CARQUIN, EDSON

2024-07-01, Aad, G., Abbott, B., Abeling, K., Abicht, N. J., Abidi, S. H., Aboulhorma, A., Abramowicz, H., Abreu, H., Abulaiti, Y., Acharya, B. S., Adam Bourdarios, C., Adamczyk, L., Adamek, L., Addepalli, S. V., Addison, M. J., Adelman, J., Adiguzel, A., Adye, T., Affolder, A. A., Afik, Y., Agaras, M. N., Agarwala, J., Aggarwal, A., Agheorghiesei, C., Ahmad, A., Ahmadov, F., Ahmed, W. S., Ahuja, S., Ai, X., Aielli, G., Aikot, A., Ait Tamlihat, M., Aitbenchikh, B., Aizenberg, I., Akbiyik, M., Åkesson, T. P.A., Akimov, A. V., Akiyama, D., Akolkar, N. N., Al Khoury, K., Alberghi, G. L., Albert, J., Albicocco, P., Albouy, G. L., Alderweireldt, S., Aleksa, M., Aleksandrov, I. N., Alexa, C., Alexopoulos, T., Alfonsi, F., Algren, M., Alhroob, M., Ali, B., Ali, H. M.J., Ali, S., Alibocus, S. W., Aliev, M., Alimonti, G., Alkakhi, W., Allaire, C., Allbrooke, B. M.M., Allen, J. F., Allendes Flores, C. A., Allport, P. P., Aloisio, A., Alonso, F., Alpigiani, C., Alvarez Estevez, M., Alvarez Fernandez, A., Alves Cardoso, M., Alviggi, M. G., Aly, M., Amaral Coutinho, Y., Ambler, A., Amelung, C., Amerl, M., Ames, C. G., Amidei, D., Amor Dos Santos, S. P., Amos, K. R., Ananiev, V., Anastopoulos, C., Andeen, T., Anders, J. K., Andrean, S. Y., Andreazza, A., Angelidakis, S., Angerami, A., Anisenkov, A. V., Annovi, A., Antel, C., Anthony, M. T., Antipov, E., Antonelli, M., Anulli, F., Aoki, M., Aoki, T., Aparisi Pozo, J. A., Aparo, M. A., Aperio Bella, L., BROOKS, WILLIAM K., CARQUIN, EDSON, Fernandez Luengo, S.I., PEZOA, RAQUEL, Carolina Robles Gajardo, TAPIA, SEBASTIAN, VIAUX MAIRA, NICOLAS

The observation of the electroweak production of single-top-quarks is made using 255 pb−1 of proton-proton collision data recorded at s√=5.02 TeV with the ATLAS detector at the Large Hadron Collider. An event selection is used to identify single-top-quark candidates arising from t-channel production with the top quark decaying semi-leptonically. Events passing the selection are then used to measure the inclusive cross-section for the combined production of single-top-quarks and antiquarks, σ(tq+t¯q), and the ratio Rt between these two. They are measured to be σ(tq+t¯q)=27.1+4.4−4.1(stat.)+4.4−3.7(syst.) pb and Rt=2.73+1.43−0.82(stat.)+1.01−0.29(syst.). The individual single-top-quark (tq) and single-top-antiquark (t¯q) production cross-sections are measured to be σ(tq)=19.8+3.9−3.1(stat.)+2.9−2.2(syst.) pb and σ(t¯q)=7.3+3.2−2.1(stat.)+2.8−1.5(syst.) pb. All measurements are in good agreement with the Standard Model predictions.

2019-09-01, Afik, Y., Agheorghiesei, C., Aguilar-Saavedra, J. A., Ahmadov, F., Aielli, G., Akatsuka, S., Åkesson, T. P.A., Akilli, E., Akimov, A. V., Alberghi, G. L., Albert, J., Albicocco, P., Alconada Verzini, M. J., Alderweireldt, S., Aleksa, M., Aleksandrov, I. N., Alexa, C., Alexopoulos, T., Alhroob, M., Ali, B., Alimonti, G., Alison, J., Alkire, S. P., Allaire, C., Allbrooke, B. M.M., Allen, B. W., Allport, P. P., Aloisio, A., Alonso, A., Alonso, F., Alpigiani, C., Alshehri, A. A., Alstaty, M. I., Alvarez Gonzalez, B., Álvarez Piqueras, D., Alviggi, M. G., Amadio, B. T., Amaral Coutinho, Y., Ambroz, L., Amelung, C., Amidei, D., Amor Dos Santos, S. P., Amoroso, S., Amrouche, C. S., Anastopoulos, C., Ancu, L. S., Andari, N., Andeen, T., Anders, C. F., Anders, J. K., Anderson, K. J., Andreazza, A., Andrei, V., Anelli, C. R., Angelidakis, S., Angelozzi, I., Angerami, A., Anisenkov, A. V., Annovi, A., Antel, C., Anthony, M. T., Antonelli, M., Antrim, D. J.A., Anulli, F., Aoki, M., Aparisi Pozo, J. A., Aperio Bella, L., Arabidze, G., Araque, J. P., Brooks, William K., CARQUIN, EDSON, S. Kuleshov, J. A. López, Pezoa, Raquel, F. Prokoshin, J. E. Salazar Loyola, S. Tapia Araya, G. A. Vasquez, Viaux Maira, Nicolas, R. White

Searches for scalar leptoquarks pair-produced in proton-proton collisions at s√=13 TeV at the Large Hadron Collider are performed by the ATLAS experiment. A data set corresponding to an integrated luminosity of 36.1 fb−1 is used. Final states containing two electrons or two muons and two or more jets are studied, as are states with one electron or muon, missing transverse momentum and two or more jets. No statistically significant excess above the Standard Model expectation is observed. The observed and expected lower limits on the leptoquark mass at 95% confidence level extend up to 1.29 TeV and 1.23 TeV for first- and second-generation leptoquarks, respectively, as postulated in the minimal Buchmüller-Rückl-Wyler model, assuming a branching ratio into a charged lepton and a quark of 50%. In addition, measurements of particle-level fiducial and differential cross sections are presented for the Z→ee, Z→μμ and tt¯ processes in several regions related to the search control regions. Predictions from a range of generators are compared with the measurements, and good agreement is seen for many of the observables. However, the predictions for the Z→ℓℓ measurements in observables sensitive to jet energies disagree with the data.

2024-07-01, Aad, G., Aakvaag, E., Abbott, B., Abdelhameed, S., Abeling, K., Abicht, N. J., Abidi, S. H., Aboelela, M., Aboulhorma, A., Abramowicz, H., Abreu, H., Abulaiti, Y., Acharya, B. S., Ackermann, A., Adam Bourdarios, C., Adamczyk, L., Addepalli, S. V., Addison, M. J., Adelman, J., Adiguzel, A., Adye, T., Affolder, A. A., Afik, Y., Agaras, M. N., Agarwala, J., Aggarwal, A., Agheorghiesei, C., Ahmad, A., Ahmadov, F., Ahmed, W. S., Ahuja, S., Ai, X., Aielli, G., Aikot, A., Ait Tamlihat, M., Aitbenchikh, B., Akbiyik, M., Åkesson, T. P.A., Akimov, A. V., Akiyama, D., Akolkar, N. N., Aktas, S., Al Khoury, K., Alberghi, G. L., Albert, J., Albicocco, P., Albouy, G. L., Alderweireldt, S., Alegria, Z. L., Aleksa, M., Aleksandrov, I. N., Alexa, C., Alexopoulos, T., Alfonsi, F., Algren, M., Alhroob, M., Ali, B., Ali, H. M.J., Ali, S., Alibocus, S. W., Aliev, M., Alimonti, G., Alkakhi, W., Allaire, C., Allbrooke, B. M.M., Allen, J. F., Allendes Flores, C. A., Allport, P. P., Aloisio, A., Alonso, F., Alpigiani, C., Alsolami, Z. M.K., Alvarez Estevez, M., Alvarez Fernandez, A., Alves Cardoso, M., Alviggi, M. G., Aly, M., Amaral Coutinho, Y., Ambler, A., Amelung, C., Amerl, M., Ames, C. G., Amidei, D., Amirie, K. J., Amor Dos Santos, S. P., Amos, K. R., An, S., Ananiev, V., Anastopoulos, C., Andeen, T., Anders, J. K., Andrean, S. Y., Andreazza, A., Angelidakis, S., Angerami, A., Anisenkov, A. V., Annovi, A., Antel, C., Antipov, E., Antonelli, M., CARQUIN, EDSON, Fernandez Luengo, S.I., Fuenzalida Garrido, S., PEZOA, RAQUEL, Carolina Robles Gajardo, TAPIA, SEBASTIAN, VIAUX MAIRA, NICOLAS

Fiducial and total 𝑊 ± and 𝑍 boson cross sections, their ratios and the ratio of top-antitop-quark pair and 𝑊 -boson fiducial cross sections are measured in proton–proton collisions at a centre-of-mass energy of √𝑠 = 13.6 TeV, corresponding to an integrated luminosity of 29 fb−1 of data collected in 2022 by the ATLAS experiment at the Large Hadron Collider. The measured fiducial cross-section values for 𝑊 + → 𝓁+𝜈, 𝑊 − → 𝓁−𝜈̄, and 𝑍 → 𝓁+𝓁− (𝓁 = 𝑒 or 𝜇) boson productions are 4250 ± 150 pb, 3310 ± 120 pb, and 744 ± 20 pb, respectively, where the uncertainty is the total uncertainty, including that arising from the luminosity of about 2.2%. The measurements are in agreement with Standard-Model predictions calculated at next-to-next-to-leading-order in 𝛼𝑠 , next-to-nextto-leading logarithmic accuracy and next-to-leading-order electroweak accuracy

2022-08-01, Aad, G., Abbott, B., Abbott, D. C., Abed Abud, A., Abeling, K., Abhayasinghe, D. K., Abidi, S. H., Aboulhorma, A., Abramowicz, H., Abreu, H., Abulaiti, Y., Abusleme Hoffman, A. C., Acharya, B. S., Achkar, B., Adam, L., Adam Bourdarios, C., Adamczyk, L., Adamek, L., Addepalli, S. V., Adelman, J., Adiguzel, A., Adorni, S., Adye, T., Affolder, A. A., Afik, Y., Agapopoulou, C., Agaras, M. N., Agarwala, J., Aggarwal, A., Agheorghiesei, C., Aguilar-Saavedra, J. A., Ahmad, A., Ahmadov, F., Ahmed, W. S., Ai, X., Aielli, G., Aizenberg, I., Akbiyik, M., Åkesson, T. P.A., Akimov, A. V., Al Khoury, K., Alberghi, G. L., Albert, J., Albicocco, P., Alconada Verzini, M. J., Alderweireldt, S., Aleksa, M., Aleksandrov, I. N., Alexa, C., Alexopoulos, T., Alfonsi, A., Alfonsi, F., Alhroob, M., Ali, B., Ali, S., Aliev, M., Alimonti, G., Allaire, C., Allbrooke, B. M.M., Allport, P. P., Aloisio, A., Alonso, F., Alpigiani, C., Alunno Camelia, E., Alvarez Estevez, M., Alviggi, M. G., Amaral Coutinho, Y., Ambler, A., Ambroz, L., Amelung, C., Amidei, D., Amor Dos Santos, S. P., Amoroso, S., Amos, K. R., Amrouche, C. S., Ananiev, V., Anastopoulos, C., Andari, N., Andeen, T., Anders, J. K., Andrean, S. Y., Andreazza, A., Angelidakis, S., Angerami, A., Anisenkov, A. V., Annovi, A., Antel, C., Anthony, M. T., Antipov, E., Antonelli, M., Antrim, D. J.A., Anulli, F., Aoki, M., Aparisi Pozo, J. A., Aparo, M. A., Brooks, William K., Pezoa, Raquel, CARQUIN, EDSON, C. M. Robles Guajardo, Viaux Maira, Nicolas

This paper presents updated Monte Carlo configurations used to model the production of single electroweak vector bosons (W, Z/γ∗) in association with jets in proton-proton collisions for the ATLAS experiment at the Large Hadron Collider. Improvements pertaining to the electroweak input scheme, parton-shower splitting kernels and scale-setting scheme are shown for multi-jet merged configurations accurate to next-to-leading order in the strong and electroweak couplings. The computational resources required for these set-ups are assessed, and approximations are introduced resulting in a factor three reduction of the per-event CPU time without affecting the physics modelling performance. Continuous statistical enhancement techniques are introduced by ATLAS in order to populate low cross-section regions of phase space and are shown to match or exceed the generated effective luminosity. This, together with the lower per-event CPU time, results in a 50% reduction in the required computing resources compared to a legacy set-up previously used by the ATLAS collaboration. The set-ups described in this paper will be used for future ATLAS analyses and lay the foundation for the next generation of Monte Carlo predictions for single vector-boson plus jets production.

2024-05-17, Filmer, E. K., Grant, C. M., Jackson, P., Kong, A. X.Y., Pandya, H. D., Potti, H., Ruggeri, T. A., Ting, E. X.L., White, M. J., Gingrich, D. M., Lindon, J. H., Nishu, N., Pinfold, J. L., Cakir, O., Yildiz, H. Duran, Kuday, S., Turk Cakir, I., Sultansoy, S., Adam Bourdarios, C., Arnaez, O., Berger, N., Castillo, F. L., Costanza, F., Delmastro, M., Di Ciaccio, L., Hryn’ova, T., Jézéquel, S., Koletsou, I., Levêque, J., Lewis, D. J., Little, J. D., Lorenzo Martinez, N., Poddar, G., Sanchez Pineda, A., Sauvan, E., Bernardi, G., Bomben, M., Li, A., Li, T., Marchiori, G., Nakkalil, K., Shen, Q., Zhang, Y., Chekanov, S., Darmora, S., Hopkins, W. H., Hoya, J., Love, J., Luongo, N. A., Metcalfe, J., Mete, A. S., Paramonov, A., Proudfoot, J., Van Gemmeren, P., Wamorkar, T., Wang, R., Zhang, J., Cheu, E., Cui, Z., Ghosh, A., Johns, K. A., Lampl, W., Lindley, R. E., Loch, P., Rutherfoord, J. P., Sardain, J., Varnes, E. W., Zhou, H., Zhou, Y., Bakshi Gupta, D., Burghgrave, B., Cardenas, J. C.J., De, K., Farbin, A., Hadavand, H. K., Myers, A. J., Ozturk, N., Usai, G., White, A., Angelidakis, S., Fassouliotis, D., Fountas, L., Gkialas, I., Kourkoumelis, C., Alexopoulos, T., Drivas-Koulouris, I., Gazis, E. N., Kitsaki, C., Maltezos, S., Paraskevopoulos, C., Perganti, M., Tzanis, P., Andeen, T., Burton, C. D., Choi, K., Onyisi, P. U.E., Panchal, D. K., Tost, M., Unal, M., Huseynov, N., Cristian Andres Allendes Flores, BROOKS, WILLIAM K., CARQUIN, EDSON, Fernandez Luengo, S.I., Fuenzalida Garrido, S., PEZOA, RAQUEL, Carolina Robles Gajardo, Tapia Araya, S., VIAUX MAIRA, NICOLAS

Angular correlations between heavy quarks provide a unique probe of the quark-gluon plasma created in ultrarelativistic heavy-ion collisions. Results are presented of a measurement of the azimuthal angle correlations between muons originating from semileptonic decays of heavy quarks produced in 5.02 TeV Pb+Pb and 𝑝⁢𝑝 collisions at the LHC. The muons are measured with transverse momenta and pseudorapidities satisfying 𝑝𝜇T>4  GeV and |𝜂𝜇|<2.4, respectively. The distributions of azimuthal angle separation Δ⁢𝜙 for muon pairs having pseudorapidity separation |Δ⁢𝜂|>0.8, are measured in different Pb+Pb centrality intervals and compared to the same distribution measured in 𝑝⁢𝑝 collisions at the same center-of-mass energy. Results are presented separately for muon pairs with opposite-sign charges, same-sign charges, and all pairs. A clear peak is observed in all Δ⁢𝜙 distributions at Δ⁢𝜙∼𝜋, consistent with the parent heavy-quark pairs being produced via hard-scattering processes. The widths of that peak, characterized using Cauchy-Lorentz fits to the Δ⁢𝜙 distributions, are found to not vary significantly as a function of Pb+Pb collision centrality and are similar for 𝑝⁢𝑝 and Pb+Pb collisions. This observation will provide important constraints on theoretical descriptions of heavy-quark interactions with the quark-gluon plasma.

2024-03-08, Filmer, E. K., Grant, C. M., Jackson, P., Kong, A. X.Y., Pandya, H. D., Potti, H., Ruggeri, T. A., Ting, E. X.L., White, M. J., Gingrich, D. M., Lindon, J. H., Nishu, N., Pinfold, J. L., Cakir, O., Yildiz, H. Duran, Kuday, S., Turk Cakir, I., Sultansoy, S., Adam Bourdarios, C., Arnaez, O., Berger, N., Castillo, F. L., Costanza, F., Delmastro, M., Di Ciaccio, L., Hryn’ova, T., Jézéquel, S., Koletsou, I., Levêque, J., Lewis, D. J., Little, J. D., Lorenzo Martinez, N., Poddar, G., Sanchez Pineda, A., Sauvan, E., Bernardi, G., Bomben, M., Li, A., Li, T., Marchiori, G., Nakkalil, K., Shen, Q., Zhang, Y., Chekanov, S., Darmora, S., Hopkins, W. H., Hoya, J., Love, J., Luongo, N. A., Metcalfe, J., Mete, A. S., Paramonov, A., Proudfoot, J., Van Gemmeren, P., Wamorkar, T., Wang, R., Zhang, J., Cheu, E., Cui, Z., Ghosh, A., Johns, K. A., Lampl, W., Lindley, R. E., Loch, P., Rutherfoord, J. P., Sardain, J., Varnes, E. W., Zhou, H., Zhou, Y., Bakshi Gupta, D., Burghgrave, B., Cardenas, J. C.J., De, K., Farbin, A., Hadavand, H. K., Myers, A. J., Ozturk, N., Usai, G., White, A., Angelidakis, S., Fassouliotis, D., Fountas, L., Gkialas, I., Kourkoumelis, C., Alexopoulos, T., Drivas-Koulouris, I., Gazis, E. N., Kitsaki, C., Maltezos, S., Paraskevopoulos, C., Perganti, M., Cristian Andres Allendes Flores, BROOKS, WILLIAM K., CARQUIN, EDSON, Fernandez Luengo, S.I., Fuenzalida Garrido, S., PEZOA, RAQUEL, Robles Gajardo, C.M., TAPIA, SEBASTIAN, Viaux Maira, N.

ATLAS measured the centrality dependence of the dijet yield using 165  nb−1 of 𝑝+Pb data collected at √𝑠NN=8.16  TeV in 2016. The event centrality, which reflects the 𝑝+Pb impact parameter, is characterized by the total transverse energy registered in the Pb-going side of the forward calorimeter. The central-to-peripheral ratio of the scaled dijet yields, 𝑅CP, is evaluated, and the results are presented as a function of variables that reflect the kinematics of the initial hard parton scattering process. The 𝑅CP shows a scaling with the Bjorken 𝑥 of the parton originating from the proton, 𝑥𝑝, while no such trend is observed as a function of 𝑥Pb. This analysis provides unique input to understanding the role of small proton spatial configurations in 𝑝+Pb collisions by covering parton momentum fractions from the valence region down to 𝑥𝑝∼10−3 and 𝑥Pb∼4×10−4.