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1,651 results on '"Aderholz, M"'

1. Hadronic Calibration of the ATLAS Liquid Argon End-Cap Calorimeter in the Pseudorapidity Region 1.6 < |eta| < 1.8 in Beam Tests

Author: Cojocaru, C., Pinfold, J., Soukup, J., Vincter, M., Datskov, V., Fedorov, A., Golubykh, S., Javadov, N., Kalinnikov, V., Kakurin, S., Kazarinov, M., Kukhtin, V., Ladygin, E., Lazarev, A., Neganov, A., Pisarev, I., Rousakovitch, N., Serochkin, E., Shilov, S., Shalyugin, A., Usov, Yu., Bruncko, D., Chytracek, R., Kladiva, E., Strizenec, P., Barreiro, F., Garcia, G., Labarga, F., Rodier, S., del Peso, J., Heldmann, M., Jakobs, K., Koepke, L., Othegraven, R., Schroff, D., Thomas, J., Zeitnitz, C., Barrillon, P., Benchouk, C., Djama, F., Henry-Couannier, F., Hinz, L., Hubaut, F., Monnier, E., Olivier, C., Pralavorio, P., Raymond, M., Sauvage, D., Serfon, C., Tisserant, S., Toth, J., Azuelos, G., Leroy, C., Mehdiyev, R., Akimov, A., Blagov, M., Komar, A., Snesarev, A., Speransky, M., Sulin, V., Yakimenko, M., Aderholz, M., Barillari, T., Bartko, H., Cwienk, W., Fischer, A., Habring, J., Huber, J., Karev, A., Kiryunin, A., Kurchaninov, L., Menke, S., Mooshofer, P., Oberlack, H., Salihagic, D., Schacht, P., Chen, T., Ping, J., Qi, M., Aoulthenko, W., Kazanin, V., Kolatchev, G., Malychev, W., Maslennikov, A., Pospelov, G., Snopkov, R., Shousharo, A., Soukharev, A., Talychev, A., Tikhonov, Y., Chekulaev, S., Denisov, S., Levitsky, M., Minaenko, A., Mitrofanov, G., Moiseev, A., Pleskatch, A., Sytnik, V., Zakamsky, L., Losty, M., Oram, C. J., Wielers, M., Birney, P. S., Fincke-Keeler, M., Gable, I., Hodges, T. A., Hughes, T., Ince, T., Kanaya, N., Keeler, R. K., Langstaff, R., Lefebvre, M., Lenckowski, M., McPherson, R., Braun, H. M., and Thadome, J.
Subjects: Physics - Instrumentation and Detectors
Abstract: A full azimuthal phi-wedge of the ATLAS liquid argon end-cap calorimeter has been exposed to beams of electrons, muons and pions in the energy range 6 GeV <= E <= 200 GeV at the CERN SPS. The angular region studied corresponds to the ATLAS impact position around the pseudorapidity interval 1.6 < |eta| < 1.8. The beam test set-up is described. A detailed study of the performance is given as well as the related intercalibration constants obtained. Following the ATLAS hadronic calibration proposal, a first study of the hadron calibration using a weighting ansatz is presented. The results are compared to predictions from Monte Carlo simulations, based on GEANT 3 and GEANT 4 models., Comment: 66 pages, 60 Postscript figures, submitted to NIM A
Published: 2004
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2. Single hadron response measurement and calorimeter jet energy scale uncertainty with the ATLAS detector at the LHC

Author: Aad, G, Abbott, B, Abdallah, J, Abdelalim, AA, Abdesselam, A, Abdinov, O, Abi, B, Abolins, M, Zeid, OSA, Abramowicz, H, Abreu, H, Acerbi, E, Acharya, BS, Adamczyk, L, Adams, DL, Addy, TN, Adelman, J, Aderholz, M, Adomeit, S, Adragna, P, Adye, T, Aefsky, S, Aguilar-Saavedra, JA, Aharrouche, M, Ahlen, SP, Ahles, F, Ahmad, A, Ahsan, M, Aielli, G, Akdogan, T, Åkesson, TPA, Akimoto, G, Akimov, AV, Akiyama, A, Alam, MS, Alam, MA, Albert, J, Albrand, S, Aleksa, M, Aleksandrov, IN, Alessandria, F, Alexa, C, Alexander, G, Alexandre, G, Alexopoulos, T, Alhroob, M, Aliev, M, Alimonti, G, Alison, J, Aliyev, M, Allbrooke, BMM, Allport, PP, Allwood-Spiers, SE, Almond, J, Aloisio, A, Alon, R, Alonso, A, Gonzalez, BA, Alviggi, MG, Amako, K, Amaral, P, Amelung, C, Ammosov, VV, Amorim, A, Amorós, G, Amram, N, Anastopoulos, C, Ancu, LS, Andari, N, Andeen, T, Anders, CF, Anders, G, Anderson, KJ, Andreazza, A, Andrei, V, Andrieux, ML, Anduaga, XS, Angerami, A, Anghinolfi, F, Anisenkov, A, Anjos, N, Annovi, A, Antonaki, A, Antonelli, M, Antonov, A, Antos, J, Anulli, F, Aoun, S, Bella, LA, Apolle, R, Arabidze, G, Aracena, I, Arai, Y, Arce, ATH, Arfaoui, S, Arguin, JF, Arik, E, Arik, M, Armbruster, AJ, and Arnaez, O
Subjects: hep-ex, Nuclear & Particles Physics, Quantum Physics, Atomic, Molecular, Nuclear, Particle and Plasma Physics, Atomic, Molecular, Nuclear, Particle and Plasma Physics
Abstract: The uncertainty on the calorimeter energy response to jets of particles is derived for the ATLAS experiment at the Large Hadron Collider (LHC). First, the calorimeter response to single isolated charged hadrons is measured and compared to the Monte Carlo simulation using proton-proton collisions at centre-of-mass energies of √s = 900 GeV and 7 TeV collected during 2009 and 2010. Then, using the decay of Ks and Λ particles, the calorimeter response to specific types of particles (positively and negatively charged pions, protons, and anti-protons) is measured and compared to the Monte Carlo predictions. Finally, the jet energy scale uncertainty is determined by propagating the response uncertainty for single charged and neutral particles to jets. The response uncertainty is 2–5 % for central isolated hadrons and 1–3 % for the final calorimeter jet energy scale.
Published: 2013

3. Single hadron response measurement and calorimeter jet energy scale uncertainty with the ATLAS detector at the LHC

Author: The ATLAS Collaboration, Aad, G, Abbott, B, Abdallah, J, Abdelalim, AA, Abdesselam, A, Abdinov, O, Abi, B, Abolins, M, AbouZeid, OS, Abramowicz, H, Abreu, H, Acerbi, E, Acharya, BS, Adamczyk, L, Adams, DL, Addy, TN, Adelman, J, Aderholz, M, Adomeit, S, Adragna, P, Adye, T, Aefsky, S, Aguilar-Saavedra, JA, Aharrouche, M, Ahlen, SP, Ahles, F, Ahmad, A, Ahsan, M, Aielli, G, Akdogan, T, Åkesson, TPA, Akimoto, G, Akimov, AV, Akiyama, A, Alam, MS, Alam, MA, Albert, J, Albrand, S, Aleksa, M, Aleksandrov, IN, Alessandria, F, Alexa, C, Alexander, G, Alexandre, G, Alexopoulos, T, Alhroob, M, Aliev, M, Alimonti, G, Alison, J, Aliyev, M, Allbrooke, BMM, Allport, PP, Allwood-Spiers, SE, Almond, J, Aloisio, A, Alon, R, Alonso, A, Alvarez Gonzalez, B, Alviggi, MG, Amako, K, Amaral, P, Amelung, C, Ammosov, VV, Amorim, A, Amorós, G, Amram, N, Anastopoulos, C, Ancu, LS, Andari, N, Andeen, T, Anders, CF, Anders, G, Anderson, KJ, Andreazza, A, Andrei, V, Andrieux, M-L, Anduaga, XS, Angerami, A, Anghinolfi, F, Anisenkov, A, Anjos, N, Annovi, A, Antonaki, A, Antonelli, M, Antonov, A, Antos, J, Anulli, F, Aoun, S, Aperio Bella, L, Apolle, R, Arabidze, G, Aracena, I, Arai, Y, Arce, ATH, Arfaoui, S, Arguin, J-F, Arik, E, Arik, M, and Armbruster, AJ
Subjects: Nuclear and Plasma Physics, Particle and High Energy Physics, Physical Sciences, 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 uncertainty on the calorimeter energy response to jets of particles is derived for the ATLAS experiment at the Large Hadron Collider (LHC). First, the calorimeter response to single isolated charged hadrons is measured and compared to the Monte Carlo simulation using proton-proton collisions at centre-of-mass energies of √s = 900 GeV and 7 TeV collected during 2009 and 2010. Then, using the decay of Ks and Λ particles, the calorimeter response to specific types of particles (positively and negatively charged pions, protons, and anti-protons) is measured and compared to the Monte Carlo predictions. Finally, the jet energy scale uncertainty is determined by propagating the response uncertainty for single charged and neutral particles to jets. The response uncertainty is 2–5 % for central isolated hadrons and 1–3 % for the final calorimeter jet energy scale.
Published: 2013

4. Jet energy measurement with the ATLAS detector in proton-proton collisions at

Author: The ATLAS Collaboration, Aad, G, Abbott, B, Abdallah, J, Abdelalim, AA, Abdesselam, A, Abdinov, O, Abi, B, Abolins, M, Abramowicz, H, Abreu, H, Acerbi, E, Acharya, BS, Adams, DL, Addy, TN, Adelman, J, Aderholz, M, Adomeit, S, Adragna, P, Adye, T, Aefsky, S, Aguilar-Saavedra, JA, Aharrouche, M, Ahlen, SP, Ahles, F, Ahmad, A, Ahsan, M, Aielli, G, Akdogan, T, Åkesson, TPA, Akimoto, G, Akimov, AV, Akiyama, A, Aktas, A, Alam, MS, Alam, MA, Albert, J, Albrand, S, Aleksa, M, Aleksandrov, IN, Alessandria, F, Alexa, C, Alexander, G, Alexandre, G, Alexopoulos, T, Alhroob, M, Aliev, M, Alimonti, G, Alison, J, Aliyev, M, Allport, PP, Allwood-Spiers, SE, Almond, J, Aloisio, A, Alon, R, Alonso, A, Alviggi, MG, Amako, K, Amaral, P, Amelung, C, Ammosov, VV, Amorim, A, Amorós, G, Amram, N, Anastopoulos, C, Ancu, LS, Andari, N, Andeen, T, Anders, CF, Anders, G, Anderson, KJ, Andreazza, A, Andrei, V, Andrieux, M-L, Anduaga, XS, Angerami, A, Anghinolfi, F, Anjos, N, Annovi, A, Antonaki, A, Antonelli, M, Antonov, A, Antos, J, Anulli, F, Aoun, S, Aperio Bella, L, Apolle, R, Arabidze, G, Aracena, I, Arai, Y, Arce, ATH, Archambault, JP, Arfaoui, S, Arguin, J-F, Arik, E, Arik, M, Armbruster, AJ, Arnaez, O, Arnault, C, and Artamonov, A
Subjects: Nuclear and Plasma Physics, Particle and High Energy Physics, Physical Sciences, 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 jet energy scale and its systematic uncertainty are determined for jets measured with the ATLAS detector at the LHC in proton-proton collision data at a centre-of-mass energy of √ s = 7 TeV corresponding to an integrated luminosity of 38 pb-1. Jets are reconstructed with the anti-kt algorithm with distance parameters R = 0.4 or R = 0.6. Jet energy and angle corrections are determined from Monte Carlo simulations to calibrate jets with transverse momenta pT ≥ 20 GeV and pseudorapidities |η| < 4.5. The jet energy systematic uncertainty is estimated using the single isolated hadron response measured in situ and in test-beams, exploiting the transverse momentum balance between central and forward jets in events with dijet topologies and studying systematic variations in Monte Carlo simulations. The jet energy uncertainty is less than 2.5 % in the central calorimeter region (|η| < 0.8) for jets with 60 ≤ pT < 800 GeV, and is maximally 14 % for pT ≤ 30 GeV in the most forward region 3.2 ≤ |η| < 4.5. The jet energy is validated for jet transverse momenta up to 1 TeV to the level of a few percent using several in situ techniques by comparing a well-known reference such as the recoiling photon pT, the sum of the transverse momenta of tracks associated to the jet, or a system of low-pT jets recoiling against a high-pT jet. More sophisticated jet calibration schemes are presented based on calorimeter cell energy density weighting or hadronic properties of jets, aiming for an improved jet energy resolution and a reduced flavour dependence of the jet response. The systematic uncertainty of the jet energy determined from a combination of in situ techniques is consistent with the one derived from single hadron response measurements over a wide kinematic range. The nominal corrections and uncertainties are derived for isolated jets in an inclusive sample of high-pT jets. Special cases such as event topologies with close-by jets, or selections of samples with an enhanced content of jets originating from light quarks, heavy quarks or gluons are also discussed and the corresponding uncertainties are determined.
Published: 2013

5. Jet energy measurement with the ATLAS detector in proton-proton collisions at √s =7 TeV

Author: Aad, G, Abbott, B, Abdallah, J, Abdelalim, AA, Abdesselam, A, Abdinov, O, Abi, B, Abolins, M, Abramowicz, H, Abreu, H, Acerbi, E, Acharya, BS, Adams, DL, Addy, TN, Adelman, J, Aderholz, M, Adomeit, S, Adragna, P, Adye, T, Aefsky, S, Aguilar-Saavedra, JA, Aharrouche, M, Ahlen, SP, Ahles, F, Ahmad, A, Ahsan, M, Aielli, G, Akdogan, T, Åkesson, TPA, Akimoto, G, Akimov, AV, Akiyama, A, Aktas, A, Alam, MS, Alam, MA, Albert, J, Albrand, S, Aleksa, M, Aleksandrov, IN, Alessandria, F, Alexa, C, Alexander, G, Alexandre, G, Alexopoulos, T, Alhroob, M, Aliev, M, Alimonti, G, Alison, J, Aliyev, M, Allport, PP, Allwood-Spiers, SE, Almond, J, Aloisio, A, Alon, R, Alonso, A, Alviggi, MG, Amako, K, Amaral, P, Amelung, C, Ammosov, VV, Amorim, A, Amorós, G, Amram, N, Anastopoulos, C, Ancu, LS, Andari, N, Andeen, T, Anders, CF, Anders, G, Anderson, KJ, Andreazza, A, Andrei, V, Andrieux, ML, Anduaga, XS, Angerami, A, Anghinolfi, F, Anjos, N, Annovi, A, Antonaki, A, Antonelli, M, Antonov, A, Antos, J, Anulli, F, Aoun, S, Aperio Bella, L, Apolle, R, Arabidze, G, Aracena, I, Arai, Y, Arce, ATH, Archambault, JP, Arfaoui, S, Arguin, JF, Arik, E, Arik, M, Armbruster, AJ, Arnaez, O, Arnault, C, and Artamonov, A
Subjects: hep-ex, Nuclear & Particles Physics, Quantum Physics, Atomic, Molecular, Nuclear, Particle and Plasma Physics, Atomic, Molecular, Nuclear, Particle and Plasma Physics
Abstract: The jet energy scale and its systematic uncertainty are determined for jets measured with the ATLAS detector at the LHC in proton-proton collision data at a centre-of-mass energy of √ s = 7 TeV corresponding to an integrated luminosity of 38 pb-1. Jets are reconstructed with the anti-kt algorithm with distance parameters R = 0.4 or R = 0.6. Jet energy and angle corrections are determined from Monte Carlo simulations to calibrate jets with transverse momenta pT ≥ 20 GeV and pseudorapidities |η| < 4.5. The jet energy systematic uncertainty is estimated using the single isolated hadron response measured in situ and in test-beams, exploiting the transverse momentum balance between central and forward jets in events with dijet topologies and studying systematic variations in Monte Carlo simulations. The jet energy uncertainty is less than 2.5 % in the central calorimeter region (|η| < 0.8) for jets with 60 ≤ pT < 800 GeV, and is maximally 14 % for pT ≤ 30 GeV in the most forward region 3.2 ≤ |η| < 4.5. The jet energy is validated for jet transverse momenta up to 1 TeV to the level of a few percent using several in situ techniques by comparing a well-known reference such as the recoiling photon pT, the sum of the transverse momenta of tracks associated to the jet, or a system of low-pT jets recoiling against a high-pT jet. More sophisticated jet calibration schemes are presented based on calorimeter cell energy density weighting or hadronic properties of jets, aiming for an improved jet energy resolution and a reduced flavour dependence of the jet response. The systematic uncertainty of the jet energy determined from a combination of in situ techniques is consistent with the one derived from single hadron response measurements over a wide kinematic range. The nominal corrections and uncertainties are derived for isolated jets in an inclusive sample of high-pT jets. Special cases such as event topologies with close-by jets, or selections of samples with an enhanced content of jets originating from light quarks, heavy quarks or gluons are also discussed and the corresponding uncertainties are determined.
Published: 2013

6. Measurement of the t-channel single top-quark production cross section in pp collisions at s=7 TeV with the ATLAS detector

Author: Aad, G, Abbott, B, Abdallah, J, Abdel Khalek, S, Abdelalim, AA, Abdesselam, A, Abdinov, O, Abi, B, Abolins, M, AbouZeid, OS, Abramowicz, H, Abreu, H, Acerbi, E, Acharya, BS, Adamczyk, L, Adams, DL, Addy, TN, Adelman, J, Aderholz, M, Adomeit, S, Adragna, P, Adye, T, Aefsky, S, Aguilar-Saavedra, JA, Aharrouche, M, Ahlen, SP, Ahles, F, Ahmad, A, Ahsan, M, Aielli, G, Akdogan, T, Åkesson, TPA, Akimoto, G, Akimov, AV, Akiyama, A, Alam, MS, Alam, MA, Albert, J, Albrand, S, Aleksa, M, Aleksandrov, IN, Alessandria, F, Alexa, C, Alexander, G, Alexandre, G, Alexopoulos, T, Alhroob, M, Aliev, M, Alimonti, G, Alison, J, Aliyev, M, Allbrooke, BMM, Allport, PP, Allwood-Spiers, SE, Almond, J, Aloisio, A, Alon, R, Alonso, A, Alvarez Gonzalez, B, Alviggi, MG, Amako, K, Amaral, P, Amelung, C, Ammosov, VV, Amorim, A, Amorós, G, Amram, N, Anastopoulos, C, Ancu, LS, Andari, N, Andeen, T, Anders, CF, Anders, G, Anderson, KJ, Andreazza, A, Andrei, V, Andrieux, ML, Anduaga, XS, Angerami, A, Anghinolfi, F, Anisenkov, A, Anjos, N, Annovi, A, Antonaki, A, Antonelli, M, Antonov, A, Antos, J, Anulli, F, Aoun, S, Aperio Bella, L, Apolle, R, Arabidze, G, Aracena, I, Arai, Y, Arce, ATH, Arfaoui, S, Arguin, JF, Arik, E, Arik, M, and Armbruster, AJ
Subjects: hep-ex, Nuclear & Particles Physics, Atomic, Molecular, Nuclear, Particle and Plasma Physics, Astronomical and Space Sciences, Mathematical Physics, Atomic, Molecular, Nuclear, Particle and Plasma Physics
Abstract: We report a measurement of the cross section of single top-quark production in the t-channel using 1.04 fb−1 of pp collision data at s=7 TeV recorded with the ATLAS detector at the LHC. Selected events feature one electron or muon, missing transverse momentum, and two or three jets, exactly one of them identified as originating from a b quark. The cross section is measured by fitting the distribution of a multivariate discriminant constructed with a neural network, yielding σt=83±4(stat.)−19+20(syst.) pb, which is in good agreement with the prediction of the Standard Model. Using the ratio of the measured to the theoretically predicted cross section and assuming that the top-quark-related CKM matrix elements obey the relation |Vtb|≫|Vts|,|Vtd|, the coupling strength at the W-t-b vertex is determined to be |Vtb|=1.13−0.13+0.14. If it is assumed that |Vtb|⩽1 a lower limit of |Vtb|>0.75 is obtained at the 95% confidence level.
Published: 2012

7. Measurement of the t-channel single top-quark production cross section in pp collisions at s=7 TeV with the ATLAS detector

Author: Collaboration, ATLAS, Aad, G, Abbott, B, Abdallah, J, Khalek, S Abdel, Abdelalim, AA, Abdesselam, A, Abdinov, O, Abi, B, Abolins, M, AbouZeid, OS, Abramowicz, H, Abreu, H, Acerbi, E, Acharya, BS, Adamczyk, L, Adams, DL, Addy, TN, Adelman, J, Aderholz, M, Adomeit, S, Adragna, P, Adye, T, Aefsky, S, Aguilar-Saavedra, JA, Aharrouche, M, Ahlen, SP, Ahles, F, Ahmad, A, Ahsan, M, Aielli, G, Akdogan, T, Åkesson, TPA, Akimoto, G, Akimov, AV, Akiyama, A, Alam, MS, Alam, MA, Albert, J, Albrand, S, Aleksa, M, Aleksandrov, IN, Alessandria, F, Alexa, C, Alexander, G, Alexandre, G, Alexopoulos, T, Alhroob, M, Aliev, M, Alimonti, G, Alison, J, Aliyev, M, Allbrooke, BMM, Allport, PP, Allwood-Spiers, SE, Almond, J, Aloisio, A, Alon, R, Alonso, A, Gonzalez, B Alvarez, Alviggi, MG, Amako, K, Amaral, P, Amelung, C, Ammosov, VV, Amorim, A, Amorós, G, Amram, N, Anastopoulos, C, Ancu, LS, Andari, N, Andeen, T, Anders, CF, Anders, G, Anderson, KJ, Andreazza, A, Andrei, V, Andrieux, M-L, Anduaga, XS, Angerami, A, Anghinolfi, F, Anisenkov, A, Anjos, N, Annovi, A, Antonaki, A, Antonelli, M, Antonov, A, Antos, J, Anulli, F, Aoun, S, Bella, L Aperio, Apolle, R, Arabidze, G, Aracena, I, Arai, Y, Arce, ATH, Arfaoui, S, Arguin, J-F, Arik, E, and Arik, M
Subjects: hep-ex, Mathematical Physics, Astronomical and Space Sciences, Atomic, Molecular, Nuclear, Particle and Plasma Physics, Nuclear & Particles Physics
Abstract: We report a measurement of the cross section of single top-quark production in the t-channel using 1.04 fb−1 of pp collision data at s=7 TeV recorded with the ATLAS detector at the LHC. Selected events feature one electron or muon, missing transverse momentum, and two or three jets, exactly one of them identified as originating from a b quark. The cross section is measured by fitting the distribution of a multivariate discriminant constructed with a neural network, yielding σt=83±4(stat.)−19+20(syst.) pb, which is in good agreement with the prediction of the Standard Model. Using the ratio of the measured to the theoretically predicted cross section and assuming that the top-quark-related CKM matrix elements obey the relation |Vtb|≫|Vts|,|Vtd|, the coupling strength at the W-t-b vertex is determined to be |Vtb|=1.13−0.13+0.14. If it is assumed that |Vtb|⩽1 a lower limit of |Vtb|>0.75 is obtained at the 95% confidence level.
Published: 2012

8. Search for TeV-scale gravity signatures in final states with leptons and jets with the ATLAS detector at √ s=7 TeV

Author: Aad, G, Abbott, B, Abdallah, J, Abdelalim, AA, Abdesselam, A, Abdinov, O, Abi, B, Abolins, M, AbouZeid, OS, Abramowicz, H, Abreu, H, Acerbi, E, Acharya, BS, Adamczyk, L, Adams, DL, Addy, TN, Adelman, J, Aderholz, M, Adomeit, S, Adragna, P, Adye, T, Aefsky, S, Aguilar-Saavedra, JA, Aharrouche, M, Ahlen, SP, Ahles, F, Ahmad, A, Ahsan, M, Aielli, G, Akdogan, T, Åkesson, TPA, Akimoto, G, Akimov, AV, Akiyama, A, Alam, MS, Alam, MA, Albert, J, Albrand, S, Aleksa, M, Aleksandrov, IN, Alessandria, F, Alexa, C, Alexander, G, Alexandre, G, Alexopoulos, T, Alhroob, M, Aliev, M, Alimonti, G, Alison, J, Aliyev, M, Allbrooke, BMM, Allport, PP, Allwood-Spiers, SE, Almond, J, Aloisio, A, Alon, R, Alonso, A, Alvarez Gonzalez, B, Alviggi, MG, Amako, K, Amaral, P, Amelung, C, Ammosov, VV, Amorim, A, Amorós, G, Amram, N, Anastopoulos, C, Ancu, LS, Andari, N, Andeen, T, Anders, CF, Anders, G, Anderson, KJ, Andreazza, A, Andrei, V, Andrieux, ML, Anduaga, XS, Angerami, A, Anghinolfi, F, Anisenkov, A, Anjos, N, Annovi, A, Antonaki, A, Antonelli, M, Antonov, A, Antos, J, Anulli, F, Aoun, S, Aperio Bella, L, Apolle, R, Arabidze, G, Aracena, I, Arai, Y, Arce, ATH, Arfaoui, S, Arguin, JF, Arik, E, Arik, M, Armbruster, AJ, and Arnaez, O
Subjects: hep-ex, Nuclear & Particles Physics, Atomic, Molecular, Nuclear, Particle and Plasma Physics, Astronomical and Space Sciences, Mathematical Physics, Atomic, Molecular, Nuclear, Particle and Plasma Physics
Abstract: The production of events with multiple high transverse momentum particles including charged leptons and jets is measured, using 1.04 fb-1 of proton-proton collision data recorded by the ATLAS detector during the first half of 2011 at √s=7 TeV. No excess beyond Standard Model expectations is observed, and upper limits on the fiducial cross sections for non-Standard Model production of these final states are set. Using models for string ball and black hole production and decay, exclusion contours are determined as a function of mass threshold and the fundamental gravity scale. © 2012 CERN.
Published: 2012

9. Measurement of the azimuthal ordering of charged hadrons with the ATLAS detector

Author: Aad, G, Abbott, B, Abdallah, J, Abdelalim, AA, Abdesselam, A, Abdinov, O, Abi, B, Abolins, M, Abouzeid, OS, Abramowicz, H, Abreu, H, Acerbi, E, Acharya, BS, Adamczyk, L, Adams, DL, Addy, TN, Adelman, J, Aderholz, M, Adomeit, S, Adragna, P, Adye, T, Aefsky, S, Aguilar-Saavedra, JA, Aharrouche, M, Ahlen, SP, Ahles, F, Ahmad, A, Ahsan, M, Aielli, G, Akdogan, T, Akesson, TPA, Akimoto, G, Akimov, AV, Akiyama, A, Alam, MS, Alam, MA, Albert, J, Albrand, S, Aleksa, M, Aleksandrov, IN, Alessandria, F, Alexa, C, Alexander, G, Alexandre, G, Alexopoulos, T, Alhroob, M, Aliev, M, Alimonti, G, Alison, J, Aliyev, M, Allport, PP, Allwood-Spiers, SE, Almond, J, Aloisio, A, Alon, R, Alonso, A, Alvarez Gonzalez, B, Alviggi, MG, Amako, K, Amaral, P, Amelung, C, Ammosov, VV, Amorim, A, Amorós, G, Amram, N, Anastopoulos, C, Ancu, LS, Andari, N, Andeen, T, Anders, CF, Anders, G, Anderson, KJ, Andreazza, A, Andrei, V, Andrieux, ML, Anduaga, XS, Angerami, A, Anghinolfi, F, Anisenkov, A, Anjos, N, Annovi, A, Antonaki, A, Antonelli, M, Antonov, A, Antos, J, Anulli, F, Aoun, S, Aperio Bella, L, Apolle, R, Arabidze, G, Aracena, I, Arai, Y, Arce, ATH, Archambault, JP, Arfaoui, S, Arguin, JF, Arik, E, Arik, M, Armbruster, AJ, and Arnaez, 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 paper presents a study of the possible ordering of charged hadrons in the azimuthal angle relative to the beam axis in high-energy proton-proton collisions at the Large Hadron Collider (LHC). A spectral analysis of correlations between longitudinal and transverse components of the momentum of the charged hadrons, driven by the search for phenomena related to the structure of the QCD field, is performed. Data were recorded with the ATLAS detector at center-of-mass energies of √s=900GeV and √s=7TeV. The correlations measured in a kinematic region dominated by low-pT particles are not well described by conventional models of hadron production. The measured spectra show features consistent with the fragmentation of a QCD string represented by a helixlike ordered gluon chain. © 2012 CERN.
Published: 2012

10. Search for second generation scalar leptoquarks in pp collisions at √s = 7 TeV with the ATLAS detector

Author: Aad, G, Abbott, B, Abdallah, J, Khalek, SA, Abdelalim, AA, Abdesselam, A, Abdinov, O, Abi, B, Abolins, M, Zeid, OSA, Abramowicz, H, Abreu, H, Acerbi, E, Acharya, BS, Adamczyk, L, Adams, DL, Addy, TN, Adelman, J, Aderholz, M, Adomeit, S, Adragna, P, Adye, T, Aefsky, S, Aguilar-Saavedra, JA, Aharrouche, M, Ahlen, SP, Ahles, F, Ahmad, A, Ahsan, M, Aielli, G, Akdogan, T, Åkesson, TPA, Akimoto, G, Akimov, AV, Akiyama, A, Alam, MS, Alam, MA, Albert, J, Albrand, S, Aleksa, M, Aleksandrov, IN, Alessandria, F, Alexa, C, Alexander, G, Alexandre, G, Alexopoulos, T, Alhroob, M, Aliev, M, Alimonti, G, Alison, J, Aliyev, M, Allbrooke, BMM, Allport, PP, Allwood-Spiers, SE, Almond, J, Aloisio, A, Alon, R, Alonso, A, Gonzalez, BA, Alviggi, MG, Amako, K, Amaral, P, Amelung, C, Ammosov, VV, Amorim, A, Amorós, G, Amram, N, Anastopoulos, C, Ancu, LS, Andari, N, Andeen, T, Anders, CF, Anders, G, Anderson, KJ, Andreazza, A, Andrei, V, Andrieux, ML, Anduaga, XS, Angerami, A, Anghinolfi, F, Anisenkov, A, Anjos, N, Annovi, A, Antonaki, A, Antonelli, M, Antonov, A, Antos, J, Anulli, F, Aoun, S, Bella, LA, Apolle, R, Arabidze, G, Aracena, I, Arai, Y, Arce, ATH, Arfaoui, S, Arguin, JF, Arik, E, Arik, M, and Armbruster, AJ
Subjects: hep-ex, Nuclear & Particles Physics, Quantum Physics, Atomic, Molecular, Nuclear, Particle and Plasma Physics, Atomic, Molecular, Nuclear, Particle and Plasma Physics
Abstract: The results of a search for the production of second generation scalar leptoquarks are presented for final states consisting of either two muons and at least two jets or a muon plus missing transverse momentum and at least two jets. A total of 1.03 fb−1 integrated luminosity of protonproton collision data produced by the Large Hadron Collider at √s = 7 TeV and recorded by the ATLAS detector is used for the search. The event yields in the signal regions are found to be consistent with the Standard Model background expectations. The production of second generation leptoquarks is excluded for a leptoquark mass mLQ < 594 (685) GeV at 95 % confidence level, for a branching ratio of 0.5 (1.0) for leptoquark decay to a muon and a quark.
Published: 2012

11. Search for TeV-scale gravity signatures in final states with leptons and jets with the ATLAS detector at s=7 TeV

Author: Collaboration, ATLAS, Aad, G, Abbott, B, Abdallah, J, Abdelalim, AA, Abdesselam, A, Abdinov, O, Abi, B, Abolins, M, AbouZeid, OS, Abramowicz, H, Abreu, H, Acerbi, E, Acharya, BS, Adamczyk, L, Adams, DL, Addy, TN, Adelman, J, Aderholz, M, Adomeit, S, Adragna, P, Adye, T, Aefsky, S, Aguilar-Saavedra, JA, Aharrouche, M, Ahlen, SP, Ahles, F, Ahmad, A, Ahsan, M, Aielli, G, Akdogan, T, Åkesson, TPA, Akimoto, G, Akimov, AV, Akiyama, A, Alam, MS, Alam, MA, Albert, J, Albrand, S, Aleksa, M, Aleksandrov, IN, Alessandria, F, Alexa, C, Alexander, G, Alexandre, G, Alexopoulos, T, Alhroob, M, Aliev, M, Alimonti, G, Alison, J, Aliyev, M, Allbrooke, BMM, Allport, PP, Allwood-Spiers, SE, Almond, J, Aloisio, A, Alon, R, Alonso, A, Gonzalez, B Alvarez, Alviggi, MG, Amako, K, Amaral, P, Amelung, C, Ammosov, VV, Amorim, A, Amorós, G, Amram, N, Anastopoulos, C, Ancu, LS, Andari, N, Andeen, T, Anders, CF, Anders, G, Anderson, KJ, Andreazza, A, Andrei, V, Andrieux, M-L, Anduaga, XS, Angerami, A, Anghinolfi, F, Anisenkov, A, Anjos, N, Annovi, A, Antonaki, A, Antonelli, M, Antonov, A, Antos, J, Anulli, F, Aoun, S, Bella, L Aperio, Apolle, R, Arabidze, G, Aracena, I, Arai, Y, Arce, ATH, Arfaoui, S, Arguin, J-F, Arik, E, Arik, M, and Armbruster, AJ
Subjects: hep-ex, Mathematical Physics, Astronomical and Space Sciences, Atomic, Molecular, Nuclear, Particle and Plasma Physics, Nuclear & Particles Physics
Abstract: The production of events with multiple high transverse momentum particles including charged leptons and jets is measured, using 1.04 fb-1 of proton-proton collision data recorded by the ATLAS detector during the first half of 2011 at √s=7 TeV. No excess beyond Standard Model expectations is observed, and upper limits on the fiducial cross sections for non-Standard Model production of these final states are set. Using models for string ball and black hole production and decay, exclusion contours are determined as a function of mass threshold and the fundamental gravity scale. © 2012 CERN.
Published: 2012

12. Search for second generation scalar leptoquarks in pp collisions at with the ATLAS detector

Author: Aad, G, Abbott, B, Abdallah, J, Abdel Khalek, S, Abdelalim, AA, Abdesselam, A, Abdinov, O, Abi, B, Abolins, M, AbouZeid, OS, Abramowicz, H, Abreu, H, Acerbi, E, Acharya, BS, Adamczyk, L, Adams, DL, Addy, TN, Adelman, J, Aderholz, M, Adomeit, S, Adragna, P, Adye, T, Aefsky, S, Aguilar-Saavedra, JA, Aharrouche, M, Ahlen, SP, Ahles, F, Ahmad, A, Ahsan, M, Aielli, G, Akdogan, T, Åkesson, TPA, Akimoto, G, Akimov, AV, Akiyama, A, Alam, MS, Alam, MA, Albert, J, Albrand, S, Aleksa, M, Aleksandrov, IN, Alessandria, F, Alexa, C, Alexander, G, Alexandre, G, Alexopoulos, T, Alhroob, M, Aliev, M, Alimonti, G, Alison, J, Aliyev, M, Allbrooke, BMM, Allport, PP, Allwood-Spiers, SE, Almond, J, Aloisio, A, Alon, R, Alonso, A, Alvarez Gonzalez, B, Alviggi, MG, Amako, K, Amaral, P, Amelung, C, Ammosov, VV, Amorim, A, Amorós, G, Amram, N, Anastopoulos, C, Ancu, LS, Andari, N, Andeen, T, Anders, CF, Anders, G, Anderson, KJ, Andreazza, A, Andrei, V, Andrieux, M-L, Anduaga, XS, Angerami, A, Anghinolfi, F, Anisenkov, A, Anjos, N, Annovi, A, Antonaki, A, Antonelli, M, Antonov, A, Antos, J, Anulli, F, Aoun, S, Aperio Bella, L, Apolle, R, Arabidze, G, Aracena, I, Arai, Y, Arce, ATH, Arfaoui, S, Arguin, J-F, Arik, E, Arik, M, and Armbruster, AJ
Subjects: Nuclear and Plasma Physics, Particle and High Energy Physics, Physical Sciences, 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 results of a search for the production of second generation scalar leptoquarks are presented for final states consisting of either two muons and at least two jets or a muon plus missing transverse momentum and at least two jets. A total of 1.03 fb−1 integrated luminosity of protonproton collision data produced by the Large Hadron Collider at √s = 7 TeV and recorded by the ATLAS detector is used for the search. The event yields in the signal regions are found to be consistent with the Standard Model background expectations. The production of second generation leptoquarks is excluded for a leptoquark mass mLQ < 594 (685) GeV at 95 % confidence level, for a branching ratio of 0.5 (1.0) for leptoquark decay to a muon and a quark.
Published: 2012

13. Search for tb Resonances in Proton-Proton Collisions at s=7 TeV with the ATLAS Detector

Author: Aad, G, Abbott, B, Abdallah, J, Khalek, S Abdel, Abdelalim, AA, Abdesselam, A, Abdinov, O, Abi, B, Abolins, M, AbouZeid, OS, Abramowicz, H, Abreu, H, Acerbi, E, Acharya, BS, Adamczyk, L, Adams, DL, Addy, TN, Adelman, J, Aderholz, M, Adomeit, S, Adragna, P, Adye, T, Aefsky, S, Aguilar-Saavedra, JA, Aharrouche, M, Ahlen, SP, Ahles, F, Ahmad, A, Ahsan, M, Aielli, G, Akdogan, T, Åkesson, TPA, Akimoto, G, Akimov, AV, Akiyama, A, Alam, MS, Alam, MA, Albert, J, Albrand, S, Aleksa, M, Aleksandrov, IN, Alessandria, F, Alexa, C, Alexander, G, Alexandre, G, Alexopoulos, T, Alhroob, M, Aliev, M, Alimonti, G, Alison, J, Aliyev, M, Allbrooke, BMM, Allport, PP, Allwood-Spiers, SE, Almond, J, Aloisio, A, Alon, R, Alonso, A, Gonzalez, B Alvarez, Alviggi, MG, Amako, K, Amaral, P, Amelung, C, Ammosov, VV, Amorim, A, Amorós, G, Amram, N, Anastopoulos, C, Ancu, LS, Andari, N, Andeen, T, Anders, CF, Anders, G, Anderson, KJ, Andreazza, A, Andrei, V, Andrieux, M-L, Anduaga, XS, Angerami, A, Anghinolfi, F, Anisenkov, A, Anjos, N, Annovi, A, Antonaki, A, Antonelli, M, Antonov, A, Antos, J, Anulli, F, Aoun, S, Bella, L Aperio, Apolle, R, Arabidze, G, Aracena, I, Arai, Y, Arce, ATH, Arfaoui, S, Arguin, J-F, Arik, E, Arik, M, and Armbruster, AJ
Subjects: Nuclear and Plasma Physics, Particle and High Energy Physics, Mathematical Physics, Mathematical Sciences, Physical Sciences, ATLAS Collaboration, hep-ex, Engineering, General Physics, Mathematical sciences, Physical sciences
Abstract: This Letter presents a search for tb resonances in 1.04 fb(-1) of LHC proton-proton collision data collected by the ATLAS detector at a center-of-mass energy of 7 TeV. Events with a lepton, missing transverse momentum, and two jets are selected and the invariant mass of the corresponding final state is reconstructed. The search exploits the shape of the tb invariant mass distribution compared to the expected standard model backgrounds. The model of a right-handed W(R)' with standard model-like couplings is chosen as the benchmark model for this search. No statistically significant excess of events is observed in the data, and upper limits on the cross section times the branching ratio of W(R)' resonances at 95% C.L. lie in the range of 6.1-1.0 pb for W(R)' masses ranging from 0.5 to 2.0 TeV. These limits are translated into a lower bound on the allowed right-handed W(R)' mass, giving m(W(R)'))>1.13 TeV at 95% C.L.
Published: 2012

14. Search for tb resonances in proton-proton collisions at √s=7 TeV with the ATLAS detector.

Author: Aad, G, Abbott, B, Abdallah, J, Abdel Khalek, S, Abdelalim, AA, Abdesselam, A, Abdinov, O, Abi, B, Abolins, M, Abouzeid, OS, Abramowicz, H, Abreu, H, Acerbi, E, Acharya, BS, Adamczyk, L, Adams, DL, Addy, TN, Adelman, J, Aderholz, M, Adomeit, S, Adragna, P, Adye, T, Aefsky, S, Aguilar-Saavedra, JA, Aharrouche, M, Ahlen, SP, Ahles, F, Ahmad, A, Ahsan, M, Aielli, G, Akdogan, T, Akesson, TPA, Akimoto, G, Akimov, AV, Akiyama, A, Alam, MS, Alam, MA, Albert, J, Albrand, S, Aleksa, M, Aleksandrov, IN, Alessandria, F, Alexa, C, Alexander, G, Alexandre, G, Alexopoulos, T, Alhroob, M, Aliev, M, Alimonti, G, Alison, J, Aliyev, M, Allbrooke, BMM, Allport, PP, Allwood-Spiers, SE, Almond, J, Aloisio, A, Alon, R, Alonso, A, Alvarez Gonzalez, B, Alviggi, MG, Amako, K, Amaral, P, Amelung, C, Ammosov, VV, Amorim, A, Amorós, G, Amram, N, Anastopoulos, C, Ancu, LS, Andari, N, Andeen, T, Anders, CF, Anders, G, Anderson, KJ, Andreazza, A, Andrei, V, Andrieux, M-L, Anduaga, XS, Angerami, A, Anghinolfi, F, Anisenkov, A, Anjos, N, Annovi, A, Antonaki, A, Antonelli, M, Antonov, A, Antos, J, Anulli, F, Aoun, S, Aperio Bella, L, Apolle, R, Arabidze, G, Aracena, I, Arai, Y, Arce, ATH, Arfaoui, S, Arguin, J-F, Arik, E, Arik, M, and Armbruster, AJ
Subjects: ATLAS Collaboration, hep-ex, General Physics, Mathematical Sciences, Physical Sciences, Engineering
Abstract: This Letter presents a search for tb resonances in 1.04 fb(-1) of LHC proton-proton collision data collected by the ATLAS detector at a center-of-mass energy of 7 TeV. Events with a lepton, missing transverse momentum, and two jets are selected and the invariant mass of the corresponding final state is reconstructed. The search exploits the shape of the tb invariant mass distribution compared to the expected standard model backgrounds. The model of a right-handed W(R)' with standard model-like couplings is chosen as the benchmark model for this search. No statistically significant excess of events is observed in the data, and upper limits on the cross section times the branching ratio of W(R)' resonances at 95% C.L. lie in the range of 6.1-1.0 pb for W(R)' masses ranging from 0.5 to 2.0 TeV. These limits are translated into a lower bound on the allowed right-handed W(R)' mass, giving m(W(R)'))>1.13 TeV at 95% C.L.
Published: 2012

15. Jet mass and substructure of inclusive jets in √s = 7TeV pp collisions with the ATLAS experiment

Author: Aad, G, Abbott, B, Abdallah, J, Abdel Khalek, S, Abdelalim, AA, Abdesselam, A, Abdinov, O, Abi, B, Abolins, M, AbouZeid, OS, Abramowicz, H, Abreu, H, Acerbi, E, Acharya, BS, Adamczyk, L, Adams, DL, Addy, TN, Adelman, J, Aderholz, M, Adomeit, S, Adragna, P, Adye, T, Aefsky, S, Aguilar-Saavedra, JA, Aharrouche, M, Ahlen, SP, Ahles, F, Ahmad, A, Ahsan, M, Aielli, G, Akdogan, T, Åkesson, TPA, Akimoto, G, Akimov, AV, Akiyama, A, Alam, MS, Alam, MA, Albert, J, Albrand, S, Aleksa, M, Aleksandrov, IN, Alessandria, F, Alexa, C, Alexander, G, Alexandre, G, Alexopoulos, T, Alhroob, M, Aliev, M, Alimonti, G, Alison, J, Aliyev, M, Allbrooke, BMM, Allport, PP, Allwood-Spiers, SE, Almond, J, Aloisio, A, Alon, R, Alonso, A, Alvarez Gonzalez, B, Alviggi, MG, Amako, K, Amaral, P, Amelung, C, Ammosov, VV, Amorim, A, Amorós, G, Amram, N, Anastopoulos, C, Ancu, LS, Andari, N, Andeen, T, Anders, CF, Anders, G, Anderson, KJ, Andreazza, A, Andrei, V, Andrieux, ML, Anduaga, XS, Angerami, A, Anghinolfi, F, Anisenkov, A, Anjos, N, Annovi, A, Antonaki, A, Antonelli, M, Antonov, A, Antos, J, Anulli, F, Aoun, S, Aperio Bella, L, Apolle, R, Arabidze, G, Aracena, I, Arai, Y, Arce, ATH, Arfaoui, S, Arguin, JF, Arik, E, Arik, M, and Armbruster, AJ
Subjects: Hadron-Hadron Scattering, hep-ex, Nuclear & Particles Physics, Mathematical Sciences, Physical Sciences, Mathematical Physics, Atomic, Molecular, Nuclear, Particle and Plasma Physics, Quantum Physics, Atomic, Molecular, Nuclear, Particle and Plasma Physics
Abstract: Recent studies have highlighted the potential of jet substructure techniques to identify the hadronic decays of boosted heavy particles. These studies all rely upon the assumption that the internal substructure of jets generated by QCD radiation is well understood. In this article, this assumption is tested on an inclusive sample of jets recorded with the ATLAS detector in 2010, which corresponds to 35 pb -1 of pp collisions delivered by the LHC at Rs = 7TeV.
Published: 2012

16. Search for pair production of a new b' quark that decays into a Z boson and a bottom quark with the ATLAS detector.

Author: Aad, G, Abbott, B, Abdallah, J, Abdel Khalek, S, Abdelalim, AA, Abdesselam, A, Abdinov, O, Abi, B, Abolins, M, Abouzeid, OS, Abramowicz, H, Abreu, H, Acerbi, E, Acharya, BS, Adamczyk, L, Adams, DL, Addy, TN, Adelman, J, Aderholz, M, Adomeit, S, Adragna, P, Adye, T, Aefsky, S, Aguilar-Saavedra, JA, Aharrouche, M, Ahlen, SP, Ahles, F, Ahmad, A, Ahsan, M, Aielli, G, Akdogan, T, Akesson, TPA, Akimoto, G, Akimov, AV, Akiyama, A, Alam, MS, Alam, MA, Albert, J, Albrand, S, Aleksa, M, Aleksandrov, IN, Alessandria, F, Alexa, C, Alexander, G, Alexandre, G, Alexopoulos, T, Alhroob, M, Aliev, M, Alimonti, G, Alison, J, Aliyev, M, Allbrooke, BMM, Allport, PP, Allwood-Spiers, SE, Almond, J, Aloisio, A, Alon, R, Alonso, A, Alvarez Gonzalez, B, Alviggi, MG, Amako, K, Amaral, P, Amelung, C, Ammosov, VV, Amorim, A, Amorós, G, Amram, N, Anastopoulos, C, Ancu, LS, Andari, N, Andeen, T, Anders, CF, Anders, G, Anderson, KJ, Andreazza, A, Andrei, V, Andrieux, M-L, Anduaga, XS, Angerami, A, Anghinolfi, F, Anisenkov, A, Anjos, N, Annovi, A, Antonaki, A, Antonelli, M, Antonov, A, Antos, J, Anulli, F, Aoun, S, Aperio Bella, L, Apolle, R, Arabidze, G, Aracena, I, Arai, Y, Arce, ATH, Arfaoui, S, Arguin, J-F, Arik, E, Arik, M, and Armbruster, AJ
Subjects: ATLAS Collaboration, hep-ex, General Physics, Mathematical Sciences, Physical Sciences, Engineering
Abstract: A search is reported for the pair production of a new quark b' with at least one b' decaying to a Z boson and a bottom quark. The data, corresponding to 2.0 fb(-1) of integrated luminosity, were collected from pp collisions at √s = 7 TeV with the ATLAS detector at the CERN Large Hadron Collider. Using events with a b-tagged jet and a Z boson reconstructed from opposite-charge electrons, the mass distribution of large transverse momentum b' candidates is tested for an enhancement. No evidence for a b' signal is detected in the observed mass distribution, resulting in the exclusion at a 95% confidence level of b' quarks with masses m (b') < 400 GeV that decay entirely via b' → Z+b. In the case of a vectorlike singlet b' mixing solely with the third standard model generation, masses m(b') < 358 GeV are excluded.
Published: 2012

17. Search for supersymmetry with jets, missing transverse momentum and at least one hadronically decaying τ lepton in proton-proton collisions at s=7TeV with the ATLAS detector

Author: Aad, G, Abbott, B, Abdallah, J, Abdel Khalek, S, Abdelalim, AA, Abdesselam, A, Abdinov, O, Abi, B, Abolins, M, AbouZeid, OS, Abramowicz, H, Abreu, H, Acerbi, E, Acharya, BS, Adamczyk, L, Adams, DL, Addy, TN, Adelman, J, Aderholz, M, Adomeit, S, Adragna, P, Adye, T, Aefsky, S, Aguilar-Saavedra, JA, Aharrouche, M, Ahlen, SP, Ahles, F, Ahmad, A, Ahsan, M, Aielli, G, Akdogan, T, Åkesson, TPA, Akimoto, G, Akimov, AV, Akiyama, A, Alam, MS, Alam, MA, Albert, J, Albrand, S, Aleksa, M, Aleksandrov, IN, Alessandria, F, Alexa, C, Alexander, G, Alexandre, G, Alexopoulos, T, Alhroob, M, Aliev, M, Alimonti, G, Alison, J, Aliyev, M, Allbrooke, BMM, Allport, PP, Allwood-Spiers, SE, Almond, J, Aloisio, A, Alon, R, Alonso, A, Alvarez Gonzalez, B, Alviggi, MG, Amako, K, Amaral, P, Amelung, C, Ammosov, VV, Amorim, A, Amorós, G, Amram, N, Anastopoulos, C, Ancu, LS, Andari, N, Andeen, T, Anders, CF, Anders, G, Anderson, KJ, Andreazza, A, Andrei, V, Andrieux, ML, Anduaga, XS, Angerami, A, Anghinolfi, F, Anisenkov, A, Anjos, N, Annovi, A, Antonaki, A, Antonelli, M, Antonov, A, Antos, J, Anulli, F, Aoun, S, Aperio Bella, L, Apolle, R, Arabidze, G, Aracena, I, Arai, Y, Arce, ATH, Arfaoui, S, Arguin, JF, Arik, E, Arik, M, and Armbruster, AJ
Subjects: Supersymmetry, GMSB, Tau lepton, hep-ex, Nuclear & Particles Physics, Atomic, Molecular, Nuclear, Particle and Plasma Physics, Astronomical and Space Sciences, Mathematical Physics, Atomic, Molecular, Nuclear, Particle and Plasma Physics
Abstract: A search for production of supersymmetric particles in final states containing jets, missing transverse momentum, and at least one hadronically decaying τ lepton is presented. The data were recorded by the ATLAS experiment in s=7TeV proton-proton collisions at the Large Hadron Collider. No excess above the Standard Model background expectation was observed in 2.05fb-1 of data. The results are interpreted in the context of gauge mediated supersymmetry breaking models with Mmess=250TeV, N5=3, μ>0, and Cgrav=1. The production of supersymmetric particles is excluded at 95% C.L. up to a supersymmetry breaking scale Λ=30TeV, independent of tanβ, and up to Λ=43TeV for large tanβ. © 2012.
Published: 2012

18. Search for events with large missing transverse momentum, jets, and at least two tau leptons in 7 TeV proton-proton collision data with the ATLAS detector

Author: Aad, G, Abbott, B, Abdallah, J, Abdel Khalek, S, Abdelalim, AA, Abdesselam, A, Abdinov, O, Abi, B, Abolins, M, AbouZeid, OS, Abramowicz, H, Abreu, H, Acerbi, E, Acharya, BS, Adamczyk, L, Adams, DL, Addy, TN, Adelman, J, Aderholz, M, Adomeit, S, Adragna, P, Adye, T, Aefsky, S, Aguilar-Saavedra, JA, Aharrouche, M, Ahlen, SP, Ahles, F, Ahmad, A, Ahsan, M, Aielli, G, Akdogan, T, A°kesson, TPA, Akimoto, G, Akimov, AV, Akiyama, A, Alam, MS, Alam, MA, Albert, J, Albrand, S, Aleksa, M, Aleksandrov, IN, Alessandria, F, Alexa, C, Alexander, G, Alexandre, G, Alexopoulos, T, Alhroob, M, Aliev, M, Alimonti, G, Alison, J, Aliyev, M, Allbrooke, BMM, Allport, PP, Allwood-Spiers, SE, Almond, J, Aloisio, A, Alon, R, Alonso, A, Alvarez Gonzalez, B, Alviggi, MG, Amako, K, Amaral, P, Amelung, C, Ammosov, VV, Amorim, A, Amorós, G, Amram, N, Anastopoulos, C, Ancu, LS, Andari, N, Andeen, T, Anders, CF, Anders, G, Anderson, KJ, Andreazza, A, Andrei, V, Andrieux, ML, Anduaga, XS, Angerami, A, Anghinolfi, F, Anisenkov, A, Anjos, N, Annovi, A, Antonaki, A, Antonelli, M, Antonov, A, Antos, J, Anulli, F, Aoun, S, Aperio Bella, L, Apolle, R, Arabidze, G, Aracena, I, Arai, Y, Arce, ATH, Arfaoui, S, Arguin, JF, Arik, E, Arik, M, and Armbruster, AJ
Subjects: hep-ex, Nuclear & Particles Physics, Atomic, Molecular, Nuclear, Particle and Plasma Physics, Astronomical and Space Sciences, Mathematical Physics, Atomic, Molecular, Nuclear, Particle and Plasma Physics
Abstract: A search for events with large missing transverse momentum, jets, and at least two tau leptons has been performed using 2 fb -1 of proton-proton collision data at s=7 TeV recorded with the ATLAS detector at the Large Hadron Collider. No excess above the Standard Model background expectation is observed and a 95% CL upper limit on the visible cross section for new phenomena is set, where the visible cross section is defined by the product of cross section, branching fraction, detector acceptance and event selection efficiency. A 95% CL lower limit of 32 TeV is set on the gauge-mediated supersymmetry breaking (GMSB) scale Λ independent of tanβ. These limits provide the most stringent tests to date in a large part of the considered parameter space. © 2012.
Published: 2012

19. Search for supersymmetry with jets, missing transverse momentum and at least one hadronically decaying τ lepton in proton–proton collisions at s=7 TeV with the ATLAS detector

Author: Collaboration, ATLAS, Aad, G, Abbott, B, Abdallah, J, Khalek, S Abdel, Abdelalim, AA, Abdesselam, A, Abdinov, O, Abi, B, Abolins, M, AbouZeid, OS, Abramowicz, H, Abreu, H, Acerbi, E, Acharya, BS, Adamczyk, L, Adams, DL, Addy, TN, Adelman, J, Aderholz, M, Adomeit, S, Adragna, P, Adye, T, Aefsky, S, Aguilar-Saavedra, JA, Aharrouche, M, Ahlen, SP, Ahles, F, Ahmad, A, Ahsan, M, Aielli, G, Akdogan, T, Åkesson, TPA, Akimoto, G, Akimov, AV, Akiyama, A, Alam, MS, Alam, MA, Albert, J, Albrand, S, Aleksa, M, Aleksandrov, IN, Alessandria, F, Alexa, C, Alexander, G, Alexandre, G, Alexopoulos, T, Alhroob, M, Aliev, M, Alimonti, G, Alison, J, Aliyev, M, Allbrooke, BMM, Allport, PP, Allwood-Spiers, SE, Almond, J, Aloisio, A, Alon, R, Alonso, A, Gonzalez, B Alvarez, Alviggi, MG, Amako, K, Amaral, P, Amelung, C, Ammosov, VV, Amorim, A, Amorós, G, Amram, N, Anastopoulos, C, Ancu, LS, Andari, N, Andeen, T, Anders, CF, Anders, G, Anderson, KJ, Andreazza, A, Andrei, V, Andrieux, M-L, Anduaga, XS, Angerami, A, Anghinolfi, F, Anisenkov, A, Anjos, N, Annovi, A, Antonaki, A, Antonelli, M, Antonov, A, Antos, J, Anulli, F, Aoun, S, Bella, L Aperio, Apolle, R, Arabidze, G, Aracena, I, Arai, Y, Arce, ATH, Arfaoui, S, Arguin, J-F, Arik, E, and Arik, M
Subjects: Supersymmetry, GMSB, Tau lepton, hep-ex, Mathematical Physics, Astronomical and Space Sciences, Atomic, Molecular, Nuclear, Particle and Plasma Physics, Nuclear & Particles Physics
Abstract: A search for production of supersymmetric particles in final states containing jets, missing transverse momentum, and at least one hadronically decaying τ lepton is presented. The data were recorded by the ATLAS experiment in s=7TeV proton-proton collisions at the Large Hadron Collider. No excess above the Standard Model background expectation was observed in 2.05fb-1 of data. The results are interpreted in the context of gauge mediated supersymmetry breaking models with Mmess=250TeV, N5=3, μ>0, and Cgrav=1. The production of supersymmetric particles is excluded at 95% C.L. up to a supersymmetry breaking scale Λ=30TeV, independent of tanβ, and up to Λ=43TeV for large tanβ. © 2012.
Published: 2012

20. Search for events with large missing transverse momentum, jets, and at least two tau leptons in 7 TeV proton–proton collision data with the ATLAS detector

Author: Collaboration, ATLAS, Aad, G, Abbott, B, Abdallah, J, Khalek, S Abdel, Abdelalim, AA, Abdesselam, A, Abdinov, O, Abi, B, Abolins, M, AbouZeid, OS, Abramowicz, H, Abreu, H, Acerbi, E, Acharya, BS, Adamczyk, L, Adams, DL, Addy, TN, Adelman, J, Aderholz, M, Adomeit, S, Adragna, P, Adye, T, Aefsky, S, Aguilar-Saavedra, JA, Aharrouche, M, Ahlen, SP, Ahles, F, Ahmad, A, Ahsan, M, Aielli, G, Akdogan, T, Åkesson, TPA, Akimoto, G, Akimov, AV, Akiyama, A, Alam, MS, Alam, MA, Albert, J, Albrand, S, Aleksa, M, Aleksandrov, IN, Alessandria, F, Alexa, C, Alexander, G, Alexandre, G, Alexopoulos, T, Alhroob, M, Aliev, M, Alimonti, G, Alison, J, Aliyev, M, Allbrooke, BMM, Allport, PP, Allwood-Spiers, SE, Almond, J, Aloisio, A, Alon, R, Alonso, A, Gonzalez, B Alvarez, Alviggi, MG, Amako, K, Amaral, P, Amelung, C, Ammosov, VV, Amorim, A, Amorós, G, Amram, N, Anastopoulos, C, Ancu, LS, Andari, N, Andeen, T, Anders, CF, Anders, G, Anderson, KJ, Andreazza, A, Andrei, V, Andrieux, M-L, Anduaga, XS, Angerami, A, Anghinolfi, F, Anisenkov, A, Anjos, N, Annovi, A, Antonaki, A, Antonelli, M, Antonov, A, Antos, J, Anulli, F, Aoun, S, Bella, L Aperio, Apolle, R, Arabidze, G, Aracena, I, Arai, Y, Arce, ATH, Arfaoui, S, Arguin, J-F, Arik, E, and Arik, M
Subjects: hep-ex, Mathematical Physics, Astronomical and Space Sciences, Atomic, Molecular, Nuclear, Particle and Plasma Physics, Nuclear & Particles Physics
Abstract: A search for events with large missing transverse momentum, jets, and at least two tau leptons has been performed using 2 fb -1 of proton-proton collision data at s=7 TeV recorded with the ATLAS detector at the Large Hadron Collider. No excess above the Standard Model background expectation is observed and a 95% CL upper limit on the visible cross section for new phenomena is set, where the visible cross section is defined by the product of cross section, branching fraction, detector acceptance and event selection efficiency. A 95% CL lower limit of 32 TeV is set on the gauge-mediated supersymmetry breaking (GMSB) scale Λ independent of tanβ. These limits provide the most stringent tests to date in a large part of the considered parameter space. © 2012.
Published: 2012

21. Measurement of inclusive jet and dijet production in pp collisions at √s=7TeV using the ATLAS detector

Author: Aad, G, Abbott, B, Abdallah, J, Abdelalim, AA, Abdesselam, A, Abdinov, O, Abi, B, Abolins, M, Abramowicz, H, Abreu, H, Acerbi, E, Acharya, BS, Adams, DL, Addy, TN, Adelman, J, Aderholz, M, Adomeit, S, Adragna, P, Adye, T, Aefsky, S, Aguilar-Saavedra, JA, Aharrouche, M, Ahlen, SP, Ahles, F, Ahmad, A, Ahsan, M, Aielli, G, Akdogan, T, Åkesson, TPA, Akimoto, G, Akimov, AV, Akiyama, A, Aktas, A, Alam, MS, Alam, MA, Albert, J, Albrand, S, Aleksa, M, Aleksandrov, IN, Alessandria, F, Alexa, C, Alexander, G, Alexandre, G, Alexopoulos, T, Alhroob, M, Aliev, M, Alimonti, G, Alison, J, Aliyev, M, Allport, PP, Allwood-Spiers, SE, Almond, J, Aloisio, A, Alon, R, Alonso, A, Alvarez Gonzalez, B, Alviggi, MG, Amako, K, Amaral, P, Amelung, C, Ammosov, VV, Amorim, A, Amorós, G, Amram, N, Anastopoulos, C, Ancu, LS, Andari, N, Andeen, T, Anders, CF, Anders, G, Anderson, KJ, Andreazza, A, Andrei, V, Andrieux, ML, Anduaga, XS, Angerami, A, Anghinolfi, F, Anjos, N, Annovi, A, Antonaki, A, Antonelli, M, Antonov, A, Antos, J, Anulli, F, Aoun, S, Aperio Bella, L, Apolle, R, Arabidze, G, Aracena, I, Arai, Y, Arce, ATH, Archambault, JP, Arfaoui, S, Arguin, JF, Arik, E, Arik, M, Armbruster, AJ, Arnaez, O, Arnault, C, 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: Inclusive jet and dijet cross sections have been measured in proton-proton collisions at a center-of-mass energy of 7 TeV using the ATLAS detector at the Large Hadron Collider. The cross sections were measured using jets clustered with the anti-kt algorithm with parameters R=0.4 and R=0.6. These measurements are based on the 2010 data sample, consisting of a total integrated luminosity of 37pb-1. Inclusive jet double-differential cross sections are presented as a function of jet transverse momentum, in bins of jet rapidity. Dijet double-differential cross sections are studied as a function of the dijet invariant mass, in bins of half the rapidity separation of the two leading jets. The measurements are performed in the jet rapidity range |y|
Published: 2012

22. Search for pair-produced heavy quarks decaying to Wq in the two-lepton channel at √(s)=7TeV with the ATLAS detector

Author: Aad, G, Abbott, B, Abdallah, J, Abdelalim, AA, Abdesselam, A, Abdinov, O, Abi, B, Abolins, M, Abouzeid, OS, Abramowicz, H, Abreu, H, Acerbi, E, Acharya, BS, Adamczyk, L, Adams, DL, Addy, TN, Adelman, J, Aderholz, M, Adomeit, S, Adragna, P, Adye, T, Aefsky, S, Aguilar-Saavedra, JA, Aharrouche, M, Ahlen, SP, Ahles, F, Ahmad, A, Ahsan, M, Aielli, G, Akdogan, T, Åkesson, TPA, Akimoto, G, Akimov, AV, Akiyama, A, Alam, MS, Alam, MA, Albert, J, Albrand, S, Aleksa, M, Aleksandrov, IN, Alessandria, F, Alexa, C, Alexander, G, Alexandre, G, Alexopoulos, T, Alhroob, M, Aliev, M, Alimonti, G, Alison, J, Aliyev, M, Allbrooke, BMM, Allport, PP, Allwood-Spiers, SE, Almond, J, Aloisio, A, Alon, R, Alonso, A, Alvarez Gonzalez, B, Alviggi, MG, Amako, K, Amaral, P, Amelung, C, Ammosov, VV, Amorim, A, Amorós, G, Amram, N, Anastopoulos, C, Ancu, LS, Andari, N, Andeen, T, Anders, CF, Anders, G, Anderson, KJ, Andreazza, A, Andrei, V, Andrieux, ML, Anduaga, XS, Angerami, A, Anghinolfi, F, Anisenkov, A, Anjos, N, Annovi, A, Antonaki, A, Antonelli, M, Antonov, A, Antos, J, Anulli, F, Aoun, S, Aperio Bella, L, Apolle, R, Arabidze, G, Aracena, I, Arai, Y, Arce, ATH, Arfaoui, S, Arguin, JF, Arik, E, Arik, M, Armbruster, AJ, and Arnaez, 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 search is presented for heavy-quark pair production (QQ̄) under the decay hypothesis QQ̄→W+qW-q̄ with q=d, s, b for up-type Q or q=u, c for down-type Q. The search is performed with 1.04fb-1 of integrated luminosity from pp collisions at √s=7TeV collected by the ATLAS detector at the CERN LHC. Dilepton final states are selected, requiring large missing transverse momentum and at least two jets. Mass reconstruction of heavy-quark candidates is performed by assuming that the W boson decay products are nearly collinear. The data are in agreement with standard model expectations; a heavy quark with mass less than 350 GeV is excluded at 95% confidence level. © 2012 CERN. Published by the American Physical Society under the terms of the http://creativecommons.org/licenses/by/ 3.0/ Creative Commons Attribution 3.0 License. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI.
Published: 2012

23. Search for Down-Type Fourth Generation Quarks with the ATLAS Detector in Events with One Lepton and Hadronically Decaying W Bosons

Author: Aad, G, Abbott, B, Abdallah, J, Abdelalim, AA, Abdesselam, A, Abdinov, O, Abi, B, Abolins, M, AbouZeid, OS, Abramowicz, H, Abreu, H, Acerbi, E, Acharya, BS, Adamczyk, L, Adams, DL, Addy, TN, Adelman, J, Aderholz, M, Adomeit, S, Adragna, P, Adye, T, Aefsky, S, Aguilar-Saavedra, JA, Aharrouche, M, Ahlen, SP, Ahles, F, Ahmad, A, Ahsan, M, Aielli, G, Akdogan, T, Åkesson, TPA, Akimoto, G, Akimov, AV, Akiyama, A, Alam, MS, Alam, MA, Albert, J, Albrand, S, Aleksa, M, Aleksandrov, IN, Alessandria, F, Alexa, C, Alexander, G, Alexandre, G, Alexopoulos, T, Alhroob, M, Aliev, M, Alimonti, G, Alison, J, Aliyev, M, Allbrooke, BMM, Allport, PP, Allwood-Spiers, SE, Almond, J, Aloisio, A, Alon, R, Alonso, A, Gonzalez, B Alvarez, Alviggi, MG, Amako, K, Amaral, P, Amelung, C, Ammosov, VV, Amorim, A, Amorós, G, Amram, N, Anastopoulos, C, Ancu, LS, Andari, N, Andeen, T, Anders, CF, Anders, G, Anderson, KJ, Andreazza, A, Andrei, V, Andrieux, M-L, Anduaga, XS, Angerami, A, Anghinolfi, F, Anisenkov, A, Anjos, N, Annovi, A, Antonaki, A, Antonelli, M, Antonov, A, Antos, J, Anulli, F, Aoun, S, Bella, L Aperio, Apolle, R, Arabidze, G, Aracena, I, Arai, Y, Arce, ATH, Arfaoui, S, Arguin, J-F, Arik, E, Arik, M, Armbruster, AJ, and Arnaez, 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 presents a search for pair production of heavy down-type quarks decaying via b' → Wt in the lepton + jets channel, as b'b' → W- tW+ t → bbW+ W- W+ W- → l± νbbqqqqqq. In addition to requiring exactly one lepton, large missing transverse momentum, and at least six jets, the invariant mass of nearby jet pairs is used to identify high transverse momentum W bosons. In data corresponding to an integrated luminosity of 1.04 fb(-1) from pp collisions at sqrt[s] = 7 TeV recorded with the ATLAS detector, a heavy down-type quark with mass less than 480 GeV can be excluded at the 95% confidence level.
Published: 2012

24. Determination of the Strange-Quark Density of the Proton from ATLAS Measurements of the W→ℓν and Z→ℓℓ Cross Sections

Author: Aad, G, Abbott, B, Abdallah, J, Abdelalim, AA, Abdesselam, A, Abdinov, O, Abi, B, Abolins, M, AbouZeid, OS, Abramowicz, H, Abreu, H, Acerbi, E, Acharya, BS, Adamczyk, L, Adams, DL, Addy, TN, Adelman, J, Aderholz, M, Adomeit, S, Adragna, P, Adye, T, Aefsky, S, Aguilar-Saavedra, JA, Aharrouche, M, Ahlen, SP, Ahles, F, Ahmad, A, Ahsan, M, Aielli, G, Akdogan, T, Åkesson, TPA, Akimoto, G, Akimov, AV, Akiyama, A, Alam, MS, Alam, MA, Albert, J, Albrand, S, Aleksa, M, Aleksandrov, IN, Alessandria, F, Alexa, C, Alexander, G, Alexandre, G, Alexopoulos, T, Alhroob, M, Aliev, M, Alimonti, G, Alison, J, Aliyev, M, Allbrooke, BMM, Allport, PP, Allwood-Spiers, SE, Almond, J, Aloisio, A, Alon, R, Alonso, A, Gonzalez, B Alvarez, Alviggi, MG, Amako, K, Amaral, P, Amelung, C, Ammosov, VV, Amorim, A, Amorós, G, Amram, N, Anastopoulos, C, Ancu, LS, Andari, N, Andeen, T, Anders, CF, Anders, G, Anderson, KJ, Andreazza, A, Andrei, V, Andrieux, M-L, Anduaga, XS, Angerami, A, Anghinolfi, F, Anisenkov, A, Anjos, N, Annovi, A, Antonaki, A, Antonelli, M, Antonov, A, Antos, J, Anulli, F, Aoun, S, Bella, L Aperio, Apolle, R, Arabidze, G, Aracena, I, Arai, Y, Arce, ATH, Arfaoui, S, Arguin, J-F, Arik, E, Arik, M, Armbruster, AJ, and Arnaez, 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: A QCD analysis is reported of ATLAS data on inclusive W(±) and Z boson production in pp collisions at the LHC, jointly with ep deep-inelastic scattering data from HERA. The ATLAS data exhibit sensitivity to the light quark sea composition and magnitude at Bjorken x∼0.01. Specifically, the data support the hypothesis of a symmetric composition of the light quark sea at low x. The ratio of the strange-to-down sea quark distributions is determined to be 1.00(-0.28)(+0.25) at absolute four-momentum transfer squared Q(2)=1.9 GeV(2) and x=0.023.
Published: 2012

25. Measurement of the azimuthal anisotropy for charged particle production in sNN=2.76 TeV lead-lead collisions with the ATLAS detector

Author: Aad, G, Abbott, B, Abdallah, J, Khalek, S Abdel, Abdelalim, AA, Abdesselam, A, Abdinov, O, Abi, B, Abolins, M, AbouZeid, OS, Abramowicz, H, Abreu, H, Acerbi, E, Acharya, BS, Adamczyk, L, Adams, DL, Addy, TN, Adelman, J, Aderholz, M, Adomeit, S, Adragna, P, Adye, T, Aefsky, S, Aguilar-Saavedra, JA, Aharrouche, M, Ahlen, SP, Ahles, F, Ahmad, A, Ahsan, M, Aielli, G, Akdogan, T, Åkesson, TPA, Akimoto, G, Akimov, AV, Akiyama, A, Alam, MS, Alam, MA, Albert, J, Albrand, S, Aleksa, M, Aleksandrov, IN, Alessandria, F, Alexa, C, Alexander, G, Alexandre, G, Alexopoulos, T, Alhroob, M, Aliev, M, Alimonti, G, Alison, J, Aliyev, M, Allbrooke, BMM, Allport, PP, Allwood-Spiers, SE, Almond, J, Aloisio, A, Alon, R, Alonso, A, Gonzalez, B Alvarez, Alviggi, MG, Amako, K, Amaral, P, Amelung, C, Ammosov, VV, Amorim, A, Amorós, G, Amram, N, Anastopoulos, C, Ancu, LS, Andari, N, Andeen, T, Anders, CF, Anders, G, Anderson, KJ, Andreazza, A, Andrei, V, Andrieux, M-L, Anduaga, XS, Angerami, A, Anghinolfi, F, Anisenkov, A, Anjos, N, Annovi, A, Antonaki, A, Antonelli, M, Antonov, A, Antos, J, Anulli, F, Aoun, S, Bella, L Aperio, Apolle, R, Arabidze, G, Aracena, I, Arai, Y, Arce, ATH, Arfaoui, S, Arguin, J-F, Arik, E, Arik, M, and Armbruster, AJ
Subjects: hep-ex, nucl-ex, Atomic, Molecular, Nuclear, Particle and Plasma Physics, Nuclear & Particles Physics
Abstract: Differential measurements of charged particle azimuthal anisotropy are presented for lead-lead collisions at √sNN = 2.76 TeV with the ATLAS detector at the LHC, based on an integrated luminosity of approximately 8 μb− 1. This anisotropy is characterized via a Fourier expansion of the distribution of charged particles in azimuthal angle relative to the reaction plane, with the coefficients vn denoting the magnitude of the anisotropy. Significant v2–v6 values are obtained as a function of transverse momentum (0.5 < pT < 20 GeV), pseudorapidity (|η| < 2.5), and centrality using an event plane method. The vn values for n ≥ 3 are found to vary weakly with both η and centrality, and their pT dependencies are found to follow an approximate scaling relation, v1/nn (pT) ∝ v1/22 (pT), except in the top 5% most central collisions. A Fourier analysis of the charged particle pair distribution in relative azimuthal angle (Δϕ = ϕa − ϕb) is performed to extract the coefficients vn, n = (cos nΔϕ). For pairs of charged particles with a large pseudorapidity gap (|Δη = ηa − ηb| > 2) and one particle with pT < 3 GeV, the v2,2–v6,6 values are found to factorize as vn, n(paT, pbT) ≈ vn(paT)vn(pbT) in central and midcentral events. Such factorization suggests that these values of v2,2–v6,6 are primarily attributable to the response of the created matter to the fluctuations in the geometry of the initial state. A detailed study shows that the v1,1(paT, pbT) data are consistent with the combined contributions from a rapidity-even v1 and global momentum conservation.A two-component fit is used to extract the v1 contribution. The extracted v1 isobserved to cross zero at pT ≈ 1.0 GeV, reaches a maximum at 4–5 GeV with a value comparable to that for v3, and decreases at higher pT.
Published: 2012

26. Measurement of inclusive jet and dijet production in pp collisions at s=7 TeV using the ATLAS detector

Author: Aad, G, Abbott, B, Abdallah, J, Abdelalim, AA, Abdesselam, A, Abdinov, O, Abi, B, Abolins, M, Abramowicz, H, Abreu, H, Acerbi, E, Acharya, BS, Adams, DL, Addy, TN, Adelman, J, Aderholz, M, Adomeit, S, Adragna, P, Adye, T, Aefsky, S, Aguilar-Saavedra, JA, Aharrouche, M, Ahlen, SP, Ahles, F, Ahmad, A, Ahsan, M, Aielli, G, Akdogan, T, Åkesson, TPA, Akimoto, G, Akimov, AV, Akiyama, A, Aktas, A, Alam, MS, Alam, MA, Albert, J, Albrand, S, Aleksa, M, Aleksandrov, IN, Alessandria, F, Alexa, C, Alexander, G, Alexandre, G, Alexopoulos, T, Alhroob, M, Aliev, M, Alimonti, G, Alison, J, Aliyev, M, Allport, PP, Allwood-Spiers, SE, Almond, J, Aloisio, A, Alon, R, Alonso, A, Gonzalez, B Alvarez, Alviggi, MG, Amako, K, Amaral, P, Amelung, C, Ammosov, VV, Amorim, A, Amorós, G, Amram, N, Anastopoulos, C, Ancu, LS, Andari, N, Andeen, T, Anders, CF, Anders, G, Anderson, KJ, Andreazza, A, Andrei, V, Andrieux, M-L, Anduaga, XS, Angerami, A, Anghinolfi, F, Anjos, N, Annovi, A, Antonaki, A, Antonelli, M, Antonov, A, Antos, J, Anulli, F, Aoun, S, Bella, L Aperio, Apolle, R, Arabidze, G, Aracena, I, Arai, Y, Arce, ATH, Archambault, JP, Arfaoui, S, Arguin, J-F, Arik, E, Arik, M, Armbruster, AJ, Arnaez, O, Arnault, C, and Artamonov, A
Subjects: hep-ex, Astronomical and Space Sciences, Atomic, Molecular, Nuclear, Particle and Plasma Physics, Quantum Physics, Nuclear & Particles Physics
Abstract: Inclusive jet and dijet cross sections have been measured in proton-proton collisions at a center-of-mass energy of 7 TeV using the ATLAS detector at the Large Hadron Collider. The cross sections were measured using jets clustered with the anti-kt algorithm with parameters R=0.4 and R=0.6. These measurements are based on the 2010 data sample, consisting of a total integrated luminosity of 37pb-1. Inclusive jet double-differential cross sections are presented as a function of jet transverse momentum, in bins of jet rapidity. Dijet double-differential cross sections are studied as a function of the dijet invariant mass, in bins of half the rapidity separation of the two leading jets. The measurements are performed in the jet rapidity range |y|
Published: 2012

27. Search for pair-produced heavy quarks decaying to Wq in the two-lepton channel at (s)=7 TeV with the ATLAS detector

Author: Aad, G, Abbott, B, Abdallah, J, Abdelalim, AA, Abdesselam, A, Abdinov, O, Abi, B, Abolins, M, AbouZeid, OS, Abramowicz, H, Abreu, H, Acerbi, E, Acharya, BS, Adamczyk, L, Adams, DL, Addy, TN, Adelman, J, Aderholz, M, Adomeit, S, Adragna, P, Adye, T, Aefsky, S, Aguilar-Saavedra, JA, Aharrouche, M, Ahlen, SP, Ahles, F, Ahmad, A, Ahsan, M, Aielli, G, Akdogan, T, Åkesson, TPA, Akimoto, G, Akimov, AV, Akiyama, A, Alam, MS, Alam, MA, Albert, J, Albrand, S, Aleksa, M, Aleksandrov, IN, Alessandria, F, Alexa, C, Alexander, G, Alexandre, G, Alexopoulos, T, Alhroob, M, Aliev, M, Alimonti, G, Alison, J, Aliyev, M, Allbrooke, BMM, Allport, PP, Allwood-Spiers, SE, Almond, J, Aloisio, A, Alon, R, Alonso, A, Gonzalez, B Alvarez, Alviggi, MG, Amako, K, Amaral, P, Amelung, C, Ammosov, VV, Amorim, A, Amorós, G, Amram, N, Anastopoulos, C, Ancu, LS, Andari, N, Andeen, T, Anders, CF, Anders, G, Anderson, KJ, Andreazza, A, Andrei, V, Andrieux, M-L, Anduaga, XS, Angerami, A, Anghinolfi, F, Anisenkov, A, Anjos, N, Annovi, A, Antonaki, A, Antonelli, M, Antonov, A, Antos, J, Anulli, F, Aoun, S, Bella, L Aperio, Apolle, R, Arabidze, G, Aracena, I, Arai, Y, Arce, ATH, Arfaoui, S, Arguin, J-F, Arik, E, Arik, M, Armbruster, AJ, and Arnaez, O
Subjects: hep-ex, Astronomical and Space Sciences, Atomic, Molecular, Nuclear, Particle and Plasma Physics, Quantum Physics, Nuclear & Particles Physics
Abstract: A search is presented for heavy-quark pair production (QQ̄) under the decay hypothesis QQ̄→W+qW-q̄ with q=d, s, b for up-type Q or q=u, c for down-type Q. The search is performed with 1.04fb-1 of integrated luminosity from pp collisions at √s=7TeV collected by the ATLAS detector at the CERN LHC. Dilepton final states are selected, requiring large missing transverse momentum and at least two jets. Mass reconstruction of heavy-quark candidates is performed by assuming that the W boson decay products are nearly collinear. The data are in agreement with standard model expectations; a heavy quark with mass less than 350 GeV is excluded at 95% confidence level. © 2012 CERN. Published by the American Physical Society under the terms of the http://creativecommons.org/licenses/by/ 3.0/ Creative Commons Attribution 3.0 License. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI.
Published: 2012

28. Forward-backward correlations and charged-particle azimuthal distributions in pp interactions using the ATLAS detector

Author: The ATLAS collaboration, Aad, G, Abbott, B, Abdallah, J, Abdelalim, AA, Abdesselam, A, Abdinov, O, Abi, B, Abolins, M, AbouZeid, OS, Abramowicz, H, Abreu, H, Acerbi, E, Acharya, BS, Adamczyk, L, Adams, DL, Addy, TN, Adelman, J, Aderholz, M, Adomeit, S, Adragna, P, Adye, T, Aefsky, S, Aguilar-Saavedra, JA, Aharrouche, M, Ahlen, SP, Ahles, F, Ahmad, A, Ahsan, M, Aielli, G, Akdogan, T, Åkesson, TPA, Akimoto, G, Akimov, AV, Akiyama, A, Alam, MS, Alam, MA, Albert, J, Albrand, S, Aleksa, M, Aleksandrov, IN, Alessandria, F, Alexa, C, Alexander, G, Alexandre, G, Alexopoulos, T, Alhroob, M, Aliev, M, Alimonti, G, Alison, J, Aliyev, M, Allbrooke, BMM, Allport, PP, Allwood-Spiers, SE, Almond, J, Aloisio, A, Alon, R, Alonso, A, Gonzalez, B Alvarez, Alviggi, MG, Amako, K, Amaral, P, Amelung, C, Ammosov, VV, Amorim, A, Amorós, G, Amram, N, Anastopoulos, C, Ancu, LS, Andari, N, Andeen, T, Anders, CF, Anders, G, Anderson, KJ, Andreazza, A, Andrei, V, Andrieux, M-L, Anduaga, XS, Angerami, A, Anghinolfi, F, Anisenkov, A, Anjos, N, Annovi, A, Antonaki, A, Antonelli, M, Antonov, A, Antos, J, Anulli, F, Aoun, S, Bella, L Aperio, Apolle, R, Arabidze, G, Aracena, I, Arai, Y, Arce, ATH, Arfaoui, S, Arguin, J-F, Arik, E, Arik, M, and Armbruster, AJ
Subjects: Hadron-Hadron Scattering, hep-ex, Mathematical Physics, Atomic, Molecular, Nuclear, Particle and Plasma Physics, Quantum Physics, Nuclear & Particles Physics
Abstract: Using inelastic proton-proton interactions at √s =900 GeV and 7TeV, recorded by the ATLAS detector at the LHC, measurements have been made of the correlations between forward and backward charged-particle multiplicities and, for the first time, between forward and backward charged-particle summed transverse momentum. In addition, jet-like structure in the events is studied by means of azimuthal distributions of charged particles relative to the charged particle with highest transverse momentum in a selected kinematic region of the event. The results are compared with predictions from tunes of the PYTHIA and HERWIG++ Monte Carlo generators, which in most cases are found to provide a reasonable description of the data.
Published: 2012

29. Measurement of τ polarization in W→τν decays with the ATLAS detector in pp collisions at

Author: Aad, G, Abbott, B, Abdallah, J, Abdel Khalek, S, Abdelalim, AA, Abdesselam, A, Abdinov, O, Abi, B, Abolins, M, AbouZeid, OS, Abramowicz, H, Abreu, H, Acerbi, E, Acharya, BS, Adamczyk, L, Adams, DL, Addy, TN, Adelman, J, Aderholz, M, Adomeit, S, Adragna, P, Adye, T, Aefsky, S, Aguilar-Saavedra, JA, Aharrouche, M, Ahlen, SP, Ahles, F, Ahmad, A, Ahsan, M, Aielli, G, Akdogan, T, Åkesson, TPA, Akimoto, G, Akimov, AV, Akiyama, A, Alam, MS, Alam, MA, Albert, J, Albrand, S, Aleksa, M, Aleksandrov, IN, Alessandria, F, Alexa, C, Alexander, G, Alexandre, G, Alexopoulos, T, Alhroob, M, Aliev, M, Alimonti, G, Alison, J, Aliyev, M, Allbrooke, BMM, Allport, PP, Allwood-Spiers, SE, Almond, J, Aloisio, A, Alon, R, Alonso, A, Alvarez Gonzalez, B, Alviggi, MG, Amako, K, Amaral, P, Amelung, C, Ammosov, VV, Amorim, A, Amorós, G, Amram, N, Anastopoulos, C, Ancu, LS, Andari, N, Andeen, T, Anders, CF, Anders, G, Anderson, KJ, Andreazza, A, Andrei, V, Andrieux, M-L, Anduaga, XS, Angerami, A, Anghinolfi, F, Anisenkov, A, Anjos, N, Annovi, A, Antonaki, A, Antonelli, M, Antonov, A, Antos, J, Anulli, F, Aoun, S, Aperio Bella, L, Apolle, R, Arabidze, G, Aracena, I, Arai, Y, Arce, ATH, Arfaoui, S, Arguin, J-F, Arik, E, Arik, M, and Armbruster, AJ
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: In this paper, a measurement of τ polarization in W→τν decays is presented. It is measured from the energies of the decay products in hadronic τ decays with a single final state charged particle. The data, corresponding to an integrated luminosity of 24 pb-1, were collected by the ATLAS experiment at the Large Hadron Collider in 2010. The measured value of the τ polarization is [Formula: see text], in agreement with the Standard Model prediction, and is consistent with a physically allowed 95 % CL interval [-1,-0.91]. Measurements of τ polarization have not previously been made at hadron colliders.
Published: 2012

30. Search for heavy neutrinos and right-handed W bosons in events with two leptons and jets in pp collisions at with the ATLAS detector

Author: Aad, G, Abbott, B, Abdallah, J, Abdelalim, AA, Abdesselam, A, Abdinov, O, Abi, B, Abolins, M, AbouZeid, OS, Abramowicz, H, Abreu, H, Acerbi, E, Acharya, BS, Adamczyk, L, Adams, DL, Addy, TN, Adelman, J, Aderholz, M, Adomeit, S, Adragna, P, Adye, T, Aefsky, S, Aguilar-Saavedra, JA, Aharrouche, M, Ahlen, SP, Ahles, F, Ahmad, A, Ahsan, M, Aielli, G, Akdogan, T, Åkesson, TPA, Akimoto, G, Akimov, AV, Akiyama, A, Alam, MS, Alam, MA, Albert, J, Albrand, S, Aleksa, M, Aleksandrov, IN, Alessandria, F, Alexa, C, Alexander, G, Alexandre, G, Alexopoulos, T, Alhroob, M, Aliev, M, Alimonti, G, Alison, J, Aliyev, M, Allbrooke, BMM, Allport, PP, Allwood-Spiers, SE, Almond, J, Aloisio, A, Alon, R, Alonso, A, Alvarez Gonzalez, B, Alviggi, MG, Amako, K, Amaral, P, Amelung, C, Ammosov, VV, Amorim, A, Amorós, G, Amram, N, Anastopoulos, C, Ancu, LS, Andari, N, Andeen, T, Anders, CF, Anders, G, Anderson, KJ, Andreazza, A, Andrei, V, Andrieux, M-L, Anduaga, XS, Angerami, A, Anghinolfi, F, Anisenkov, A, Anjos, N, Annovi, A, Antonaki, A, Antonelli, M, Antonov, A, Antos, J, Anulli, F, Aoun, S, Aperio Bella, L, Apolle, R, Arabidze, G, Aracena, I, Arai, Y, Arce, ATH, Arfaoui, S, Arguin, J-F, Arik, E, Arik, M, Armbruster, AJ, and Arnaez, O
Subjects: Nuclear and Plasma Physics, Particle and High Energy Physics, Physical Sciences, The 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 letter reports on a search for hypothetical heavy neutrinos, N, and right-handed gauge bosons, WR, in events with high transverse momentum objects which include two reconstructed leptons and at least one hadronic jet. The results were obtained from data corresponding to an integrated luminosity of 2.1 fb-1 collected in proton-proton collisions at [Formula: see text] with the ATLAS detector at the CERN Large Hadron Collider. No excess above the Standard Model background expectation is observed. Excluded mass regions for Majorana and Dirac neutrinos are presented using two approaches for interactions that violate lepton and lepton-flavor numbers. One approach uses an effective operator framework, the other approach is guided by the Left-Right Symmetric Model. The results described in this letter represent the most stringent limits to date on the masses of heavy neutrinos and WR bosons obtained in direct searches.
Published: 2012

31. Search for Pair Production of a Heavy Up-Type Quark Decaying to a W Boson and a b Quark in the lepton+jets Channel with the ATLAS Detector

Author: Aad, G, Abbott, B, Abdallah, J, Abdelalim, AA, Abdesselam, A, Abdinov, O, Abi, B, Abolins, M, AbouZeid, OS, Abramowicz, H, Abreu, H, Acerbi, E, Acharya, BS, Adamczyk, L, Adams, DL, Addy, TN, Adelman, J, Aderholz, M, Adomeit, S, Adragna, P, Adye, T, Aefsky, S, Aguilar-Saavedra, JA, Aharrouche, M, Ahlen, SP, Ahles, F, Ahmad, A, Ahsan, M, Aielli, G, Akdogan, T, Åkesson, TPA, Akimoto, G, Akimov, AV, Akiyama, A, Alam, MS, Alam, MA, Albert, J, Albrand, S, Aleksa, M, Aleksandrov, IN, Alessandria, F, Alexa, C, Alexander, G, Alexandre, G, Alexopoulos, T, Alhroob, M, Aliev, M, Alimonti, G, Alison, J, Aliyev, M, Allbrooke, BMM, Allport, PP, Allwood-Spiers, SE, Almond, J, Aloisio, A, Alon, R, Alonso, A, Gonzalez, B Alvarez, Alviggi, MG, Amako, K, Amaral, P, Amelung, C, Ammosov, VV, Amorim, A, Amorós, G, Amram, N, Anastopoulos, C, Ancu, LS, Andari, N, Andeen, T, Anders, CF, Anders, G, Anderson, KJ, Andreazza, A, Andrei, V, Andrieux, M-L, Anduaga, XS, Angerami, A, Anghinolfi, F, Anisenkov, A, Anjos, N, Annovi, A, Antonaki, A, Antonelli, M, Antonov, A, Antos, J, Anulli, F, Aoun, S, Bella, L Aperio, Apolle, R, Arabidze, G, Aracena, I, Arai, Y, Arce, ATH, Arfaoui, S, Arguin, J-F, Arik, E, Arik, M, Armbruster, AJ, and Arnaez, 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: A search is presented for production of a heavy up-type quark (t') together with its antiparticle, assuming subsequent decay to a W boson and a b quark, t't[over ¯]'→W(+)bW(-)b[over ¯]. The search is based on 1.04 fb(-1) of proton-proton collisions at √[s]=7 TeV collected by the ATLAS detector at the CERN Large Hadron Collider. Data are analyzed in the lepton+jets final state, characterized by a high transverse momentum isolated electron or muon, high missing transverse momentum, and at least three jets. No significant excess of events above the background expectation is observed. A 95% C.L. lower limit of 404 GeV is set for the mass of the t' quark.
Published: 2012

32. Search for pair production of a heavy up-type quark decaying to a W boson and a b quark in the lepton + jets channel with the ATLAS detector.

Author: Aad, G, Abbott, B, Abdallah, J, Abdelalim, AA, Abdesselam, A, Abdinov, O, Abi, B, Abolins, M, AbouZeid, OS, Abramowicz, H, Abreu, H, Acerbi, E, Acharya, BS, Adamczyk, L, Adams, DL, Addy, TN, Adelman, J, Aderholz, M, Adomeit, S, Adragna, P, Adye, T, Aefsky, S, Aguilar-Saavedra, JA, Aharrouche, M, Ahlen, SP, Ahles, F, Ahmad, A, Ahsan, M, Aielli, G, Akdogan, T, Åkesson, TPA, Akimoto, G, Akimov, AV, Akiyama, A, Alam, MS, Alam, MA, Albert, J, Albrand, S, Aleksa, M, Aleksandrov, IN, Alessandria, F, Alexa, C, Alexander, G, Alexandre, G, Alexopoulos, T, Alhroob, M, Aliev, M, Alimonti, G, Alison, J, Aliyev, M, Allbrooke, BMM, Allport, PP, Allwood-Spiers, SE, Almond, J, Aloisio, A, Alon, R, Alonso, A, Alvarez Gonzalez, B, Alviggi, MG, Amako, K, Amaral, P, Amelung, C, Ammosov, VV, Amorim, A, Amorós, G, Amram, N, Anastopoulos, C, Ancu, LS, Andari, N, Andeen, T, Anders, CF, Anders, G, Anderson, KJ, Andreazza, A, Andrei, V, Andrieux, M-L, Anduaga, XS, Angerami, A, Anghinolfi, F, Anisenkov, A, Anjos, N, Annovi, A, Antonaki, A, Antonelli, M, Antonov, A, Antos, J, Anulli, F, Aoun, S, Aperio Bella, L, Apolle, R, Arabidze, G, Aracena, I, Arai, Y, Arce, ATH, Arfaoui, S, Arguin, J-F, Arik, E, Arik, M, Armbruster, AJ, and Arnaez, O
Subjects: ATLAS Collaboration, hep-ex, General Physics, Mathematical Sciences, Physical Sciences, Engineering
Abstract: A search is presented for production of a heavy up-type quark (t') together with its antiparticle, assuming subsequent decay to a W boson and a b quark, t't[over ¯]'→W(+)bW(-)b[over ¯]. The search is based on 1.04 fb(-1) of proton-proton collisions at √[s]=7 TeV collected by the ATLAS detector at the CERN Large Hadron Collider. Data are analyzed in the lepton+jets final state, characterized by a high transverse momentum isolated electron or muon, high missing transverse momentum, and at least three jets. No significant excess of events above the background expectation is observed. A 95% C.L. lower limit of 404 GeV is set for the mass of the t' quark.
Published: 2012

33. Search for resonant WZ production in the WZ → ℓνℓ′ ℓ ′ channel in √ (s) = 7 TeV pp collisions with the ATLAS detector

Author: Aad, G, Abbott, B, Abdallah, J, Abdel Khalek, S, Abdelalim, AA, Abdesselam, A, Abdinov, O, Abi, B, Abolins, M, AbouZeid, OS, Abramowicz, H, Abreu, H, Acerbi, E, Acharya, BS, Adamczyk, L, Adams, DL, Addy, TN, Adelman, J, Aderholz, M, Adomeit, S, Adragna, P, Adye, T, Aefsky, S, Aguilar-Saavedra, JA, Aharrouche, M, Ahlen, SP, Ahles, F, Ahmad, A, Ahsan, M, Aielli, G, Akdogan, T, Åkesson, TPA, Akimoto, G, Akimov, AV, Akiyama, A, Alam, MS, Alam, MA, Albert, J, Albrand, S, Aleksa, M, Aleksandrov, IN, Alessandria, F, Alexa, C, Alexander, G, Alexandre, G, Alexopoulos, T, Alhroob, M, Aliev, M, Alimonti, G, Alison, J, Aliyev, M, Allbrooke, BMM, Allport, PP, Allwood-Spiers, SE, Almond, J, Aloisio, A, Alon, R, Alonso, A, Alvarez Gonzalez, B, Alviggi, MG, Amako, K, Amaral, P, Amelung, C, Ammosov, VV, Amorim, A, Amorós, G, Amram, N, Anastopoulos, C, Ancu, LS, Andari, N, Andeen, T, Anders, CF, Anders, G, Anderson, KJ, Andreazza, A, Andrei, V, Andrieux, ML, Anduaga, XS, Angerami, A, Anghinolfi, F, Anisenkov, A, Anjos, N, Annovi, A, Antonaki, A, Antonelli, M, Antonov, A, Antos, J, Anulli, F, Aoun, S, Aperio Bella, L, Apolle, R, Arabidze, G, Aracena, I, Arai, Y, Arce, ATH, Arfaoui, S, Arguin, JF, Arik, E, Arik, M, and Armbruster, AJ
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 generic search is presented for a heavy particle decaying to WZ → ℓν′ ℓ ′ (ℓ, ℓ′ = e, μ)final states. The data were recorded by the ATLAS detector in ffiffiffis √ s = 7 TeV pp collisions at the Large Hadron Collider and correspond to an integrated luminosity of 1:02 fb-1. The transverse mass distribution of the selected WZ candidates is found to be consistent with the standard model expectation. Upper limits on the production cross section times branching ratio are derived using two benchmark models predicting a heavy particle decaying to a WZ pair.
Published: 2012

34. Search for a Light Higgs Boson Decaying to Long-Lived Weakly Interacting Particles in Proton-Proton Collisions at s=7 TeV with the ATLAS Detector

Author: Aad, G, Abbott, B, Abdallah, J, Abdelalim, AA, Abdesselam, A, Abdinov, O, Abi, B, Abolins, M, AbouZeid, OS, Abramowicz, H, Abreu, H, Acerbi, E, Acharya, BS, Adamczyk, L, Adams, DL, Addy, TN, Adelman, J, Aderholz, M, Adomeit, S, Adragna, P, Adye, T, Aefsky, S, Aguilar-Saavedra, JA, Aharrouche, M, Ahlen, SP, Ahles, F, Ahmad, A, Ahsan, M, Aielli, G, Akdogan, T, Åkesson, TPA, Akimoto, G, Akimov, AV, Akiyama, A, Alam, MS, Alam, MA, Albert, J, Albrand, S, Aleksa, M, Aleksandrov, IN, Alessandria, F, Alexa, C, Alexander, G, Alexandre, G, Alexopoulos, T, Alhroob, M, Aliev, M, Alimonti, G, Alison, J, Aliyev, M, Allport, PP, Allwood-Spiers, SE, Almond, J, Aloisio, A, Alon, R, Alonso, A, Gonzalez, B Alvarez, Alviggi, MG, Amako, K, Amaral, P, Amelung, C, Ammosov, VV, Amorim, A, Amorós, G, Amram, N, Anastopoulos, C, Ancu, LS, Andari, N, Andeen, T, Anders, CF, Anders, G, Anderson, KJ, Andreazza, A, Andrei, V, Andrieux, M-L, Anduaga, XS, Angerami, A, Anghinolfi, F, Anisenkov, A, Anjos, N, Annovi, A, Antonaki, A, Antonelli, M, Antonov, A, Antos, J, Anulli, F, Aoun, S, Bella, L Aperio, Apolle, R, Arabidze, G, Aracena, I, Arai, Y, Arce, ATH, Archambault, JP, Arfaoui, S, Arguin, J-F, Arik, E, Arik, M, Armbruster, AJ, and Arnaez, O
Subjects: Nuclear and Plasma Physics, Particle and High Energy Physics, Physical Sciences, Mesons, Models, Theoretical, Nuclear Physics, Particle Accelerators, Protons, Spectrum Analysis, ATLAS Collaboration, hep-ex, Mathematical Sciences, Engineering, General Physics, Mathematical sciences, Physical sciences
Abstract: A search for the decay of a light Higgs boson (120-140 GeV) to a pair of weakly interacting, long-lived particles in 1.94 fb(-1) of proton-proton collisions at sqrt[s] = 7 TeV recorded in 2011 by the ATLAS detector is presented. The search strategy requires that both long-lived particles decay inside the muon spectrometer. No excess of events is observed above the expected background and limits on the Higgs boson production times branching ratio to weakly interacting, long-lived particles are derived as a function of the particle proper decay length.
Published: 2012

35. Search for a light Higgs boson decaying to long-lived weakly interacting particles in proton-proton collisions at sqrt[s] = 7 TeV with the ATLAS detector.

Author: Aad, G, Abbott, B, Abdallah, J, Abdelalim, AA, Abdesselam, A, Abdinov, O, Abi, B, Abolins, M, Abouzeid, OS, Abramowicz, H, Abreu, H, Acerbi, E, Acharya, BS, Adamczyk, L, Adams, DL, Addy, TN, Adelman, J, Aderholz, M, Adomeit, S, Adragna, P, Adye, T, Aefsky, S, Aguilar-Saavedra, JA, Aharrouche, M, Ahlen, SP, Ahles, F, Ahmad, A, Ahsan, M, Aielli, G, Akdogan, T, Akesson, TPA, Akimoto, G, Akimov, AV, Akiyama, A, Alam, MS, Alam, MA, Albert, J, Albrand, S, Aleksa, M, Aleksandrov, IN, Alessandria, F, Alexa, C, Alexander, G, Alexandre, G, Alexopoulos, T, Alhroob, M, Aliev, M, Alimonti, G, Alison, J, Aliyev, M, Allport, PP, Allwood-Spiers, SE, Almond, J, Aloisio, A, Alon, R, Alonso, A, Alvarez Gonzalez, B, Alviggi, MG, Amako, K, Amaral, P, Amelung, C, Ammosov, VV, Amorim, A, Amorós, G, Amram, N, Anastopoulos, C, Ancu, LS, Andari, N, Andeen, T, Anders, CF, Anders, G, Anderson, KJ, Andreazza, A, Andrei, V, Andrieux, M-L, Anduaga, XS, Angerami, A, Anghinolfi, F, Anisenkov, A, Anjos, N, Annovi, A, Antonaki, A, Antonelli, M, Antonov, A, Antos, J, Anulli, F, Aoun, S, Aperio Bella, L, Apolle, R, Arabidze, G, Aracena, I, Arai, Y, Arce, ATH, Archambault, JP, Arfaoui, S, Arguin, J-F, Arik, E, Arik, M, Armbruster, AJ, and Arnaez, O
Subjects: ATLAS Collaboration, Protons, Spectrum Analysis, Nuclear Physics, Mesons, Particle Accelerators, Models, Theoretical, hep-ex, General Physics, Mathematical Sciences, Physical Sciences, Engineering
Abstract: A search for the decay of a light Higgs boson (120-140 GeV) to a pair of weakly interacting, long-lived particles in 1.94 fb(-1) of proton-proton collisions at sqrt[s] = 7 TeV recorded in 2011 by the ATLAS detector is presented. The search strategy requires that both long-lived particles decay inside the muon spectrometer. No excess of events is observed above the expected background and limits on the Higgs boson production times branching ratio to weakly interacting, long-lived particles are derived as a function of the particle proper decay length.
Published: 2012

36. Search for supersymmetry in pp collisions at √s=7TeV in final states with missing transverse momentum and b-jets with the ATLAS detector

Author: Aad, G, Abbott, B, Abdallah, J, Abdel Khalek, S, Abdelalim, AA, Abdesselam, A, Abdinov, O, Abi, B, Abolins, M, Abouzeid, OS, Abramowicz, H, Abreu, H, Acerbi, E, Acharya, BS, Adamczyk, L, Adams, DL, Addy, TN, Adelman, J, Aderholz, M, Adomeit, S, Adragna, P, Adye, T, Aefsky, S, Aguilar-Saavedra, JA, Aharrouche, M, Ahlen, SP, Ahles, F, Ahmad, A, Ahsan, M, Aielli, G, Akdogan, T, Akesson, TPA, Akimoto, G, Akimov, AV, Akiyama, A, Alam, MS, Alam, MA, Albert, J, Albrand, S, Aleksa, M, Aleksandrov, IN, Alessandria, F, Alexa, C, Alexander, G, Alexandre, G, Alexopoulos, T, Alhroob, M, Aliev, M, Alimonti, G, Alison, J, Aliyev, M, Allbrooke, BMM, Allport, PP, Allwood-Spiers, SE, Almond, J, Aloisio, A, Alon, R, Alonso, A, Alvarez Gonzalez, B, Alviggi, MG, Amako, K, Amaral, P, Amelung, C, Ammosov, VV, Amorim, A, Amorós, G, Amram, N, Anastopoulos, C, Ancu, LS, Andari, N, Andeen, T, Anders, CF, Anders, G, Anderson, KJ, Andreazza, A, Andrei, V, Andrieux, ML, Anduaga, XS, Angerami, A, Anghinolfi, F, Anisenkov, A, Anjos, N, Annovi, A, Antonaki, A, Antonelli, M, Antonov, A, Antos, J, Anulli, F, Aoun, S, Aperio Bella, L, Apolle, R, Arabidze, G, Aracena, I, Arai, Y, Arce, ATH, Arfaoui, S, Arguin, JF, Arik, E, Arik, M, and Armbruster, AJ
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: The results of a search for supersymmetry in events with large missing transverse momentum and heavy-flavor jets using an integrated luminosity corresponding to 2.05fb-1 of pp collisions at √s=7TeV recorded with the ATLAS detector at the Large Hadron Collider are reported. No significant excess is observed with respect to the prediction for standard model processes. Results are interpreted in a variety of R-parity conserving models in which scalar bottoms and tops are the only scalar quarks to appear in the gluino decay cascade, and in an SO(10) model framework. Gluino masses up to 600-900GeV are excluded, depending on the model considered. © 2012 CERN. Published by the American Physical Society.
Published: 2012

37. Search for gluinos in events with two same-sign leptons, jets, and missing transverse momentum with the ATLAS detector in pp collisions at sqrt[s]=7 TeV.

Author: Aad, G, Abbott, B, Abdallah, J, Abdel Khalek, S, Abdelalim, AA, Abdesselam, A, Abdinov, O, Abi, B, Abolins, M, AbouZeid, OS, Abramowicz, H, Abreu, H, Acerbi, E, Acharya, BS, Adamczyk, L, Adams, DL, Addy, TN, Adelman, J, Aderholz, M, Adomeit, S, Adragna, P, Adye, T, Aefsky, S, Aguilar-Saavedra, JA, Aharrouche, M, Ahlen, SP, Ahles, F, Ahmad, A, Ahsan, M, Aielli, G, Akdogan, T, Åkesson, TPA, Akimoto, G, Akimov, AV, Akiyama, A, Alam, MS, Alam, MA, Albert, J, Albrand, S, Aleksa, M, Aleksandrov, IN, Alessandria, F, Alexa, C, Alexander, G, Alexandre, G, Alexopoulos, T, Alhroob, M, Aliev, M, Alimonti, G, Alison, J, Aliyev, M, Allbrooke, BMM, Allport, PP, Allwood-Spiers, SE, Almond, J, Aloisio, A, Alon, R, Alonso, A, Alvarez Gonzalez, B, Alviggi, MG, Amako, K, Amaral, P, Amelung, C, Ammosov, VV, Amorim, A, Amorós, G, Amram, N, Anastopoulos, C, Ancu, LS, Andari, N, Andeen, T, Anders, CF, Anders, G, Anderson, KJ, Andreazza, A, Andrei, V, Andrieux, M-L, Anduaga, XS, Angerami, A, Anghinolfi, F, Anisenkov, A, Anjos, N, Annovi, A, Antonaki, A, Antonelli, M, Antonov, A, Antos, J, Anulli, F, Aoun, S, Aperio Bella, L, Apolle, R, Arabidze, G, Aracena, I, Arai, Y, Arce, ATH, Arfaoui, S, Arguin, J-F, Arik, E, Arik, M, and Armbruster, AJ
Subjects: ATLAS Collaboration, hep-ex, General Physics, Mathematical Sciences, Physical Sciences, Engineering
Abstract: A search is presented for gluinos decaying via the supersymmetric partner of the top quark using events with two same-sign leptons, jets, and missing transverse momentum. The analysis is performed with 2.05 fb(-1) of integrated luminosity from pp collisions at sqrt[s]=7 TeV collected by the ATLAS detector at the LHC. No excess beyond the standard model expectation is observed, and exclusion limits are derived for simplified models where the gluino decays via the supersymmetric partner of the top quark and in the minimal supergravity and constrained minimal supersymmetric standard model framework. In those scenarios, gluino masses below 550 GeV are excluded at 95% C.L. within the parameter space considered, significantly extending the coverage with respect to existing limits. Depending on the model parameters, gluino masses up to 750 GeV can also be excluded at 95% C.L.
Published: 2012

38. Measurement of the WW cross section in √s=7 TeV pp collisions with the ATLAS detector and limits on anomalous gauge couplings

Author: Aad, G, Abbott, B, Abdallah, J, Abdel Khalek, S, Abdelalim, AA, Abdesselam, A, Abdinov, O, Abi, B, Abolins, M, AbouZeid, OS, Abramowicz, H, Abreu, H, Acerbi, E, Acharya, BS, Adamczyk, L, Adams, DL, Addy, TN, Adelman, J, Aderholz, M, Adomeit, S, Adragna, P, Adye, T, Aefsky, S, Aguilar-Saavedra, JA, Aharrouche, M, Ahlen, SP, Ahles, F, Ahmad, A, Ahsan, M, Aielli, G, Akdogan, T, A°kesson, TPA, Akimoto, G, Akimov, AV, Akiyama, A, Alam, MS, Alam, MA, Albert, J, Albrand, S, Aleksa, M, Aleksandrov, IN, Alessandria, F, Alexa, C, Alexander, G, Alexandre, G, Alexopoulos, T, Alhroob, M, Aliev, M, Alimonti, G, Alison, J, Aliyev, M, Allbrooke, BMM, Allport, PP, Allwood-Spiers, SE, Almond, J, Aloisio, A, Alon, R, Alonso, A, Alvarez Gonzalez, B, Alviggi, MG, Amako, K, Amaral, P, Amelung, C, Ammosov, VV, Amorim, A, Amorós, G, Amram, N, Anastopoulos, C, Ancu, LS, Andari, N, Andeen, T, Anders, CF, Anders, G, Anderson, KJ, Andreazza, A, Andrei, V, Andrieux, ML, Anduaga, XS, Angerami, A, Anghinolfi, F, Anisenkov, A, Anjos, N, Annovi, A, Antonaki, A, Antonelli, M, Antonov, A, Antos, J, Anulli, F, Aoun, S, Aperio Bella, L, Apolle, R, Arabidze, G, Aracena, I, Arai, Y, Arce, ATH, Arfaoui, S, Arguin, JF, Arik, E, Arik, M, and Armbruster, AJ
Subjects: hep-ex, Nuclear & Particles Physics, Atomic, Molecular, Nuclear, Particle and Plasma Physics, Astronomical and Space Sciences, Mathematical Physics, Atomic, Molecular, Nuclear, Particle and Plasma Physics
Abstract: This Letter reports a measurement of the WW production cross section in √s=7 TeV pp collisions using data corresponding to an integrated luminosity of 1.02 fb -1 collected with the ATLAS detector. Using leptonic decays of oppositely charged W bosons, the total measured cross section is σ(pp→WW)=54.4±4.0(stat.)±3.9(syst.)±2.0(lumi.) pb, consistent with the Standard Model prediction of σ(pp→WW)=44.4±2.8 pb. Limits on anomalous electroweak triple-gauge couplings are extracted from a fit to the transverse-momentum distribution of the leading charged lepton in the event. © 2012 CERN.
Published: 2012

39. Search for new particles decaying to ZZ using final states with leptons and jets with the ATLAS detector in √s=7 TeV proton-proton collisions

Author: Aad, G, Abbott, B, Abdallah, J, Abdelalim, AA, Abdesselam, A, Abdinov, O, Abi, B, Abolins, M, AbouZeid, OS, Abramowicz, H, Abreu, H, Acerbi, E, Acharya, BS, Adamczyk, L, Adams, DL, Addy, TN, Adelman, J, Aderholz, M, Adomeit, S, Adragna, P, Adye, T, Aefsky, S, Aguilar-Saavedra, JA, Aharrouche, M, Ahlen, SP, Ahles, F, Ahmad, A, Ahsan, M, Aielli, G, Akdogan, T, Åkesson, TPA, Akimoto, G, Akimov, AV, Akiyama, A, Alam, MS, Alam, MA, Albert, J, Albrand, S, Aleksa, M, Aleksandrov, IN, Alessandria, F, Alexa, C, Alexander, G, Alexandre, G, Alexopoulos, T, Alhroob, M, Aliev, M, Alimonti, G, Alison, J, Aliyev, M, Allbrooke, BMM, Allport, PP, Allwood-Spiers, SE, Almond, J, Aloisio, A, Alon, R, Alonso, A, Alvarez Gonzalez, B, Alviggi, MG, Amako, K, Amaral, P, Amelung, C, Ammosov, VV, Amorim, A, Amorós, G, Amram, N, Anastopoulos, C, Ancu, LS, Andari, N, Andeen, T, Anders, CF, Anders, G, Anderson, KJ, Andreazza, A, Andrei, V, Andrieux, ML, Anduaga, XS, Angerami, A, Anghinolfi, F, Anisenkov, A, Anjos, N, Annovi, A, Antonaki, A, Antonelli, M, Antonov, A, Antos, J, Anulli, F, Aoun, S, Aperio Bella, L, Apolle, R, Arabidze, G, Aracena, I, Arai, Y, and Arce, ATH
Subjects: hep-ex, Nuclear & Particles Physics, Atomic, Molecular, Nuclear, Particle and Plasma Physics, Astronomical and Space Sciences, Mathematical Physics, Atomic, Molecular, Nuclear, Particle and Plasma Physics
Abstract: A search is presented for a narrow resonance decaying to a pair of Z bosons using data corresponding to 1.02fb-1 of integrated luminosity collected by the ATLAS experiment from pp collisions at √s=7TeV. Events containing either four charged leptons (ℓℓℓℓ) or two charged leptons and two jets (ℓℓjj) are analyzed and found to be consistent with the Standard Model background expectation. Lower limits on a resonance mass are set using the Randall-Sundrum (RS1) graviton model as a benchmark. Using both ℓℓℓℓ and ℓℓjj events, an RS1 graviton with k/m-pl=0.1 and mass between 325 and 845 GeV is excluded at 95% confidence level. In addition, the ℓℓℓℓ events are used to set a model-independent fiducial cross section limit of σfid(pp→X→ZZ)
Published: 2012

40. Search for FCNC single top-quark production at √s=7 TeV with the ATLAS detector

Author: Aad, G, Abbott, B, Abdallah, J, Abdelalim, AA, Abdesselam, A, Abdinov, O, Abi, B, Abolins, M, AbouZeid, OS, Abramowicz, H, Abreu, H, Acerbi, E, Acharya, BS, Adamczyk, L, Adams, DL, Addy, TN, Adelman, J, Aderholz, M, Adomeit, S, Adragna, P, Adye, T, Aefsky, S, Aguilar-Saavedra, JA, Aharrouche, M, Ahlen, SP, Ahles, F, Ahmad, A, Ahsan, M, Aielli, G, Akdogan, T, Åkesson, TPA, Akimoto, G, Akimov, AV, Akiyama, A, Alam, MS, Alam, MA, Albert, J, Albrand, S, Aleksa, M, Aleksandrov, IN, Alessandria, F, Alexa, C, Alexander, G, Alexandre, G, Alexopoulos, T, Alhroob, M, Aliev, M, Alimonti, G, Alison, J, Aliyev, M, Allbrooke, BMM, Allport, PP, Allwood-Spiers, SE, Almond, J, Aloisio, A, Alon, R, Alonso, A, Alvarez Gonzalez, B, Alviggi, MG, Amako, K, Amaral, P, Amelung, C, Ammosov, VV, Amorim, A, Amorós, G, Amram, N, Anastopoulos, C, Ancu, LS, Andari, N, Andeen, T, Anders, CF, Anders, G, Anderson, KJ, Andreazza, A, Andrei, V, Andrieux, ML, Anduaga, XS, Angerami, A, Anghinolfi, F, Anisenkov, A, Anjos, N, Annovi, A, Antonaki, A, Antonelli, M, Antonov, A, Antos, J, Anulli, F, Aoun, S, Aperio Bella, L, Apolle, R, Arabidze, G, Aracena, I, Arai, Y, Arce, ATH, Arfaoui, S, Arguin, JF, Arik, E, Arik, M, Armbruster, AJ, and Arnaez, O
Subjects: Top physics, Heavy-quark production, FCNC, Single top quark, hep-ex, Nuclear & Particles Physics, Atomic, Molecular, Nuclear, Particle and Plasma Physics, Astronomical and Space Sciences, Mathematical Physics, Atomic, Molecular, Nuclear, Particle and Plasma Physics
Abstract: A search for the production of single top-quarks via flavour-changing neutral-currents is presented. Data collected with the ATLAS detector at a centre-of-mass energy of s=7 TeV, corresponding to an integrated luminosity of 2.05 fb−1, are used. Candidate events with a semileptonic top-quark decay signature are classified as signal- or background-like events by using several kinematic variables as input to a neural network. No signal is observed in the neural network output distribution and a Bayesian upper limit is placed on the production cross-section. The observed upper limit at 95% confidence level on the cross-section multiplied by the t→Wb branching fraction is measured to be σqg→t×B(t→Wb)
Published: 2012

41. Measurement of the cross section for top-quark pair production in pp collisions at √s = 7 TeV with the ATLAS detector using final states with two high-pT leptons

Author: Aad, G, Abbott, B, Abdallah, J, Abdelalim, AA, Abdesselam, A, Abdinov, O, Abi, B, Abolins, M, AbouZeid, OS, Abramowicz, H, Abreu, H, Acerbi, E, Acharya, BS, Adamczyk, L, Adams, DL, Addy, TN, Adelman, J, Aderholz, M, Adomeit, S, Adragna, P, Adye, T, Aefsky, S, Aguilar-Saavedra, JA, Aharrouche, M, Ahlen, SP, Ahles, F, Ahmad, A, Ahsan, M, Aielli, G, Akdogan, T, Åkesson, TPA, Akimoto, G, Akimov, AV, Akiyama, A, Alam, MS, Alam, MA, Albert, J, Albrand, S, Aleksa, M, Aleksandrov, IN, Alessandria, F, Alexa, C, Alexander, G, Alexandre, G, Alexopoulos, T, Alhroob, M, Aliev, M, Alimonti, G, Alison, J, Aliyev, M, Allport, PP, Allwood-Spiers, SE, Almond, J, Aloisio, A, Alon, R, Alonso, A, Alvarez Gonzalez, B, Alviggi, MG, Amako, K, Amaral, P, Amelung, C, Ammosov, VV, Amorim, A, Amorós, G, Amram, N, Anastopoulos, C, Ancu, LS, Andari, N, Andeen, T, Anders, CF, Anders, G, Anderson, KJ, Andreazza, A, Andrei, V, Andrieux, ML, Anduaga, XS, Angerami, A, Anghinolfi, F, Anisenkov, A, Anjos, N, Annovi, A, Antonaki, A, Antonelli, M, Antonov, A, Antos, J, Anulli, F, Aoun, S, Aperio Bella, L, Apolle, R, Arabidze, G, Aracena, I, Arai, Y, Arce, ATH, Archambault, JP, Arfaoui, S, Arguin, JF, Arik, E, Arik, M, Armbruster, AJ, and Arnaez, O
Subjects: Hadron-Hadron Scattering, hep-ex, Nuclear & Particles Physics, Mathematical Sciences, Physical Sciences, Mathematical Physics, Atomic, Molecular, Nuclear, Particle and Plasma Physics, Quantum Physics, Atomic, Molecular, Nuclear, Particle and Plasma Physics
Abstract: A measurement is reported of the production cross section of top-quark pairs (tt̄) in proton-proton collisions at a center-of-mass energy of 7 TeV recorded with the ATLAS detector at the LHC. Candidate events have a signature consistent with containing two isolated leptons, large missing transverse momentum, and at least two jets. Using a data sample corresponding to an integrated luminosity of 0.70 fb-1, a tt̄ production cross section σtt̄ = 176 ± 5(stat.)-1111+(syst.) ± 8(lum.) pb is measured for an assumed top-quark mass of mt = 172.5 GeV. This measurement is in good agreement with Standard Model predictions. © CERN.
Published: 2012

42. Measurement of the WW cross section in s=7 TeV pp collisions with the ATLAS detector and limits on anomalous gauge couplings

Author: Collaboration, ATLAS, Aad, G, Abbott, B, Abdallah, J, Khalek, S Abdel, Abdelalim, AA, Abdesselam, A, Abdinov, O, Abi, B, Abolins, M, AbouZeid, OS, Abramowicz, H, Abreu, H, Acerbi, E, Acharya, BS, Adamczyk, L, Adams, DL, Addy, TN, Adelman, J, Aderholz, M, Adomeit, S, Adragna, P, Adye, T, Aefsky, S, Aguilar-Saavedra, JA, Aharrouche, M, Ahlen, SP, Ahles, F, Ahmad, A, Ahsan, M, Aielli, G, Akdogan, T, Åkesson, TPA, Akimoto, G, Akimov, AV, Akiyama, A, Alam, MS, Alam, MA, Albert, J, Albrand, S, Aleksa, M, Aleksandrov, IN, Alessandria, F, Alexa, C, Alexander, G, Alexandre, G, Alexopoulos, T, Alhroob, M, Aliev, M, Alimonti, G, Alison, J, Aliyev, M, Allbrooke, BMM, Allport, PP, Allwood-Spiers, SE, Almond, J, Aloisio, A, Alon, R, Alonso, A, Gonzalez, B Alvarez, Alviggi, MG, Amako, K, Amaral, P, Amelung, C, Ammosov, VV, Amorim, A, Amorós, G, Amram, N, Anastopoulos, C, Ancu, LS, Andari, N, Andeen, T, Anders, CF, Anders, G, Anderson, KJ, Andreazza, A, Andrei, V, Andrieux, M-L, Anduaga, XS, Angerami, A, Anghinolfi, F, Anisenkov, A, Anjos, N, Annovi, A, Antonaki, A, Antonelli, M, Antonov, A, Antos, J, Anulli, F, Aoun, S, Bella, L Aperio, Apolle, R, Arabidze, G, Aracena, I, Arai, Y, Arce, ATH, Arfaoui, S, Arguin, J-F, Arik, E, and Arik, M
Subjects: hep-ex, Mathematical Physics, Astronomical and Space Sciences, Atomic, Molecular, Nuclear, Particle and Plasma Physics, Nuclear & Particles Physics
Abstract: This Letter reports a measurement of the WW production cross section in √s=7 TeV pp collisions using data corresponding to an integrated luminosity of 1.02 fb -1 collected with the ATLAS detector. Using leptonic decays of oppositely charged W bosons, the total measured cross section is σ(pp→WW)=54.4±4.0(stat.)±3.9(syst.)±2.0(lumi.) pb, consistent with the Standard Model prediction of σ(pp→WW)=44.4±2.8 pb. Limits on anomalous electroweak triple-gauge couplings are extracted from a fit to the transverse-momentum distribution of the leading charged lepton in the event. © 2012 CERN.
Published: 2012

43. Search for FCNC single top-quark production at s=7 TeV with the ATLAS detector

Author: Collaboration, ATLAS, Aad, G, Abbott, B, Abdallah, J, Abdelalim, AA, Abdesselam, A, Abdinov, O, Abi, B, Abolins, M, AbouZeid, OS, Abramowicz, H, Abreu, H, Acerbi, E, Acharya, BS, Adamczyk, L, Adams, DL, Addy, TN, Adelman, J, Aderholz, M, Adomeit, S, Adragna, P, Adye, T, Aefsky, S, Aguilar-Saavedra, JA, Aharrouche, M, Ahlen, SP, Ahles, F, Ahmad, A, Ahsan, M, Aielli, G, Akdogan, T, Åkesson, TPA, Akimoto, G, Akimov, AV, Akiyama, A, Alam, MS, Alam, MA, Albert, J, Albrand, S, Aleksa, M, Aleksandrov, IN, Alessandria, F, Alexa, C, Alexander, G, Alexandre, G, Alexopoulos, T, Alhroob, M, Aliev, M, Alimonti, G, Alison, J, Aliyev, M, Allbrooke, BMM, Allport, PP, Allwood-Spiers, SE, Almond, J, Aloisio, A, Alon, R, Alonso, A, Gonzalez, B Alvarez, Alviggi, MG, Amako, K, Amaral, P, Amelung, C, Ammosov, VV, Amorim, A, Amorós, G, Amram, N, Anastopoulos, C, Ancu, LS, Andari, N, Andeen, T, Anders, CF, Anders, G, Anderson, KJ, Andreazza, A, Andrei, V, Andrieux, M-L, Anduaga, XS, Angerami, A, Anghinolfi, F, Anisenkov, A, Anjos, N, Annovi, A, Antonaki, A, Antonelli, M, Antonov, A, Antos, J, Anulli, F, Aoun, S, Bella, L Aperio, Apolle, R, Arabidze, G, Aracena, I, Arai, Y, Arce, ATH, Arfaoui, S, Arguin, J-F, Arik, E, Arik, M, and Armbruster, AJ
Subjects: Top physics, Heavy-quark production, FCNC, Single top quark, hep-ex, Mathematical Physics, Astronomical and Space Sciences, Atomic, Molecular, Nuclear, Particle and Plasma Physics, Nuclear & Particles Physics
Abstract: A search for the production of single top-quarks via flavour-changing neutral-currents is presented. Data collected with the ATLAS detector at a centre-of-mass energy of s=7 TeV, corresponding to an integrated luminosity of 2.05 fb−1, are used. Candidate events with a semileptonic top-quark decay signature are classified as signal- or background-like events by using several kinematic variables as input to a neural network. No signal is observed in the neural network output distribution and a Bayesian upper limit is placed on the production cross-section. The observed upper limit at 95% confidence level on the cross-section multiplied by the t→Wb branching fraction is measured to be σqg→t×B(t→Wb)
Published: 2012

44. Search for supersymmetry in pp collisions at s=7 TeV in final states with missing transverse momentum and b-jets with the ATLAS detector

Author: Aad, G, Abbott, B, Abdallah, J, Khalek, S Abdel, Abdelalim, AA, Abdesselam, A, Abdinov, O, Abi, B, Abolins, M, AbouZeid, OS, Abramowicz, H, Abreu, H, Acerbi, E, Acharya, BS, Adamczyk, L, Adams, DL, Addy, TN, Adelman, J, Aderholz, M, Adomeit, S, Adragna, P, Adye, T, Aefsky, S, Aguilar-Saavedra, JA, Aharrouche, M, Ahlen, SP, Ahles, F, Ahmad, A, Ahsan, M, Aielli, G, Akdogan, T, Åkesson, TPA, Akimoto, G, Akimov, AV, Akiyama, A, Alam, MS, Alam, MA, Albert, J, Albrand, S, Aleksa, M, Aleksandrov, IN, Alessandria, F, Alexa, C, Alexander, G, Alexandre, G, Alexopoulos, T, Alhroob, M, Aliev, M, Alimonti, G, Alison, J, Aliyev, M, Allbrooke, BMM, Allport, PP, Allwood-Spiers, SE, Almond, J, Aloisio, A, Alon, R, Alonso, A, Gonzalez, B Alvarez, Alviggi, MG, Amako, K, Amaral, P, Amelung, C, Ammosov, VV, Amorim, A, Amorós, G, Amram, N, Anastopoulos, C, Ancu, LS, Andari, N, Andeen, T, Anders, CF, Anders, G, Anderson, KJ, Andreazza, A, Andrei, V, Andrieux, M-L, Anduaga, XS, Angerami, A, Anghinolfi, F, Anisenkov, A, Anjos, N, Annovi, A, Antonaki, A, Antonelli, M, Antonov, A, Antos, J, Anulli, F, Aoun, S, Bella, L Aperio, Apolle, R, Arabidze, G, Aracena, I, Arai, Y, Arce, ATH, Arfaoui, S, Arguin, J-F, Arik, E, Arik, M, and Armbruster, AJ
Subjects: hep-ex, Astronomical and Space Sciences, Atomic, Molecular, Nuclear, Particle and Plasma Physics, Quantum Physics, Nuclear & Particles Physics
Abstract: The results of a search for supersymmetry in events with large missing transverse momentum and heavy-flavor jets using an integrated luminosity corresponding to 2.05fb-1 of pp collisions at √s=7TeV recorded with the ATLAS detector at the Large Hadron Collider are reported. No significant excess is observed with respect to the prediction for standard model processes. Results are interpreted in a variety of R-parity conserving models in which scalar bottoms and tops are the only scalar quarks to appear in the gluino decay cascade, and in an SO(10) model framework. Gluino masses up to 600-900GeV are excluded, depending on the model considered. © 2012 CERN. Published by the American Physical Society.
Published: 2012

45. Search for resonant WZ production in the WZ→lνl′l′ channel in (s)=7 TeV pp collisions with the ATLAS detector

Author: Aad, G, Abbott, B, Abdallah, J, Khalek, S Abdel, Abdelalim, AA, Abdesselam, A, Abdinov, O, Abi, B, Abolins, M, AbouZeid, OS, Abramowicz, H, Abreu, H, Acerbi, E, Acharya, BS, Adamczyk, L, Adams, DL, Addy, TN, Adelman, J, Aderholz, M, Adomeit, S, Adragna, P, Adye, T, Aefsky, S, Aguilar-Saavedra, JA, Aharrouche, M, Ahlen, SP, Ahles, F, Ahmad, A, Ahsan, M, Aielli, G, Akdogan, T, Åkesson, TPA, Akimoto, G, Akimov, AV, Akiyama, A, Alam, MS, Alam, MA, Albert, J, Albrand, S, Aleksa, M, Aleksandrov, IN, Alessandria, F, Alexa, C, Alexander, G, Alexandre, G, Alexopoulos, T, Alhroob, M, Aliev, M, Alimonti, G, Alison, J, Aliyev, M, Allbrooke, BMM, Allport, PP, Allwood-Spiers, SE, Almond, J, Aloisio, A, Alon, R, Alonso, A, Gonzalez, B Alvarez, Alviggi, MG, Amako, K, Amaral, P, Amelung, C, Ammosov, VV, Amorim, A, Amorós, G, Amram, N, Anastopoulos, C, Ancu, LS, Andari, N, Andeen, T, Anders, CF, Anders, G, Anderson, KJ, Andreazza, A, Andrei, V, Andrieux, M-L, Anduaga, XS, Angerami, A, Anghinolfi, F, Anisenkov, A, Anjos, N, Annovi, A, Antonaki, A, Antonelli, M, Antonov, A, Antos, J, Anulli, F, Aoun, S, Bella, L Aperio, Apolle, R, Arabidze, G, Aracena, I, Arai, Y, Arce, ATH, Arfaoui, S, Arguin, J-F, Arik, E, Arik, M, and Armbruster, AJ
Subjects: hep-ex, Astronomical and Space Sciences, Atomic, Molecular, Nuclear, Particle and Plasma Physics, Quantum Physics, Nuclear & Particles Physics
Abstract: A generic search is presented for a heavy particle decaying to WZ → ℓν′ ℓ ′ (ℓ, ℓ′ = e, μ)final states. The data were recorded by the ATLAS detector in ffiffiffis √ s = 7 TeV pp collisions at the Large Hadron Collider and correspond to an integrated luminosity of 1:02 fb-1. The transverse mass distribution of the selected WZ candidates is found to be consistent with the standard model expectation. Upper limits on the production cross section times branching ratio are derived using two benchmark models predicting a heavy particle decaying to a WZ pair.
Published: 2012

46. Search for new particles decaying to ZZ using final states with leptons and jets with the ATLAS detector in s=7 TeV proton–proton collisions

Author: Collaboration, ATLAS, Aad, G, Abbott, B, Abdallah, J, Abdelalim, AA, Abdesselam, A, Abdinov, O, Abi, B, Abolins, M, AbouZeid, OS, Abramowicz, H, Abreu, H, Acerbi, E, Acharya, BS, Adamczyk, L, Adams, DL, Addy, TN, Adelman, J, Aderholz, M, Adomeit, S, Adragna, P, Adye, T, Aefsky, S, Aguilar-Saavedra, JA, Aharrouche, M, Ahlen, SP, Ahles, F, Ahmad, A, Ahsan, M, Aielli, G, Akdogan, T, Åkesson, TPA, Akimoto, G, Akimov, AV, Akiyama, A, Alam, MS, Alam, MA, Albert, J, Albrand, S, Aleksa, M, Aleksandrov, IN, Alessandria, F, Alexa, C, Alexander, G, Alexandre, G, Alexopoulos, T, Alhroob, M, Aliev, M, Alimonti, G, Alison, J, Aliyev, M, Allbrooke, BMM, Allport, PP, Allwood-Spiers, SE, Almond, J, Aloisio, A, Alon, R, Alonso, A, Gonzalez, B Alvarez, Alviggi, MG, Amako, K, Amaral, P, Amelung, C, Ammosov, VV, Amorim, A, Amorós, G, Amram, N, Anastopoulos, C, Ancu, LS, Andari, N, Andeen, T, Anders, CF, Anders, G, Anderson, KJ, Andreazza, A, Andrei, V, Andrieux, M-L, Anduaga, XS, Angerami, A, Anghinolfi, F, Anisenkov, A, Anjos, N, Annovi, A, Antonaki, A, Antonelli, M, Antonov, A, Antos, J, Anulli, F, Aoun, S, Bella, L Aperio, Apolle, R, Arabidze, G, Aracena, I, Arai, Y, Arce, ATH, Arfaoui, S, Arguin, J-F, Arik, E, Arik, M, and Armbruster, AJ
Subjects: hep-ex, Mathematical Physics, Astronomical and Space Sciences, Atomic, Molecular, Nuclear, Particle and Plasma Physics, Nuclear & Particles Physics
Abstract: A search is presented for a narrow resonance decaying to a pair of Z bosons using data corresponding to 1.02fb-1 of integrated luminosity collected by the ATLAS experiment from pp collisions at √s=7TeV. Events containing either four charged leptons (ℓℓℓℓ) or two charged leptons and two jets (ℓℓjj) are analyzed and found to be consistent with the Standard Model background expectation. Lower limits on a resonance mass are set using the Randall-Sundrum (RS1) graviton model as a benchmark. Using both ℓℓℓℓ and ℓℓjj events, an RS1 graviton with k/m-pl=0.1 and mass between 325 and 845 GeV is excluded at 95% confidence level. In addition, the ℓℓℓℓ events are used to set a model-independent fiducial cross section limit of σfid(pp→X→ZZ)
Published: 2012

47. Search for anomaly-mediated supersymmetry breaking with the ATLAS detector based on a disappearing-track signature in pp collisions at √s=7 TeV

Author: Aad, G, Abbott, B, Abdallah, J, Abdelalim, AA, Abdesselam, A, Abdinov, O, Abi, B, Abolins, M, Abramowicz, H, Abreu, H, Acerbi, E, Acharya, BS, Adams, DL, Addy, TN, Adelman, J, Aderholz, M, Adomeit, S, Adragna, P, Adye, T, Aefsky, S, Aguilar-Saavedra, JA, Aharrouche, M, Ahlen, SP, Ahles, F, Ahmad, A, Ahsan, M, Aielli, G, Akdogan, T, Åkesson, TPA, Akimoto, G, Akimov, AV, Akiyama, A, Alam, MS, Alam, MA, Albert, J, Albrand, S, Aleksa, M, Aleksandrov, IN, Alessandria, F, Alexa, C, Alexander, G, Alexandre, G, Alexopoulos, T, Alhroob, M, Aliev, M, Alimonti, G, Alison, J, Aliyev, M, Allport, PP, Allwood-Spiers, SE, Almond, J, Aloisio, A, Alon, R, Alonso, A, Alvarez Gonzalez, B, Alviggi, MG, Amako, K, Amaral, P, Amelung, C, Ammosov, VV, Amorim, A, Amorós, G, Amram, N, Anastopoulos, C, Ancu, LS, Andari, N, Andeen, T, Anders, CF, Anders, G, Anderson, KJ, Andreazza, A, Andrei, V, Andrieux, ML, Anduaga, XS, Angerami, A, Anghinolfi, F, Anisenkov, A, Anjos, N, Annovi, A, Antonaki, A, Antonelli, M, Antonov, A, Antos, J, Anulli, F, Aoun, S, Aperio Bella, L, Apolle, R, Arabidze, G, Aracena, I, Arai, Y, Arce, ATH, Archambault, JP, Arfaoui, S, Arguin, JF, Arik, E, Arik, M, Armbruster, AJ, Arnaez, O, Arnault, C, and Artamonov, A
Subjects: hep-ex, Nuclear & Particles Physics, Atomic, Molecular, Nuclear, Particle and Plasma Physics, Quantum Physics
Abstract: In models of anomaly-mediated supersymmetry breaking (AMSB), the lightest chargino is predicted to have a lifetime long enough to be detected in collider experiments. This letter explores AMSB scenarios in pp collisions at (Formula Presented) = 7 TeV by attempting to identify decaying charginos which result in tracks that appear to have few associated hits in the outer region of the tracking system. The search was based on data corresponding to an integrated luminosity of 1.02 fb−1collected with the ATLAS detector in 2011. The pT spectrum of candidate tracks is found to be consistent with the expectation from Standard Model background processes and constraints on the lifetime and the production cross section were obtained. In the minimal AMSB framework with m3/2< 32 TeV, m0< 1.5 TeV, tanβ = 5 and μ > 0, a chargino having mass below 92 GeV and a lifetime between 0.5 ns and 2 ns is excluded at 95 % confidence level.
Published: 2012

48. Measurement of the top quark mass with the template method in the channel using ATLAS data

Author: The ATLAS Collaboration, Aad, G, Abbott, B, Abdallah, J, Abdelalim, AA, Abdesselam, A, Abdinov, O, Abi, B, Abolins, M, AbouZeid, OS, Abramowicz, H, Abreu, H, Acerbi, E, Acharya, BS, Adamczyk, L, Adams, DL, Addy, TN, Adelman, J, Aderholz, M, Adomeit, S, Adragna, P, Adye, T, Aefsky, S, Aguilar-Saavedra, JA, Aharrouche, M, Ahlen, SP, Ahles, F, Ahmad, A, Ahsan, M, Aielli, G, Akdogan, T, Åkesson, TPA, Akimoto, G, Akimov, AV, Akiyama, A, Alam, MS, Alam, MA, Albert, J, Albrand, S, Aleksa, M, Aleksandrov, IN, Alessandria, F, Alexa, C, Alexander, G, Alexandre, G, Alexopoulos, T, Alhroob, M, Aliev, M, Alimonti, G, Alison, J, Aliyev, M, Allbrooke, BMM, Allport, PP, Allwood-Spiers, SE, Almond, J, Aloisio, A, Alon, R, Alonso, A, Alvarez Gonzalez, B, Alviggi, MG, Amako, K, Amaral, P, Amelung, C, Ammosov, VV, Amorim, A, Amorós, G, Amram, N, Anastopoulos, C, Ancu, LS, Andari, N, Andeen, T, Anders, CF, Anders, G, Anderson, KJ, Andreazza, A, Andrei, V, Andrieux, M-L, Anduaga, XS, Angerami, A, Anghinolfi, F, Anisenkov, A, Anjos, N, Annovi, A, Antonaki, A, Antonelli, M, Antonov, A, Antos, J, Anulli, F, Aoun, S, Aperio Bella, L, Apolle, R, Arabidze, G, Aracena, I, Arai, Y, Arce, ATH, Arfaoui, S, Arguin, J-F, Arik, E, Arik, M, and Armbruster, AJ
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 has been measured using the template method in the [Formula: see text] channel based on data recorded in 2011 with the ATLAS detector at the LHC. The data were taken at a proton-proton centre-of-mass energy of [Formula: see text] and correspond to an integrated luminosity of 1.04 fb-1. The analyses in the e+jets and μ+jets decay channels yield consistent results. The top quark mass is measured to be mtop=174.5±0.6stat±2.3syst GeV.
Published: 2012

49. Measurement of the charge asymmetry in top quark pair production in pp collisions at using the ATLAS detector

Author: The ATLAS Collaboration, Aad, G, Abbott, B, Abdallah, J, Abdelalim, AA, Abdesselam, A, Abdinov, O, Abi, B, Abolins, M, AbouZeid, OS, Abramowicz, H, Abreu, H, Acerbi, E, Acharya, BS, Adamczyk, L, Adams, DL, Addy, TN, Adelman, J, Aderholz, M, Adomeit, S, Adragna, P, Adye, T, Aefsky, S, Aguilar-Saavedra, JA, Aharrouche, M, Ahlen, SP, Ahles, F, Ahmad, A, Ahsan, M, Aielli, G, Akdogan, T, Åkesson, TPA, Akimoto, G, Akimov, AV, Akiyama, A, Alam, MS, Alam, MA, Albert, J, Albrand, S, Aleksa, M, Aleksandrov, IN, Alessandria, F, Alexa, C, Alexander, G, Alexandre, G, Alexopoulos, T, Alhroob, M, Aliev, M, Alimonti, G, Alison, J, Aliyev, M, Allport, PP, Allwood-Spiers, SE, Almond, J, Aloisio, A, Alon, R, Alonso, A, Alvarez Gonzalez, B, Alviggi, MG, Amako, K, Amaral, P, Amelung, C, Ammosov, VV, Amorim, A, Amorós, G, Amram, N, Anastopoulos, C, Ancu, LS, Andari, N, Andeen, T, Anders, CF, Anders, G, Anderson, KJ, Andreazza, A, Andrei, V, Andrieux, M-L, Anduaga, XS, Angerami, A, Anghinolfi, F, Anisenkov, A, Anjos, N, Annovi, A, Antonaki, A, Antonelli, M, Antonov, A, Antos, J, Anulli, F, Aoun, S, Aperio Bella, L, Apolle, R, Arabidze, G, Aracena, I, Arai, Y, Arce, ATH, Archambault, JP, Arfaoui, S, Arguin, J-F, Arik, E, Arik, M, and Armbruster, AJ
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 measurement of the top-antitop production charge asymmetry AC is presented using data corresponding to an integrated luminosity of 1.04 fb-1 of pp collisions at [Formula: see text] TeV collected by the ATLAS detector at the LHC. Events are selected with a single lepton (electron or muon), missing transverse momentum and at least four jets of which at least one jet is identified as coming from a b-quark. A kinematic fit is used to reconstruct the [Formula: see text] event topology. After background subtraction, a Bayesian unfolding procedure is performed to correct for acceptance and detector effects. The measured value of AC is [Formula: see text], consistent with the prediction from the MC@NLO Monte Carlo generator of AC =0.006±0.002. Measurements of AC in two ranges of invariant mass of the top-antitop pair are also shown.
Published: 2012

50. Measurement of production with a veto on additional central jet activity in pp collisions at TeV using the ATLAS detector

Author: The ATLAS Collaboration, Aad, G, Abbott, B, Abdallah, J, Abdel Khalek, S, Abdelalim, AA, Abdesselam, A, Abdinov, O, Abi, B, Abolins, M, AbouZeid, OS, Abramowicz, H, Abreu, H, Acerbi, E, Acharya, BS, Adamczyk, L, Adams, DL, Addy, TN, Adelman, J, Aderholz, M, Adomeit, S, Adragna, P, Adye, T, Aefsky, S, Aguilar-Saavedra, JA, Aharrouche, M, Ahlen, SP, Ahles, F, Ahmad, A, Ahsan, M, Aielli, G, Akdogan, T, Åkesson, TPA, Akimoto, G, Akimov, AV, Akiyama, A, Alam, MS, Alam, MA, Albert, J, Albrand, S, Aleksa, M, Aleksandrov, IN, Alessandria, F, Alexa, C, Alexander, G, Alexandre, G, Alexopoulos, T, Alhroob, M, Aliev, M, Alimonti, G, Alison, J, Aliyev, M, Allbrooke, BMM, Allport, PP, Allwood-Spiers, SE, Almond, J, Aloisio, A, Alon, R, Alonso, A, Alvarez Gonzalez, B, Alviggi, MG, Amako, K, Amaral, P, Amelung, C, Ammosov, VV, Amorim, A, Amorós, G, Amram, N, Anastopoulos, C, Ancu, LS, Andari, N, Andeen, T, Anders, CF, Anders, G, Anderson, KJ, Andreazza, A, Andrei, V, Andrieux, M-L, Anduaga, XS, Angerami, A, Anghinolfi, F, Anisenkov, A, Anjos, N, Annovi, A, Antonaki, A, Antonelli, M, Antonov, A, Antos, J, Anulli, F, Aoun, S, Aperio Bella, L, Apolle, R, Arabidze, G, Aracena, I, Arai, Y, Arce, ATH, Arfaoui, S, Arguin, J-F, Arik, E, and Arik, M
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 measurement of the jet activity in [Formula: see text] events produced in proton-proton collisions at a centre-of-mass energy of 7 TeV is presented, using 2.05 fb-1 of integrated luminosity collected by the ATLAS detector at the Large Hadron Collider. The [Formula: see text] events are selected in the dilepton decay channel with two identified b-jets from the top quark decays. Events are vetoed if they contain an additional jet with transverse momentum above a threshold in a central rapidity interval. The fraction of events surviving the jet veto is presented as a function of this threshold for four different central rapidity interval definitions. An alternate measurement is also performed, in which events are vetoed if the scalar transverse momentum sum of the additional jets in each rapidity interval is above a threshold. In both measurements, the data are corrected for detector effects and compared to the theoretical models implemented in MC@NLO, Powheg, Alpgen and Sherpa. The experimental uncertainties are often smaller than the spread of theoretical predictions, allowing deviations between data and theory to be observed in some regions of phase space.
Published: 2012

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