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1. Search for the nonresonant production of Higgs boson pairs via gluon fusion and vector-boson fusion in the bb¯τ+τ− final state in proton-proton collisions at s=13  TeV with the ATLAS detector

Author

Aad, G, Aakvaag, E, Abbott, B, Abeling, K, Abicht, NJ, Abidi, SH, Aboelela, M, Aboulhorma, A, Abramowicz, H, Abreu, H, Abulaiti, Y, Acharya, BS, Ackermann, A, Adam Bourdarios, C, Adamczyk, L, Addepalli, SV, Addison, MJ, Adelman, J, Adiguzel, A, Adye, T, Affolder, AA, Afik, Y, Agaras, MN, Agarwala, J, Aggarwal, A, Agheorghiesei, C, Ahmad, A, Ahmadov, F, Ahmed, WS, Ahuja, S, Ai, X, Aielli, G, Aikot, A, Ait Tamlihat, M, Aitbenchikh, B, Aizenberg, I, Akbiyik, M, Åkesson, TPA, Akimov, AV, Akiyama, D, Akolkar, NN, Aktas, S, Al Khoury, K, Alberghi, GL, Albert, J, Albicocco, P, Albouy, GL, Alderweireldt, S, Alegria, ZL, Aleksa, M, Aleksandrov, IN, Alexa, C, Alexopoulos, T, Alfonsi, F, Algren, M, Alhroob, M, Ali, B, Ali, HMJ, Ali, S, Alibocus, SW, Aliev, M, Alimonti, G, Alkakhi, W, Allaire, C, Allbrooke, BMM, Allen, JF, Allendes Flores, CA, Allport, PP, Aloisio, A, Alonso, F, Alpigiani, C, Alvarez Estevez, M, Alvarez Fernandez, A, Alves Cardoso, M, Alviggi, MG, Aly, M, Amaral Coutinho, Y, Ambler, A, Amelung, C, Amerl, M, Ames, CG, Amidei, D, Amirie, KJ, Amor Dos Santos, SP, Amos, KR, Ananiev, V, Anastopoulos, C, Andeen, T, Anders, JK, Andrean, SY, Andreazza, A, Angelidakis, S, Angerami, A, Anisenkov, AV, Annovi, A, Antel, C, Anthony, MT, Antipov, E, Antonelli, M, and Anulli, F

Abstract

A search for the nonresonant production of Higgs boson pairs in the HH→bb¯τ+τ− channel is performed using 140  fb−1 of proton-proton collisions at a center-of-mass energy of 13 TeV recorded by the ATLAS detector at the CERN Large Hadron Collider. The analysis strategy is optimized to probe anomalous values of the Higgs boson self-coupling modifier κλ and of the quartic HHVV (V=W,Z) coupling modifier κ2V. No significant excess above the expected background from Standard Model processes is observed. An observed (expected) upper limit μHH

Published
2024

2. Search for low-mass resonances decaying into two jets and produced in association with a photon or a jet at s=13 TeV with the ATLAS detector

Author

Aad, G, Aakvaag, E, Abbott, B, Abeling, K, Abicht, NJ, Abidi, SH, Aboelela, M, Aboulhorma, A, Abramowicz, H, Abreu, H, Abulaiti, Y, Acharya, BS, Ackermann, A, Bourdarios, C Adam, Adamczyk, L, Addepalli, SV, Addison, MJ, Adelman, J, Adiguzel, A, Adye, T, Affolder, AA, Afik, Y, Agaras, MN, Agarwala, J, Aggarwal, A, Agheorghiesei, C, Ahmad, A, Ahmadov, F, Ahmed, WS, Ahuja, S, Ai, X, Aielli, G, Aikot, A, Tamlihat, M Ait, Aitbenchikh, B, Aizenberg, I, Akbiyik, M, Åkesson, TPA, Akimov, AV, Akiyama, D, Akolkar, NN, Aktas, S, Al Khoury, K, Alberghi, GL, Albert, J, Albicocco, P, Albouy, GL, Alderweireldt, S, Alegria, ZL, Aleksa, M, Aleksandrov, IN, Alexa, C, Alexopoulos, T, Alfonsi, F, Algren, M, Alhroob, M, Ali, B, Ali, HMJ, Ali, S, Alibocus, SW, Aliev, M, Alimonti, G, Alkakhi, W, Allaire, C, Allbrooke, BMM, Allen, JF, Flores, CA Allendes, Allport, PP, Aloisio, A, Alonso, F, Alpigiani, C, Estevez, M Alvarez, Fernandez, A Alvarez, Cardoso, M Alves, Alviggi, MG, Aly, M, Coutinho, Y Amaral, Ambler, A, Amelung, C, Amerl, M, Ames, CG, Amidei, D, Amirie, KJ, Dos Santos, SP Amor, Amos, KR, An, S, Ananiev, V, Anastopoulos, C, Andeen, T, Anders, JK, Andrean, SY, Andreazza, A, Angelidakis, S, Angerami, A, Anisenkov, AV, Annovi, A, Antel, C, Anthony, MT, Antipov, E, and Antonelli, M

Subjects
Nuclear and Plasma Physics, Particle and High Energy Physics, Physical Sciences
Abstract

A search is performed for localized excesses in the low-mass dijet invariant mass distribution, targeting a hypothetical new particle decaying into two jets and produced in association with either a high transverse momentum photon or a jet. The search uses the full Run 2 data sample from LHC proton-proton collisions collected by the ATLAS experiment at a center-of-mass energy of 13 TeV during 2015–2018. Two variants of the search are presented for each type of initial-state radiation: one that makes no jet flavor requirements and one that requires both of the jets to have been identified as containing b-hadrons. No excess is observed relative to the Standard Model prediction, and the data are used to set upper limits on the production cross section for a benchmark Z′ model and, separately, for generic, beyond the Standard Model scenarios which might produce a Gaussian-shaped contribution to dijet invariant mass distributions. The results extend the current constraints on dijet resonances to the mass range between 200 and 650 GeV. © 2024 CERN, for the ATLAS Collaboration 2024 CERN

Published
2024

3. Search for charged-lepton-flavor violating μτqt interactions in top-quark production and decay in pp collisions at s=13  TeV with the ATLAS detector at the LHC

Author

Aad, G, Aakvaag, E, Abbott, B, Abeling, K, Abicht, NJ, Abidi, SH, Aboelela, M, Aboulhorma, A, Abramowicz, H, Abreu, H, Abulaiti, Y, Acharya, BS, Ackermann, A, Adam Bourdarios, C, Adamczyk, L, Addepalli, SV, Addison, MJ, Adelman, J, Adiguzel, A, Adye, T, Affolder, AA, Afik, Y, Agaras, MN, Agarwala, J, Aggarwal, A, Agheorghiesei, C, Ahmad, A, Ahmadov, F, Ahmed, WS, Ahuja, S, Ai, X, Aielli, G, Aikot, A, Ait Tamlihat, M, Aitbenchikh, B, Aizenberg, I, Akbiyik, M, Åkesson, TPA, Akimov, AV, Akiyama, D, Akolkar, NN, Aktas, S, Al Khoury, K, Alberghi, GL, Albert, J, Albicocco, P, Albouy, GL, Alderweireldt, S, Alegria, ZL, Aleksa, M, Aleksandrov, IN, Alexa, C, Alexopoulos, T, Alfonsi, F, Algren, M, Alhroob, M, Ali, B, Ali, HMJ, Ali, S, Alibocus, SW, Aliev, M, Alimonti, G, Alkakhi, W, Allaire, C, Allbrooke, BMM, Allen, JF, Allendes Flores, CA, Allport, PP, Aloisio, A, Alonso, F, Alpigiani, C, Alvarez Estevez, M, Alvarez Fernandez, A, Alves Cardoso, M, Alviggi, MG, Aly, M, Amaral Coutinho, Y, Ambler, A, Amelung, C, Amerl, M, Ames, CG, Amidei, D, Amirie, KJ, Amor Dos Santos, SP, Amos, KR, An, S, Ananiev, V, Anastopoulos, C, Andeen, T, Anders, JK, Andrean, SY, Andreazza, A, Angelidakis, S, Angerami, A, Anisenkov, AV, Annovi, A, Antel, C, Anthony, MT, Antipov, E, and Antonelli, M

Abstract

A search for charged-lepton-flavor violating μτqt (q=u, c) interactions is presented, considering both top-quark production and decay. The data analyzed correspond to 140  fb−1 of proton-proton collisions at a center-of-mass energy of s=13  TeV recorded with the ATLAS detector at the Large Hadron Collider. The analysis targets events containing two muons with the same electric charge, a hadronically decaying τ-lepton and at least one jet, with exactly one b-tagged jet, produced by a μτqt interaction. Agreement with the Standard Model expectation within 1.6 standard deviations is observed, and limits are set at the 95% confidence level (CL) on the charged-lepton-flavor violation branching ratio of B(t→μτq)

Published
2024

4. Measurement of jet substructure in boosted tt¯ events with the ATLAS detector using 140 fb-1 of 13 TeV pp collisions

Author

Aad, G, Abbott, B, Abeling, K, Abicht, NJ, Abidi, SH, Aboulhorma, A, Abramowicz, H, Abreu, H, Abulaiti, Y, Hoffman, AC Abusleme, Acharya, BS, Bourdarios, C Adam, Adamczyk, L, Adamek, L, Addepalli, SV, Addison, MJ, Adelman, J, Adiguzel, A, Adye, T, Affolder, AA, Afik, Y, Agaras, MN, Agarwala, J, Aggarwal, A, Agheorghiesei, C, Ahmad, A, Ahmadov, F, Ahmed, WS, Ahuja, S, Ai, X, Aielli, G, Aikot, A, Tamlihat, M Ait, Aitbenchikh, B, Aizenberg, I, Akbiyik, M, Åkesson, TPA, Akimov, AV, Akiyama, D, Akolkar, NN, Al Khoury, K, Alberghi, GL, Albert, J, Albicocco, P, Albouy, GL, Alderweireldt, S, Aleksa, M, Aleksandrov, IN, Alexa, C, Alexopoulos, T, Alfonsi, F, Algren, M, Alhroob, M, Ali, B, Ali, HMJ, Ali, S, Alibocus, SW, Aliev, M, Alimonti, G, Alkakhi, W, Allaire, C, Allbrooke, BMM, Allen, JF, Flores, CA Allendes, Allport, PP, Aloisio, A, Alonso, F, Alpigiani, C, Estevez, M Alvarez, Fernandez, A Alvarez, Cardoso, M Alves, Alviggi, MG, Aly, M, Coutinho, Y Amaral, Ambler, A, Amelung, C, Amerl, M, Ames, CG, Amidei, D, Dos Santos, SP Amor, Amos, KR, Ananiev, V, Anastopoulos, C, Andeen, T, Anders, JK, Andrean, SY, Andreazza, A, Angelidakis, S, Angerami, A, Anisenkov, AV, Annovi, A, Antel, C, Anthony, MT, Antipov, E, Antonelli, M, Anulli, F, Aoki, M, Aoki, T, Pozo, JA Aparisi, and Aparo, MA

Subjects
Nuclear and Plasma Physics, Particle and High Energy Physics, Physical Sciences
Abstract

Measurements of the substructure of top-quark jets are presented, using Formula Presented of 13 TeV Formula Presented collision data recorded with the ATLAS detector at the LHC. Top-quark jets reconstructed with the anti-Formula Presented algorithm with a radius parameter Formula Presented are selected in top-quark pair (Formula Presented) events where one top quark decays semileptonically and the other hadronically, or where both top quarks decay hadronically. The top-quark jets are required to have transverse momentum Formula Presented, yielding large samples of data events with jet Formula Presented values between 350 and 600 GeV. One- and two-dimensional differential cross sections for eight substructure variables, defined using only the charged components of the jets, are measured in a particle-level phase space by correcting for the smearing and acceptance effects induced by the detector. The differential cross sections are compared with the predictions of several Monte Carlo simulations in which top-quark pair-production quantum chromodynamic matrix-element calculations at next-to-leading-order precision in the strong coupling constant Formula Presented are passed to leading-order parton shower and hadronization generators. The Monte Carlo predictions for measures of the broadness, and also the two-body structure, of the top-quark jets are found to be in good agreement with the measurements, while variables sensitive to the three-body structure of the top-quark jets exhibit some tension with the measured distributions.

Published
2024

5. Search for singly produced vectorlike top partners in multilepton final states with 139 fb-1 of pp collision data at s=13 TeV with the ATLAS detector

Author

Aad, G, Abbott, B, Abeling, K, Abicht, NJ, Abidi, SH, Aboulhorma, A, Abramowicz, H, Abreu, H, Abulaiti, Y, Hoffman, AC Abusleme, Acharya, BS, Bourdarios, C Adam, Adamczyk, L, Adamek, L, Addepalli, SV, Addison, MJ, Adelman, J, Adiguzel, A, Adye, T, Affolder, AA, Afik, Y, Agaras, MN, Agarwala, J, Aggarwal, A, Agheorghiesei, C, Ahmad, A, Ahmadov, F, Ahmed, WS, Ahuja, S, Ai, X, Aielli, G, Tamlihat, M Ait, Aitbenchikh, B, Aizenberg, I, Akbiyik, M, Åkesson, TPA, Akimov, AV, Akiyama, D, Akolkar, NN, Al Khoury, K, Alberghi, GL, Albert, J, Albicocco, P, Albouy, GL, Alderweireldt, S, Aleksa, M, Aleksandrov, IN, Alexa, C, Alexopoulos, T, Alfonsi, A, Alfonsi, F, Algren, M, Alhroob, M, Ali, B, Ali, HMJ, Ali, S, Alibocus, SW, Aliev, M, Alimonti, G, Alkakhi, W, Allaire, C, Allbrooke, BMM, Allen, JF, Flores, CA Allendes, Allport, PP, Aloisio, A, Alonso, F, Alpigiani, C, Estevez, M Alvarez, Fernandez, A Alvarez, Cardoso, M Alves, Alviggi, MG, Aly, M, Coutinho, Y Amaral, Ambler, A, Amelung, C, Amerl, M, Ames, CG, Amidei, D, Dos Santos, SP Amor, Amos, KR, Ananiev, V, Anastopoulos, C, Andeen, T, Anders, JK, Andrean, SY, Andreazza, A, Angelidakis, S, Angerami, A, Anisenkov, AV, Annovi, A, Antel, C, Anthony, MT, Antipov, E, Antonelli, M, Antrim, DJA, Anulli, F, Aoki, M, Aoki, T, and Pozo, JA Aparisi

Subjects
Particle and High Energy Physics, Physical Sciences
Abstract

A search for the single production of a vectorlike top partner (Formula Presented) with mass greater than 1 TeV decaying into a Formula Presented boson and a top quark is presented, using the full Run 2 dataset corresponding to Formula Presented of Formula Presented collisions at Formula Presented, collected in 2015-2018 with the ATLAS detector at the Large Hadron Collider. The targeted final state is characterized by the presence of a pair of electrons or muons with opposite-sign charges which form a Formula Presented-boson candidate, as well as by the presence of Formula Presented-tagged jets and forward jets. Events with exactly two or at least three leptons are categorized into two independently optimized analysis channels. No significant excess above the background expectation is observed and the results from the two channels are statistically combined to set exclusion limits at 95% confidence level on the masses and couplings of Formula Presented. The results are interpreted in several benchmark scenarios to set limits on the mass and universal coupling strength (Formula Presented) of the vectorlike quark. For singlet Formula Presented quarks, Formula Presented values between 0.22 and 0.64 are excluded for masses between 1000 and 1975 GeV. For Formula Presented quarks in the doublet scenario, where the production cross section is much lower, Formula Presented values between 0.54 and 0.88 are excluded for masses between 1000 and 1425 GeV.

Published
2024

6. Search for pair production of higgsinos in events with two Higgs bosons and missing transverse momentum in s=13 TeV pp collisions at the ATLAS experiment

Author

Aad, G, Abbott, B, Abeling, K, Abicht, NJ, Abidi, SH, Aboulhorma, A, Abramowicz, H, Abreu, H, Abulaiti, Y, Acharya, BS, Bourdarios, C Adam, Adamczyk, L, Addepalli, SV, Addison, MJ, Adelman, J, Adiguzel, A, Adye, T, Affolder, AA, Afik, Y, Agaras, MN, Agarwala, J, Aggarwal, A, Agheorghiesei, C, Ahmad, A, Ahmadov, F, Ahmed, WS, Ahuja, S, Ai, X, Aielli, G, Aikot, A, Tamlihat, M Ait, Aitbenchikh, B, Aizenberg, I, Akbiyik, M, Åkesson, TPA, Akimov, AV, Akiyama, D, Akolkar, NN, Aktas, S, Al Khoury, K, Alberghi, GL, Albert, J, Albicocco, P, Albouy, GL, Alderweireldt, S, Alegria, ZL, Aleksa, M, Aleksandrov, IN, Alexa, C, Alexopoulos, T, Alfonsi, F, Algren, M, Alhroob, M, Ali, B, Ali, HMJ, Ali, S, Alibocus, SW, Aliev, M, Alimonti, G, Alkakhi, W, Allaire, C, Allbrooke, BMM, Allen, JF, Flores, CA Allendes, Allport, PP, Aloisio, A, Alonso, F, Alpigiani, C, Estevez, M Alvarez, Fernandez, A Alvarez, Cardoso, M Alves, Alviggi, MG, Aly, M, Coutinho, Y Amaral, Ambler, A, Amelung, C, Amerl, M, Ames, CG, Amidei, D, Dos Santos, SP Amor, Amos, KR, Ananiev, V, Anastopoulos, C, Andeen, T, Anders, JK, Andrean, SY, Andreazza, A, Angelidakis, S, Angerami, A, Anisenkov, AV, Annovi, A, Antel, C, Anthony, MT, Antipov, E, Antonelli, M, Anulli, F, Aoki, M, Aoki, T, Pozo, JA Aparisi, and Aparo, MA

Subjects
Nuclear and Plasma Physics, Particle and High Energy Physics, Physical Sciences
Abstract

This paper presents a search for pair production of higgsinos, the supersymmetric partners of the Higgs bosons, in scenarios with gauge-mediated supersymmetry breaking. Each higgsino is assumed to decay into a Higgs boson and a nearly massless gravitino. The search targets events where each Higgs boson decays into Formula Presented, leading to a reconstructed final state with at least three energetic Formula Presented-jets and missing transverse momentum. Two complementary analysis channels are used, with each channel specifically targeting either low or high values of the higgsino mass. The low-mass (high-mass) channel exploits Formula Presented of Formula Presented data collected by the ATLAS detector during Run 2 of the Large Hadron Collider. No significant excess above the Standard Model prediction is found. At 95% confidence level, masses between 130 GeV and 940 GeV are excluded for higgsinos decaying exclusively into Higgs bosons and gravitinos. Exclusion limits as a function of the higgsino decay branching ratio to a Higgs boson are also reported.

Published
2024

7. Search for high-mass resonances in final states with a τ-lepton and missing transverse momentum with the ATLAS detector

Author

Aad, G, Abbott, B, Abbott, DC, Abud, A Abed, Abeling, K, Abhayasinghe, DK, Abidi, SH, Abramowicz, H, Abreu, H, Abulaiti, Y, Hoffman, AC Abusleme, Acharya, BS, Achkar, B, Adam, L, Bourdarios, C Adam, Adamczyk, L, Adamek, L, Addepalli, SV, Adelman, J, Adiguzel, A, Adorni, S, Adye, T, Affolder, AA, Afik, Y, Agapopoulou, C, Agaras, MN, Agarwala, J, Aggarwal, A, Agheorghiesei, C, Aguilar-Saavedra, JA, Ahmad, A, Ahmadov, F, Ahmed, WS, Ai, X, Aielli, G, Aizenberg, I, Akatsuka, S, Akbiyik, M, Åkesson, TPA, Akimov, AV, Al Khoury, K, Alberghi, GL, Albert, J, Albicocco, P, Verzini, MJ Alconada, Alderweireldt, S, Aleksa, M, Aleksandrov, IN, Alexa, C, Alexopoulos, T, Alfonsi, A, Alfonsi, F, Alhroob, M, Ali, B, Ali, S, Aliev, M, Alimonti, G, Allaire, C, Allbrooke, BMM, Allport, PP, Aloisio, A, Alonso, F, Alpigiani, C, Camelia, E Alunno, Estevez, M Alvarez, Alviggi, MG, Coutinho, Y Amaral, Ambler, A, Ambroz, L, Amelung, C, Amidei, D, Dos Santos, SP Amor, Amoroso, S, Amrouche, CS, Anastopoulos, C, Andari, N, Andeen, T, Anders, JK, Andrean, SY, Andreazza, A, Angelidakis, S, Angerami, A, Anisenkov, AV, Annovi, A, Antel, C, Anthony, MT, Antipov, E, Antonelli, M, Antrim, DJA, Anulli, F, Aoki, M, Pozo, JA Aparisi, Aparo, MA, Bella, L Aperio, Aranzabal, N, Ferraz, V Araujo, Arcangeletti, C, Arce, ATH, Arena, E, and Arguin, J-F

Subjects
Nuclear and Plasma Physics, Particle and High Energy Physics, Physical Sciences
Abstract

A search for high-mass resonances decaying into a Formula Presented-lepton and a neutrino using proton-proton collisions at a center-of-mass energy of Formula Presented is presented. The full run 2 data sample corresponding to an integrated luminosity of Formula Presented recorded by the ATLAS experiment in the years 2015-2018 is analyzed. The Formula Presented-lepton is reconstructed in its hadronic decay modes and the total transverse momentum carried out by neutrinos is inferred from the reconstructed missing transverse momentum. The search for new physics is performed on the transverse mass between the Formula Presented-lepton and the missing transverse momentum. No excess of events above the Standard Model expectation is observed and upper exclusion limits are set on the Formula Presented production cross section. Heavy Formula Presented vector bosons with masses up to 5.0 TeV are excluded at 95% confidence level, assuming that they have the same couplings as the Standard Model Formula Presented boson. For nonuniversal couplings, Formula Presented bosons are excluded for masses less than 3.5-5.0 TeV, depending on the model parameters. In addition, model-independent limits on the visible cross section times branching ratio are determined as a function of the lower threshold on the transverse mass of the Formula Presented-lepton and missing transverse momentum.

Published
2024

8. Search for quantum black hole production in lepton+jet final states using proton-proton collisions at s=13 TeV with the ATLAS detector

Author

Aad, G, Abbott, B, Abbott, DC, Abud, A Abed, Abeling, K, Abhayasinghe, DK, Abidi, SH, AbouZeid, OS, Abraham, NL, Abramowicz, H, Abreu, H, Abulaiti, Y, Acharya, BS, Achkar, B, Adam, L, Bourdarios, C Adam, Adamczyk, L, Adamek, L, Adelman, J, Adersberger, M, Adiguzel, A, Adorni, S, Adye, T, Affolder, AA, Afik, Y, Agapopoulou, C, Agaras, MN, Aggarwal, A, Agheorghiesei, C, Aguilar-Saavedra, JA, Ahmad, A, Ahmadov, F, Ahmed, WS, Ai, X, Aielli, G, Akatsuka, S, Akbiyik, M, Åkesson, TPA, Akilli, E, Akimov, AV, Al Khoury, K, Alberghi, GL, Albert, J, Verzini, MJ Alconada, Alderweireldt, S, Aleksa, M, Aleksandrov, IN, Alexa, C, Alexopoulos, T, Alfonsi, A, Alfonsi, F, Alhroob, M, Ali, B, Ali, S, Aliev, M, Alimonti, G, Allaire, C, Allbrooke, BMM, Allen, BW, Allport, PP, Aloisio, A, Alonso, F, Alpigiani, C, Camelia, E Alunno, Estevez, M Alvarez, Alviggi, MG, Coutinho, Y Amaral, Ambler, A, Ambroz, L, Amelung, C, Amidei, D, Dos Santos, SP Amor, Amoroso, S, Amrouche, CS, An, F, Anastopoulos, C, Andari, N, Andeen, T, Anders, JK, Andrean, SY, Andreazza, A, Andrei, V, Anelli, CR, Angelidakis, S, Angerami, A, Anisenkov, AV, Annovi, A, Antel, C, Anthony, MT, Antipov, E, Antonelli, M, Antrim, DJA, Anulli, F, Aoki, M, Pozo, JA Aparisi, Aparo, MA, Bella, L Aperio, Aranzabal, N, Ferraz, V Araujo, and Pereira, R Araujo

Subjects
Nuclear and Plasma Physics, Particle and High Energy Physics, Physical Sciences
Abstract

A search for quantum black holes in electron + jet and muon + jet invariant mass spectra is performed with 140 fb-1 of data collected by the ATLAS detector in proton-proton collisions at √s = 13 TeV at the Large Hadron Collider. The observed invariant mass spectrum of lepton + jet pairs is consistent with Standard Model expectations. Upper limits are set at 95% confidence level on the production cross section times branching fractions for quantum black holes decaying into a lepton and a quark in a search region with invariant mass above 2.0 TeV. The resulting quantum black hole lower mass threshold limit is 9.2 TeV in the Arkani-Hamed-Dimopoulos-Dvali model, and 6.8 TeV in the Randall-Sundrum model.

Published
2024

9. Pursuit of paired dijet resonances in the Run 2 dataset with ATLAS

Author

Aad, G, Abbott, B, Abeling, K, Abicht, NJ, Abidi, SH, Aboulhorma, A, Abramowicz, H, Abreu, H, Abulaiti, Y, Acharya, BS, Bourdarios, C Adam, Adamczyk, L, Addepalli, SV, Addison, MJ, Adelman, J, Adiguzel, A, Adye, T, Affolder, AA, Afik, Y, Agaras, MN, Agarwala, J, Aggarwal, A, Agheorghiesei, C, Ahmad, A, Ahmadov, F, Ahmed, WS, Ahuja, S, Ai, X, Aielli, G, Aikot, A, Tamlihat, M Ait, Aitbenchikh, B, Aizenberg, I, Akbiyik, M, Åkesson, TPA, Akimov, AV, Akiyama, D, Akolkar, NN, Al Khoury, K, Alberghi, GL, Albert, J, Albicocco, P, Albouy, GL, Alderweireldt, S, Aleksa, M, Aleksandrov, IN, Alexa, C, Alexopoulos, T, Alfonsi, F, Algren, M, Alhroob, M, Ali, B, Ali, HMJ, Ali, S, Alibocus, SW, Aliev, M, Alimonti, G, Alkakhi, W, Allaire, C, Allbrooke, BMM, Allen, JF, Flores, CA Allendes, Allport, PP, Aloisio, A, Alonso, F, Alpigiani, C, Estevez, M Alvarez, Fernandez, A Alvarez, Cardoso, M Alves, Alviggi, MG, Aly, M, Coutinho, Y Amaral, Ambler, A, Amelung, C, Amerl, M, Ames, CG, Amidei, D, Dos Santos, SP Amor, Amos, KR, Ananiev, V, Anastopoulos, C, Andeen, T, Anders, JK, Andrean, SY, Andreazza, A, Angelidakis, S, Angerami, A, Anisenkov, AV, Annovi, A, Antel, C, Anthony, MT, Antipov, E, Antonelli, M, Anulli, F, Aoki, M, Aoki, T, Pozo, JA Aparisi, Aparo, MA, Bella, L Aperio, and Appelt, C

Subjects
Nuclear and Plasma Physics, Particle and High Energy Physics, Physical Sciences
Abstract

New particles with large masses that decay into hadronically interacting particles are predicted by many models of physics beyond the Standard Model. A search for a massive resonance that decays into pairs of dijet resonances is performed using Formula Presented of proton-proton collisions at Formula Presented recorded by the ATLAS detector during Run 2 of the Large Hadron Collider. Resonances are searched for in the invariant mass of the tetrajet system, and in the average invariant mass of the pair of dijet systems. A data-driven background estimate is obtained by fitting the tetrajet and dijet invariant mass distributions with a four-parameter dijet function and a search for local excesses from resonant production of dijet pairs is performed. No significant excess of events beyond the Standard Model expectation is observed, and upper limits are set on the production cross sections of new physics scenarios.

Published
2023

10. Search for a new pseudoscalar decaying into a pair of muons in events with a top-quark pair at s=13 TeV with the ATLAS detector

Author

Aad, G, Abbott, B, Abeling, K, Abicht, NJ, Abidi, SH, Aboulhorma, A, Abramowicz, H, Abreu, H, Abulaiti, Y, Hoffman, AC Abusleme, Acharya, BS, Bourdarios, C Adam, Adamczyk, L, Adamek, L, Addepalli, SV, Addison, MJ, Adelman, J, Adiguzel, A, Adye, T, Affolder, AA, Afik, Y, Agaras, MN, Agarwala, J, Aggarwal, A, Agheorghiesei, C, Ahmad, A, Ahmadov, F, Ahmed, WS, Ahuja, S, Ai, X, Aielli, G, Aikot, A, Tamlihat, M Ait, Aitbenchikh, B, Aizenberg, I, Akbiyik, M, Åkesson, TPA, Akimov, AV, Akiyama, D, Akolkar, NN, Al Khoury, K, Alberghi, GL, Albert, J, Albicocco, P, Albouy, GL, Alderweireldt, S, Aleksa, M, Aleksandrov, IN, Alexa, C, Alexopoulos, T, Alfonsi, A, Alfonsi, F, Algren, M, Alhroob, M, Ali, B, Ali, HMJ, Ali, S, Alibocus, SW, Aliev, M, Alimonti, G, Alkakhi, W, Allaire, C, Allbrooke, BMM, Allen, JF, Flores, CA Allendes, Allport, PP, Aloisio, A, Alonso, F, Alpigiani, C, Estevez, M Alvarez, Fernandez, A Alvarez, Cardoso, M Alves, Alviggi, MG, Aly, M, Coutinho, Y Amaral, Ambler, A, Amelung, C, Amerl, M, Ames, CG, Amidei, D, Dos Santos, SP Amor, Amos, KR, Ananiev, V, Anastopoulos, C, Andeen, T, Anders, JK, Andrean, SY, Andreazza, A, Angelidakis, S, Angerami, A, Anisenkov, AV, Annovi, A, Antel, C, Anthony, MT, Antipov, E, Antonelli, M, Antrim, DJA, Anulli, F, Aoki, M, and Aoki, T

Subjects
Nuclear and Plasma Physics, Particle and High Energy Physics, Physical Sciences
Abstract

A search for a new pseudoscalar Formula Presented-boson produced in events with a top-quark pair, where the Formula Presented-boson decays into a pair of muons, is performed using Formula Presented Formula Presented collision data collected with the ATLAS detector at the LHC, corresponding to an integrated luminosity of Formula Presented. The search targets the final state where only one top quark decays to an electron or muon, resulting in a signature with three leptons Formula Presented and Formula Presented. No significant excess of events above the Standard Model expectation is observed and upper limits are set on two signal models: Formula Presented and Formula Presented with Formula Presented, Formula Presented, where Formula Presented, in the mass ranges Formula Presented and Formula Presented.

Published
2023

11. Integrated and differential fiducial cross-section measurements for the vector boson fusion production of the Higgs boson in the H→WW*→eνμν decay channel at 13 TeV with the ATLAS detector

Author

Aad, G, Abbott, B, Abeling, K, Abicht, NJ, Abidi, SH, Aboulhorma, A, Abramowicz, H, Abreu, H, Abulaiti, Y, Hoffman, AC Abusleme, Acharya, BS, Bourdarios, C Adam, Adamczyk, L, Adamek, L, Addepalli, SV, Addison, MJ, Adelman, J, Adiguzel, A, Adye, T, Affolder, AA, Afik, Y, Agaras, MN, Agarwala, J, Aggarwal, A, Agheorghiesei, C, Ahmad, A, Ahmadov, F, Ahmed, WS, Ahuja, S, Ai, X, Aielli, G, Tamlihat, M Ait, Aitbenchikh, B, Aizenberg, I, Akbiyik, M, Åkesson, TPA, Akimov, AV, Akiyama, D, Akolkar, NN, Al Khoury, K, Alberghi, GL, Albert, J, Albicocco, P, Albouy, GL, Alderweireldt, S, Aleksa, M, Aleksandrov, IN, Alexa, C, Alexopoulos, T, Alfonsi, A, Alfonsi, F, Algren, M, Alhroob, M, Ali, B, Ali, HMJ, Ali, S, Alibocus, SW, Aliev, M, Alimonti, G, Alkakhi, W, Allaire, C, Allbrooke, BMM, Allen, JF, Flores, CA Allendes, Allport, PP, Aloisio, A, Alonso, F, Alpigiani, C, Estevez, M Alvarez, Fernandez, A Alvarez, Alviggi, MG, Aly, M, Coutinho, Y Amaral, Ambler, A, Amelung, C, Amerl, M, Ames, CG, Amidei, D, Dos Santos, SP Amor, Amos, KR, Ananiev, V, Anastopoulos, C, Andeen, T, Anders, JK, Andrean, SY, Andreazza, A, Angelidakis, S, Angerami, A, Anisenkov, AV, Annovi, A, Antel, C, Anthony, MT, Antipov, E, Antonelli, M, Antrim, DJA, Anulli, F, Aoki, M, Aoki, T, Pozo, JA Aparisi, and Aparo, MA

Subjects
Nuclear and Plasma Physics, Particle and High Energy Physics, Synchrotrons and Accelerators, Physical Sciences
Abstract

The vector-boson production cross section for the Higgs boson decay in the Formula Presented channel is measured as a function of kinematic observables sensitive to the Higgs boson production and decay properties as well as integrated in a fiducial phase space. The analysis is performed using the proton-proton collision data collected by the ATLAS detector in Run 2 of the LHC at Formula Presented center-of-mass energy, corresponding to an integrated luminosity of Formula Presented. The different flavor final state is studied by selecting an electron and a muon originating from a pair of Formula Presented bosons and compatible with the Higgs boson decay. The data are corrected for the effects of detector inefficiency and resolution, and the measurements are compared with different state-of-the-art theoretical predictions. The differential cross sections are used to constrain anomalous interactions described by dimension-six operators in an effective field theory.

Published
2023

12. Search for nonresonant pair production of Higgs bosons in the bb¯bb¯ final state in pp collisions at s=13 TeV with the ATLAS detector

Author

Aad, G, Abbott, B, Abeling, K, Abidi, SH, Aboulhorma, A, Abramowicz, H, Abreu, H, Abulaiti, Y, Hoffman, AC Abusleme, Acharya, BS, Bourdarios, C Adam, Adamczyk, L, Adamek, L, Addepalli, SV, Adelman, J, Adiguzel, A, Adorni, S, Adye, T, Affolder, AA, Afik, Y, Agaras, MN, Agarwala, J, Aggarwal, A, Agheorghiesei, C, Aguilar-Saavedra, JA, Ahmad, A, Ahmadov, F, Ahmed, WS, Ahuja, S, Ai, X, Aielli, G, Tamlihat, M Ait, Aitbenchikh, B, Aizenberg, I, Akbiyik, M, Åkesson, TPA, Akimov, AV, Al Khoury, K, Alberghi, GL, Albert, J, Albicocco, P, Alderweireldt, S, Aleksa, M, Aleksandrov, IN, Alexa, C, Alexopoulos, T, Alfonsi, A, Alfonsi, F, Alhroob, M, Ali, B, Ali, S, Aliev, M, Alimonti, G, Alkakhi, W, Allaire, C, Allbrooke, BMM, Flores, CA Allendes, Allport, PP, Aloisio, A, Alonso, F, Alpigiani, C, Estevez, M Alvarez, Fernandez, A Alvarez, Alviggi, MG, Aly, M, Coutinho, Y Amaral, Ambler, A, Amelung, C, Amerl, M, Ames, CG, Amidei, D, Dos Santos, SP Amor, Amos, KR, Ananiev, V, Anastopoulos, C, Andeen, T, Anders, JK, Andrean, SY, Andreazza, A, Angelidakis, S, Angerami, A, Anisenkov, AV, Annovi, A, Antel, C, Anthony, MT, Antipov, E, Antonelli, M, Antrim, DJA, Anulli, F, Aoki, M, Aoki, T, Pozo, JA Aparisi, Aparo, MA, Bella, L Aperio, Appelt, C, Aranzabal, N, Ferraz, V Araujo, Arcangeletti, C, Arce, ATH, and Arena, E

Subjects
Nuclear and Plasma Physics, Particle and High Energy Physics, Physical Sciences
Abstract

A search for nonresonant Higgs boson pair production in the Formula Presented final state is presented. The analysis uses Formula Presented of Formula Presented collision data at Formula Presented collected with the ATLAS detector at the Large Hadron Collider, and targets both the gluon-gluon fusion and vector-boson fusion production modes. No evidence of the signal is found and the observed (expected) upper limit on the cross section for nonresonant Higgs boson pair production is determined to be 5.4 (8.1) times the Standard Model predicted cross section at 95% confidence level. Constraints are placed on modifiers to the Formula Presented and Formula Presented couplings. The observed (expected) Formula Presented constraints on the Formula Presented coupling modifier, Formula Presented, are determined to be Formula Presented (Formula Presented), while the corresponding constraints for the Formula Presented coupling modifier, Formula Presented, are Formula Presented (Formula Presented). In addition, constraints on relevant coefficients are derived in the context of the Standard Model effective field theory and Higgs effective field theory, and upper limits on the Formula Presented production cross section are placed in seven Higgs effective field theory benchmark scenarios.

Published
2023

13. Anomaly detection search for new resonances decaying into a Higgs boson and a generic new particle X in hadronic final states using s=13 TeV pp collisions with the ATLAS detector

Author

Aad, G, Abbott, B, Abbott, DC, Abeling, K, Abidi, SH, Aboulhorma, A, Abramowicz, H, Abreu, H, Abulaiti, Y, Hoffman, AC Abusleme, Acharya, BS, Achkar, B, Bourdarios, C Adam, Adamczyk, L, Adamek, L, Addepalli, SV, Adelman, J, Adiguzel, A, Adorni, S, Adye, T, Affolder, AA, Afik, Y, Agaras, MN, Agarwala, J, Aggarwal, A, Agheorghiesei, C, Aguilar-Saavedra, JA, Ahmad, A, Ahmadov, F, Ahmed, WS, Ahuja, S, Ai, X, Aielli, G, Aizenberg, I, Akbiyik, M, Åkesson, TPA, Akimov, AV, Al Khoury, K, Alberghi, GL, Albert, J, Albicocco, P, Alderweireldt, S, Aleksa, M, Aleksandrov, IN, Alexa, C, Alexopoulos, T, Alfonsi, A, Alfonsi, F, Alhroob, M, Ali, B, Ali, S, Aliev, M, Alimonti, G, Alkakhi, W, Allaire, C, Allbrooke, BMM, Allport, PP, Aloisio, A, Alonso, F, Alpigiani, C, Camelia, E Alunno, Estevez, M Alvarez, Alviggi, MG, Aly, M, Coutinho, Y Amaral, Ambler, A, Amelung, C, Amerl, M, Ames, CG, Amidei, D, Dos Santos, SP Amor, Amoroso, S, Amos, KR, Ananiev, V, Anastopoulos, C, Andeen, T, Anders, JK, Andrean, SY, Andreazza, A, Angelidakis, S, Angerami, A, Anisenkov, AV, Annovi, A, Antel, C, Anthony, MT, Antipov, E, Antonelli, M, Antrim, DJA, Anulli, F, Aoki, M, Aoki, T, Pozo, JA Aparisi, Aparo, MA, Bella, L Aperio, Appelt, C, Aranzabal, N, Ferraz, V Araujo, Arcangeletti, C, Arce, ATH, and Arena, E

Subjects
Nuclear and Plasma Physics, Particle and High Energy Physics, Physical Sciences
Abstract

A search is presented for a heavy resonance Formula Presented decaying into a Standard Model Higgs boson Formula Presented and a new particle Formula Presented in a fully hadronic final state. The full Large Hadron Collider run 2 dataset of proton-proton collisions at Formula Presented collected by the ATLAS detector from 2015 to 2018 is used and corresponds to an integrated luminosity of Formula Presented. The search targets the high Formula Presented-mass region, where the Formula Presented and Formula Presented have a significant Lorentz boost in the laboratory frame. A novel application of anomaly detection is used to define a general signal region, where events are selected solely because of their incompatibility with a learned background-only model. It is constructed using a jet-level tagger for signal-model-independent selection of the boosted Formula Presented particle, representing the first application of fully unsupervised machine learning to an ATLAS analysis. Two additional signal regions are implemented to target a benchmark Formula Presented decay into two quarks, covering topologies where the Formula Presented is reconstructed as either a single large-radius jet or two small-radius jets. The analysis selects Higgs boson decays into Formula Presented, and a dedicated neural-network-based tagger provides sensitivity to the boosted heavy-flavor topology. No significant excess of data over the expected background is observed, and the results are presented as upper limits on the production cross section Formula Presented) for signals with Formula Presented between 1.5 and 6 TeV and Formula Presented between 65 and 3000 GeV.

Published
2023

14. Search for displaced photons produced in exotic decays of the Higgs boson using 13 TeV pp collisions with the ATLAS detector

Author

Aad, G, Abbott, B, Abbott, DC, Abeling, K, Abidi, SH, Aboulhorma, A, Abramowicz, H, Abreu, H, Abulaiti, Y, Hoffman, AC Abusleme, Acharya, BS, Achkar, B, Adam, L, Bourdarios, C Adam, Adamczyk, L, Adamek, L, Addepalli, SV, Adelman, J, Adiguzel, A, Adorni, S, Adye, T, Affolder, AA, Afik, Y, Agaras, MN, Agarwala, J, Aggarwal, A, Agheorghiesei, C, Aguilar-Saavedra, JA, Ahmad, A, Ahmadov, F, Ahmed, WS, Ahuja, S, Ai, X, Aielli, G, Aizenberg, I, Akbiyik, M, Åkesson, TPA, Akimov, AV, Al Khoury, K, Alberghi, GL, Albert, J, Albicocco, P, Verzini, MJ Alconada, Alderweireldt, S, Aleksa, M, Aleksandrov, IN, Alexa, C, Alexopoulos, T, Alfonsi, A, Alfonsi, F, Alhroob, M, Ali, B, Ali, S, Aliev, M, Alimonti, G, Allaire, C, Allbrooke, BMM, Allport, PP, Almazan, ER, Aloisio, A, Alonso, F, Alpigiani, C, Camelia, E Alunno, Estevez, M Alvarez, Alviggi, MG, Coutinho, Y Amaral, Ambler, A, Amelung, C, Ames, CG, Amidei, D, Dos Santos, SP Amor, Amoroso, S, Amos, KR, Amrouche, CS, Ananiev, V, Anastopoulos, C, Andari, N, Andeen, T, Anders, JK, Andrean, SY, Andreazza, A, Angelidakis, S, Angerami, A, Anisenkov, AV, Annovi, A, Antel, C, Anthony, MT, Antipov, E, Antonelli, M, Antrim, DJA, Anulli, F, Aoki, M, Pozo, JA Aparisi, Aparo, MA, Bella, L Aperio, Appelt, C, Aranzabal, N, Ferraz, V Araujo, Arcangeletti, C, and Arce, ATH

Subjects
Nuclear and Plasma Physics, Particle and High Energy Physics, Physical Sciences
Abstract

A search is performed for delayed and nonpointing photons originating from the displaced decay of a neutral long-lived particle (LLP). The analysis uses the full run 2 dataset of proton-proton collisions delivered by the LHC at a center-of-mass energy of Formula Presented between 2015 and 2018 and recorded by the ATLAS detector, corresponding to an integrated luminosity of Formula Presented. The capabilities of the ATLAS electromagnetic calorimeter are exploited to precisely measure the arrival times and trajectories of photons. The results are interpreted in a scenario where the LLPs are pair produced in exotic decays of the 125 GeV Higgs boson, and each LLP subsequently decays into a photon and a particle that escapes direct detection, giving rise to missing transverse momentum. No significant excess is observed above the expectation due to Standard Model background processes. The results are used to set upper limits on the branching ratio of the exotic decay of the Higgs boson. A model-independent limit is also set on the production of photons with large values of displacement and time delay.

Published
2023

15. Search for flavor-changing neutral-current couplings between the top quark and the Z boson with proton-proton collisions at s=13 TeV with the ATLAS detector

Author

Aad, G, Abbott, B, Abbott, DC, Abud, A Abed, Abeling, K, Abhayasinghe, DK, Abidi, SH, Aboulhorma, A, Abramowicz, H, Abreu, H, Abulaiti, Y, Hoffman, AC Abusleme, Acharya, BS, Achkar, B, Adam, L, Bourdarios, C Adam, Adamczyk, L, Adamek, L, Addepalli, SV, Adelman, J, Adiguzel, A, Adorni, S, Adye, T, Affolder, AA, Afik, Y, Agapopoulou, C, Agaras, MN, Agarwala, J, Aggarwal, A, Agheorghiesei, C, Aguilar-Saavedra, JA, Ahmad, A, Ahmadov, F, Ahmed, WS, Ai, X, Aielli, G, Aizenberg, I, Akatsuka, S, Akbiyik, M, Åkesson, TPA, Akimov, AV, Al Khoury, K, Alberghi, GL, Albert, J, Albicocco, P, Verzini, MJ Alconada, Alderweireldt, S, Aleksa, M, Aleksandrov, IN, Alexa, C, Alexopoulos, T, Alfonsi, A, Alfonsi, F, Alhroob, M, Ali, B, Ali, S, Aliev, M, Alimonti, G, Allaire, C, Allbrooke, BMM, Allport, PP, Aloisio, A, Alonso, F, Alpigiani, C, Camelia, E Alunno, Estevez, M Alvarez, Alviggi, MG, Coutinho, Y Amaral, Ambler, A, Ambroz, L, Amelung, C, Amidei, D, Dos Santos, SP Amor, Amoroso, S, Amos, KR, Amrouche, CS, Ananiev, V, Anastopoulos, C, Andari, N, Andeen, T, Anders, JK, Andrean, SY, Andreazza, A, Angelidakis, S, Angerami, A, Anisenkov, AV, Annovi, A, Antel, C, Anthony, MT, Antipov, E, Antonelli, M, Antrim, DJA, Anulli, F, Aoki, M, Pozo, JA Aparisi, Aparo, MA, Bella, L Aperio, Aranzabal, N, Ferraz, V Araujo, and Arcangeletti, C

Subjects
Nuclear and Plasma Physics, Particle and High Energy Physics, Physical Sciences
Abstract

A search for flavor-changing neutral-current couplings between a top quark, an up or charm quark, and a Formula Presented boson is presented, using proton-proton collision data at Formula Presented collected by the ATLAS detector at the Large Hadron Collider. The analyzed data set corresponds to an integrated luminosity of Formula Presented. The search targets both single-top-quark events produced as Formula Presented (with Formula Presented, Formula Presented) and top-quark-pair events, with one top quark decaying through the Formula Presented channel. The analysis considers events with three leptons (electrons or muons), a Formula Presented-tagged jet, possible additional jets, and missing transverse momentum. The data are found to be consistent with the background-only hypothesis and 95% confidence-level limits on the Formula Presented branching ratios, assuming only tensor operators of the Standard Model effective field theory framework contribute to the Formula Presented vertices. These are Formula Presented (Formula Presented) for Formula Presented (Formula Presented) for a left-handed Formula Presented coupling, and Formula Presented (Formula Presented) in the case of a right-handed coupling. These results are interpreted as 95% CL upper limits on the strength of the corresponding couplings, yielding limits for Formula Presented and Formula Presented (Formula Presented and Formula Presented) of 0.15 (0.16), and limits for Formula Presented and Formula Presented (Formula Presented and Formula Presented) of 0.22 (0.21), assuming a new-physics energy scale Formula Presented of 1 TeV.

Published
2023

16. Search for the charged-lepton-flavor-violating decay Z→eμ in pp collisions at s=13 TeV with the ATLAS detector

Author

Aad, G, Abbott, B, Abbott, DC, Abud, A Abed, Abeling, K, Abhayasinghe, DK, Abidi, SH, Aboulhorma, A, Abramowicz, H, Abreu, H, Abulaiti, Y, Hoffman, AC Abusleme, Acharya, BS, Achkar, B, Adam, L, Bourdarios, C Adam, Adamczyk, L, Adamek, L, Addepalli, SV, Adelman, J, Adiguzel, A, Adorni, S, Adye, T, Affolder, AA, Afik, Y, Agapopoulou, C, Agaras, MN, Agarwala, J, Aggarwal, A, Agheorghiesei, C, Aguilar-Saavedra, JA, Ahmad, A, Ahmadov, F, Ahmed, WS, Ai, X, Aielli, G, Aizenberg, I, Akatsuka, S, Akbiyik, M, Åkesson, TPA, Akimov, AV, Al Khoury, K, Alberghi, GL, Albert, J, Albicocco, P, Verzini, MJ Alconada, Alderweireldt, S, Aleksa, M, Aleksandrov, IN, Alexa, C, Alexopoulos, T, Alfonsi, A, Alfonsi, F, Alhroob, M, Ali, B, Ali, S, Aliev, M, Alimonti, G, Allaire, C, Allbrooke, BMM, Allport, PP, Aloisio, A, Alonso, F, Alpigiani, C, Camelia, E Alunno, Estevez, M Alvarez, Alviggi, MG, Coutinho, Y Amaral, Ambler, A, Ambroz, L, Amelung, C, Amidei, D, Dos Santos, SP Amor, Amoroso, S, Amos, KR, Amrouche, CS, Ananiev, V, Anastopoulos, C, Andari, N, Andeen, T, Anders, JK, Andrean, SY, Andreazza, A, Angelidakis, S, Angerami, A, Anisenkov, AV, Annovi, A, Antel, C, Anthony, MT, Antipov, E, Antonelli, M, Antrim, DJA, Anulli, F, Aoki, M, Pozo, JA Aparisi, Aparo, MA, Bella, L Aperio, Aranzabal, N, Ferraz, V Araujo, and Arcangeletti, C

Subjects
Nuclear and Plasma Physics, Particle and High Energy Physics, Physical Sciences
Abstract

A search for the charged-lepton-flavor-violating process Formula Presented is presented, using Formula Presented of Formula Presented Formula Presented collision data collected by the ATLAS experiment at the LHC. An excess in the Formula Presented invariant mass spectrum near the Formula Presented boson mass would be a striking signature of new physics. No excess is observed, and an upper limit Formula Presented is placed on the branching fraction at 95% confidence level, which is the most stringent limit to date.

Published
2023

17. Measurement of the inclusive tt¯ production cross section in the lepton+jets channel in pp collisions at s=7 TeV with the ATLAS detector using support vector machines

Author

Aaboud, M, Aad, G, Abbott, B, Abbott, DC, Abhayasinghe, DK, Abidi, SH, AbouZeid, OS, Abraham, NL, Abramowicz, H, Abreu, H, Abulaiti, Y, Acharya, BS, Adachi, S, Adam, L, Bourdarios, C Adam, Adamczyk, L, Adamek, L, Adelman, J, Adersberger, M, Adiguzel, A, Adye, T, Affolder, AA, Afik, Y, Agapopoulou, C, Agaras, MN, Aggarwal, A, Agheorghiesei, C, Aguilar-Saavedra, JA, Ahmadov, F, Aielli, G, Akatsuka, S, Åkesson, TPA, Akilli, E, Akimov, AV, Al Khoury, K, Alberghi, GL, Albert, J, Verzini, MJ Alconada, Alderweireldt, S, Aleksa, M, Aleksandrov, IN, Alexa, C, Alexandre, D, Alexopoulos, T, Alhroob, M, Ali, B, Alimonti, G, Alison, J, Alkire, SP, Allaire, C, Allbrooke, BMM, Allen, BW, Allport, PP, Aloisio, A, Alonso, A, Alonso, F, Alpigiani, C, Alshehri, AA, Alstaty, MI, Estevez, M Alvarez, Gonzalez, B Alvarez, Piqueras, D Álvarez, Alviggi, MG, Coutinho, Y Amaral, Ambler, A, Ambroz, L, Amelung, C, Amidei, D, Dos Santos, SP Amor, Amoroso, S, Amrouche, CS, An, F, Anastopoulos, C, Andari, N, Andeen, T, Anders, CF, Anders, JK, Andreazza, A, Andrei, V, Anelli, CR, Angelidakis, S, Angelozzi, I, Angerami, A, Anisenkov, AV, Annovi, A, Antel, C, Anthony, MT, Antonelli, M, Antrim, DJA, Anulli, F, Aoki, M, Pozo, JA Aparisi, Bella, L Aperio, Arabidze, G, Araque, JP, Ferraz, V Araujo, Pereira, R Araujo, Arce, ATH, Arduh, FA, and Arguin, J-F

Subjects
Nuclear and Plasma Physics, Particle and High Energy Physics, Physical Sciences
Abstract

A measurement of the top quark pair-production cross section in the lepton + jets decay channel is presented. It is based on 4.6 fb - 1 of s = 7 TeV p p collision data collected during 2011 by the ATLAS experiment at the CERN Large Hadron Collider. A three-class, multidimensional event classifier based on support vector machines is used to differentiate t t ¯ events from backgrounds. The t t ¯ production cross section is found to be σ t t ¯ = 168.5 ± 0.7 ( stat ) - 5.9 + 6.2 ( syst ) - 3.2 + 3.4 ( lumi ) pb . The result is consistent with the Standard Model prediction based on QCD calculations at next-to-next-to-leading order.

Published
2023

18. Measurement of the production of a W boson in association with a charmed hadron in pp collisions at s=13 TeV with the ATLAS detector

Author

Aad, G, Abbott, B, Abeling, K, Abidi, SH, Aboulhorma, A, Abramowicz, H, Abreu, H, Abulaiti, Y, Hoffman, AC Abusleme, Acharya, BS, Bourdarios, C Adam, Adamczyk, L, Adamek, L, Addepalli, SV, Adelman, J, Adiguzel, A, Adorni, S, Adye, T, Affolder, AA, Afik, Y, Agaras, MN, Agarwala, J, Aggarwal, A, Agheorghiesei, C, Aguilar-Saavedra, JA, Ahmad, A, Ahmadov, F, Ahmed, WS, Ahuja, S, Ai, X, Aielli, G, Tamlihat, M Ait, Aitbenchikh, B, Aizenberg, I, Akbiyik, M, Åkesson, TPA, Akimov, AV, Akiyama, D, Akolkar, NN, Al Khoury, K, Alberghi, GL, Albert, J, Albicocco, P, Alderweireldt, S, Aleksa, M, Aleksandrov, IN, Alexa, C, Alexopoulos, T, Alfonsi, A, Alfonsi, F, Alhroob, M, Ali, B, Ali, S, Aliev, M, Alimonti, G, Alkakhi, W, Allaire, C, Allbrooke, BMM, Flores, CA Allendes, Allport, PP, Aloisio, A, Alonso, F, Alpigiani, C, Estevez, M Alvarez, Fernandez, A Alvarez, Alviggi, MG, Aly, M, Coutinho, Y Amaral, Ambler, A, Amelung, C, Amerl, M, Ames, CG, Amidei, D, Dos Santos, SP Amor, Amos, KR, Ananiev, V, Anastopoulos, C, Andeen, T, Anders, JK, Andrean, SY, Andreazza, A, Angelidakis, S, Angerami, A, Anisenkov, AV, Annovi, A, Antel, C, Anthony, MT, Antipov, E, Antonelli, M, Antrim, DJA, Anulli, F, Aoki, M, Aoki, T, Pozo, JA Aparisi, Aparo, MA, Bella, L Aperio, Appelt, C, Aranzabal, N, Ferraz, V Araujo, and Arcangeletti, C

Subjects
Nuclear and Plasma Physics, Particle and High Energy Physics, Mathematical Physics, Mathematical Sciences, Physical Sciences
Abstract

The production of a W boson in association with a single charm quark is studied using 140 fb - 1 of s = 13 TeV proton-proton collision data collected with the ATLAS detector at the Large Hadron Collider. The charm quark is tagged by the presence of a charmed hadron reconstructed with a secondary-vertex fit. The W boson is reconstructed from the decay to either an electron or a muon and the missing transverse momentum present in the event. The charmed mesons reconstructed are D + → K - π + π + and D * + → D 0 π + → ( K - π + ) π + and the charge conjugate decays in the fiducial regions where p T ( e , μ ) > 30 GeV , | η ( e , μ ) | < 2.5 , p T ( D ( * ) ) > 8 GeV , and | η ( D ( * ) ) | < 2.2 . The integrated and normalized differential cross sections as a function of the pseudorapidity of the lepton from the W boson decay, and of the transverse momentum of the charmed hadron, are extracted from the data using a profile likelihood fit. The measured total fiducial cross sections are σ fid OS - SS ( W - + D + ) = 50.2 ± 0.2 ( stat ) - 2.3 + 2.4 ( syst ) pb , σ fid OS - SS ( W + + D - ) = 48.5 ± 0.2 ( stat ) - 2.2 + 2.3 ( syst ) pb , σ fid OS - SS ( W - + D * + ) = 51.1 ± 0.4 ( stat ) - 1.8 + 1.9 ( syst ) pb , and σ fid OS - SS ( W + + D * - ) = 50.0 ± 0.4 ( stat ) - 1.8 + 1.9 ( syst ) pb . Results are compared with the predictions of next-to-leading-order quantum chromodynamics calculations performed using state-of-the-art parton distribution functions. Additionally, the ratio of charm to anticharm production cross sections is studied to probe the s - s ¯ quark asymmetry. The ratio is found to be R c ± = 0.971 ± 0.006 ( stat ) ± 0.011 ( syst ) . The ratio and cross-section measurements are consistent with the predictions obtained with parton distribution function sets that have a symmetric s - s ¯ sea, indicating that any s - s ¯ asymmetry in the Bjorken- x region relevant for this measurement is small.

Published
2023

19. Measurements of Higgs boson production by gluon-gluon fusion and vector-boson fusion using H→WW*→eνμν decays in pp collisions at s=13 TeV with the ATLAS detector

Author

Aad, G, Abbott, B, Abbott, DC, Abud, A Abed, Abeling, K, Abidi, SH, Aboulhorma, A, Abramowicz, H, Abreu, H, Abulaiti, Y, Hoffman, AC Abusleme, Acharya, BS, Achkar, B, Adam, L, Bourdarios, C Adam, Adamczyk, L, Adamek, L, Addepalli, SV, Adelman, J, Adiguzel, A, Adorni, S, Adye, T, Affolder, AA, Afik, Y, Agaras, MN, Agarwala, J, Aggarwal, A, Agheorghiesei, C, Aguilar-Saavedra, JA, Ahmad, A, Ahmadov, F, Ahmed, WS, Ai, X, Aielli, G, Aizenberg, I, Akbiyik, M, Åkesson, TPA, Akimov, AV, Al Khoury, K, Alberghi, GL, Albert, J, Albicocco, P, Verzini, MJ Alconada, Alderweireldt, S, Aleksa, M, Aleksandrov, IN, Alexa, C, Alexopoulos, T, Alfonsi, A, Alfonsi, F, Alhroob, M, Ali, B, Ali, S, Aliev, M, Alimonti, G, Allaire, C, Allbrooke, BMM, Allport, PP, Aloisio, A, Alonso, F, Alpigiani, C, Camelia, E Alunno, Estevez, M Alvarez, Alviggi, MG, Coutinho, Y Amaral, Ambler, A, Amelung, C, Ames, CG, Amidei, D, Dos Santos, SP Amor, Amoroso, S, Amos, KR, Amrouche, CS, Ananiev, V, Anastopoulos, C, Andari, N, Andeen, T, Anders, JK, Andrean, SY, Andreazza, A, Angelidakis, S, Angerami, A, Anisenkov, AV, Annovi, A, Antel, C, Anthony, MT, Antipov, E, Antonelli, M, Antrim, DJA, Anulli, F, Aoki, M, Pozo, JA Aparisi, Aparo, MA, Bella, L Aperio, Appelt, C, Aranzabal, N, Ferraz, V Araujo, Arcangeletti, C, Arce, ATH, and Arena, E

Subjects
Nuclear and Plasma Physics, Particle and High Energy Physics, Physical Sciences
Abstract

Higgs boson production via gluon-gluon fusion and vector-boson fusion in proton-proton collisions is measured in the H → W W * → e ν μ ν decay channel. The Large Hadron Collider delivered proton-proton collisions at a center-of-mass energy of 13 TeV between 2015 and 2018, which were recorded by the ATLAS detector, corresponding to an integrated luminosity of 139 fb - 1 . The total cross sections for Higgs boson production by gluon-gluon fusion and vector-boson fusion times the H → W W * branching ratio are measured to be 12.0 ± 1.4 and 0.75 - 0.16 + 0.19 pb , respectively, in agreement with the Standard Model predictions of 10.4 ± 0.6 and 0.81 ± 0.02 pb . Higgs boson production is further characterized through measurements of Simplified Template Cross Sections in a total of 11 kinematic fiducial regions.

Published
2023

20. Measurement of cross sections for production of a Z boson in association with a flavor-inclusive or doubly b-tagged large-radius jet in proton-proton collisions at s=13 TeV with the ATLAS experiment

Author

Aad, G, Abbott, B, Abbott, DC, Abud, A Abed, Abeling, K, Abhayasinghe, DK, Abidi, SH, AbouZeid, OS, Abraham, NL, Abramowicz, H, Abreu, H, Abulaiti, Y, Acharya, BS, Achkar, B, Adam, L, Bourdarios, C Adam, Adamczyk, L, Adamek, L, Adelman, J, Adiguzel, A, Adorni, S, Adye, T, Affolder, AA, Afik, Y, Agapopoulou, C, Agaras, MN, Aggarwal, A, Agheorghiesei, C, Aguilar-Saavedra, JA, Ahmad, A, Ahmadov, F, Ahmed, WS, Ai, X, Aielli, G, Akatsuka, S, Akbiyik, M, Åkesson, TPA, Akilli, E, Akimov, AV, Al Khoury, K, Alberghi, GL, Albert, J, Verzini, MJ Alconada, Alderweireldt, S, Aleksa, M, Aleksandrov, IN, Alexa, C, Alexopoulos, T, Alfonsi, A, Alfonsi, F, Alhroob, M, Ali, B, Ali, S, Aliev, M, Alimonti, G, Allaire, C, Allbrooke, BMM, Allport, PP, Aloisio, A, Alonso, F, Alpigiani, C, Camelia, E Alunno, Estevez, M Alvarez, Alviggi, MG, Coutinho, Y Amaral, Ambler, A, Ambroz, L, Amelung, C, Amidei, D, Dos Santos, SP Amor, Amoroso, S, Amrouche, CS, An, F, Anastopoulos, C, Andari, N, Andeen, T, Anders, JK, Andrean, SY, Andreazza, A, Andrei, V, Anelli, CR, Angelidakis, S, Angerami, A, Anisenkov, AV, Annovi, A, Antel, C, Anthony, MT, Antipov, E, Antonelli, M, Antrim, DJA, Anulli, F, Aoki, M, Pozo, JA Aparisi, Aparo, MA, Bella, L Aperio, Aranzabal, N, Ferraz, V Araujo, Pereira, R Araujo, Arcangeletti, C, and Arce, ATH

Subjects
Nuclear and Plasma Physics, Particle and High Energy Physics, Physical Sciences
Abstract

We present measurements of cross sections for production of a leptonically decaying Z boson in association with a large-radius jet in 13 TeV proton-proton collisions at the LHC, using 36 fb - 1 of data from the ATLAS detector. Integrated and differential cross sections are measured at particle level in both a flavor inclusive and a doubly b -tagged fiducial phase space. The large-radius jet mass and transverse momentum, its kinematic relationship to the Z boson, and the angular separation of b -tagged small-radius track jets within the large-radius jet are measured. This measurement constitutes an important test of perturbative quantum chromodynamics in kinematic and flavor configurations relevant to several Higgs boson and beyond-Standard-Model physics analyses. The results highlight issues with modeling of additional hadronic activity in the flavor-inclusive selection, and a distinction between flavor-number schemes in the b -tagged phase space.

Published
2023

21. Search in diphoton and dielectron final states for displaced production of Higgs or Z bosons with the ATLAS detector in s=13 TeV pp collisions

Author

Aad, G, Abbott, B, Abbott, DC, Abeling, K, Abidi, SH, Aboulhorma, A, Abramowicz, H, Abreu, H, Abulaiti, Y, Hoffman, AC Abusleme, Acharya, BS, Achkar, B, Bourdarios, C Adam, Adamczyk, L, Adamek, L, Addepalli, SV, Adelman, J, Adiguzel, A, Adorni, S, Adye, T, Affolder, AA, Afik, Y, Agaras, MN, Agarwala, J, Aggarwal, A, Agheorghiesei, C, Aguilar-Saavedra, JA, Ahmad, A, Ahmadov, F, Ahmed, WS, Ahuja, S, Ai, X, Aielli, G, Aizenberg, I, Akbiyik, M, Åkesson, TPA, Akimov, AV, Al Khoury, K, Alberghi, GL, Albert, J, Albicocco, P, Alderweireldt, S, Aleksa, M, Aleksandrov, IN, Alexa, C, Alexopoulos, T, Alfonsi, A, Alfonsi, F, Alhroob, M, Ali, B, Ali, S, Aliev, M, Alimonti, G, Alkakhi, W, Allaire, C, Allbrooke, BMM, Allport, PP, Aloisio, A, Alonso, F, Alpigiani, C, Camelia, E Alunno, Estevez, M Alvarez, Alviggi, MG, Aly, M, Coutinho, Y Amaral, Ambler, A, Amelung, C, Amerl, M, Ames, CG, Amidei, D, Dos Santos, SP Amor, Amoroso, S, Amos, KR, Ananiev, V, Anastopoulos, C, Andeen, T, Anders, JK, Andrean, SY, Andreazza, A, Angelidakis, S, Angerami, A, Anisenkov, AV, Annovi, A, Antel, C, Anthony, MT, Antipov, E, Antonelli, M, Antrim, DJA, Anulli, F, Aoki, M, Aoki, T, Pozo, JA Aparisi, Aparo, MA, Bella, L Aperio, Appelt, C, Aranzabal, N, Ferraz, V Araujo, Arcangeletti, C, Arce, ATH, and Arena, E

Subjects
Nuclear and Plasma Physics, Particle and High Energy Physics, Physical Sciences
Abstract

A search is presented for displaced production of Higgs bosons or Z bosons, originating from the decay of a neutral long-lived particle (LLP) and reconstructed in the decay modes H → γ γ and Z → e e . The analysis uses the full Run 2 dataset of proton-proton collisions delivered by the LHC at an energy of s = 13 TeV between 2015 and 2018 and recorded by the ATLAS detector, corresponding to an integrated luminosity of 139 fb - 1 . Exploiting the capabilities of the ATLAS liquid argon calorimeter to precisely measure the arrival times and trajectories of electromagnetic objects, the analysis searches for the signature of pairs of photons or electrons which arise from a common displaced vertex and which arrive after some delay at the calorimeter. The results are interpreted in a gauge-mediated supersymmetry breaking model with pair-produced Higgsinos that decay to LLPs, and each LLP subsequently decays into either a Higgs boson or a Z boson. The final state includes at least two particles that escape direct detection, giving rise to missing transverse momentum. No significant excess is observed above the background expectation. The results are used to set upper limits on the cross section for Higgsino pair production, up to a χ ˜ 1 0 mass of 369 (704) GeV for decays with 100% branching ratio of χ ˜ 1 0 to Higgs ( Z ) bosons for a χ ˜ 1 0 lifetime of 2 ns. A model-independent limit is also set on the production of pairs of photons or electrons with a significant delay in arrival at the calorimeter.

Published
2023

22. Search for Higgs boson pair production in the two bottom quarks plus two photons final state in pp collisions at s=13 TeV with the ATLAS detector

Author

Aad, G, Abbott, B, Abbott, DC, Abud, A Abed, Abeling, K, Abhayasinghe, DK, Abidi, SH, Abramowicz, H, Abreu, H, Abulaiti, Y, Hoffman, AC Abusleme, Acharya, BS, Achkar, B, Adam, L, Bourdarios, C Adam, Adamczyk, L, Adamek, L, Adelman, J, Adiguzel, A, Adorni, S, Adye, T, Affolder, AA, Afik, Y, Agapopoulou, C, Agaras, MN, Agarwala, J, Aggarwal, A, Agheorghiesei, C, Aguilar-Saavedra, JA, Ahmad, A, Ahmadov, F, Ahmed, WS, Ai, X, Aielli, G, Akatsuka, S, Akbiyik, M, Åkesson, TPA, Akimov, AV, Al Khoury, K, Alberghi, GL, Albert, J, Verzini, MJ Alconada, Alderweireldt, S, Aleksa, M, Aleksandrov, IN, Alexa, C, Alexopoulos, T, Alfonsi, A, Alfonsi, F, Alhroob, M, Ali, B, Ali, S, Aliev, M, Alimonti, G, Allaire, C, Allbrooke, BMM, Allport, PP, Aloisio, A, Alonso, F, Alpigiani, C, Camelia, E Alunno, Estevez, M Alvarez, Alviggi, MG, Coutinho, Y Amaral, Ambler, A, Ambroz, L, Amelung, C, Amidei, D, Dos Santos, SP Amor, Amoroso, S, Amrouche, CS, Anastopoulos, C, Andari, N, Andeen, T, Anders, JK, Andrean, SY, Andreazza, A, Andrei, V, Angelidakis, S, Angerami, A, Anisenkov, AV, Annovi, A, Antel, C, Anthony, MT, Antipov, E, Antonelli, M, Antrim, DJA, Anulli, F, Aoki, M, Pozo, JA Aparisi, Aparo, MA, Bella, L Aperio, Aranzabal, N, Ferraz, V Araujo, Arcangeletti, C, Arce, ATH, Arena, E, Arguin, J-F, Argyropoulos, S, and Arling, J-H

Subjects
Nuclear and Plasma Physics, Particle and High Energy Physics, Physical Sciences
Abstract

Searches are performed for nonresonant and resonant di-Higgs boson production in the bb¯γγ final state. The dataset used corresponds to an integrated luminosity of 139 fb-1 of proton-proton collisions at a center-of-mass energy of 13 TeV recorded by the ATLAS detector at the CERN Large Hadron Collider. No excess above the expected background is found and upper limits on the di-Higgs boson production cross sections are set. A 95% confidence-level upper limit of 4.2 times the cross section predicted by the Standard Model is set on pp→HH nonresonant production, where the expected limit is 5.7 times the Standard Model predicted value. The expected constraints are obtained for a background hypothesis excluding pp→HH production. The observed (expected) constraints on the Higgs boson trilinear coupling modifier κλ are determined to be [-1.5,6.7] ([-2.4,7.7]) at 95% confidence level, where the expected constraints on κλ are obtained excluding pp→HH production from the background hypothesis. For resonant production of a new hypothetical scalar particle X (X→HH→bb¯γγ), limits on the cross section for pp→X→HH are presented in the narrow-width approximation as a function of mX in the range 251 GeV≤mX≤1000 GeV. The observed (expected) limits on the cross section for pp→X→HH range from 640 fb to 44 fb (391 fb to 46 fb) over the considered mass range.

Published
2022

23. Measurements of jet observables sensitive to b-quark fragmentation in tt¯ events at the LHC with the ATLAS detector

Author

Aad, G, Abbott, B, Abbott, DC, Abud, A Abed, Abeling, K, Abhayasinghe, DK, Abidi, SH, AbouZeid, OS, Abraham, NL, Abramowicz, H, Abreu, H, Abulaiti, Y, Acharya, BS, Achkar, B, Adam, L, Bourdarios, C Adam, Adamczyk, L, Adamek, L, Adelman, J, Adiguzel, A, Adorni, S, Adye, T, Affolder, AA, Afik, Y, Agapopoulou, C, Agaras, MN, Aggarwal, A, Agheorghiesei, C, Aguilar-Saavedra, JA, Ahmad, A, Ahmadov, F, Ahmed, WS, Ai, X, Aielli, G, Akatsuka, S, Akbiyik, M, Åkesson, TPA, Akilli, E, Akimov, AV, Al Khoury, K, Alberghi, GL, Albert, J, Verzini, MJ Alconada, Alderweireldt, S, Aleksa, M, Aleksandrov, IN, Alexa, C, Alexopoulos, T, Alfonsi, A, Alfonsi, F, Alhroob, M, Ali, B, Ali, S, Aliev, M, Alimonti, G, Allaire, C, Allbrooke, BMM, Allport, PP, Aloisio, A, Alonso, F, Alpigiani, C, Camelia, E Alunno, Estevez, M Alvarez, Alviggi, MG, Coutinho, Y Amaral, Ambler, A, Ambroz, L, Amelung, C, Amidei, D, Dos Santos, SP Amor, Amoroso, S, Amrouche, CS, An, F, Anastopoulos, C, Andari, N, Andeen, T, Anders, JK, Andrean, SY, Andreazza, A, Andrei, V, Anelli, CR, Angelidakis, S, Angerami, A, Anisenkov, AV, Annovi, A, Antel, C, Anthony, MT, Antipov, E, Antonelli, M, Antrim, DJA, Anulli, F, Aoki, M, Pozo, JA Aparisi, Aparo, MA, Bella, L Aperio, Aranzabal, N, Ferraz, V Araujo, Pereira, R Araujo, Arcangeletti, C, and Arce, ATH

Subjects
Nuclear and Plasma Physics, Particle and High Energy Physics, Physical Sciences
Abstract

Several observables sensitive to the fragmentation of b quarks into b hadrons are measured using 36 fb-1 of s=13 TeV proton-proton collision data collected with the ATLAS detector at the LHC. Jets containing b hadrons are obtained from a sample of dileptonic tt¯ events, and the associated set of charged-particle tracks is separated into those from the primary pp interaction vertex and those from the displaced b-decay secondary vertex. This division is used to construct observables that characterize the longitudinal and transverse momentum distributions of the b hadron within the jet. The measurements have been corrected for detector effects and provide a test of heavy-quark-fragmentation modeling at the LHC in a system where the top-quark decay products are color connected to the proton beam remnants. The unfolded distributions are compared with the predictions of several modern Monte Carlo parton-shower generators and generator tunes, and a wide range of agreement with the data is observed, with p values varying from 5×10-4 to 0.98. These measurements complement similar measurements from e+e- collider experiments in which the b quarks originate from a color singlet Z/γ∗.

Published
2022

24. Search for events with a pair of displaced vertices from long-lived neutral particles decaying into hadronic jets in the ATLAS muon spectrometer in pp collisions at s =13 TeV

Author

Aad, G, Abbott, B, Abbott, DC, Abed Abud, A, Abeling, K, Abhayasinghe, DK, Abidi, SH, Aboulhorma, A, Abramowicz, H, Abreu, H, Abulaiti, Y, Abusleme Hoffman, AC, Acharya, BS, Achkar, B, Adam, L, Adam Bourdarios, C, Adamczyk, L, Adamek, L, Addepalli, SV, Adelman, J, Adiguzel, A, Adorni, S, Adye, T, Affolder, AA, Afik, Y, Agapopoulou, C, Agaras, MN, Agarwala, J, Aggarwal, A, Agheorghiesei, C, Aguilar-Saavedra, JA, Ahmad, A, Ahmadov, F, Ahmed, WS, Ai, X, Aielli, G, Aizenberg, I, Akatsuka, S, Akbiyik, M, Åkesson, TPA, Akimov, AV, Al Khoury, K, Alberghi, GL, Albert, J, Albicocco, P, Alconada Verzini, MJ, Alderweireldt, S, Aleksa, M, Aleksandrov, IN, Alexa, C, Alexopoulos, T, Alfonsi, A, Alfonsi, F, Alhroob, M, Ali, B, Ali, S, Aliev, M, Alimonti, G, Allaire, C, Allbrooke, BMM, Allport, PP, Aloisio, A, Alonso, F, Alpigiani, C, Alunno Camelia, E, Alvarez Estevez, M, Alviggi, MG, Amaral Coutinho, Y, Ambler, A, Ambroz, L, Amelung, C, Amidei, D, Amor Dos Santos, SP, Amoroso, S, Amos, KR, Amrouche, CS, Ananiev, V, Anastopoulos, C, Andari, N, Andeen, T, Anders, JK, Andrean, SY, Andreazza, A, Angelidakis, S, Angerami, A, Anisenkov, AV, Annovi, A, Antel, C, Anthony, MT, Antipov, E, Antonelli, M, Antrim, DJA, Anulli, F, Aoki, M, Aparisi Pozo, JA, Aparo, MA, Aperio Bella, L, Aranzabal, N, Araujo Ferraz, V, and Arcangeletti, C

Subjects
Nuclear and Plasma Physics, Particle and High Energy Physics, Physical Sciences, Astronomical and Space Sciences, Atomic, Molecular, Nuclear, Particle and Plasma Physics, Quantum Physics, Nuclear & Particles Physics, Mathematical physics, Astronomical sciences, Particle and high energy physics
Abstract

A search for events with two displaced vertices from long-lived particle (LLP) pairs using data collected by the ATLAS detector at the LHC is presented. This analysis uses 139 fb-1 of proton-proton collision data at s=13 TeV recorded in 2015-2018. The search employs techniques for reconstructing vertices of LLPs decaying to jets in the muon spectrometer displaced between 3 and 14 m with respect to the primary interaction vertex. The observed numbers of events are consistent with the expected background and limits for several benchmark signals are determined. For the Higgs boson with a mass of 125 GeV, the paper reports the first exclusion limits for branching fractions into neutral long-lived particles below 0.1%, while branching fractions above 10% are excluded at 95% confidence level for LLP proper lifetimes ranging from 4 cm to 72.4 m. In addition, the paper present the first results for the decay of LLPs into tt¯ in the ATLAS muon spectrometer.

Published
2022

25. Search for single production of a vectorlike T quark decaying into a Higgs boson and top quark with fully hadronic final states using the ATLAS detector

Author

Aad, G, Abbott, B, Abbott, DC, Abud, A Abed, Abeling, K, Abhayasinghe, DK, Abidi, SH, Aboulhorma, A, Abramowicz, H, Abreu, H, Abulaiti, Y, Hoffman, AC Abusleme, Acharya, BS, Achkar, B, Adam, L, Bourdarios, C Adam, Adamczyk, L, Adamek, L, Addepalli, SV, Adelman, J, Adiguzel, A, Adorni, S, Adye, T, Affolder, AA, Afik, Y, Agaras, MN, Agarwala, J, Aggarwal, A, Agheorghiesei, C, Aguilar-Saavedra, JA, Ahmad, A, Ahmadov, F, Ahmed, WS, Ai, X, Aielli, G, Aizenberg, I, Akbiyik, M, Åkesson, TPA, Akimov, AV, Al Khoury, K, Alberghi, GL, Albert, J, Albicocco, P, Verzini, MJ Alconada, Alderweireldt, S, Aleksa, M, Aleksandrov, IN, Alexa, C, Alexopoulos, T, Alfonsi, A, Alfonsi, F, Alhroob, M, Ali, B, Ali, S, Aliev, M, Alimonti, G, Allaire, C, Allbrooke, BMM, Allport, PP, Aloisio, A, Alonso, F, Alpigiani, C, Camelia, E Alunno, Estevez, M Alvarez, Alviggi, MG, Coutinho, Y Amaral, Ambler, A, Ambroz, L, Amelung, C, Amidei, D, Dos Santos, SP Amor, Amoroso, S, Amos, KR, Amrouche, CS, Ananiev, V, Anastopoulos, C, Andari, N, Andeen, T, Anders, JK, Andrean, SY, Andreazza, A, Angelidakis, S, Angerami, A, Anisenkov, AV, Annovi, A, Antel, C, Anthony, MT, Antipov, E, Antonelli, M, Antrim, DJA, Anulli, F, Aoki, M, Pozo, JA Aparisi, Aparo, MA, Bella, L Aperio, Appelt, C, Aranzabal, N, Ferraz, V Araujo, Arcangeletti, C, and Arce, ATH

Subjects
Nuclear and Plasma Physics, Particle and High Energy Physics, Physical Sciences
Abstract

A search is made for a vectorlike T quark decaying into a Higgs boson and a top quark in 13 TeV proton-proton collisions using the ATLAS detector at the Large Hadron Collider with a data sample corresponding to an integrated luminosity of 139 fb-1. The Higgs-boson and top-quark candidates are identified in the all-hadronic decay mode, where H→bb¯ and t→bW→bqq¯′ are reconstructed as large-radius jets. The candidate Higgs boson, top quark, and associated B hadrons are identified using tagging algorithms. No significant excess is observed above the background, so limits are set on the production cross section of a singlet T quark at 95% confidence level, depending on the mass mT and coupling κT of the vectorlike T quark to Standard Model particles. In the considered mass range between 1.0 and 2.3 TeV, the upper limit on the allowed coupling values increases with mT from a minimum value of 0.35 for 1.07

Published
2022

26. Search for resonant pair production of Higgs bosons in the bb¯bb¯ final state using pp collisions at s=13 TeV with the ATLAS detector

Author

Aad, G, Abbott, B, Abbott, DC, Abud, A Abed, Abeling, K, Abhayasinghe, DK, Abidi, SH, Abramowicz, H, Abreu, H, Abulaiti, Y, Hoffman, AC Abusleme, Acharya, BS, Achkar, B, Adam, L, Bourdarios, C Adam, Adamczyk, L, Adamek, L, Addepalli, SV, Adelman, J, Adiguzel, A, Adorni, S, Adye, T, Affolder, AA, Afik, Y, Agapopoulou, C, Agaras, MN, Agarwala, J, Aggarwal, A, Agheorghiesei, C, Aguilar-Saavedra, JA, Ahmad, A, Ahmadov, F, Ahmed, WS, Ai, X, Aielli, G, Aizenberg, I, Akatsuka, S, Akbiyik, M, Åkesson, TPA, Akimov, AV, Al Khoury, K, Alberghi, GL, Albert, J, Albicocco, P, Verzini, MJ Alconada, Alderweireldt, S, Aleksa, M, Aleksandrov, IN, Alexa, C, Alexopoulos, T, Alfonsi, A, Alfonsi, F, Alhroob, M, Ali, B, Ali, S, Aliev, M, Alimonti, G, Allaire, C, Allbrooke, BMM, Allport, PP, Aloisio, A, Alonso, F, Alpigiani, C, Camelia, E Alunno, Estevez, M Alvarez, Alviggi, MG, Coutinho, Y Amaral, Ambler, A, Ambroz, L, Amelung, C, Amidei, D, Dos Santos, SP Amor, Amoroso, S, Amrouche, CS, Anastopoulos, C, Andari, N, Andeen, T, Anders, JK, Andrean, SY, Andreazza, A, Angelidakis, S, Angerami, A, Anisenkov, AV, Annovi, A, Antel, C, Anthony, MT, Antipov, E, Antonelli, M, Antrim, DJA, Anulli, F, Aoki, M, Pozo, JA Aparisi, Aparo, MA, Bella, L Aperio, Aranzabal, N, Ferraz, V Araujo, Arcangeletti, C, Arce, ATH, Arena, E, and Arguin, J-F

Subjects
Nuclear and Plasma Physics, Particle and High Energy Physics, Physical Sciences
Abstract

A search for resonant Higgs boson pair production in the bb¯bb¯ final state is presented. The analysis uses 126 fb-1-139 fb-1 of pp collision data at s=13 TeV collected with the ATLAS detector at the Large Hadron Collider. The analysis is divided into two channels, targeting Higgs boson decays which are reconstructed as pairs of small-radius jets or as individual large-radius jets. Spin-0 and spin-2 benchmark signal models are considered, both of which correspond to resonant HH production via gluon-gluon fusion. The data are consistent with Standard Model predictions. Upper limits are set on the production cross section times branching ratio to Higgs boson pairs of a new resonance in the mass range from 251 GeV to 5 TeV.

Published
2022

27. Constraints on Higgs boson production with large transverse momentum using H→bb¯ decays in the ATLAS detector

Author

Aad, G, Abbott, B, Abbott, DC, Abud, A Abed, Abeling, K, Abhayasinghe, DK, Abidi, SH, Aboulhorma, A, Abramowicz, H, Abreu, H, Abulaiti, Y, Hoffman, AC Abusleme, Acharya, BS, Achkar, B, Adam, L, Bourdarios, C Adam, Adamczyk, L, Adamek, L, Addepalli, SV, Adelman, J, Adiguzel, A, Adorni, S, Adye, T, Affolder, AA, Afik, Y, Agapopoulou, C, Agaras, MN, Agarwala, J, Aggarwal, A, Agheorghiesei, C, Aguilar-Saavedra, JA, Ahmad, A, Ahmadov, F, Ahmed, WS, Ai, X, Aielli, G, Aizenberg, I, Akatsuka, S, Akbiyik, M, Åkesson, TPA, Akimov, AV, Al Khoury, K, Alberghi, GL, Albert, J, Albicocco, P, Verzini, MJ Alconada, Alderweireldt, S, Aleksa, M, Aleksandrov, IN, Alexa, C, Alexopoulos, T, Alfonsi, A, Alfonsi, F, Alhroob, M, Ali, B, Ali, S, Aliev, M, Alimonti, G, Allaire, C, Allbrooke, BMM, Allport, PP, Aloisio, A, Alonso, F, Alpigiani, C, Camelia, E Alunno, Estevez, M Alvarez, Alviggi, MG, Coutinho, Y Amaral, Ambler, A, Ambroz, L, Amelung, C, Amidei, D, Dos Santos, SP Amor, Amoroso, S, Amos, KR, Amrouche, CS, Ananiev, V, Anastopoulos, C, Andari, N, Andeen, T, Anders, JK, Andrean, SY, Andreazza, A, Angelidakis, S, Angerami, A, Anisenkov, AV, Annovi, A, Antel, C, Anthony, MT, Antipov, E, Antonelli, M, Antrim, DJA, Anulli, F, Aoki, M, Pozo, JA Aparisi, Aparo, MA, Bella, L Aperio, Aranzabal, N, Ferraz, V Araujo, and Arcangeletti, C

Subjects
Nuclear and Plasma Physics, Particle and High Energy Physics, Physical Sciences
Abstract

This paper reports constraints on Higgs boson production with transverse momentum above 1 TeV. The analyzed data from proton-proton collisions at a center-of-mass energy of 13 TeV were recorded with the ATLAS detector at the Large Hadron Collider from 2015 to 2018 and correspond to an integrated luminosity of 136 fb-1. Higgs bosons decaying into bb¯ are reconstructed as single large-radius jets recoiling against a hadronic system and are identified by the experimental signature of two b-hadron decays. The experimental techniques are validated in the same kinematic regime using the Z→bb¯ process. The 95% confidence-level upper limit on the cross section for Higgs boson production with transverse momentum above 450 GeV is 115 fb, and above 1 TeV it is 9.6 fb. The Standard Model cross section predictions for a Higgs boson with a mass of 125 GeV in the same kinematic regions are 18.4 fb and 0.13 fb, respectively.

Published
2022

28. Search for Higgs boson decays into a pair of pseudoscalar particles in the bbμμ final state with the ATLAS detector in pp collisions at s=13 TeV

Author

Aad, G, Abbott, B, Abbott, DC, Abud, A Abed, Abeling, K, Abhayasinghe, DK, Abidi, SH, Aboulhorma, A, Abramowicz, H, Abreu, H, Abulaiti, Y, Hoffman, AC Abusleme, Acharya, BS, Achkar, B, Adam, L, Bourdarios, C Adam, Adamczyk, L, Adamek, L, Addepalli, SV, Adelman, J, Adiguzel, A, Adorni, S, Adye, T, Affolder, AA, Afik, Y, Agapopoulou, C, Agaras, MN, Agarwala, J, Aggarwal, A, Agheorghiesei, C, Aguilar-Saavedra, JA, Ahmad, A, Ahmadov, F, Ahmed, WS, Ai, X, Aielli, G, Aizenberg, I, Akatsuka, S, Akbiyik, M, Åkesson, TPA, Akimov, AV, Al Khoury, K, Alberghi, GL, Albert, J, Albicocco, P, Verzini, MJ Alconada, Alderweireldt, S, Aleksa, M, Aleksandrov, IN, Alexa, C, Alexopoulos, T, Alfonsi, A, Alfonsi, F, Alhroob, M, Ali, B, Ali, S, Aliev, M, Alimonti, G, Allaire, C, Allbrooke, BMM, Allport, PP, Aloisio, A, Alonso, F, Alpigiani, C, Camelia, E Alunno, Estevez, M Alvarez, Alviggi, MG, Coutinho, Y Amaral, Ambler, A, Ambroz, L, Amelung, C, Amidei, D, Dos Santos, SP Amor, Amoroso, S, Amrouche, CS, Ananiev, V, Anastopoulos, C, Andari, N, Andeen, T, Anders, JK, Andrean, SY, Andreazza, A, Angelidakis, S, Angerami, A, Anisenkov, AV, Annovi, A, Antel, C, Anthony, MT, Antipov, E, Antonelli, M, Antrim, DJA, Anulli, F, Aoki, M, Pozo, JA Aparisi, Aparo, MA, Bella, L Aperio, Aranzabal, N, Ferraz, V Araujo, Arcangeletti, C, and Arce, ATH

Subjects
Nuclear and Plasma Physics, Particle and High Energy Physics, Physical Sciences
Abstract

This paper presents a search for decays of the Higgs boson with a mass of 125 GeV into a pair of new pseudoscalar particles, H→aa, where one a-boson decays into a b-quark pair and the other into a muon pair. The search uses 139 fb-1 of proton-proton collision data at a center-of-mass energy of s=13 TeV recorded between 2015 and 2018 by the ATLAS experiment at the LHC. A narrow dimuon resonance is searched for in the invariant mass spectrum between 16 GeV and 62 GeV. The largest excess of events above the Standard Model backgrounds is observed at a dimuon invariant mass of 52 GeV and corresponds to a local (global) significance of 3.3σ (1.7σ). Upper limits at 95% confidence level are placed on the branching ratio of the Higgs boson to the bbμμ final state, B(H→aa→bbμμ), and are in the range 0.2-4.0×10-4, depending on the signal mass hypothesis.

Published
2022

29. Search for heavy particles in the b-tagged dijet mass distribution with additional b-tagged jets in proton-proton collisions at s=13 TeV with the ATLAS experiment

Author

Aad, G, Abbott, B, Abbott, DC, Abud, A Abed, Abeling, K, Abhayasinghe, DK, Abidi, SH, Abramowicz, H, Abreu, H, Abulaiti, Y, Hoffman, AC Abusleme, Acharya, BS, Achkar, B, Adam, L, Bourdarios, C Adam, Adamczyk, L, Adamek, L, Adelman, J, Adiguzel, A, Adorni, S, Adye, T, Affolder, AA, Afik, Y, Agapopoulou, C, Agaras, MN, Agarwala, J, Aggarwal, A, Agheorghiesei, C, Aguilar-Saavedra, JA, Ahmad, A, Ahmadov, F, Ahmed, WS, Ai, X, Aielli, G, Akatsuka, S, Akbiyik, M, Åkesson, TPA, Akimov, AV, Khoury, K Al, Alberghi, GL, Albert, J, Verzini, MJ Alconada, Alderweireldt, S, Aleksa, M, Aleksandrov, IN, Alexa, C, Alexopoulos, T, Alfonsi, A, Alfonsi, F, Alhroob, M, Ali, B, Ali, S, Aliev, M, Alimonti, G, Allaire, C, Allbrooke, BMM, Allport, PP, Aloisio, A, Alonso, F, Alpigiani, C, Camelia, E Alunno, Estevez, M Alvarez, Alviggi, MG, Coutinho, Y Amaral, Ambler, A, Ambroz, L, Amelung, C, Amidei, D, Dos Santos, SP Amor, Amoroso, S, Amrouche, CS, Anastopoulos, C, Andari, N, Andeen, T, Anders, JK, Andrean, SY, Andreazza, A, Andrei, V, Angelidakis, S, Angerami, A, Anisenkov, AV, Annovi, A, Antel, C, Anthony, MT, Antipov, E, Antonelli, M, Antrim, DJA, Anulli, F, Aoki, M, Pozo, JA Aparisi, Aparo, MA, Bella, L Aperio, Aranzabal, N, Ferraz, V Araujo, Arcangeletti, C, Arce, ATH, Arena, E, Arguin, J-F, Argyropoulos, S, and Arling, J-H

Subjects
Astronomical and Space Sciences, Atomic, Molecular, Nuclear, Particle and Plasma Physics, Quantum Physics, Nuclear & Particles Physics
Abstract

A search optimized for new heavy particles decaying to two b-quarks and produced in association with additional b-quarks is reported. The sensitivity is improved by b-tagging at least one lower-pT jet in addition to the two highest-pT jets. The data used in this search correspond to an integrated luminosity of 103 fb-1 collected with a dedicated trijet trigger during the 2017 and 2018 s=13 TeV proton-proton collision runs with the ATLAS detector at the LHC. The search looks for resonant peaks in the b-tagged dijet invariant mass spectrum over a smoothly falling background. The background is estimated with an innovative data-driven method based on orthonormal functions. The observed b-tagged dijet invariant mass spectrum is compatible with the background-only hypothesis. Upper limits at 95% confidence level on a heavy vector-boson production cross section times branching ratio to a pair of b-quarks are derived.

Published
2022

30. Search for charginos and neutralinos in final states with two boosted hadronically decaying bosons and missing transverse momentum in pp collisions at s=13 TeV with the ATLAS detector

Author

Aad, G, Abbott, B, Abbott, DC, Abud, A Abed, Abeling, K, Abhayasinghe, DK, Abidi, SH, Abramowicz, H, Abreu, H, Abulaiti, Y, Hoffman, AC Abusleme, Acharya, BS, Achkar, B, Adam, L, Bourdarios, C Adam, Adamczyk, L, Adamek, L, Addepalli, SV, Adelman, J, Adiguzel, A, Adorni, S, Adye, T, Affolder, AA, Afik, Y, Agapopoulou, C, Agaras, MN, Agarwala, J, Aggarwal, A, Agheorghiesei, C, Aguilar-Saavedra, JA, Ahmad, A, Ahmadov, F, Ahmed, WS, Ai, X, Aielli, G, Aizenberg, I, Akatsuka, S, Akbiyik, M, Åkesson, TPA, Akimov, AV, Al Khoury, K, Alberghi, GL, Albert, J, Albicocco, P, Verzini, MJ Alconada, Alderweireldt, S, Aleksa, M, Aleksandrov, IN, Alexa, C, Alexopoulos, T, Alfonsi, A, Alfonsi, F, Alhroob, M, Ali, B, Ali, S, Aliev, M, Alimonti, G, Allaire, C, Allbrooke, BMM, Allport, PP, Aloisio, A, Alonso, F, Alpigiani, C, Camelia, E Alunno, Estevez, M Alvarez, Alviggi, MG, Coutinho, Y Amaral, Ambler, A, Ambroz, L, Amelung, C, Amidei, D, Dos Santos, SP Amor, Amoroso, S, Amrouche, CS, Anastopoulos, C, Andari, N, Andeen, T, Anders, JK, Andrean, SY, Andreazza, A, Angelidakis, S, Angerami, A, Anisenkov, AV, Annovi, A, Antel, C, Anthony, MT, Antipov, E, Antonelli, M, Antrim, DJA, Anulli, F, Aoki, M, Pozo, JA Aparisi, Aparo, MA, Bella, L Aperio, Aranzabal, N, Ferraz, V Araujo, Arcangeletti, C, Arce, ATH, Arena, E, and Arguin, J-F

Subjects
Nuclear and Plasma Physics, Particle and High Energy Physics, Physical Sciences
Abstract

A search for charginos and neutralinos at the Large Hadron Collider using fully hadronic final states and missing transverse momentum is reported. Pair-produced charginos or neutralinos are explored, each decaying into a high-pT Standard Model weak boson. Fully hadronic final states are studied to exploit the advantage of the large branching ratio, and the efficient rejection of backgrounds by identifying the high-pT bosons using large-radius jets and jet substructure information. An integrated luminosity of 139 fb-1 of proton-proton collision data collected by the ATLAS detector at a center-of-mass energy of 13 TeV is used. No significant excess is found beyond the Standard Model expectation. Exclusion limits at the 95% confidence level are set on wino or higgsino production with various assumptions about the decay branching ratios and the type of lightest supersymmetric particle. A wino (higgsino) mass up to 1060 (900) GeV is excluded when the lightest supersymmetry particle mass is below 400 (240) GeV and the mass splitting is larger than 400 (450) GeV. The sensitivity to high-mass winos and higgsinos is significantly extended relative to previous LHC searches using other final states.

Published
2021

31. Search for new phenomena in pp collisions in final states with tau leptons, b-jets, and missing transverse momentum with the ATLAS detector

Author

Aad, G, Abbott, B, Abbott, DC, Abud, A Abed, Abeling, K, Abhayasinghe, DK, Abidi, SH, AbouZeid, OS, Abramowicz, H, Abreu, H, Abulaiti, Y, Hoffman, AC Abusleme, Acharya, BS, Achkar, B, Adam, L, Bourdarios, C Adam, Adamczyk, L, Adamek, L, Adelman, J, Adiguzel, A, Adorni, S, Adye, T, Affolder, AA, Afik, Y, Agapopoulou, C, Agaras, MN, Agarwala, J, Aggarwal, A, Agheorghiesei, C, Aguilar-Saavedra, JA, Ahmad, A, Ahmadov, F, Ahmed, WS, Ai, X, Aielli, G, Akatsuka, S, Akbiyik, M, Åkesson, TPA, Akimov, AV, Al Khoury, K, Alberghi, GL, Albert, J, Verzini, MJ Alconada, Alderweireldt, S, Aleksa, M, Aleksandrov, IN, Alexa, C, Alexopoulos, T, Alfonsi, A, Alfonsi, F, Alhroob, M, Ali, B, Ali, S, Aliev, M, Alimonti, G, Allaire, C, Allbrooke, BMM, Allport, PP, Aloisio, A, Alonso, F, Alpigiani, C, Camelia, E Alunno, Estevez, M Alvarez, Alviggi, MG, Coutinho, Y Amaral, Ambler, A, Ambroz, L, Amelung, C, Amidei, D, Dos Santos, SP Amor, Amoroso, S, Amrouche, CS, Anastopoulos, C, Andari, N, Andeen, T, Anders, JK, Andrean, SY, Andreazza, A, Andrei, V, Angelidakis, S, Angerami, A, Anisenkov, AV, Annovi, A, Antel, C, Anthony, MT, Antipov, E, Antonelli, M, Antrim, DJA, Anulli, F, Aoki, M, Pozo, JA Aparisi, Aparo, MA, Bella, L Aperio, Aranzabal, N, Ferraz, V Araujo, Arcangeletti, C, Arce, ATH, Arena, E, Arguin, J-F, and Argyropoulos, S

Subjects
Nuclear and Plasma Physics, Particle and High Energy Physics, Physical Sciences
Abstract

A search for new phenomena in final states with hadronically decaying tau leptons, b-jets, and missing transverse momentum is presented. The analyzed dataset comprises pp collision data at a center-of-mass energy of s=13 TeV with an integrated luminosity of 139 fb-1, delivered by the Large Hadron Collider and recorded with the ATLAS detector from 2015 to 2018. The observed data are compatible with the expected Standard Model background. The results are interpreted in simplified models for two different scenarios. The first model is based on supersymmetry and considers pair production of top squarks, each of which decays into a b-quark, a neutrino and a tau slepton. Each tau slepton in turn decays into a tau lepton and a nearly massless gravitino. Within this model, top-squark masses up to 1.4 TeV can be excluded at the 95% confidence level over a wide range of tau-slepton masses. The second model considers pair production of leptoquarks with decays into third-generation leptons and quarks. Depending on the branching fraction into charged leptons, leptoquarks with masses up to around 1.25 TeV can be excluded at the 95% confidence level for the case of scalar leptoquarks and up to 1.8 TeV (1.5 TeV) for vector leptoquarks in a Yang-Mills (minimal-coupling) scenario. In addition, model-independent upper limits are set on the cross section of processes beyond the Standard Model.

Published
2021

32. Search for heavy long-lived multicharged particles in proton-proton collisions at s=13  TeV using the ATLAS detector

Author

Aaboud, M, Aad, G, Abbott, B, Abbott, DC, Abdinov, O, Abeloos, B, Abhayasinghe, DK, Abidi, SH, AbouZeid, OS, Abraham, NL, Abramowicz, H, Abreu, H, Abulaiti, Y, Acharya, BS, Adachi, S, Adam, L, Adamczyk, L, Adamek, L, Adelman, J, Adersberger, M, Adiguzel, A, Adye, T, Affolder, AA, Afik, Y, Agheorghiesei, C, Aguilar-Saavedra, JA, Ahmadov, F, Aielli, G, Akatsuka, S, Åkesson, TPA, Akilli, E, Akimov, AV, Alberghi, GL, Albert, J, Albicocco, P, Alconada Verzini, MJ, Alderweireldt, S, Aleksa, M, Aleksandrov, IN, Alexa, C, Alexandre, D, Alexopoulos, T, Alhroob, M, Ali, B, Alimonti, G, Alison, J, Alkire, SP, Allaire, C, Allbrooke, BMM, Allen, BW, Allport, PP, Aloisio, A, Alonso, A, Alonso, F, Alpigiani, C, Alshehri, AA, Alstaty, MI, Alvarez Gonzalez, B, Álvarez Piqueras, D, Alviggi, MG, Amadio, BT, Amaral Coutinho, Y, Ambler, A, Ambroz, L, Amelung, C, Amidei, D, Amor Dos Santos, SP, Amoroso, S, Amrouche, CS, An, F, Anastopoulos, C, Ancu, LS, Andari, N, Andeen, T, Anders, CF, Anders, JK, Anderson, KJ, Andreazza, A, Andrei, V, Anelli, CR, Angelidakis, S, Angelozzi, I, Angerami, A, Anisenkov, AV, Annovi, A, Antel, C, Anthony, MT, Antonelli, M, Antrim, DJA, Anulli, F, Aoki, M, Aparisi Pozo, JA, Aperio Bella, L, Arabidze, G, Araque, JP, Araujo Ferraz, V, Araujo Pereira, R, Arce, ATH, Ardell, RE, and Arduh, FA

Published
2021

33. Search for bottom-squark pair production in pp collision events at s=13 TeV with hadronically decaying τ-leptons, b-jets, and missing transverse momentum using the ATLAS detector

Author

Aad, G, Abbott, B, Abbott, DC, Abud, A Abed, Abeling, K, Abhayasinghe, DK, Abidi, SH, AbouZeid, OS, Abraham, NL, Abramowicz, H, Abreu, H, Abulaiti, Y, Acharya, BS, Achkar, B, Adam, L, Bourdarios, C Adam, Adamczyk, L, Adamek, L, Adelman, J, Adiguzel, A, Adorni, S, Adye, T, Affolder, AA, Afik, Y, Agapopoulou, C, Agaras, MN, Aggarwal, A, Agheorghiesei, C, Aguilar-Saavedra, JA, Ahmad, A, Ahmadov, F, Ahmed, WS, Ai, X, Aielli, G, Akatsuka, S, Akbiyik, M, Åkesson, TPA, Akilli, E, Akimov, AV, Al Khoury, K, Alberghi, GL, Albert, J, Verzini, MJ Alconada, Alderweireldt, S, Aleksa, M, Aleksandrov, IN, Alexa, C, Alexopoulos, T, Alfonsi, A, Alfonsi, F, Alhroob, M, Ali, B, Ali, S, Aliev, M, Alimonti, G, Allaire, C, Allbrooke, BMM, Allen, BW, Allport, PP, Aloisio, A, Alonso, F, Alpigiani, C, Camelia, E Alunno, Estevez, M Alvarez, Alviggi, MG, Coutinho, Y Amaral, Ambler, A, Ambroz, L, Amelung, C, Amidei, D, Dos Santos, SP Amor, Amoroso, S, Amrouche, CS, An, F, Anastopoulos, C, Andari, N, Andeen, T, Anders, JK, Andrean, SY, Andreazza, A, Andrei, V, Anelli, CR, Angelidakis, S, Angerami, A, Anisenkov, AV, Annovi, A, Antel, C, Anthony, MT, Antipov, E, Antonelli, M, Antrim, DJA, Anulli, F, Aoki, M, Pozo, JA Aparisi, Aparo, MA, Bella, L Aperio, Aranzabal, N, Ferraz, V Araujo, Pereira, R Araujo, and Arcangeletti, C

Subjects
Nuclear and Plasma Physics, Particle and High Energy Physics, Physical Sciences
Abstract

A search for pair production of bottom squarks in events with hadronically decaying τ-leptons, b-tagged jets, and large missing transverse momentum is presented. The analyzed dataset is based on proton-proton collisions at s=13 TeV delivered by the Large Hadron Collider and recorded by the ATLAS detector from 2015 to 2018, and corresponds to an integrated luminosity of 139 fb-1. The observed data are compatible with the expected Standard Model background. Results are interpreted in a simplified model where each bottom squark is assumed to decay into the second-lightest neutralino χ 20 and a bottom quark, with χ 20 decaying into a Higgs boson and the lightest neutralino χ 10. The search focuses on final states where at least one Higgs boson decays into a pair of hadronically decaying τ-leptons. This allows the acceptance and thus the sensitivity to be significantly improved relative to the previous results at low masses of the χ 20, where bottom-squark masses up to 850 GeV are excluded at the 95% confidence level, assuming a mass difference of 130 GeV between χ 20 and χ 10. Model-independent upper limits are also set on the cross section of processes beyond the Standard Model.

Published
2021

34. Search for bottom-squark pair production in pp collision events at s =13 TeV with hadronically decaying τ -leptons, b -jets, and missing transverse momentum using the ATLAS detector

Author

Aad, G, Abbott, B, Abbott, DC, Abed Abud, A, Abeling, K, Abhayasinghe, DK, Abidi, SH, Abouzeid, OS, Abraham, NL, Abramowicz, H, Abreu, H, Abulaiti, Y, Acharya, BS, Achkar, B, Adam, L, Adam Bourdarios, C, Adamczyk, L, Adamek, L, Adelman, J, Adiguzel, A, Adorni, S, Adye, T, Affolder, AA, Afik, Y, Agapopoulou, C, Agaras, MN, Aggarwal, A, Agheorghiesei, C, Aguilar-Saavedra, JA, Ahmad, A, Ahmadov, F, Ahmed, WS, Ai, X, Aielli, G, Akatsuka, S, Akbiyik, M, Åkesson, TPA, Akilli, E, Akimov, AV, Al Khoury, K, Alberghi, GL, Albert, J, Alconada Verzini, MJ, Alderweireldt, S, Aleksa, M, Aleksandrov, IN, Alexa, C, Alexopoulos, T, Alfonsi, A, Alfonsi, F, Alhroob, M, Ali, B, Ali, S, Aliev, M, Alimonti, G, Allaire, C, Allbrooke, BMM, Allen, BW, Allport, PP, Aloisio, A, Alonso, F, Alpigiani, C, Alunno Camelia, E, Alvarez Estevez, M, Alviggi, MG, Amaral Coutinho, Y, Ambler, A, Ambroz, L, Amelung, C, Amidei, D, Amor Dos Santos, SP, Amoroso, S, Amrouche, CS, An, F, Anastopoulos, C, Andari, N, Andeen, T, Anders, JK, Andrean, SY, Andreazza, A, Andrei, V, Anelli, CR, Angelidakis, S, Angerami, A, Anisenkov, AV, Annovi, A, Antel, C, Anthony, MT, Antipov, E, Antonelli, M, Antrim, DJA, Anulli, F, Aoki, M, Aparisi Pozo, JA, Aparo, MA, Aperio Bella, L, Aranzabal, N, Araujo Ferraz, V, Araujo Pereira, R, and Arcangeletti, C

Abstract

A search for pair production of bottom squarks in events with hadronically decaying τ-leptons, b-tagged jets, and large missing transverse momentum is presented. The analyzed dataset is based on proton-proton collisions at s=13 TeV delivered by the Large Hadron Collider and recorded by the ATLAS detector from 2015 to 2018, and corresponds to an integrated luminosity of 139 fb-1. The observed data are compatible with the expected Standard Model background. Results are interpreted in a simplified model where each bottom squark is assumed to decay into the second-lightest neutralino χ 20 and a bottom quark, with χ 20 decaying into a Higgs boson and the lightest neutralino χ 10. The search focuses on final states where at least one Higgs boson decays into a pair of hadronically decaying τ-leptons. This allows the acceptance and thus the sensitivity to be significantly improved relative to the previous results at low masses of the χ 20, where bottom-squark masses up to 850 GeV are excluded at the 95% confidence level, assuming a mass difference of 130 GeV between χ 20 and χ 10. Model-independent upper limits are also set on the cross section of processes beyond the Standard Model.

Published
2021

35. Measurement of the relative Bc±/B± production cross section with the ATLAS detector at s=8 TeV

Author

Aaboud, M, Aad, G, Abbott, B, Abbott, DC, Abdinov, O, Abud, A Abed, Abhayasinghe, DK, Abidi, SH, AbouZeid, OS, Abraham, NL, Abramowicz, H, Abreu, H, Abulaiti, Y, Acharya, BS, Adachi, S, Adam, L, Bourdarios, C Adam, Adamczyk, L, Adamek, L, Adelman, J, Adersberger, M, Adiguzel, A, Adorni, S, Adye, T, Affolder, AA, Afik, Y, Agapopoulou, C, Agaras, MN, Aggarwal, A, Agheorghiesei, C, Aguilar-Saavedra, JA, Ahmadov, F, Aielli, G, Akatsuka, S, Åkesson, TPA, Akilli, E, Akimov, AV, Al Khoury, K, Alberghi, GL, Albert, J, Verzini, MJ Alconada, Alderweireldt, S, Aleksa, M, Aleksandrov, IN, Alexa, C, Alexandre, D, Alexopoulos, T, Alfonsi, A, Alhroob, M, Ali, B, Alimonti, G, Alison, J, Alkire, SP, Allaire, C, Allbrooke, BMM, Allen, BW, Allport, PP, Aloisio, A, Alonso, A, Alonso, F, Alpigiani, C, Alshehri, AA, Alstaty, MI, Estevez, M Alvarez, Gonzalez, B Alvarez, Piqueras, D Álvarez, Alviggi, MG, Coutinho, Y Amaral, Ambler, A, Ambroz, L, Amelung, C, Amidei, D, Dos Santos, SP Amor, Amoroso, S, Amrouche, CS, An, F, Anastopoulos, C, Andari, N, Andeen, T, Anders, CF, Anders, JK, Andreazza, A, Andrei, V, Anelli, CR, Angelidakis, S, Angelozzi, I, Angerami, A, Anisenkov, AV, Annovi, A, Antel, C, Anthony, MT, Antonelli, M, Antrim, DJA, Anulli, F, Aoki, M, Pozo, JA Aparisi, Bella, L Aperio, Arabidze, G, Araque, JP, and Ferraz, V Araujo

Subjects
Nuclear and Plasma Physics, Particle and High Energy Physics, Physical Sciences
Abstract

The total cross section and differential cross sections for the production of Bc± mesons, times their branching fraction to J/ψπ±, are measured relative to those for the production of B± mesons, times their branching fraction to J/ψK±. The data used for this study correspond to an integrated luminosity of 20.3 fb-1 of pp collisions recorded by the ATLAS detector at the Large Hadron Collider in 2012 at a center-of-mass energy of s=8 TeV. The measurement is performed differentially in bins of transverse momentum pT for 13 GeV22 GeV and in bins of rapidity y for |y|13 GeV and |y|

Published
2021

36. Measurement of the relative Bc± /B± production cross section with the ATLAS detector at s =8 TeV MEASUREMENT of the RELATIVE Bc± /B± ... AABOUD M. et al.

Author

Aaboud, M, Aad, G, Abbott, B, Abbott, DC, Abdinov, O, Abed Abud, A, Abhayasinghe, DK, Abidi, SH, Abouzeid, OS, Abraham, NL, Abramowicz, H, Abreu, H, Abulaiti, Y, Acharya, BS, Adachi, S, Adam, L, Adam Bourdarios, C, Adamczyk, L, Adamek, L, Adelman, J, Adersberger, M, Adiguzel, A, Adorni, S, Adye, T, Affolder, AA, Afik, Y, Agapopoulou, C, Agaras, MN, Aggarwal, A, Agheorghiesei, C, Aguilar-Saavedra, JA, Ahmadov, F, Aielli, G, Akatsuka, S, Åkesson, TPA, Akilli, E, Akimov, AV, Al Khoury, K, Alberghi, GL, Albert, J, Alconada Verzini, MJ, Alderweireldt, S, Aleksa, M, Aleksandrov, IN, Alexa, C, Alexandre, D, Alexopoulos, T, Alfonsi, A, Alhroob, M, Ali, B, Alimonti, G, Alison, J, Alkire, SP, Allaire, C, Allbrooke, BMM, Allen, BW, Allport, PP, Aloisio, A, Alonso, A, Alonso, F, Alpigiani, C, Alshehri, AA, Alstaty, MI, Alvarez Estevez, M, Alvarez Gonzalez, B, Álvarez Piqueras, D, Alviggi, MG, Amaral Coutinho, Y, Ambler, A, Ambroz, L, Amelung, C, Amidei, D, Amor Dos Santos, SP, Amoroso, S, Amrouche, CS, An, F, Anastopoulos, C, Andari, N, Andeen, T, Anders, CF, Anders, JK, Andreazza, A, Andrei, V, Anelli, CR, Angelidakis, S, Angelozzi, I, Angerami, A, Anisenkov, AV, Annovi, A, Antel, C, Anthony, MT, Antonelli, M, Antrim, DJA, Anulli, F, Aoki, M, Aparisi Pozo, JA, Aperio Bella, L, Arabidze, G, Araque, JP, and Araujo Ferraz, V

Abstract

The total cross section and differential cross sections for the production of Bc± mesons, times their branching fraction to J/ψπ±, are measured relative to those for the production of B± mesons, times their branching fraction to J/ψK±. The data used for this study correspond to an integrated luminosity of 20.3 fb-1 of pp collisions recorded by the ATLAS detector at the Large Hadron Collider in 2012 at a center-of-mass energy of s=8 TeV. The measurement is performed differentially in bins of transverse momentum pT for 13 GeV22 GeV and in bins of rapidity y for |y|13 GeV and |y|

Published
2021

37. Search for new phenomena in events with an energetic jet and missing transverse momentum in pp collisions at s=13 TeV with the ATLAS detector

Author

Aad, G, Abbott, B, Abbott, DC, Abud, A Abed, Abeling, K, Abhayasinghe, DK, Abidi, SH, AbouZeid, OS, Abraham, NL, Abramowicz, H, Abreu, H, Abulaiti, Y, Acharya, BS, Achkar, B, Adam, L, Bourdarios, C Adam, Adamczyk, L, Adamek, L, Adelman, J, Adiguzel, A, Adorni, S, Adye, T, Affolder, AA, Afik, Y, Agapopoulou, C, Agaras, MN, Aggarwal, A, Agheorghiesei, C, Aguilar-Saavedra, JA, Ahmad, A, Ahmadov, F, Ahmed, WS, Ai, X, Aielli, G, Akatsuka, S, Akbiyik, M, Åkesson, TPA, Akilli, E, Akimov, AV, Al Khoury, K, Alberghi, GL, Albert, J, Verzini, MJ Alconada, Alderweireldt, S, Aleksa, M, Aleksandrov, IN, Alexa, C, Alexopoulos, T, Alfonsi, A, Alfonsi, F, Alhroob, M, Ali, B, Ali, S, Aliev, M, Alimonti, G, Allaire, C, Allbrooke, BMM, Allen, BW, Allport, PP, Aloisio, A, Alonso, F, Alpigiani, C, Camelia, E Alunno, Estevez, M Alvarez, Alviggi, MG, Coutinho, Y Amaral, Ambler, A, Ambroz, L, Amelung, C, Amidei, D, Dos Santos, SP Amor, Amoroso, S, Amrouche, CS, An, F, Anastopoulos, C, Andari, N, Andeen, T, Anders, JK, Andrean, SY, Andreazza, A, Andrei, V, Anelli, CR, Angelidakis, S, Angerami, A, Anisenkov, AV, Annovi, A, Antel, C, Anthony, MT, Antipov, E, Antonelli, M, Antrim, DJA, Anulli, F, Aoki, M, Pozo, JA Aparisi, Aparo, MA, Bella, L Aperio, Aranzabal, N, Ferraz, V Araujo, Pereira, R Araujo, and Arcangeletti, C

Subjects
Nuclear and Plasma Physics, Particle and High Energy Physics, Physical Sciences, hep-ex
Abstract

Results of a search for new physics in final states with an energetic jet and large missing transverse momentum are reported. The search uses proton-proton collision data corresponding to an integrated luminosity of 139 fb-1 at a center-of-mass energy of 13 TeV collected in the period 2015-2018 with the ATLAS detector at the Large Hadron Collider. Compared to previous publications, in addition to an increase of almost a factor of four in the data size, the analysis implements a number of improvements in the signal selection and the background determination leading to enhanced sensitivity. Events are required to have at least one jet with transverse momentum above 150 GeV and no reconstructed leptons (e, μ or τ) or photons. Several signal regions are considered with increasing requirements on the missing transverse momentum starting at 200 GeV. Overall agreement is observed between the number of events in data and the Standard Model predictions. Model-independent 95% confidence-level limits on visible cross sections for new processes are obtained in the range between 736 fb and 0.3 fb. Results are also translated into improved exclusion limits in models with pair-produced weakly interacting dark-matter candidates, large extra spatial dimensions, supersymmetric particles in several compressed scenarios, axionlike particles, and new scalar particles in dark-energy-inspired models. In addition, the data are translated into bounds on the invisible branching ratio of the Higgs boson.

Published
2021

38. Search for trilepton resonances from chargino and neutralino pair production in s=13 TeV pp collisions with the ATLAS detector

Author

Aad, G, Abbott, B, Abbott, DC, Abud, A Abed, Abeling, K, Abhayasinghe, DK, Abidi, SH, AbouZeid, OS, Abraham, NL, Abramowicz, H, Abreu, H, Abulaiti, Y, Acharya, BS, Achkar, B, Adam, L, Bourdarios, C Adam, Adamczyk, L, Adamek, L, Adelman, J, Adersberger, M, Adiguzel, A, Adorni, S, Adye, T, Affolder, AA, Afik, Y, Agapopoulou, C, Agaras, MN, Aggarwal, A, Agheorghiesei, C, Aguilar-Saavedra, JA, Ahmad, A, Ahmadov, F, Ahmed, WS, Ai, X, Aielli, G, Akatsuka, S, Akbiyik, M, Åkesson, TPA, Akilli, E, Akimov, AV, Al Khoury, K, Alberghi, GL, Albert, J, Verzini, MJ Alconada, Alderweireldt, S, Aleksa, M, Aleksandrov, IN, Alexa, C, Alexopoulos, T, Alfonsi, A, Alfonsi, F, Alhroob, M, Ali, B, Ali, S, Aliev, M, Alimonti, G, Allaire, C, Allbrooke, BMM, Allen, BW, Allport, PP, Aloisio, A, Alonso, F, Alpigiani, C, Camelia, E Alunno, Estevez, M Alvarez, Alviggi, MG, Coutinho, Y Amaral, Ambler, A, Ambroz, L, Amelung, C, Amidei, D, Dos Santos, SP Amor, Amoroso, S, Amrouche, CS, An, F, Anastopoulos, C, Andari, N, Andeen, T, Anders, JK, Andrean, SY, Andreazza, A, Andrei, V, Anelli, CR, Angelidakis, S, Angerami, A, Anisenkov, AV, Annovi, A, Antel, C, Anthony, MT, Antipov, E, Antonelli, M, Antrim, DJA, Anulli, F, Aoki, M, Pozo, JA Aparisi, Aparo, MA, Bella, L Aperio, Aranzabal, N, Ferraz, V Araujo, and Pereira, R Araujo

Subjects
Nuclear and Plasma Physics, Particle and High Energy Physics, Physical Sciences, hep-ex
Abstract

A search is performed for the electroweak pair production of charginos and associated production of a chargino and neutralino, each of which decays through an R-parity-violating coupling into a lepton and a W, Z, or Higgs boson. The trilepton invariant-mass spectrum is constructed from events with three or more leptons, targeting chargino decays that include an electron or muon and a leptonically decaying Z boson. The analyzed dataset corresponds to an integrated luminosity of 139 fb-1 of proton-proton collision data produced by the Large Hadron Collider at a center-of-mass energy of s=13 TeV and collected by the ATLAS experiment between 2015 and 2018. The data are found to be consistent with predictions from the Standard Model. The results are interpreted as limits at 95% confidence level on model-independent cross sections for processes beyond the Standard Model. Limits are also set on the production of charginos and neutralinos for a minimal supersymmetric Standard Model with an approximate B-L symmetry. Charginos and neutralinos with masses between 100 and 1100 GeV are excluded depending on the assumed decay branching fractions into a lepton (electron, muon, or τ lepton) plus a boson (W, Z, or Higgs).

Published
2021

39. Search for new phenomena in events with an energetic jet and missing transverse momentum in pp collisions at s =13 TeV with the ATLAS detector

Author

Aad, G, Abbott, B, Abbott, DC, Abed Abud, A, Abeling, K, Abhayasinghe, DK, Abidi, SH, Abouzeid, OS, Abraham, NL, Abramowicz, H, Abreu, H, Abulaiti, Y, Acharya, BS, Achkar, B, Adam, L, Adam Bourdarios, C, Adamczyk, L, Adamek, L, Adelman, J, Adiguzel, A, Adorni, S, Adye, T, Affolder, AA, Afik, Y, Agapopoulou, C, Agaras, MN, Aggarwal, A, Agheorghiesei, C, Aguilar-Saavedra, JA, Ahmad, A, Ahmadov, F, Ahmed, WS, Ai, X, Aielli, G, Akatsuka, S, Akbiyik, M, Åkesson, TPA, Akilli, E, Akimov, AV, Al Khoury, K, Alberghi, GL, Albert, J, Alconada Verzini, MJ, Alderweireldt, S, Aleksa, M, Aleksandrov, IN, Alexa, C, Alexopoulos, T, Alfonsi, A, Alfonsi, F, Alhroob, M, Ali, B, Ali, S, Aliev, M, Alimonti, G, Allaire, C, Allbrooke, BMM, Allen, BW, Allport, PP, Aloisio, A, Alonso, F, Alpigiani, C, Alunno Camelia, E, Alvarez Estevez, M, Alviggi, MG, Amaral Coutinho, Y, Ambler, A, Ambroz, L, Amelung, C, Amidei, D, Amor Dos Santos, SP, Amoroso, S, Amrouche, CS, An, F, Anastopoulos, C, Andari, N, Andeen, T, Anders, JK, Andrean, SY, Andreazza, A, Andrei, V, Anelli, CR, Angelidakis, S, Angerami, A, Anisenkov, AV, Annovi, A, Antel, C, Anthony, MT, Antipov, E, Antonelli, M, Antrim, DJA, Anulli, F, Aoki, M, Aparisi Pozo, JA, Aparo, MA, Aperio Bella, L, Aranzabal, N, Araujo Ferraz, V, Araujo Pereira, R, and Arcangeletti, C

Subjects
hep-ex
Abstract

Results of a search for new physics in final states with an energetic jet and large missing transverse momentum are reported. The search uses proton-proton collision data corresponding to an integrated luminosity of 139 fb-1 at a center-of-mass energy of 13 TeV collected in the period 2015-2018 with the ATLAS detector at the Large Hadron Collider. Compared to previous publications, in addition to an increase of almost a factor of four in the data size, the analysis implements a number of improvements in the signal selection and the background determination leading to enhanced sensitivity. Events are required to have at least one jet with transverse momentum above 150 GeV and no reconstructed leptons (e, μ or τ) or photons. Several signal regions are considered with increasing requirements on the missing transverse momentum starting at 200 GeV. Overall agreement is observed between the number of events in data and the Standard Model predictions. Model-independent 95% confidence-level limits on visible cross sections for new processes are obtained in the range between 736 fb and 0.3 fb. Results are also translated into improved exclusion limits in models with pair-produced weakly interacting dark-matter candidates, large extra spatial dimensions, supersymmetric particles in several compressed scenarios, axionlike particles, and new scalar particles in dark-energy-inspired models. In addition, the data are translated into bounds on the invisible branching ratio of the Higgs boson.

Published
2021

40. Search for trilepton resonances from chargino and neutralino pair production in s =13 TeV pp collisions with the ATLAS detector

Author

Aad, G, Abbott, B, Abbott, DC, Abed Abud, A, Abeling, K, Abhayasinghe, DK, Abidi, SH, Abouzeid, OS, Abraham, NL, Abramowicz, H, Abreu, H, Abulaiti, Y, Acharya, BS, Achkar, B, Adam, L, Adam Bourdarios, C, Adamczyk, L, Adamek, L, Adelman, J, Adersberger, M, Adiguzel, A, Adorni, S, Adye, T, Affolder, AA, Afik, Y, Agapopoulou, C, Agaras, MN, Aggarwal, A, Agheorghiesei, C, Aguilar-Saavedra, JA, Ahmad, A, Ahmadov, F, Ahmed, WS, Ai, X, Aielli, G, Akatsuka, S, Akbiyik, M, Åkesson, TPA, Akilli, E, Akimov, AV, Al Khoury, K, Alberghi, GL, Albert, J, Alconada Verzini, MJ, Alderweireldt, S, Aleksa, M, Aleksandrov, IN, Alexa, C, Alexopoulos, T, Alfonsi, A, Alfonsi, F, Alhroob, M, Ali, B, Ali, S, Aliev, M, Alimonti, G, Allaire, C, Allbrooke, BMM, Allen, BW, Allport, PP, Aloisio, A, Alonso, F, Alpigiani, C, Alunno Camelia, E, Alvarez Estevez, M, Alviggi, MG, Amaral Coutinho, Y, Ambler, A, Ambroz, L, Amelung, C, Amidei, D, Amor Dos Santos, SP, Amoroso, S, Amrouche, CS, An, F, Anastopoulos, C, Andari, N, Andeen, T, Anders, JK, Andrean, SY, Andreazza, A, Andrei, V, Anelli, CR, Angelidakis, S, Angerami, A, Anisenkov, AV, Annovi, A, Antel, C, Anthony, MT, Antipov, E, Antonelli, M, Antrim, DJA, Anulli, F, Aoki, M, Aparisi Pozo, JA, Aparo, MA, Aperio Bella, L, Aranzabal, N, Araujo Ferraz, V, and Araujo Pereira, R

Subjects
hep-ex
Abstract

A search is performed for the electroweak pair production of charginos and associated production of a chargino and neutralino, each of which decays through an R-parity-violating coupling into a lepton and a W, Z, or Higgs boson. The trilepton invariant-mass spectrum is constructed from events with three or more leptons, targeting chargino decays that include an electron or muon and a leptonically decaying Z boson. The analyzed dataset corresponds to an integrated luminosity of 139 fb-1 of proton-proton collision data produced by the Large Hadron Collider at a center-of-mass energy of s=13 TeV and collected by the ATLAS experiment between 2015 and 2018. The data are found to be consistent with predictions from the Standard Model. The results are interpreted as limits at 95% confidence level on model-independent cross sections for processes beyond the Standard Model. Limits are also set on the production of charginos and neutralinos for a minimal supersymmetric Standard Model with an approximate B-L symmetry. Charginos and neutralinos with masses between 100 and 1100 GeV are excluded depending on the assumed decay branching fractions into a lepton (electron, muon, or τ lepton) plus a boson (W, Z, or Higgs).

Published
2021

41. Search for resonances decaying into a weak vector boson and a Higgs boson in the fully hadronic final state produced in proton-proton collisions at s =13 TeV with the ATLAS detector

Author

Aad, G, Abbott, B, Abbott, DC, Abed Abud, A, Abeling, K, Abhayasinghe, DK, Abidi, SH, Abouzeid, OS, Abraham, NL, Abramowicz, H, Abreu, H, Abulaiti, Y, Acharya, BS, Achkar, B, Adam, L, Adam Bourdarios, C, Adamczyk, L, Adamek, L, Adelman, J, Adersberger, M, Adiguzel, A, Adorni, S, Adye, T, Affolder, AA, Afik, Y, Agapopoulou, C, Agaras, MN, Aggarwal, A, Agheorghiesei, C, Aguilar-Saavedra, JA, Ahmad, A, Ahmadov, F, Ahmed, WS, Ai, X, Aielli, G, Akatsuka, S, Akbiyik, M, Åkesson, TPA, Akilli, E, Akimov, AV, Al Khoury, K, Alberghi, GL, Albert, J, Alconada Verzini, MJ, Alderweireldt, S, Aleksa, M, Aleksandrov, IN, Alexa, C, Alexopoulos, T, Alfonsi, A, Alfonsi, F, Alhroob, M, Ali, B, Ali, S, Aliev, M, Alimonti, G, Allaire, C, Allbrooke, BMM, Allen, BW, Allport, PP, Aloisio, A, Alonso, F, Alpigiani, C, Alunno Camelia, E, Alvarez Estevez, M, Alviggi, MG, Amaral Coutinho, Y, Ambler, A, Ambroz, L, Amelung, C, Amidei, D, Amor Dos Santos, SP, Amoroso, S, Amrouche, CS, An, F, Anastopoulos, C, Andari, N, Andeen, T, Anders, JK, Andrean, SY, Andreazza, A, Andrei, V, Anelli, CR, Angelidakis, S, Angerami, A, Anisenkov, AV, Annovi, A, Antel, C, Anthony, MT, Antipov, E, Antonelli, M, Antrim, DJA, Anulli, F, Aoki, M, Aparisi Pozo, JA, Aparo, MA, Aperio Bella, L, Aranzabal Barrio, N, Araujo Ferraz, V, and Araujo Pereira, R

Subjects
hep-ex
Abstract

A search for heavy resonances decaying into a W or Z boson and a Higgs boson produced in proton-proton collisions at the Large Hadron Collider at s=13 TeV is presented. The analysis utilizes the dominant W→qq¯′ or Z→qq¯ and H→bb¯ decays with substructure techniques applied to large-radius jets. A sample corresponding to an integrated luminosity of 139 fb-1 collected with the ATLAS detector is analyzed and no significant excess of data is observed over the background prediction. The results are interpreted in the context of the heavy vector triplet model with spin-1 W′ and Z′ bosons. Upper limits on the cross section are set for resonances with mass between 1.5 and 5.0 TeV, ranging from 6.8 to 0.53 fb for W′→WH and from 8.7 to 0.53 fb for Z′→ZH at the 95% confidence level.

Published
2020

42. Search for Higgs boson decays into two new low-mass spin-0 particles in the 4b channel with the ATLAS detector using pp collisions at √s = 13 TeV

Author

Aad, G, Abbott, B, Abbott, DC, Abdinov, O, Abud, AA, Abeling, K, Abhayasinghe, DK, Abidi, SH, AbouZeid, OS, Abraham, NL, Abramowicz, H, Abreu, H, Abulaiti, Y, Acharya, BS, Achkar, B, Adachi, S, Adam, L, Bourdarios, CA, Adamczyk, L, Adamek, L, Adelman, J, Adersberger, M, Adiguzel, A, Adorni, S, Adye, T, Affolder, AA, Afik, Y, Agapopoulou, C, Agaras, MN, Aggarwal, A, Agheorghiesei, C, Aguilar-Saavedra, JA, Ahmadov, F, Ahmed, WS, Ai, X, Aielli, G, Akatsuka, S, Åkesson, TPA, Akilli, E, Akimov, AV, Al Khoury, K, Alberghi, GL, Albert, J, Verzini, MJA, Alderweireldt, S, Aleksa, M, Aleksandrov, IN, Alexa, C, Alexandre, D, Alexopoulos, T, Alfonsi, A, Alhroob, M, Ali, B, Alimonti, G, Alison, J, Alkire, SP, Allaire, C, Allbrooke, BMM, Allen, BW, Allport, PP, Aloisio, A, Alonso, A, Alonso, F, Alpigiani, C, Alshehri, AA, Estevez, MA, Piqueras, DÁ, Alviggi, MG, Coutinho, YA, Ambler, A, Ambroz, L, Amelung, C, Amidei, D, Dos Santos, SPA, Amoroso, S, Amrouche, CS, An, F, Anastopoulos, C, Andari, N, Andeen, T, Anders, CF, Anders, JK, Andreazza, A, Andrei, V, Anelli, CR, Angelidakis, S, Angerami, A, Anisenkov, AV, Annovi, A, Antel, C, Anthony, MT, Antonelli, M, Antrim, DJA, Anulli, F, Aoki, M, Pozo, JAA, Bella, LA, Arabidze, G, Araque, JP, and Ferraz, VA

Subjects
hep-ex
Abstract

This paper describes a search for beyond the Standard Model decays of the Higgs boson into a pair of new spin-0 particles subsequently decaying into b-quark pairs, H → aa → (bb¯)(bb¯), using protonproton collision data collected by the ATLAS detector at the Large Hadron Collider at center-of-mass energy √s = 13 TeV. This search focuses on the range 15 GeV ≤ ma ≤ 30 GeV, where the decay products are collimated; it is complementary to a previous search in the same final state targeting the range 20 GeV ≤ ma ≤ 60 GeV, where the decay products are well separated. A novel strategy for the identification of the a → bb¯ decays is deployed to enhance the efficiency for topologies with small separation angles. The search is performed with 36 fb-1 of integrated luminosity collected in 2015 and 2016 and sets upper limits on the production cross section of H → aa → (bb¯)(bb¯), where the Higgs boson is produced in association with a Z boson.

Published
2020

43. Search for Higgs boson decays into two new low-mass spin-0 particles in the 4b channel with the ATLAS detector using pp collisions at s=13 TeV

Author

Aad, G, Abbott, B, Abbott, DC, Abud, A Abed, Abeling, K, Abhayasinghe, DK, Abidi, SH, AbouZeid, OS, Abraham, NL, Abramowicz, H, Abreu, H, Abulaiti, Y, Acharya, BS, Achkar, B, Adam, L, Bourdarios, C Adam, Adamczyk, L, Adamek, L, Adelman, J, Adersberger, M, Adiguzel, A, Adorni, S, Adye, T, Affolder, AA, Afik, Y, Agapopoulou, C, Agaras, MN, Aggarwal, A, Agheorghiesei, C, Aguilar-Saavedra, JA, Ahmad, A, Ahmadov, F, Ahmed, WS, Ai, X, Aielli, G, Akatsuka, S, Akbiyik, M, Åkesson, TPA, Akilli, E, Akimov, AV, Al Khoury, K, Alberghi, GL, Albert, J, Verzini, MJ Alconada, Alderweireldt, S, Aleksa, M, Aleksandrov, IN, Alexa, C, Alexopoulos, T, Alfonsi, A, Alfonsi, F, Alhroob, M, Ali, B, Ali, S, Aliev, M, Alimonti, G, Allaire, C, Allbrooke, BMM, Allen, BW, Allport, PP, Aloisio, A, Alonso, F, Alpigiani, C, Camelia, E Alunno, Estevez, M Alvarez, Alviggi, MG, Coutinho, Y Amaral, Ambler, A, Ambroz, L, Amelung, C, Amidei, D, Dos Santos, SP Amor, Amoroso, S, Amrouche, CS, An, F, Anastopoulos, C, Andari, N, Andeen, T, Anders, JK, Andrean, SY, Andreazza, A, Andrei, V, Anelli, CR, Angelidakis, S, Angerami, A, Anisenkov, AV, Annovi, A, Antel, C, Anthony, MT, Antipov, E, Antonelli, M, Antrim, DJA, Anulli, F, Aoki, M, Pozo, JA Aparisi, Aparo, MA, Bella, L Aperio, Aranzabal, N, Ferraz, V Araujo, and Pereira, R Araujo

Subjects
Nuclear and Plasma Physics, Particle and High Energy Physics, Physical Sciences, hep-ex
Abstract

This paper describes a search for beyond the Standard Model decays of the Higgs boson into a pair of new spin-0 particles subsequently decaying into b-quark pairs, H → aa → (bb¯)(bb¯), using protonproton collision data collected by the ATLAS detector at the Large Hadron Collider at center-of-mass energy √s = 13 TeV. This search focuses on the range 15 GeV ≤ ma ≤ 30 GeV, where the decay products are collimated; it is complementary to a previous search in the same final state targeting the range 20 GeV ≤ ma ≤ 60 GeV, where the decay products are well separated. A novel strategy for the identification of the a → bb¯ decays is deployed to enhance the efficiency for topologies with small separation angles. The search is performed with 36 fb-1 of integrated luminosity collected in 2015 and 2016 and sets upper limits on the production cross section of H → aa → (bb¯)(bb¯), where the Higgs boson is produced in association with a Z boson.

Published
2020

44. Search for resonances decaying into a weak vector boson and a Higgs boson in the fully hadronic final state produced in proton-proton collisions at s=13 TeV with the ATLAS detector

Author

Aad, G, Abbott, B, Abbott, DC, Abud, A Abed, Abeling, K, Abhayasinghe, DK, Abidi, SH, AbouZeid, OS, Abraham, NL, Abramowicz, H, Abreu, H, Abulaiti, Y, Acharya, BS, Achkar, B, Adam, L, Bourdarios, C Adam, Adamczyk, L, Adamek, L, Adelman, J, Adersberger, M, Adiguzel, A, Adorni, S, Adye, T, Affolder, AA, Afik, Y, Agapopoulou, C, Agaras, MN, Aggarwal, A, Agheorghiesei, C, Aguilar-Saavedra, JA, Ahmad, A, Ahmadov, F, Ahmed, WS, Ai, X, Aielli, G, Akatsuka, S, Akbiyik, M, Åkesson, TPA, Akilli, E, Akimov, AV, Al Khoury, K, Alberghi, GL, Albert, J, Verzini, MJ Alconada, Alderweireldt, S, Aleksa, M, Aleksandrov, IN, Alexa, C, Alexopoulos, T, Alfonsi, A, Alfonsi, F, Alhroob, M, Ali, B, Ali, S, Aliev, M, Alimonti, G, Allaire, C, Allbrooke, BMM, Allen, BW, Allport, PP, Aloisio, A, Alonso, F, Alpigiani, C, Camelia, E Alunno, Estevez, M Alvarez, Alviggi, MG, Coutinho, Y Amaral, Ambler, A, Ambroz, L, Amelung, C, Amidei, D, Dos Santos, SP Amor, Amoroso, S, Amrouche, CS, An, F, Anastopoulos, C, Andari, N, Andeen, T, Anders, JK, Andrean, SY, Andreazza, A, Andrei, V, Anelli, CR, Angelidakis, S, Angerami, A, Anisenkov, AV, Annovi, A, Antel, C, Anthony, MT, Antipov, E, Antonelli, M, Antrim, DJA, Anulli, F, Aoki, M, Pozo, JA Aparisi, Aparo, MA, Bella, L Aperio, Barrio, N Aranzabal, Ferraz, V Araujo, and Pereira, R Araujo

Subjects
Nuclear and Plasma Physics, Particle and High Energy Physics, Physical Sciences, hep-ex
Abstract

A search for heavy resonances decaying into a W or Z boson and a Higgs boson produced in proton-proton collisions at the Large Hadron Collider at s=13 TeV is presented. The analysis utilizes the dominant W→qq¯′ or Z→qq¯ and H→bb¯ decays with substructure techniques applied to large-radius jets. A sample corresponding to an integrated luminosity of 139 fb-1 collected with the ATLAS detector is analyzed and no significant excess of data is observed over the background prediction. The results are interpreted in the context of the heavy vector triplet model with spin-1 W′ and Z′ bosons. Upper limits on the cross section are set for resonances with mass between 1.5 and 5.0 TeV, ranging from 6.8 to 0.53 fb for W′→WH and from 8.7 to 0.53 fb for Z′→ZH at the 95% confidence level.

Published
2020

45. Search for heavy neutral Higgs bosons produced in association with b-quarks and decaying into b-quarks at s=13 TeV with the ATLAS detector

Author

Aad, G, Abbott, B, Abbott, DC, Abdinov, O, Abud, A Abed, Abeling, K, Abhayasinghe, DK, Abidi, SH, AbouZeid, OS, Abraham, NL, Abramowicz, H, Abreu, H, Abulaiti, Y, Acharya, BS, Achkar, B, Adachi, S, Adam, L, Bourdarios, C Adam, Adamczyk, L, Adamek, L, Adelman, J, Adersberger, M, Adiguzel, A, Adorni, S, Adye, T, Affolder, AA, Afik, Y, Agapopoulou, C, Agaras, MN, Aggarwal, A, Agheorghiesei, C, Aguilar-Saavedra, JA, Ahmadov, F, Ahmed, WS, Ai, X, Aielli, G, Akatsuka, S, Åkesson, TPA, Akilli, E, Akimov, AV, Al Khoury, K, Alberghi, GL, Albert, J, Verzini, MJ Alconada, Alderweireldt, S, Aleksa, M, Aleksandrov, IN, Alexa, C, Alexandre, D, Alexopoulos, T, Alfonsi, A, Alhroob, M, Ali, B, Alimonti, G, Alison, J, Alkire, SP, Allaire, C, Allbrooke, BMM, Allen, BW, Allport, PP, Aloisio, A, Alonso, A, Alonso, F, Alpigiani, C, Alshehri, AA, Estevez, M Alvarez, Piqueras, D Álvarez, Alviggi, MG, Coutinho, Y Amaral, Ambler, A, Ambroz, L, Amelung, C, Amidei, D, Dos Santos, SP Amor, Amoroso, S, Amrouche, CS, An, F, Anastopoulos, C, Andari, N, Andeen, T, Anders, CF, Anders, JK, Andreazza, A, Andrei, V, Anelli, CR, Angelidakis, S, Angerami, A, Anisenkov, AV, Annovi, A, Antel, C, Anthony, MT, Antonelli, M, Antrim, DJA, Anulli, F, Aoki, M, Pozo, JA Aparisi, Bella, L Aperio, Arabidze, G, Araque, JP, and Ferraz, V Araujo

Subjects
Nuclear and Plasma Physics, Particle and High Energy Physics, Physical Sciences, hep-ex
Abstract

A search for heavy neutral Higgs bosons produced in association with one or two b-quarks and decaying to b-quark pairs is presented using 27.8 fb-1 of s=13 TeV proton-proton collision data recorded by the ATLAS detector at the Large Hadron Collider during 2015 and 2016. No evidence of a signal is found. Upper limits on the heavy neutral Higgs boson production cross section times its branching ratio to bb¯ are set, ranging from 4.0 to 0.6 pb at 95% confidence level over a Higgs boson mass range of 450 to 1400 GeV. Results are interpreted within the two-Higgs-doublet model and the minimal supersymmetric Standard Model.

Published
2020

46. Search for long-lived, massive particles in events with a displaced vertex and a muon with large impact parameter in pp collisions at s=13 TeV with the ATLAS detector

Author

Aad, G, Abbott, B, Abbott, DC, Abud, A Abed, Abeling, K, Abhayasinghe, DK, Abidi, SH, AbouZeid, OS, Abraham, NL, Abramowicz, H, Abreu, H, Abulaiti, Y, Acharya, BS, Achkar, B, Adachi, S, Adam, L, Bourdarios, C Adam, Adamczyk, L, Adamek, L, Adelman, J, Adersberger, M, Adiguzel, A, Adorni, S, Adye, T, Affolder, AA, Afik, Y, Agapopoulou, C, Agaras, MN, Aggarwal, A, Agheorghiesei, C, Aguilar-Saavedra, JA, Ahmadov, F, Ahmed, WS, Ai, X, Aielli, G, Akatsuka, S, Åkesson, TPA, Akilli, E, Akimov, AV, Al Khoury, K, Alberghi, GL, Albert, J, Verzini, MJ Alconada, Alderweireldt, S, Aleksa, M, Aleksandrov, IN, Alexa, C, Alexandre, D, Alexopoulos, T, Alfonsi, A, Alfonsi, F, Alhroob, M, Ali, B, Alimonti, G, Alison, J, Alkire, SP, Allaire, C, Allbrooke, BMM, Allen, BW, Allport, PP, Aloisio, A, Alonso, A, Alonso, F, Alpigiani, C, Alshehri, AA, Estevez, M Alvarez, Piqueras, D Álvarez, Alviggi, MG, Coutinho, Y Amaral, Ambler, A, Ambroz, L, Amelung, C, Amidei, D, Dos Santos, SP Amor, Amoroso, S, Amrouche, CS, An, F, Anastopoulos, C, Andari, N, Andeen, T, Anders, CF, Anders, JK, Andreazza, A, Andrei, V, Anelli, CR, Angelidakis, S, Angerami, A, Anisenkov, AV, Annovi, A, Antel, C, Anthony, MT, Antonelli, M, Antrim, DJA, Anulli, F, Aoki, M, Pozo, JA Aparisi, Bella, L Aperio, Arabidze, G, Araque, JP, and Ferraz, V Araujo

Subjects
Nuclear and Plasma Physics, Particle and High Energy Physics, Physical Sciences, hep-ex
Abstract

A search for long-lived particles decaying into hadrons and at least one muon is presented. The analysis selects events that pass a muon or missing-transverse-momentum trigger and contain a displaced muon track and a displaced vertex. The analyzed dataset of proton-proton collisions at s=13 TeV was collected with the ATLAS detector and corresponds to 136 fb-1. The search employs dedicated reconstruction techniques that significantly increase the sensitivity to long-lived particle decays that occur in the ATLAS inner detector. Background estimates for Standard Model processes and instrumental effects are extracted from data. The observed event yields are compatible with those expected from background processes. The results are presented as limits at 95% confidence level on model-independent cross sections for processes beyond the Standard Model, and interpreted as exclusion limits in scenarios with pair production of long-lived top squarks that decay via a small R-parity-violating coupling into a quark and a muon. Top squarks with masses up to 1.7 TeV are excluded for a lifetime of 0.1 ns, and masses below 1.3 TeV are excluded for lifetimes between 0.01 ns and 30 ns.

Published
2020

47. Search for long-lived, massive particles in events with a displaced vertex and a muon with large impact parameter in pp collisions at s =13 TeV with the ATLAS detector

Author

Aad, G, Abbott, B, Abbott, DC, Abed Abud, A, Abeling, K, Abhayasinghe, DK, Abidi, SH, Abouzeid, OS, Abraham, NL, Abramowicz, H, Abreu, H, Abulaiti, Y, Acharya, BS, Achkar, B, Adachi, S, Adam, L, Adam Bourdarios, C, Adamczyk, L, Adamek, L, Adelman, J, Adersberger, M, Adiguzel, A, Adorni, S, Adye, T, Affolder, AA, Afik, Y, Agapopoulou, C, Agaras, MN, Aggarwal, A, Agheorghiesei, C, Aguilar-Saavedra, JA, Ahmadov, F, Ahmed, WS, Ai, X, Aielli, G, Akatsuka, S, Åkesson, TPA, Akilli, E, Akimov, AV, Al Khoury, K, Alberghi, GL, Albert, J, Alconada Verzini, MJ, Alderweireldt, S, Aleksa, M, Aleksandrov, IN, Alexa, C, Alexandre, D, Alexopoulos, T, Alfonsi, A, Alfonsi, F, Alhroob, M, Ali, B, Alimonti, G, Alison, J, Alkire, SP, Allaire, C, Allbrooke, BMM, Allen, BW, Allport, PP, Aloisio, A, Alonso, A, Alonso, F, Alpigiani, C, Alshehri, AA, Alvarez Estevez, M, Álvarez Piqueras, D, Alviggi, MG, Amaral Coutinho, Y, Ambler, A, Ambroz, L, Amelung, C, Amidei, D, Amor Dos Santos, SP, Amoroso, S, Amrouche, CS, An, F, Anastopoulos, C, Andari, N, Andeen, T, Anders, CF, Anders, JK, Andreazza, A, Andrei, V, Anelli, CR, Angelidakis, S, Angerami, A, Anisenkov, AV, Annovi, A, Antel, C, Anthony, MT, Antonelli, M, Antrim, DJA, Anulli, F, Aoki, M, Aparisi Pozo, JA, Aperio Bella, L, Arabidze, G, Araque, JP, and Araujo Ferraz, V

Subjects
hep-ex, Astronomical and Space Sciences, Atomic, Molecular, Nuclear, Particle and Plasma Physics, Quantum Physics, Nuclear & Particles Physics
Abstract

A search for long-lived particles decaying into hadrons and at least one muon is presented. The analysis selects events that pass a muon or missing-transverse-momentum trigger and contain a displaced muon track and a displaced vertex. The analyzed dataset of proton-proton collisions at s=13 TeV was collected with the ATLAS detector and corresponds to 136 fb-1. The search employs dedicated reconstruction techniques that significantly increase the sensitivity to long-lived particle decays that occur in the ATLAS inner detector. Background estimates for Standard Model processes and instrumental effects are extracted from data. The observed event yields are compatible with those expected from background processes. The results are presented as limits at 95% confidence level on model-independent cross sections for processes beyond the Standard Model, and interpreted as exclusion limits in scenarios with pair production of long-lived top squarks that decay via a small R-parity-violating coupling into a quark and a muon. Top squarks with masses up to 1.7 TeV are excluded for a lifetime of 0.1 ns, and masses below 1.3 TeV are excluded for lifetimes between 0.01 ns and 30 ns.

Published
2020

48. Search for heavy neutral Higgs bosons produced in association with b-quarks and decaying into b-quarks at s =13 TeV with the ATLAS detector

Author

Aad, G, Abbott, B, Abbott, DC, Abdinov, O, Abed Abud, A, Abeling, K, Abhayasinghe, DK, Abidi, SH, Abouzeid, OS, Abraham, NL, Abramowicz, H, Abreu, H, Abulaiti, Y, Acharya, BS, Achkar, B, Adachi, S, Adam, L, Adam Bourdarios, C, Adamczyk, L, Adamek, L, Adelman, J, Adersberger, M, Adiguzel, A, Adorni, S, Adye, T, Affolder, AA, Afik, Y, Agapopoulou, C, Agaras, MN, Aggarwal, A, Agheorghiesei, C, Aguilar-Saavedra, JA, Ahmadov, F, Ahmed, WS, Ai, X, Aielli, G, Akatsuka, S, Åkesson, TPA, Akilli, E, Akimov, AV, Al Khoury, K, Alberghi, GL, Albert, J, Alconada Verzini, MJ, Alderweireldt, S, Aleksa, M, Aleksandrov, IN, Alexa, C, Alexandre, D, Alexopoulos, T, Alfonsi, A, Alhroob, M, Ali, B, Alimonti, G, Alison, J, Alkire, SP, Allaire, C, Allbrooke, BMM, Allen, BW, Allport, PP, Aloisio, A, Alonso, A, Alonso, F, Alpigiani, C, Alshehri, AA, Alvarez Estevez, M, Álvarez Piqueras, D, Alviggi, MG, Amaral Coutinho, Y, Ambler, A, Ambroz, L, Amelung, C, Amidei, D, Amor Dos Santos, SP, Amoroso, S, Amrouche, CS, An, F, Anastopoulos, C, Andari, N, Andeen, T, Anders, CF, Anders, JK, Andreazza, A, Andrei, V, Anelli, CR, Angelidakis, S, Angerami, A, Anisenkov, AV, Annovi, A, Antel, C, Anthony, MT, Antonelli, M, Antrim, DJA, Anulli, F, Aoki, M, Aparisi Pozo, JA, Aperio Bella, L, Arabidze, G, Araque, JP, and Araujo Ferraz, V

Subjects
hep-ex, Nuclear & Particles Physics, Astronomical and Space Sciences, Atomic, Molecular, Nuclear, Particle and Plasma Physics, Quantum Physics
Abstract

A search for heavy neutral Higgs bosons produced in association with one or two b-quarks and decaying to b-quark pairs is presented using 27.8 fb-1 of s=13 TeV proton-proton collision data recorded by the ATLAS detector at the Large Hadron Collider during 2015 and 2016. No evidence of a signal is found. Upper limits on the heavy neutral Higgs boson production cross section times its branching ratio to bb¯ are set, ranging from 4.0 to 0.6 pb at 95% confidence level over a Higgs boson mass range of 450 to 1400 GeV. Results are interpreted within the two-Higgs-doublet model and the minimal supersymmetric Standard Model.

Published
2020

49. Search for chargino-neutralino production with mass splittings near the electroweak scale in three-lepton final states in s=13 TeV pp collisions with the ATLAS detector

Author

Aad, G, Abbott, B, Abbott, DC, Abud, A Abed, Abeling, K, Abhayasinghe, DK, Abidi, SH, AbouZeid, OS, Abraham, NL, Abramowicz, H, Abreu, H, Abulaiti, Y, Acharya, BS, Achkar, B, Adachi, S, Adam, L, Bourdarios, C Adam, Adamczyk, L, Adamek, L, Adelman, J, Adersberger, M, Adiguzel, A, Adorni, S, Adye, T, Affolder, AA, Afik, Y, Agapopoulou, C, Agaras, MN, Aggarwal, A, Agheorghiesei, C, Aguilar-Saavedra, JA, Ahmadov, F, Ahmed, WS, Ai, X, Aielli, G, Akatsuka, S, Åkesson, TPA, Akilli, E, Akimov, AV, Al Khoury, K, Alberghi, GL, Albert, J, Verzini, MJ Alconada, Alderweireldt, S, Aleksa, M, Aleksandrov, IN, Alexa, C, Alexandre, D, Alexopoulos, T, Alfonsi, A, Alfonsi, F, Alhroob, M, Ali, B, Alimonti, G, Alison, J, Alkire, SP, Allaire, C, Allbrooke, BMM, Allen, BW, Allport, PP, Aloisio, A, Alonso, A, Alonso, F, Alpigiani, C, Alshehri, AA, Estevez, M Alvarez, Piqueras, D Álvarez, Alviggi, MG, Coutinho, Y Amaral, Ambler, A, Ambroz, L, Amelung, C, Amidei, D, Dos Santos, SP Amor, Amoroso, S, Amrouche, CS, An, F, Anastopoulos, C, Andari, N, Andeen, T, Anders, CF, Anders, JK, Andreazza, A, Andrei, V, Anelli, CR, Angelidakis, S, Angerami, A, Anisenkov, AV, Annovi, A, Antel, C, Anthony, MT, Antonelli, M, Antrim, DJA, Anulli, F, Aoki, M, Pozo, JA Aparisi, Bella, L Aperio, Arabidze, G, Araque, JP, and Ferraz, V Araujo

Subjects
Nuclear and Plasma Physics, Particle and High Energy Physics, Physical Sciences, hep-ex
Abstract

A search for supersymmetry through the pair production of electroweakinos with mass splittings near the electroweak scale and decaying via on-shell W and Z bosons is presented for a three-lepton final state. The analyzed proton-proton collision data taken at a center-of-mass energy of s=13 TeV were collected between 2015 and 2018 by the ATLAS experiment at the Large Hadron Collider, corresponding to an integrated luminosity of 139 fb-1. A search, emulating the recursive jigsaw reconstruction technique with easily reproducible laboratory-frame variables, is performed. The two excesses observed in the 2015-2016 data recursive jigsaw analysis in the low-mass three-lepton phase space are reproduced. Results with the full data set are in agreement with the Standard Model expectations. They are interpreted to set exclusion limits at the 95% confidence level on simplified models of chargino-neutralino pair production for masses up to 345 GeV.

Published
2020

50. Search for chargino-neutralino production with mass splittings near the electroweak scale in three-lepton final states in s =13 TeV pp collisions with the ATLAS detector

Author

Aad, G, Abbott, B, Abbott, DC, Abed Abud, A, Abeling, K, Abhayasinghe, DK, Abidi, SH, Abouzeid, OS, Abraham, NL, Abramowicz, H, Abreu, H, Abulaiti, Y, Acharya, BS, Achkar, B, Adachi, S, Adam, L, Adam Bourdarios, C, Adamczyk, L, Adamek, L, Adelman, J, Adersberger, M, Adiguzel, A, Adorni, S, Adye, T, Affolder, AA, Afik, Y, Agapopoulou, C, Agaras, MN, Aggarwal, A, Agheorghiesei, C, Aguilar-Saavedra, JA, Ahmadov, F, Ahmed, WS, Ai, X, Aielli, G, Akatsuka, S, Åkesson, TPA, Akilli, E, Akimov, AV, Al Khoury, K, Alberghi, GL, Albert, J, Alconada Verzini, MJ, Alderweireldt, S, Aleksa, M, Aleksandrov, IN, Alexa, C, Alexandre, D, Alexopoulos, T, Alfonsi, A, Alfonsi, F, Alhroob, M, Ali, B, Alimonti, G, Alison, J, Alkire, SP, Allaire, C, Allbrooke, BMM, Allen, BW, Allport, PP, Aloisio, A, Alonso, A, Alonso, F, Alpigiani, C, Alshehri, AA, Alvarez Estevez, M, Álvarez Piqueras, D, Alviggi, MG, Amaral Coutinho, Y, Ambler, A, Ambroz, L, Amelung, C, Amidei, D, Amor Dos Santos, SP, Amoroso, S, Amrouche, CS, An, F, Anastopoulos, C, Andari, N, Andeen, T, Anders, CF, Anders, JK, Andreazza, A, Andrei, V, Anelli, CR, Angelidakis, S, Angerami, A, Anisenkov, AV, Annovi, A, Antel, C, Anthony, MT, Antonelli, M, Antrim, DJA, Anulli, F, Aoki, M, Aparisi Pozo, JA, Aperio Bella, L, Arabidze, G, Araque, JP, and Araujo Ferraz, V

Subjects
hep-ex
Abstract

A search for supersymmetry through the pair production of electroweakinos with mass splittings near the electroweak scale and decaying via on-shell W and Z bosons is presented for a three-lepton final state. The analyzed proton-proton collision data taken at a center-of-mass energy of s=13 TeV were collected between 2015 and 2018 by the ATLAS experiment at the Large Hadron Collider, corresponding to an integrated luminosity of 139 fb-1. A search, emulating the recursive jigsaw reconstruction technique with easily reproducible laboratory-frame variables, is performed. The two excesses observed in the 2015-2016 data recursive jigsaw analysis in the low-mass three-lepton phase space are reproduced. Results with the full data set are in agreement with the Standard Model expectations. They are interpreted to set exclusion limits at the 95% confidence level on simplified models of chargino-neutralino pair production for masses up to 345 GeV.

Published
2020

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