A, Amoroso, S, Amram, N, Amundsen, G, Anastopoulos, C, Ancu, LS, Andari, N, Andeen, T, Anders, CF, Anders, G, Anders, JK, Anderson, KJ, Andreazza, A, Andrei, V, Angelidakis, S, Angelozzi, I, Anger, P, Angerami, A, Anghinolfi, F, Anisenkov, AV, Anjos, N, Annovi, A, Antonelli, M, Antonov, A, Antos, J, Anulli, F, Aoki, M, Bella, L Aperio, Arabidze, G, Arai, Y, Araque, JP, Arce, ATH, Arduh, FA, Arguin, J-F, Argyropoulos, S, Arik, M, Armbruster, AJ, Arnaez, O, Arnal, V, Arnold, H, Arratia, M, Arslan, O, and Artamonov, A
Subjects: Nuclear and Plasma Physics, Particle and High Energy Physics, Physical Sciences, ATLAS Collaboration, hep-ex, Mathematical Sciences, Engineering, General Physics, Mathematical sciences, Physical sciences
Abstract: A search for new phenomena in LHC proton-proton collisions at a center-of-mass energy of sqrt[s]=8 TeV was performed with the ATLAS detector using an integrated luminosity of 17.3 fb^{-1}. The angular distributions are studied in events with at least two jets; the highest dijet mass observed is 5.5 TeV. All angular distributions are consistent with the predictions of the standard model. In a benchmark model of quark contact interactions, a compositeness scale below 8.1 TeV in a destructive interference scenario and 12.0 TeV in a constructive interference scenario is excluded at 95% C.L.; median expected limits are 8.9 TeV for the destructive interference scenario and 14.1 TeV for the constructive interference scenario.
Published: 2015

245. Search for massive supersymmetric particles decaying to many jets using the ATLAS detector in pp collisions at s=8 TeV

Author: Aad, G, Abbott, B, Abdallah, J, Khalek, S Abdel, Abdinov, O, Aben, R, Abi, B, Abolins, M, AbouZeid, OS, Abramowicz, H, Abreu, H, Abreu, R, Abulaiti, Y, Acharya, BS, Adamczyk, L, Adams, DL, Adelman, J, Adomeit, S, Adye, T, Agatonovic-Jovin, T, Aguilar-Saavedra, JA, Agustoni, M, Ahlen, SP, Ahmadov, F, Aielli, G, Akerstedt, H, Åkesson, TPA, Akimoto, G, Akimov, AV, Alberghi, GL, Albert, J, Albrand, S, Verzini, MJ Alconada, Aleksa, M, Aleksandrov, IN, Alexa, C, Alexander, G, Alexopoulos, T, Alhroob, M, Alimonti, G, Alio, L, Alison, J, Allbrooke, BMM, Allison, LJ, Allport, PP, Aloisio, A, Alonso, A, Alonso, F, Alpigiani, C, Altheimer, A, Gonzalez, B Alvarez, Alviggi, MG, Amako, K, Coutinho, Y Amaral, Amelung, C, Amidei, D, Dos Santos, SP Amor, Amorim, A, Amoroso, S, Amram, N, Amundsen, G, Anastopoulos, C, Ancu, LS, Andari, N, Andeen, T, Anders, CF, Anders, G, Anderson, KJ, Andreazza, A, Andrei, V, Anduaga, XS, Angelidakis, S, Angelozzi, I, Anger, P, Angerami, A, Anghinolfi, F, Anisenkov, AV, Anjos, N, Annovi, A, Antonelli, M, Antonov, A, Antos, J, Anulli, F, Aoki, M, Bella, L Aperio, Arabidze, G, Arai, Y, Araque, JP, Arce, ATH, Arduh, FA, Arguin, J-F, Argyropoulos, S, Arik, M, Armbruster, AJ, Arnaez, O, Arnal, V, Arnold, H, Arratia, M, Arslan, O, and Artamonov, A
Subjects: Nuclear and Plasma Physics, Particle and High Energy Physics, Mathematical Physics, Mathematical Sciences, Physical Sciences, hep-ex
Abstract: Results of a search for decays of massive particles to fully hadronic final states are presented. This search uses 20.3 fb-1 of data collected by the ATLAS detector in s=8 TeV proton-proton collisions at the LHC. Signatures based on high jet multiplicities without requirements on the missing transverse momentum are used to search for R-parity-violating supersymmetric gluino pair production with subsequent decays to quarks. The analysis is performed using a requirement on the number of jets, in combination with separate requirements on the number of b-tagged jets, as well as a topological observable formed from the scalar sum of the mass values of large-radius jets in the event. Results are interpreted in the context of all possible branching ratios of direct gluino decays to various quark flavors. No significant deviation is observed from the expected Standard Model backgrounds estimated using jet counting as well as data-driven templates of the total-jet-mass spectra. Gluino pair decays to ten or more quarks via intermediate neutralinos are excluded for a gluino with mass mg
Published: 2015

246. Measurement of the top pair production cross section in 8 TeV proton-proton collisions using kinematic information in the lepton+jets final state with ATLAS

Author: Aad, G, Abbott, B, Abdallah, J, Khalek, S Abdel, Abdinov, O, Aben, R, Abi, B, Abolins, M, AbouZeid, OS, Abramowicz, H, Abreu, H, Abreu, R, Abulaiti, Y, Acharya, BS, Adamczyk, L, Adams, DL, Adelman, J, Adomeit, S, Adye, T, Agatonovic-Jovin, T, Aguilar-Saavedra, JA, Agustoni, M, Ahlen, SP, Ahmadov, F, Aielli, G, Akerstedt, H, Åkesson, TPA, Akimoto, G, Akimov, AV, Alberghi, GL, Albert, J, Albrand, S, Verzini, MJ Alconada, Aleksa, M, Aleksandrov, IN, Alexa, C, Alexander, G, Alexandre, G, Alexopoulos, T, Alhroob, M, Alimonti, G, Alio, L, Alison, J, Allbrooke, BMM, Allison, LJ, Allport, PP, Aloisio, A, Alonso, A, Alonso, F, Alpigiani, C, Altheimer, A, Gonzalez, B Alvarez, Alviggi, MG, Amako, K, Coutinho, Y Amaral, Amelung, C, Amidei, D, Dos Santos, SP Amor, Amorim, A, Amoroso, S, Amram, N, Amundsen, G, Anastopoulos, C, Ancu, LS, Andari, N, Andeen, T, Anders, CF, Anders, G, Anderson, KJ, Andreazza, A, Andrei, V, Anduaga, XS, Angelidakis, S, Angelozzi, I, Anger, P, Angerami, A, Anghinolfi, F, Anisenkov, AV, Anjos, N, Annovi, A, Antonelli, M, Antonov, A, Antos, J, Anulli, F, Aoki, M, Bella, L Aperio, Arabidze, G, Arai, Y, Araque, JP, Arce, ATH, Arduh, FA, Arguin, J-F, Argyropoulos, S, Arik, M, Armbruster, AJ, Arnaez, O, Arnal, V, Arnold, H, Arratia, M, and Arslan, O
Subjects: Nuclear and Plasma Physics, Particle and High Energy Physics, Physical Sciences, hep-ex
Abstract: A measurement is presented of the (formula presented) inclusive production cross section in pp collisions at a center-of-mass energy of (formula presented) using data collected by the ATLAS detector at the CERN Large Hadron pffiffi Collider. The measurement was performed in the lepton + jets final state using a data set corresponding to an integrated luminosity of 20.3 fb-1. The cross section was obtained using a likelihood discriminant fit and b-jet identification was used to improve the signal-to-background ratio. The inclusive tt production cross section was measured to be (formula presented) pb assuming a top-quark mass of 172.5 GeV, in good agreement with the theoretical prediction of (formula presented) pb. The (formula presented) production cross section in the fiducial region determined by the detector acceptance is also reported.
Published: 2015

247. Search for vectorlike B quarks in events with one isolated lepton, missing transverse momentum, and jets at s=8 TeV with the ATLAS detector

Author: Aad, G, Abbott, B, Abdallah, J, Abdinov, O, Aben, R, Abolins, M, AbouZeid, OS, Abramowicz, H, Abreu, H, Abreu, R, Abulaiti, Y, Acharya, BS, Adamczyk, L, Adams, DL, Adelman, J, Adomeit, S, Adye, T, Affolder, AA, Agatonovic-Jovin, T, Aguilar-Saavedra, JA, Agustoni, M, Ahlen, SP, Ahmadov, F, Aielli, G, Akerstedt, H, Åkesson, TPA, Akimoto, G, Akimov, AV, Alberghi, GL, Albert, J, Albrand, S, Verzini, MJ Alconada, Aleksa, M, Aleksandrov, IN, Alexa, C, Alexander, G, Alexopoulos, T, Alhroob, M, Alimonti, G, Alio, L, Alison, J, Alkire, SP, Allbrooke, BMM, Allport, PP, Aloisio, A, Alonso, A, Alonso, F, Alpigiani, C, Altheimer, A, Gonzalez, B Alvarez, Piqueras, D Álvarez, Alviggi, MG, Amako, K, Coutinho, Y Amaral, Amelung, C, Amidei, D, Dos Santos, SP Amor, Amorim, A, Amoroso, S, Amram, N, Amundsen, G, Anastopoulos, C, Ancu, LS, Andari, N, Andeen, T, Anders, CF, Anders, G, Anderson, KJ, Andreazza, A, Andrei, V, Angelidakis, S, Angelozzi, I, Anger, P, Angerami, A, Anghinolfi, F, Anisenkov, AV, Anjos, N, Annovi, A, Antonelli, M, Antonov, A, Antos, J, Anulli, F, Aoki, M, Bella, L Aperio, Arabidze, G, Arai, Y, Araque, JP, Arce, ATH, Arduh, FA, Arguin, J-F, Argyropoulos, S, Arik, M, Armbruster, AJ, Arnaez, O, Arnal, V, Arnold, H, Arratia, M, Arslan, O, Artamonov, A, and Artoni, G
Subjects: Nuclear and Plasma Physics, Particle and High Energy Physics, Mathematical Physics, Mathematical Sciences, Physical Sciences, hep-ex
Abstract: A search has been performed for pair production of heavy vectorlike down-type (B) quarks. The analysis explores the lepton-plus-jets final state, characterized by events with one isolated charged lepton (electron or muon), significant missing transverse momentum, and multiple jets. One or more jets are required to be tagged as arising from b quarks, and at least one pair of jets must be tagged as arising from the hadronic decay of an electroweak boson. The analysis uses the full data sample of pp collisions recorded in 2012 by the ATLAS detector at the LHC, operating at a center-of-mass energy of 8 TeV, corresponding to an integrated luminosity of 20.3 fb-1. No significant excess of events is observed above the expected background. Limits are set on vectorlike B production, as a function of the B branching ratios, assuming the allowable decay modes are B→Wt/Zb/Hb. In the chiral limit with a branching ratio of 100% for the decay B→Wt, the observed (expected) 95% C.L. lower limit on the vectorlike B mass is 810 GeV (760 GeV). In the case where the vectorlike B quark has branching ratio values corresponding to those of an SU(2) singlet state, the observed (expected) 95% C.L. lower limit on the vectorlike B mass is 640 GeV (505 GeV). The same analysis, when used to investigate pair production of a colored, charge 5/3 exotic fermion T5/3, with subsequent decay T5/3→Wt, sets an observed (expected) 95% C.L. lower limit on the T5/3 mass of 840 GeV (780 GeV).
Published: 2015

248. Search for a new resonance decaying to a W or Z boson and a Higgs boson in the ℓℓ/ℓν/νν+bb¯ final states with the ATLAS detector

Author: Aad, G, Abbott, B, Abdallah, J, Abdinov, O, Aben, R, Abolins, M, AbouZeid, OS, Abramowicz, H, Abreu, H, Abreu, R, Abulaiti, Y, Acharya, BS, Adamczyk, L, Adams, DL, Adelman, J, Adomeit, S, Adye, T, Affolder, AA, Agatonovic-Jovin, T, Aguilar-Saavedra, JA, Ahlen, SP, Ahmadov, F, Aielli, G, Akerstedt, H, Åkesson, TPA, Akimoto, G, Akimov, AV, Alberghi, GL, Albert, J, Albrand, S, Alconada Verzini, MJ, Aleksa, M, Aleksandrov, IN, Alexa, C, Alexander, G, Alexopoulos, T, Alhroob, M, Alimonti, G, Alio, L, Alison, J, Alkire, SP, Allbrooke, BMM, Allport, PP, Aloisio, A, Alonso, A, Alonso, F, Alpigiani, C, Altheimer, A, Alvarez Gonzalez, B, Piqueras, D Álvarez, Alviggi, MG, Amadio, BT, Amako, K, Amaral Coutinho, Y, Amelung, C, Amidei, D, Amor Dos Santos, SP, Amorim, A, Amoroso, S, Amram, N, Amundsen, G, Anastopoulos, C, Ancu, LS, Andari, N, Andeen, T, Anders, CF, Anders, G, Anders, JK, Anderson, KJ, Andreazza, A, Andrei, V, Angelidakis, S, Angelozzi, I, Anger, P, Angerami, A, Anghinolfi, F, Anisenkov, AV, Anjos, N, Annovi, A, Antonelli, M, Antonov, A, Antos, J, Anulli, F, Aoki, M, Aperio Bella, L, Arabidze, G, Arai, Y, Araque, JP, Arce, ATH, Arduh, FA, Arguin, J-F, Argyropoulos, S, Arik, M, Armbruster, AJ, Arnaez, O, Arnal, V, Arnold, H, Arratia, M, Arslan, O, and Artamonov, A
Subjects: Nuclear and Plasma Physics, Particle and High Energy Physics, Physical Sciences, ATLAS collaboration, hep-ex, Atomic, Molecular, Nuclear, Particle and Plasma Physics, Quantum Physics, Nuclear & Particles Physics, Astronomical sciences, Atomic, molecular and optical physics, Particle and high energy physics
Abstract: A search for a new resonance decaying to a W or Z boson and a Higgs boson in the [Formula: see text] final states is performed using 20.3 fb[Formula: see text] of pp collision data recorded at [Formula: see text] 8 TeV with the ATLAS detector at the Large Hadron Collider. The search is conducted by examining the WH / ZH invariant mass distribution for a localized excess. No significant deviation from the Standard Model background prediction is observed. The results are interpreted in terms of constraints on the Minimal Walking Technicolor model and on a simplified approach based on a phenomenological Lagrangian of Heavy Vector Triplets.
Published: 2015

249. Differential top-antitop cross-section measurements as a function of observables constructed from final-state particles using pp collisions at s=7 TeV in the ATLAS detector

Author: The ATLAS collaboration, Aad, G, Abbott, B, Abdallah, J, Abdel Khalek, S, Abdinov, O, Aben, R, Abi, B, Abolins, M, AbouZeid, OS, Abramowicz, H, Abreu, H, Abreu, R, Abulaiti, Y, Acharya, BS, Adamczyk, L, Adams, DL, Adelman, J, Adomeit, S, Adye, T, Agatonovic-Jovin, T, Aguilar-Saavedra, JA, Agustoni, M, Ahlen, SP, Ahmadov, F, Aielli, G, Akerstedt, H, Åkesson, TPA, Akimoto, G, Akimov, AV, Alberghi, GL, Albert, J, Albrand, S, Alconada Verzini, MJ, Aleksa, M, Aleksandrov, IN, Alexa, C, Alexander, G, Alexandre, G, Alexopoulos, T, Alhroob, M, Alimonti, G, Alio, L, Alison, J, Allbrooke, BMM, Allison, LJ, Allport, PP, Aloisio, A, Alonso, A, Alonso, F, Alpigiani, C, Altheimer, A, Alvarez Gonzalez, B, Alviggi, MG, Amako, K, Amaral Coutinho, Y, Amelung, C, Amidei, D, Amor Dos Santos, SP, Amorim, A, Amoroso, S, Amram, N, Amundsen, G, Anastopoulos, C, Ancu, LS, Andari, N, Andeen, T, Anders, CF, Anders, G, Anderson, KJ, Andreazza, A, Andrei, V, Anduaga, XS, Angelidakis, S, Angelozzi, I, Anger, P, Angerami, A, Anghinolfi, F, Anisenkov, AV, Anjos, N, Annovi, A, Antonelli, M, Antonov, A, Antos, J, Anulli, F, Aoki, M, Aperio Bella, L, Arabidze, G, Arai, Y, Araque, JP, Arce, ATH, Arduh, FA, Arguin, J-F, Argyropoulos, S, Arik, M, Armbruster, AJ, Arnaez, O, Arnal, V, Arnold, H, and Arratia, M
Subjects: Nuclear and Plasma Physics, Particle and High Energy Physics, Mathematical Physics, Mathematical Sciences, Physical Sciences, Hadron-Hadron Scattering, Top physics, hep-ex, Atomic, Molecular, Nuclear, Particle and Plasma Physics, Quantum Physics, Nuclear & Particles Physics, Mathematical physics, Nuclear and plasma physics, Particle and high energy physics
Abstract: Abstract: Various differential cross-sections are measured in top-quark pair (tt) events produced in proton-proton collisions at a centre-of-mass energy of √s = 7 TeV at the LHC with the ATLAS detector. These differential cross-sections are presented in a data set corresponding to an integrated luminosity of 4.6 fb−1. The differential cross-sections are presented in terms of kinematic variables, such as momentum, rapidity and invariant mass, of a top-quark proxy referred to as the pseudo-top-quark as well as the pseudo-top-quark pair system. The dependence of the measurement on theoretical models is minimal. The measurements are performed on tt events in the lepton+jets channel, requiring exactly one charged lepton and at least four jets with at least two of them tagged as originating from a b-quark. The hadronic and leptonic pseudo-top-quarks are defined via the leptonic or hadronic decay mode of the W boson produced by the top-quark decay in events with a single charged lepton. Differential cross-section measurements of the pseudo-top-quark variables are compared with several Monte Carlo models that implement next-to-leading order or leading-order multi-leg matrix-element calculations.
Published: 2015

250. Measurement of the charge asymmetry in dileptonic decays of top quark pairs in pp collisions at √s = 7 TeV using the ATLAS detector

Author: The ATLAS collaboration, Aad, G, Abbott, B, Abdallah, J, Abdel Khalek, S, Abdinov, O, Aben, R, Abi, B, Abolins, M, AbouZeid, OS, Abramowicz, H, Abreu, H, Abreu, R, Abulaiti, Y, Acharya, BS, Adamczyk, L, Adams, DL, Adelman, J, Adomeit, S, Adye, T, Agatonovic-Jovin, T, Aguilar-Saavedra, JA, Agustoni, M, Ahlen, SP, Ahmadov, F, Aielli, G, Akerstedt, H, Åkesson, TPA, Akimoto, G, Akimov, AV, Alberghi, GL, Albert, J, Albrand, S, Alconada Verzini, MJ, Aleksa, M, Aleksandrov, IN, Alexa, C, Alexander, G, Alexandre, G, Alexopoulos, T, Alhroob, M, Alimonti, G, Alio, L, Alison, J, Allbrooke, BMM, Allison, LJ, Allport, PP, Aloisio, A, Alonso, A, Alonso, F, Alpigiani, C, Altheimer, A, Alvarez Gonzalez, B, Alviggi, MG, Amako, K, Amaral Coutinho, Y, Amelung, C, Amidei, D, Amor Dos Santos, SP, Amorim, A, Amoroso, S, Amram, N, Amundsen, G, Anastopoulos, C, Ancu, LS, Andari, N, Andeen, T, Anders, CF, Anders, G, Anderson, KJ, Andreazza, A, Andrei, V, Anduaga, XS, Angelidakis, S, Angelozzi, I, Anger, P, Angerami, A, Anghinolfi, F, Anisenkov, AV, Anjos, N, Annovi, A, Antonaki, A, Antonelli, M, Antonov, A, Antos, J, Anulli, F, Aoki, M, Aperio Bella, L, Apolle, R, Arabidze, G, Aracena, I, Arai, Y, Araque, JP, Arce, ATH, Arduh, FA, Arguin, JF, Argyropoulos, S, Arik, M, Armbruster, AJ, and Arnaez, O
Subjects: Hadron-Hadron Scattering, Top physics, hep-ex, Nuclear & Particles Physics, Mathematical Physics, Atomic, Molecular, Nuclear, Particle and Plasma Physics, Quantum Physics
Abstract: A measurement of the top-antitop (tt¯) charge asymmetry is presented using data corresponding to an integrated luminosity of 4.6 fb−1 of LHC pp collisions at a centreof-mass energy of 7 TeV collected by the ATLAS detector. Events with two charged leptons, at least two jets and large missing transverse momentum are selected. Two observables are studied: ACℓℓ based on the identified charged leptons, and (Formula Presented.), based on the reconstructed tt final state. The asymmetries are measured to be (Formula Presented.). The measured values are in agreement with the Standard Model predictions.[Figure not available: see fulltext.]
Published: 2015

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