Física de partículas y campos
Permanent URI for this collection
Browse
Browsing Física de partículas y campos by Author "Abbott B."
A search for heavy Higgs bosons decaying into vector bosons in same-sign two-lepton final states in pp collisions at ?s=13 TeV with the ATLAS detector
(SPRINGER, 2023/07/26) Aad G.; Abbott B.; Abbott D. C.; Abeling 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.; 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.; Akesson T. P. A.; Akimov A. V.; Al Khoury K.; Alberghi G. L.; Albert J.
A search for heavy Higgs bosons produced in association with a vector boson and decaying into a pair of vector bosons is performed in final states with two leptons (electrons or muons) of the same electric charge, missing transverse momentum and jets. A data sample of proton-proton collisions at a centre-of-mass energy of 13 TeV recorded with the ATLAS detector at the Large Hadron Collider between 2015 and 2018 is used. The data correspond to a total integrated luminosity of 139 fb(-1). The observed data are in agreement with Standard Model background expectations. The results are interpreted using higher-dimensional operators in an effective field theory. Upper limits on the production cross-section are calculated at 95% confidence level as a function of the heavy Higgs boson's mass and coupling strengths to vector bosons. Limits are set in the Higgs boson mass range from 300 to 1500 GeV, and depend on the assumed couplings. The highest excluded mass for a heavy Higgs boson with the coupling combinations explored is 900 GeV. Limits on coupling strengths are also provided.
A search for new resonances in multiple final states with a high transverse momentum Z boson in ?s=13 TeV pp collisions with the ATLAS detector
(SPRINGER, 2023/06/07) Aad G.; Abbott B.; Abbott D. C.; Abeling K.; Abidi S. H.; Aboulhorma A.; Abramowicz H.; Abreu H.; Abulaiti Y.; Abusleme Hoffman A. C.; Acharya B. S.; Achkar B.; Adam Bourdarios C.; 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-Saavedra 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.; Al Khoury K.; Alberghi G. L.; Albert J.
A generic search for resonances is performed with events containing a Z boson with transverse momentum greater than 100 GeV, decaying into e(+)e(-) or mu(+)mu(-). The analysed data collected with the ATLAS detector in proton-proton collisions at a centre-of-mass energy of 13TeV at the Large Hadron Collider correspond to an integrated luminosity of 139 fb(-1). Two invariant mass distributions are examined for a localised excess relative to the expected Standard Model background in six independent event categories (and their inclusive sum) to increase the sensitivity. No significant excess is observed. Exclusion limits at 95% confidence level are derived for two cases: a model-independent interpretation of Gaussian-shaped resonances with the mass width between 3% and 10% of the resonance mass, and a specific heavy vector triplet model with the decay mode W' -> ZW -> llqq.
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
(AMER PHYSICAL SOC, 2023/09/18) Aad G.; Abbott B.; Abbott D. C.; Abeling 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.; 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.; Akesson T. P. A.; Akimov A. V.; Al Khoury K.; Alberghi G. L.; Albert J.
A search is presented for a heavy resonance Y decaying into a Standard Model Higgs boson H and a new particle X in a fully hadronic final state. The full Large Hadron Collider run 2 dataset of proton-proton collisions at root s =13 TeV collected by the ATLAS detector from 2015 to 2018 is used and corresponds to an integrated luminosity of 139 fb(-1). The search targets the high Y-mass region, where the H and X 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 X particle, representing the first application of fully unsupervised machine learning to an ATLAS analysis. Two additional signal regions are implemented to target a benchmark X decay into two quarks, covering topologies where the X is reconstructed as either a single large-radius jet or two small-radius jets. The analysis selects Higgs boson decays into bb, 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 sigma(pp -> Y -> XH -> qqbb) for signals with m(Y) between 1.5 and 6 TeV and m(X) between 65 and 3000 GeV.
ATLAS flavour-tagging algorithms for the LHC Run 2 pp collision dataset
(SPRINGER, 2023/07/31) Aad G.; Abbott B.; Abeling K.; Abicht N. J.; Abidi S. H.; Aboulhorma A.; Abramowicz H.; Abreu H.; Abulaiti Y.; Abusleme Hoffman A. C.; Acharya B. S.; Adam Bourdarios C.; Adamczyk L.; Adamek L.; Addepalli S. V.; Addison M. J.; Adelman J.; Adiguzel A.; Adorni S.; 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.; Ait Tamlihat M.; Aitbenchikh B.; Aizenberg I.; Akbiyik M.; Akesson T. P. A.; Akimov A. V.; Akiyama D.; Akolkar N. N.
The flavour-tagging algorithms developed by the AvTLAS Collaboration and used to analyse its dataset of root s = 13 TeV pp collisions from Run 2 of the Large Hadron Collider are presented. These new tagging algorithms are based on recurrent and deep neural networks, and their performance is evaluated in simulated collision events. These developments yield considerable improvements over previous jet-flavour identification strategies. At the 77% b-jet identification efficiency operating point, light-jet (charm-jet) rejection factors of 170 (5) are achieved in a sample of simulated Standard Model t (t) over bar events; similarly, at a c-jet identification efficiency of 30%, a light-jet (b-jet) rejection factor of 70 (9) is obtained.
Calibration of the light-flavour jet mistagging efficiency of the b-tagging algorithms with Z plus jets events using 139 fb-1 of ATLAS proton-proton collision data at ?s=13 TeV
(SPRINGER, 2023/08/14) Aad G.; Abbott B.; Abbott D. C.; Abeling 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.; 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.; Akesson T. P. A.; Akimov A. V.; Al Khoury K.; Alberghi G. L.; Albert J.
The identification of b-jets, referred to as b-tagging, is an important part of many physics analyses in the ATLAS experiment at the Large Hadron Collider and an accurate calibration of its performance is essential for high-quality physics results. This publication describes the calibration of the light-flavour jet mistagging efficiency in a data sample of proton-proton collision events at root s = 13 TeV corresponding to an integrated luminosity of 139 fb(-1). The calibration is performed in a sample of Z bosons produced in association with jets. Due to the low mistagging efficiency for light-flavour jets, a method which uses modified versions of the b-tagging algorithms referred to as flip taggers is used in this work. A fit to the jet-flavour-sensitive secondary-vertex mass is performed to extract a scale factor from data, to correct the light-flavour jet mistagging efficiency in Monte Carlo simulations, while simultaneously correcting the b-jet efficiency. With this procedure, uncertainties coming from the modeling of jets from heavy-flavour hadrons are considerably lower than in previous calibrations of the mistagging scale factors, where they were dominant. The scale factors obtained in this calibration are consistent with unity within uncertainties.
Comparison of inclusive and photon-tagged jet suppression in 5.02 TeV Pb+Pb collisions with ATLAS
(ELSEVIER, 2023/11/10) Aad G.; Abbott B.; Abeling K.; Abicht N. J.; Abidi S. H.; Aboulhorma A.; Abramowicz H.; Abreu H.; Abulaiti Y.; Acharya B. S.; Bourdarios C. Adam; 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.; Tamlihat M. Ait; Aitbenchikh B.; Aizenberg I.; Akbiyik M.; Akesson T. P. A.; Akimov A. V.; Akiyama D.; Akolkar N. N.; Al Khoury K.; Alberghi G. L.
Parton energy loss in the quark-gluon plasma (QGP) is studied with a measurement of photon-tagged jet production in 1.7 nb-1 of Pb+Pb data and 260 pb-1 of pp data, both at root sNN = 5.02 TeV, with the ATLAS detector. The process pp -> gamma +jet+X and its analogue in Pb+Pb collisions is measured in events containing an isolated photon with transverse momentum (pT) above 50 GeV and reported as a function of jet pT. This selection results in a sample of jets with a steeply falling pT distribution that are mostly initiated by the showering of quarks. The pp and Pb+Pb measurements are used to report the nuclear modification factor, RAA, and the fractional energy loss, Sloss, for photon-tagged jets. In addition, the results are compared with the analogous ones for inclusive jets, which have a significantly smaller quark-initiated fraction. The RAA and Sloss values are found to be significantly different between those for photon-tagged jets and inclusive jets, demonstrating that energy loss in the QGP is sensitive to the colour-charge of the initiating parton. The results are also compared with a variety of theoretical models of colour-charge-dependent energy loss. (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 SCOAP3.
Constraints on spin-0 dark matter mediators and invisible Higgs decays using ATLAS 13 TeV pp collision data with two top quarks and missing transverse momentum in the final state
(SPRINGER, 2023/06/13) Aad G.; Abbott B.; Abbott D. C.; Abeling 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.; 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.; Akesson T. P. A.; Akimov A. V.; Al Khoury K.; Alberghi G. L.; Albert J.
This paper presents a statistical combination of searches targeting final states with two top quarks and invisible particles, characterised by the presence of zero, one or two leptons, at least one jet originating from a b-quark and missing transverse momentum. The analyses are searches for phenomena beyond the Standard Model consistent with the direct production of dark matter in pp collisions at the LHC, using 139 fb(-1) of data collected with the ATLAS detector at a centre-of-mass energy of 13 TeV. The results are interpreted in terms of simplified dark matter models with a spin-0 scalar or pseudoscalar mediator particle. In addition, the results are interpreted in terms of upper limits on the Higgs boson invisible branching ratio, where the Higgs boson is produced according to the StandardModel in associationwith a pair of top quarks. For scalar (pseudoscalar) dark matter models, with all couplings set to unity, the statistical combination extends the mass range excluded by the best of the individual channels by 50 (25) GeV, excluding mediator masses up to 370 GeV. In addition, the statistical combination improves the expected coupling exclusion reach by 14% (24%), assuming a scalar (pseudoscalar) mediator mass of 10 GeV. An upper limit on the Higgs boson invisible branching ratio of 0.38 (0.30(-0.09)(+0.13)) is observed (expected) at 95% confidence level.
Constraints on the Higgs boson self-coupling from single- and double-Higgs production with the ATLAS detector using pp collisions at?s=13 TeV
(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 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.; 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.; Akesson T. P. A.; Akimov A. V.; Al Khoury K.; Alberghi G. L.; Albert J.
Constraints on the Higgs boson self-coupling are set by combining double-Higgs boson analyses in the bb over bar bb over bar , bb over bar & tau;+& tau;- and bb over bar & gamma; & gamma; decay channels with single-Higgs boson analyses targeting the & gamma;& gamma;, Z Z*, W W *, & tau;+& tau;- and bb over bar decay channels. The data used in these analyses were recorded by the ATLAS detector at the LHC in proton-proton collisions at & RADIC;s = 13 TeV and correspond to an integrated luminosity of 126-139 fb-1. The combination of the double-Higgs analyses sets an upper limit of & mu;HH < 2.4 at 95% confidence level on the double-Higgs production cross-section normalised to its Standard Model prediction. Combining the single-Higgs and double-Higgs analyses, with the assumption that new physics affects only the Higgs boson self-coupling (& lambda;HHH), values outside the interval -0.4 < & kappa;& lambda; = (& lambda;HHH/& lambda;SM H H H ) < 6.3 are excluded at 95% confidence level. The combined single-Higgs and double-Higgs analyses provide results with fewer assumptions, by adding in the fit more coupling modifiers introduced to account for the Higgs boson interactions with the other Standard Model particles. In this relaxed scenario, the constraint becomes -1.4 < & kappa;& lambda; < 6.1 at 95% CL. & COPY; 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 SCOAP3.
Cross-section measurements for the production of a Z boson in association with high-transverse-momentum jets in pp collisions at ?s=13 TeV with the ATLAS detector
(SPRINGER, 2023/06/14) Aad G.; Abbott B.; Abbott D. C.; Abeling 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.; 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.; Akesson T. P. A.; Akimov A. V.; Al Khoury K.; Alberghi G. L.; Albert J.
Cross-section measurements for a Z boson produced in association with high-transverse-momentum jets ((pT) >= 100 GeV) and decaying into a charged-lepton pair (e(+) e(-), mu(+)mu(-)) are presented. The measurements are performed using proton-proton collisions at root s = 13TeV corresponding to an integrated luminosity of 139 fb(-1) collected by the ATLAS experiment at the LHC. Measurements of angular correlations between the Z boson and the closest jet are performed in events with at least one jet with (pT) >= 500 GeV. Event topologies of particular interest are the collinear emission of a Z boson in dijet events and a boosted Z boson recoiling against a jet. Fiducial cross sections are compared with state-of-the-art theoretical predictions. The data are found to agree with next-to-nextto-leading-order predictions by NNLOjet and with the next-to-leading-order multi-leg generators MadGraph5_aMC@NLO and Sherpa.
Differential t(t)over-tilde cross-section measurements using boosted top quarks in the all-hadronic final state with 139 fb-1 of ATLAS data
(SPRINGER, 2023/04/18) Aad G.; Abbott B.; Abbott D. C.; Abud A. Abed; Abeling K.; Abhayasinghe D. K.; Abidi S. H.; Aboulhorma A.; Abramowicz H.; Abreu H.; Abulaiti Y.; Hoffman A. C. Abusleme; Acharya B. S.; Achkar B.; Adam L.; 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-Saavedra J. A.; Ahmad A.; Ahmadov F.; Ahmed W. S.; Ai X.; Aielli G.; Aizenberg I.; Akbiyik M.; Akesson T. P. A.; Akimov A. V.; Al Khoury K.
Measurements of single-, double-, and triple-differential cross-sections are presented for boosted top-quark pair-production in 13 TeV proton-proton collisions recorded by the ATLAS detector at the LHC. The top quarks are observed through their hadronic decay and reconstructed as large-radius jets with the leading jet having transverse momentum (p(T)) greater than 500 GeV. The observed data are unfolded to remove detector effects. The particle-level cross-section, multiplied by the t (t) over bar branching fraction and measured in a fiducial phase space defined by requiring the leading and second-leading jets to have p(T)> 500 GeV and p(T)> 350 GeV, respectively, is 331 +/- 3(stat.) +/- 39(syst.) fb. This is approximately 20% lower than the prediction of 398(-49)(+48) fb by Powheg+Pythia 8 with next-to-leading-order (NLO) accuracy but consistent within the theoretical uncertainties. Results are also presented at the parton level, where the effects of top-quark decay, parton showering, and hadronization are removed such that they can be compared with fixed-order next-to-next-to-leading-order (NNLO) calculations. The parton-level cross-section, measured in a fiducial phase space similar to that at particle level, is 1.94 +/- 0.02(stat.) +/- 0.25(syst.) pb. This agrees with the NNLO prediction of 1.96(-0.17)(+0.02) pb. Reasonable agreement with the differential cross-sections is found for most NLO models, while the NNLO calculations are generally in better agreement with the data. The differential cross-sections are interpreted using a Standard Model effective field-theory formalism and limits are set on Wilson coefficients of several four-fermion operators.
Evidence for the charge asymmetry in pp ? t(t)over-bar production at ?s=13 TeV with the ATLAS detector
(SPRINGER, 2023/08/16) Aad G.; Abbott B.; Abbott D. C.; Abeling 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.; 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.; Akesson T. P. A.; Akimov A. V.; Al Khoury K.; Alberghi G. L.; Albert J.
Inclusive and differential measurements of the top-antitop ( t (t) over bar) charge asymmetry A(C)(t (t) over bar) and the leptonic asymmetry A(C)(l (l) over bar) are presented in proton-proton collisions at root s = 13 TeV recorded by the ATLAS experiment at the CERN Large Hadron Collider. The measurement uses the complete Run 2 dataset, corresponding to an integrated luminosity of 139 fb(-1), combines data in the single-lepton and dilepton channels, and employs reconstruction techniques adapted to both the resolved and boosted topologies. A Bayesian unfolding procedure is performed to correct for detector resolution and acceptance effects. The combined inclusive t (t) over bar charge asymmetry is measured to be A(C)(t (t) over bar) = 0.0068 +/- 0.0015, which differs from zero by 4.7 standard deviations. Differential measurements are performed as a function of the invariant mass, transverse momentum and longitudinal boost of the t (t) over bar system. Both the inclusive and differential measurements are found to be compatible with the Standard Model predictions, at next-to-next-to-leading order in quantum chromodynamics perturbation theory with next-to-leading-order electroweak corrections. The measurements are interpreted in the framework of the Standard Model effective field theory, placing competitive bounds on several Wilson coefficients.
Evidence of off-shell Higgs boson production from ZZ leptonic decay channels and constraints on its total width with the ATLAS detector
(ELSEVIER, 2023/11/10) Aad G.; Abbott B.; Abeling K.; Abidi S. H.; Aboulhorma A.; Abramowicz H.; Abreu H.; Abulaiti Y.; Abusleme Hoffman A. C.; Acharya B. S.; 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-Saavedra J. A.; Ahmad A.; Ahmadov F.; Ahmed W. S.; Ahuja S.; Ai X.; Aielli G.; Tamlihat M. Ait; Aitbenchikh B.; Aizenberg I; Akbiyik M.; Akesson T. P. A.; Akimov A. V; Akolkar N. N.; Al Khoury K.; Alberghi G. L.
This Letter reports on a search for off-shell production of the Higgs boson using 139 fb(-1) of pp collision data at root s = 13 TeV collected by the ATLAS detector at the Large Hadron Collider. The signature is a pair of Z bosons, with contributions from both the production and subsequent decay of a virtual Higgs boson and the interference of that process with other processes. The two observable final states are ZZ -> 4l and Z Z -> 2l2 nu with l = e or mu. In the ZZ -> 4l final state, a dense Neural Network is used to enhance analysis sensitivity with respect to matrix element-based discrimination. The background-only hypothesis is rejected with an observed (expected) significance of 3.3 (2.2) standard deviations, representing experimental evidence for off-shell Higgs boson production. Assuming that no new particles enter the production of the virtual Higgs boson, its total width can be deduced from the measurement of its off-shell production cross-section. The measured total width of the Higgs boson is 4.5(-2.5)(+3.3) MeV, and the observed (expected) upper limit on the total width is found to be 10.5 (10.9) MeV at 95% confidence level. (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/).
Evidence of pair production of longitudinally polarised vector bosons and study of CP properties in ZZ ? 4l events with the ATLAS detector at ?s=13 TeV
(SPRINGER, 2023/12/15) Aad G.; Abbott B.; Abeling K.; Abicht N. J.; Abidi S. H.; Aboulhorma A.; Abramowicz H.; Abreu H.; Abulaiti Y.; Acharya B. S.; Bourdarios C. Adam; Adamczyk L.; Addepalli S. V; Addison M. J.; Adelman J.; Adiguzel A.; Adye T.; Afolder A. A.; Afk 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.; Tamlihat M. Ait; Aitbenchikh B.; Aizenberg I; Akbiyik M.; Akesson T. P. A.; Akimov A. V; Akiyama D.; Akolkar N. N.; Al Khoury K.; Alberghi G. L.
A study of the polarisation and CP properties in ZZ production is presented. The used data set corresponds to an integrated luminosity of 140 fb(-1) of proton-proton collisions at a centre-of-mass energy of 13TeV recorded by the ATLAS detector at the Large Hadron Collider. The ZZ candidate events are reconstructed using two same-flavour opposite-charge electron or muon pairs. The production of two longitudinally polarised Z bosons is measured with a significance of 4.3 standard deviations, and its cross-section is measured in a fiducial phase space to be 2.45 +/- 0.60 fb, consistent with the next-to-leadingorder Standard Model prediction. The inclusive differential cross-section as a function of a CP-sensitive angular observable is also measured. The results are used to constrain anomalous CP-odd neutral triple gauge couplings.
Exclusive dielectron production in ultraperipheral Pb plus Pb collisions at ?sNN=5.02 TeV with ATLAS
(SPRINGER, 2023/06/27) Aad G.; Abbott B.; Abbott D. C.; Abeling 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.; 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.; Akesson T. P. A.; Akimov A. V.; Al Khoury K.; Alberghi G. L.; Albert J.
Exclusive production of dielectron pairs, gamma gamma -> e(+) e(-), is studied using L-int = 1.72 nb(-1) of data from ultraperipheral collisions of lead nuclei at root s(NN) = 5.02TeV recorded by the ATLAS detector at the LHC. The process of interest proceeds via photon-photon interactions in the strong electromagnetic fields of relativistic lead nuclei. Dielectron production is measured in the fiducial region defined by following requirements: electron transverse momentum p(T)(e) > 2.5 GeV, absolute electron pseudorapidity |eta(e)| < 2.5, dielectron invariant mass m(ee) > 5 GeV, and dielectron transverse momentum p(T)(ee) < 2 GeV. Differential cross-sections are measured as a function of mee, average peT, absolute dielectron rapidity |y(ee)|, and scattering angle in the dielectron rest frame, | cos theta* |, in the inclusive sample, and also with a requirement of no activity in the forward direction. The total integrated fiducial cross-section is measured to be 215 +/- 1(stat.) (+23)(-20)(syst.) +/- 4(lumi.) mu b. Within experimental uncertainties the measured integrated cross-section is in good agreement with the QED predictions from the Monte Carlo programs Starlight and SuperChic, confirming the broad features of the initial photon fluxes. The differential cross-sections show systematic differences from these predictions which are more pronounced at high |y(ee)| and | cos theta* | values.
Inclusive and differential cross-sections for dilepton t(t)over-bar production measured in ?s=13 TeV pp collisions with the ATLAS detector
(SPRINGER, 2023/07/17) Aad G.; Abbott B.; Abeling K.; Abicht N. J.; Abidi S. H.; Aboulhorma A.; Abramowicz H.; Abreu H.; Abulaiti Y.; Abusleme Hoffman A. C.; Acharya B. S.; Adam Bourdarios C.; Adamczyk L.; Adamek L.; Addepalli S. V.; Addison M. J.; Adelman J.; Adiguzel A.; Adorni S.; 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.; Ait Tamlihat M.; Aitbenchikh B.; Aizenberg I.; Akbiyik M.; Akesson T. P. A.; Akimov A. V.; Akiyama D.; Akolkar N. N.
Differential and double-differential distributions of kinematic variables of leptons from decays of top-quark pairs (t (t) over bar) are measured using the full LHC Run 2 data sample collected with the ATLAS detector. The data were collected at a pp collision energy of root s = 13TeV and correspond to an integrated luminosity of 140 fb(-1). The measurements use events containing an oppositely charged e mu pair and b-tagged jets. The results are compared with predictions from several Monte Carlo generators. While no prediction is found to be consistent with all distributions, a better agreement with measurements of the lepton p(T) distributions is obtained by reweighting the t (t) over bar sample so as to reproduce the top-quark p(T) distribution from an NNLO calculation. The inclusive top-quark pair production cross-section is measured as well, both in a fiducial region and in the full phase-space. The total inclusive cross-section is found to be sigma(t (t) over bar) = 829 +/- 1 (stat) +/- 13 (syst) +/- 8 (lumi) +/- 2 (beam) pb, where the uncertainties are due to statistics, systematic effects, the integrated luminosity and the beam energy. This is in excellent agreement with the theoretical expectation.
Integrated and differential fiducial cross-section measurements for the vector boson fusion production of the Higgs boson in the H ? WW* ? e??? decay channel at 13 TeV with the ATLAS detector
(AMER PHYSICAL SOC, 2023/10/11) Aad G.; Abbott B.; Abeling K.; Abicht N. J.; Abidi S. H.; Aboulhorma A.; Abramowicz H.; Abreu H.; Abulaiti Y.; Acharya B. S.; Bourdarios C. Adam; 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.; Tamlihat M. Ait; Aitbenchikh B.; Aizenberg I.; Akbiyik M.; Akesson T. P. A.; Akimov A. V.; Akiyama D.; Akolkar N. N.; Al Khoury K.; Alberghi G. L.
The vector-boson production cross section for the Higgs boson decay in the H -> WW* -> e nu mu nu 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 root s = 13 TeV center-of-mass energy, corresponding to an integrated luminosity of 139 fb(-1). The different flavor final state is studied by selecting an electron and a muon originating from a pair of W 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.
Luminosity determination in pp collisions at ?s=13TeV using the ATLAS detector at the LHC
(SPRINGER, 2023/10/31) Aad G.; Abbott B.; Abeling K.; Abidi S. H.; Aboulhorma A.; Abramowicz H.; Abreu H.; Abulaiti Y.; Hoffman A. C. Abusleme; Acharya B. S.; Bourdarios C. Adam; Adamczyk L.; Adamek L.; Addepalli S. V.; Addison M. J.; Adelman J.; Adiguzel A.; Adorni S.; 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.; Tamlihat M. Ait; Aitbenchikh B.; Aizenberg I.; Akbiyik M.; Akesson T. P. A.; Akimov A. V.; Akiyama D.; Akolkar N. N.; Al Khoury K.
The luminosity determination for the ATLAS detector at the LHC during Run 2 is presented, with pp collisions at a centre-of-mass energy root s = 13TeV. The absolute luminosity scale is determined using van der Meer beam separation scans during dedicated running periods in each year, and extrapolated to the physics data-taking regime using complementary measurements from several luminosity-sensitive detectors. The total uncertainties in the integrated luminosity for each individual year of datataking range from 0.9% to 1.1%, and are partially correlated between years. After standard data-quality selections, the full Run 2 pp data sample corresponds to an integrated luminosity of 140.1 +/- 1.2fb(-1), i.e. an uncertainty of 0.83%. A dedicated sample of low-pileup data recorded in 2017-2018 for precision Standard Model physics measurements is analysed separately, and has an integrated luminosity of 338.1 +/- 3.1pb(-1).
Measurement of electroweak Z(v (v)over-bar)? jj production and limits on anomalous quartic gauge couplings in pp collisions at ?s=13 TeV with the ATLAS detector
(SPRINGER, 2023/06/14) Aad G.; Abbott B.; Abbott D. C.; Abeling 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.; 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.; Akesson T. P. A.; Akimov A. V.; Al Khoury K.; Alberghi G. L.; Albert J.
The electroweak production of Z(v (v) over bar)gamma in association with two jets is studied in a regime with a photon of high transverse momentum above 150 GeV using proton-proton collisions at a centre-of-mass energy of 13TeV at the Large Hadron Collider. The analysis uses a data sample with an integrated luminosity of 139 fb(-1) collected by the ATLAS detector during the 2015-2018 LHC data-taking period. This process is an important probe of the electroweak symmetry breaking mechanism in the Standard Model and is sensitive to quartic gauge boson couplings via vector-boson scattering. The fiducial Z( v (v) over bar)gamma jj cross section for electroweak production is measured to be 0.77(-0.30)(+0.34) fb and is consistent with the Standard Model prediction. Evidence of electroweak Z( v (v) over bar)gamma jj production is found with an observed significance of 3.2 sigma for the background-only hypothesis, compared with an expected significance of 3.7 sigma. The combination of this result with the previously published ATLAS observation of electroweak Z(v (v) over bar)gamma jj production yields an observed (expected) signal significance of 6.3 sigma (6.6 sigma). Limits on anomalous quartic gauge boson couplings are obtained in the framework of effective field theory with dimension-8 operators.
Measurement of exclusive pion pair production in proton-proton collisions at ?s=7 TeV with the ATLAS detector
(SPRINGER, 2023/07/17) Aad G.; Abbott B.; Abbott D. C.; Abeling 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.; 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.; Akesson T. P. A.; Akimov A. V.; Al Khoury K.; Alberghi G. L.; Albert J.
The exclusive production of pion pairs in the process pp -> pp pi(+)pi(-) has been measured at root s = 7TeV with the ATLAS detector at the LHC, using 80 mu b(-1) of low-luminosity data. The pion pairs were detected in the ATLAS central detector while outgoing protons were measured in the forwardATLASALFAdetector system. This represents the first use of proton tagging to measure an exclusive hadronic final state at the LHC. Across-sectionmeasurement is performed in two kinematic regions defined by the proton momenta, the pion rapidities and transverse momenta, and the pion-pion invariant mass. Cross-section values of 4.8 +/- 1.0 (stat)(-0.2) (+0.3)(syst) mu b and 9 +/- 6 (stat)(-2)(+2) (syst) mu b are obtained in the two regions; they are compared with theoretical models and provide a demonstration of the feasibility of measurements of this type.
Measurement of single top-quark production in the s-channel in proton-proton collisions at ?s=13 TeV with the ATLAS detector
(SPRINGER, 2023/06/27) Aad G.; Abbott B.; Abbott D. C.; Abeling 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.; 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.; Akesson T. P. A.; Akimov A. V.; Al Khoury K.; Alberghi G. L.; Albert J.
A measurement of single top-quark production in the s-channel is performed in proton-proton collisions at a centre-of-mass energy of 13TeV with the ATLAS detector at the CERN Large Hadron Collider. The dataset corresponds to an integrated luminosity of 139 fb(-1). The analysis is performed on events with an electron or muon, missing transverse momentum and exactly two b-tagged jets in the final state. A discriminant based on matrix element calculations is used to separate single-top-quark s-channel events from the main background contributions, which are top-quark pair production and W-boson production in association with jets. The observed (expected) signal significance over the background-only hypothesis is 3.3 (3.9) standard deviations, and the measured cross-section is sigma = 8.2(-2.9)(+3.5) pb, consistent with the Standard Model prediction of sigma(SM) = 10.32(-0.36)(+0.40) pb.