Browsing by Author "Abusleme Hoffmana A. C."
Measurement of the polarisation of Wbosons produced in top-quark decays using dilepton events at ?s=13TeV with the ATLAS experiment
(ELSEVIER, 2023/08/10) Aad G.; Abbott B.; Abbott D. C.; Abeling K.; Abidi S. H.; Aboulhormae A.; Abramowicz H.; Abreu H.; Abulaiti Y.; Abusleme Hoffmana A. C.; Acharyaa B. S.; Bourdarios C. Adam; Adamczyka L.; Adamek L.; Addepalli S. V.; Adelman J.; Adiguzelc A.; Adorni S.; Adye T.; Affolder A. A.; Afik Y.; Agaras M. N.; Agarwalaa J.; Aggarwal A.; Agheorghieseic C.; Aguilar-Saavedraf J. A.; Ahmad A.; Ahmadov F.; Ahmed W. S.; Ahuja S.; Ai X.; Aiellia G.; Tamlihate M. Ait; Aitbenchikh B.; Aizenberg I.; Akbiyik M.; Akesson T. P. A.; Akimov A. V.; Al Khoury K.; Alberghib G. L.
A measurement of the polarisation of Wbosons produced in top-quark decays is presented, using proton-proton collision data at a centre-of-mass energy of v s= 13TeV. The data were collected by the ATLAS detector at the Large Hadron Collider and correspond to an integrated luminosity of 139fb(-1). The measurement is performed selecting t tevents decaying into final states with two charged leptons (electrons or muons) and at least two b-tagged jets. The polarisation is extracted from the differential cross-section distribution of the cos theta* variable, where theta(*) is the angle between the momentum direction of the charged lepton from the Wboson decay and the reversed momentum direction of the b-quark from the top-quark decay, both calculated in the Wboson rest frame. Parton-level results, corrected for the detector acceptance and resolution, are presented for the cos theta* angle. The measured fractions of longitudinal, left- and right-handed polarisation states are found to be f(0) = 0.684 +/- 0.005 (stat.)+/- 0.014 (syst.), f(L)= 0.318 +/- 0.003 (stat.)+/- 0.008 (syst.) and f(R)=-0.002 +/- 0.002 (stat.)+/- 0.014 (syst.), in agreement with the Standard Model prediction. (c) 2023 The Author(s). Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/). Funded by SCOAP(3).
Observation of gauge boson joint-polarisation states in W� Z production from pp collisions at ?s=13TeV with the ATLAS detector
(ELSEVIER, 2023/08/10) Aad G.; Abbott B.; Abbott D. C.; Abeling K.; Abidi S. H.; Aboulhorma A.; Abramowicz H.; Abreu H.; Abulaiti Y.; Abusleme Hoffmana A. C.; Acharya B. S.; Achkar B.; Bourdarios C. Adam; Adamczyk L.; Adamek L.; Addepalli S. V.; Adelman J.; Adiguzel A.; Adorni S.; Adye T.; Affolder A. A.; Afik Y.; Agaras M. N.; Agarwala J.; Aggarwal A.; Agheorghiesei C.; Aguilar-Saavedraf J. A.; Ahmad A.; Ahmadov F.; Ahmed W. S.; Ahuja S.; Ai X.; Aielli G.; Aizenberg I.; Akbiyik M.; Akesson T. P. A.; Akimov A. V.; AlKhoury K.; Alberghi G. L.; Albert J.
Measurements of joint-polarisation states of Wand Zgauge bosons in W +/- Z production are presented. The data set used corresponds to an integrated luminosity of 139fb(-1) of proton-proton collisions at a centre-of-mass energy of 13TeV recorded by the ATLAS detector at the CERN Large Hadron Collider. The W +/- Z candidate events are reconstructed using leptonic decay modes of the gauge bosons into electrons and muons. The simultaneous pair-production of longitudinally polarised vector bosons is measured for the first time with a significance of 7.1 standard deviations. The measured joint helicity fractions integrated over the fiducial region are f(00)= 0.067 +/- 0.010, f(0T) = 0.110 +/- 0.029, f(T0) = 0.179 +/- 0.023 and f(TT) = 0.644 +/- 0.032, in agreement with the next-to-leading-order Standard Model predictions. Individual helicity fractions of the Wand Zbosons are also measured and found to be consistent with joint helicity fractions within the expected amounts of correlation. Both the joint and individual helicity fractions are also measured separately in W+Z and W-Z events. Inclusive and differential cross sections for several kinematic observables sensitive to polarisation are presented. (c) 2023 Published by Elsevier B.V. This is an open access article under the CC BY license (http:// creativecommons.org/licenses/by/4.0/). Funded by SCOAP(3).