SwePub - sökning: WFRF:(Pereira Sanchez Laura 19...

Numrering	Referens	Omslagsbild	Hitta
1.	Aad, G., et al. (författare) Combined Measurement of the Higgs Boson Mass from the H → γγ and H → ZZ* → 4ℓ Decay Channels with the ATLAS Detector Using √s=7, 8, and 13 TeV pp Collision Data 2023 Ingår i: Physical Review Letters. - : American Physical Society. - 0031-9007 .- 1079-7114. ; 131:25 Tidskriftsartikel (refereegranskat)abstract A measurement of the mass of the Higgs boson combining the H→ZZ*→4ℓ and H→γγ decay channels is presented. The result is based on 140 fb−1 of proton-proton collision data collected by the ATLAS detector during LHC run 2 at a center-of-mass energy of 13 TeV combined with the run 1 ATLAS mass measurement, performed at center-of-mass energies of 7 and 8 TeV, yielding a Higgs boson mass of 125.11±0.09(stat)±0.06(syst)=125.11±0.11 GeV. This corresponds to a 0.09% precision achieved on this fundamental parameter of the Standard Model of particle physics.
2.	Aad, G., et al. (författare) Evidence for the Higgs Boson Decay to a Z Boson and a Photon at the LHC 2024 Ingår i: Physical Review Letters. - : American Physical Society (APS). - 0031-9007 .- 1079-7114. ; 132:2 Tidskriftsartikel (refereegranskat)abstract The first evidence for the Higgs boson decay to a Z boson and a photon is presented, with a statistical significance of 3.4 standard deviations. The result is derived from a combined analysis of the searches performed by the ATLAS and CMS Collaborations with proton-proton collision datasets collected at the CERN Large Hadron Collider (LHC) from 2015 to 2018. These correspond to integrated luminosities of around 140 fb−1 for each experiment, at a center-of-mass energy of 13 TeV. The measured signal yield is 2.2±0.7 times the standard model prediction, and agrees with the theoretical expectation within 1.9 standard deviations.
3.	Aad, G., et al. (författare) 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 2023 Ingår i: Journal of High Energy Physics (JHEP). - : Springer. - 1126-6708 .- 1029-8479. ; 2023:12 Tidskriftsartikel (refereegranskat)abstract 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 13 TeV 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-leading-order 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.
4.	Aad, G., et al. (författare) Fast b-tagging at the high-level trigger of the ATLAS experiment in LHC Run 3 2023 Ingår i: Journal of Instrumentation. - : Institute of Physics. - 1748-0221. ; 18:11 Tidskriftsartikel (refereegranskat)abstract The ATLAS experiment relies on real-time hadronic jet reconstruction and b-tagging to record fully hadronic events containing b-jets. These algorithms require track reconstruction, which is computationally expensive and could overwhelm the high-level-trigger farm, even at the reduced event rate that passes the ATLAS first stage hardware-based trigger. In LHC Run 3, ATLAS has mitigated these computational demands by introducing a fast neural-network-based b-tagger, which acts as a low-precision filter using input from hadronic jets and tracks. It runs after a hardware trigger and before the remaining high-level-trigger reconstruction. This design relies on the negligible cost of neural-network inference as compared to track reconstruction, and the cost reduction from limiting tracking to specific regions of the detector. In the case of Standard Model HH → bb̅bb̅, a key signature relying on b-jet triggers, the filter lowers the input rate to the remaining high-level trigger by a factor of five at the small cost of reducing the overall signal efficiency by roughly 2%.
5.	Aad, G., et al. (författare) Measurement of the B0s → μμ effective lifetime with the ATLAS detector 2023 Ingår i: Journal of High Energy Physics (JHEP). - : Springer Nature. - 1126-6708 .- 1029-8479. ; 2023:9 Tidskriftsartikel (refereegranskat)abstract This paper reports the first ATLAS measurement of the → μμ effective lifetime. The measurement is based on the data collected in 2015–2016, amounting to 26.3 fb−1 of 13 TeV LHC proton-proton collisions. The proper decay-time distribution of 58 ± 13 background-subtracted signal candidates is fit with simulated signal templates parameterised as a function of the effective lifetime, with statistical uncertainties extracted through a Neyman construction. The resulting effective measurement of the → μμ lifetime is (stat.) ± 0.17 (syst.) ps and it is found to be consistent with the Standard Model.
6.	Aad, G., et al. (författare) Measurement of the H→ γγ and H→ ZZ∗→ 4 ℓ cross-sections in pp collisions at √s=13.6 TeV with the ATLAS detector 2024 Ingår i: European Physical Journal C. - : Institute for Ionics. - 1434-6044 .- 1434-6052. ; 84:1 Tidskriftsartikel (refereegranskat)abstract The inclusive Higgs boson production cross-section is measured in the di-photon and the ZZ∗→ 4 ℓ decay channels using 31.4 and 29.0 fb - 1 of pp collision data respectively, collected with the ATLAS detector at a centre-of-mass energy of s=13.6 TeV . To reduce the model dependence, the measurement in each channel is restricted to a particle-level phase space that closely matches the channel’s detector-level kinematic selection, and it is corrected for detector effects. These measured fiducial cross-sections are σfid,γγ= 76-13+14 fb, and σfid,4ℓ= 2.80±0.74 fb, in agreement with the corresponding Standard Model predictions of 67.6 ± 3.7 fb and 3.67 ± 0.19 fb. Assuming Standard Model acceptances and branching fractions for the two channels, the fiducial measurements are extrapolated to the full phase space yielding total cross-sections of σ(pp→H)=67-11+12 pb and 46 ± 12 pb at 13.6 TeV from the di-photon and ZZ∗→ 4 ℓ measurements respectively. The two measurements are combined into a total cross-section measurement of σ(pp→ H) = 58.2 ± 8.7 pb, to be compared with the Standard Model prediction of σ(pp→ H) SM= 59.9 ± 2.6 pb.
7.	Aad, G., et al. (författare) Measurement of the production cross-section of J/ψ and ψ(2S) mesons in pp collisions at √s=13 TeV with the ATLAS detector 2024 Ingår i: European Physical Journal C. - : Springer Nature. - 1434-6044 .- 1434-6052. ; 84:2 Tidskriftsartikel (refereegranskat)abstract Measurements of the differential production cross-sections of prompt and non-prompt ?/? and ?(2S) mesons with transverse momenta between 8 and 360 GeV and rapidity in the range \|?\|<2 are reported. Furthermore, measurements of the non-prompt fractions of ?/? and ?(2S), and the prompt and non-prompt ?(2S)-to-?/? production ratios, are presented. The analysis is performed using 140 fb−1 of √?=13 TeV pp collision data recorded by the ATLAS detector at the LHC during the years 2015–2018.
8.	Aad, G., et al. (författare) Measurement of the t¯t¯ cross section and its ratio to the Z production cross section using pp collisions at √s=13.6 TeV with the ATLAS detector 2024 Ingår i: Physics Letters B. - : Elsevier. - 0370-2693 .- 1873-2445. ; 848 Tidskriftsartikel (refereegranskat)abstract The inclusive top-quark-pair production cross section ???̄ and its ratio to the ?-boson production cross section have been measured in proton–proton collisions at √? = 13.6 TeV, using 29 fb−1 of data collected in 2022 with the ATLAS experiment at the Large Hadron Collider. Using events with an opposite-charge electron-muon pair and ?-tagged jets, and assuming Standard Model decays, the top-quark-pair production cross section is measured to be ???̄ = 850± 3(stat.) ± 18(syst.) ± 20(lumi.) pb. The ratio of the ??̄ and the ?-boson production cross sections is also measured, where the ?-boson contribution is determined for inclusive ?+?− and ?+?− events in a fiducial phase space. The relative uncertainty on the ratio is reduced compared to the ??̄ cross section, thanks to the cancellation of several systematic uncertainties. The result for the ratio, ???̄∕? = 1.145 ± 0.003(stat.) ± 0.021(syst.)±0.002(lumi.) is consistent with the Standard Model prediction using the PDF4LHC21 PDF set.
9.	Aad, G., et al. (författare) Performance and calibration of quark/gluon-jet taggers using 140 fb-1 of pp collisions at √s=13 TeV with the ATLAS detector 2024 Ingår i: Chinese Physics C. - : IOP Publishing. - 1674-1137 .- 2058-6132. ; 48:2 Tidskriftsartikel (refereegranskat)abstract The identification of jets originating from quarks and gluons, often referred to as quark/gluon tagging, plays an important role in various analyses performed at the Large Hadron Collider, as Standard Model measurements and searches for new particles decaying to quarks often rely on suppressing a large gluon-induced background. This paper describes the measurement of the efficiencies of quark/gluon taggers developed within the ATLAS Collaboration, using √?=13 TeV proton–proton collision data with an integrated luminosity of 140 fb−1 collected by the ATLAS experiment. Two taggers with high performances in rejecting jets from gluon over jets from quarks are studied: one tagger is based on requirements on the number of inner-detector tracks associated with the jet, and the other combines several jet substructure observables using a boosted decision tree. A method is established to determine the quark/gluon fraction in data, by using quark/gluon-enriched subsamples defined by the jet pseudorapidity. Differences in tagging efficiency between data and simulation are provided for jets with transverse momentum between 500 GeV and 2 TeV and for multiple tagger working points.
10.	Aad, G., et al. (författare) Pursuit of paired dijet resonances in the Run 2 dataset with ATLAS 2023 Ingår i: Physical Review D. - 2470-0010 .- 2470-0029. ; 108:11 Tidskriftsartikel (refereegranskat)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 140 fb−1 of proton-proton collisions at √s=13 TeV 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.
11.	Aad, G., et al. (författare) Search for a CP-odd Higgs boson decaying into a heavy CP-even Higgs boson and a Z boson in the ℓ+ℓ−??¯ and ??¯??¯ final states using 140 fb−1 of data collected with the ATLAS detector 2024 Ingår i: Journal of High Energy Physics (JHEP). - 1126-6708 .- 1029-8479. ; 2024:2 Tidskriftsartikel (refereegranskat)abstract A search for a heavy CP-odd Higgs boson, A, decaying into a Z boson and a heavy CP-even Higgs boson, H, is presented. It uses the full LHC Run 2 dataset of pp collisions at √? = 13 TeV collected with the ATLAS detector, corresponding to an integrated luminosity of 140 fb−1. The search for A → ZH is performed in the ℓ+ℓ− and final states and surpasses the reach of previous searches in different final states in the region with mH > 350 GeV and mA > 800 GeV. No significant deviation from the Standard Model expectation is found. Upper limits are placed on the production cross-section times the decay branching ratios. Limits with less model dependence are also presented as functions of the reconstructed and distributions in the ℓ+ℓ− and channels, respectively. In addition, the results are interpreted in the context of two-Higgs-doublet models.
12.	Aad, G., et al. (författare) Search for a new heavy scalar particle decaying into a Higgs boson and a new scalar singlet in final states with one or two light leptons and a pair of τ-leptons with the ATLAS detector 2023 Ingår i: Journal of High Energy Physics (JHEP). - : Springer Nature. - 1126-6708 .- 1029-8479. ; 2023:10 Tidskriftsartikel (refereegranskat)abstract A search for a new heavy scalar particle X decaying into a Standard Model (SM) Higgs boson and a new singlet scalar particle S is presented. The search uses a proton-proton (pp) collision data sample with an integrated luminosity of 140 fb−1 recorded at a centre-of-mass energy of √s= 13 TeV with the ATLAS detector at the Large Hadron Collider. The most sensitive mass parameter space is explored in X mass ranging from 500 to 1500 GeV, with the corresponding S mass in the range 200–500 GeV. The search selects events with two hadronically decaying τ-lepton candidates from H → τ+τ− decays and one or two light leptons (ℓ = e, μ) from S → VV (V = W, Z) decays while the remaining V boson decays hadronically or to neutrinos. A multivariate discriminant based on event kinematics is used to separate the signal from the background. No excess is observed beyond the expected SM background and 95% confidence level upper limits between 72 fb and 542 fb are derived on the cross-section σ(pp → X → SH) assuming the same SM-Higgs boson-like decay branching ratios for the S → VV decay. Upper limits on the visible cross-sections σ(pp → X → SH → WWττ) and σ(pp → X → SH → ZZττ) are also set in the ranges 3–26 fb and 6–33 fb, respectively.
13.	Aad, G., et al. (författare) Search for direct production of electroweakinos in final states with one lepton, jets and missing transverse momentum in pp collisions at √s=13 TeV with the ATLAS detector 2023 Ingår i: Journal of High Energy Physics (JHEP). - : Springer Nature. - 1126-6708 .- 1029-8479. ; 2023:12 Tidskriftsartikel (refereegranskat)abstract Searches for electroweak production of wino-like chargino pairs, , and of wino-like chargino and next-to-lightest neutralino, , are presented. The models explored assume that the charginos decay into a W boson and the lightest neutralino, . The next-to-lightest neutralinos are degenerate in mass with the chargino and decay to and either a Z or a Higgs boson, or . The searches exploit the presence of a single isolated lepton and missing transverse momentum from the W boson decay products and the lightest neutralinos, and the presence of jets from hadronically decaying Z or W bosons or from the Higgs boson decaying into a pair of b-quarks. The searches use 139 fb−1 of √s = 13 TeV proton-proton collisions data collected by the ATLAS detector at the Large Hadron Collider between 2015 and 2018. No deviations from the Standard Model expectations are found, and 95% confidence level exclusion limits are set. Chargino masses ranging from 260 to 520 GeV are excluded for a massless in chargino pair production models. Degenerate chargino and next-to-lightest neutralino masses ranging from 260 to 420 GeV are excluded for a massless for . For decays through an on-shell Higgs boson and for mass-splitting between and as small as the Higgs boson mass, mass limits are improved by up to 40 GeV in the range of 200–260 GeV and 280–470 GeV compared to previous ATLAS constraints.
14.	Aad, G., et al. (författare) Search for flavour-changing neutral tqH interactions with H → γγ in pp collisions at √s=13 TeV using the ATLAS detector 2023 Ingår i: Journal of High Energy Physics (JHEP). - : Springer. - 1126-6708 .- 1029-8479. ; 2023:12 Tidskriftsartikel (refereegranskat)abstract A search for flavour-changing neutral interactions involving the top quark, the Higgs boson and an up-type quark q (q = c, u) is presented. The proton-proton collision data set used, with an integrated luminosity of 139 fb−1, was collected at √s = 13 TeV by the ATLAS experiment at the Large Hadron Collider. Both the decay process t → qH in production and the production process pp → tH, with the Higgs boson decaying into two photons, are investigated. No significant excess is observed and upper limits are set on the t → cH and the t → uH branching ratios of 4.3 × 10−4 and 3.8 × 10−4, respectively, at the 95% confidence level, while the expected limits in the absence of signal are 4.7 × 10−4 and 3.9 × 10−4. Combining this search with ATLAS searches in the H → τ+τ− and H → final states yields observed (expected) upper limits on the t → cH branching ratio of 5.8 × 10−4 (3.0 × 10−4) at the 95% confidence level. The corresponding observed (expected) upper limit on the t → uH branching ratio is 4.0 × 10−4 (2.4 × 10−4).
15.	Aad, G., et al. (författare) Search for Majorana neutrinos in same-sign WW scattering events from pp collisions at √s=13 TeV 2023 Ingår i: European Physical Journal C. - : Institute for Ionics. - 1434-6044 .- 1434-6052. ; 83:9 Tidskriftsartikel (refereegranskat)abstract A search for Majorana neutrinos in same-sign WW scattering events is presented. The analysis uses √s=13 TeV proton–proton collision data with an integrated luminosity of 140 fb−1 recorded during 2015–2018 by the ATLAS detector at the Large Hadron Collider. The analysis targets final states including exactly two same-sign muons and at least two hadronic jets well separated in rapidity. The modelling of the main backgrounds, from Standard Model same-sign WW scattering and WZ production, is constrained with data in dedicated signal-depleted control regions. The distribution of the transverse momentum of the second-hardest muon is used to search for signals originating from a heavy Majorana neutrino with a mass between 50 GeV and 20 TeV. No significant excess is observed over the background expectation. The results are interpreted in a benchmark scenario of the Phenomenological Type-I Seesaw model. In addition, the sensitivity to the Weinberg operator is investigated. Upper limits at the 95% confidence level are placed on the squared muon-neutrino–heavy-neutrino mass-mixing matrix element \|VμN\|2 as a function of the heavy Majorana neutrino’s mass mN, and on the effective μμ Majorana neutrino mass \|mμμ\|.
16.	Aad, G., et al. (författare) Search for resonant production of dark quarks in the dijet final state with the ATLAS detector 2024 Ingår i: Journal of High Energy Physics (JHEP). - : Springer Nature. - 1126-6708 .- 1029-8479. ; 2024:2 Tidskriftsartikel (refereegranskat)abstract This paper presents a search for a new Z′ resonance decaying into a pair of dark quarks which hadronise into dark hadrons before promptly decaying back as Standard Model particles. This analysis is based on proton-proton collision data recorded at √? = 13 TeV with the ATLAS detector at the Large Hadron Collider between 2015 and 2018, corresponding to an integrated luminosity of 139 fb−1. After selecting events containing large-radius jets with high track multiplicity, the invariant mass distribution of the two highest-transverse-momentum jets is scanned to look for an excess above a data-driven estimate of the Standard Model multijet background. No significant excess of events is observed and the results are thus used to set 95% confidence-level upper limits on the production cross-section times branching ratio of the Z′ to dark quarks as a function of the Z′ mass for various dark-quark scenarios.
17.	Aad, G., et al. (författare) Search for the Zγ decay mode of new high-mass resonances in pp collisions at √?=13 TeV with the ATLAS detector 2024 Ingår i: Physics Letters B. - 0370-2693 .- 1873-2445. ; 848 Tidskriftsartikel (refereegranskat)abstract This letter presents a search for narrow, high-mass resonances in the Zγ final state with the Z boson decaying into a pair of electrons or muons. The √?=13 TeV pp collision data were recorded by the ATLAS detector at the CERN Large Hadron Collider and have an integrated luminosity of 140 fb−1. The data are found to be in agreement with the Standard Model background expectation. Upper limits are set on the resonance production cross section times the decay branching ratio into Zγ. For spin-0 resonances produced via gluon–gluon fusion, the observed limits at 95% confidence level vary between 65.5 fb and 0.6 fb, while for spin-2 resonances produced via gluon–gluon fusion (or quark–antiquark initial states) limits vary between 77.4 (76.1) fb and 0.6 (0.5) fb, for the mass range from 220 GeV to 3400 GeV.
18.	Aad, G., et al. (författare) Studies of new Higgs boson interactions through nonresonant HH production in the b¯bγγ final state in pp collisions at √s = 13 TeV with the ATLAS detector 2024 Ingår i: Journal of High Energy Physics (JHEP). - : Springer. - 1126-6708 .- 1029-8479. ; 2024:1 Tidskriftsartikel (refereegranskat)abstract A search for nonresonant Higgs boson pair production in the final state is performed using 140 fb−1 of proton-proton collisions at a centre-of-mass energy of 13 TeV recorded by the ATLAS detector at the CERN Large Hadron Collider. This analysis supersedes and expands upon the previous nonresonant ATLAS results in this final state based on the same data sample. The analysis strategy is optimised to probe anomalous values not only of the Higgs (H) boson self-coupling modifier κλ but also 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 upper limit μHH < 4.0 is set at 95% confidence level on the Higgs boson pair production cross-section normalised to its Standard Model prediction. The 95% confidence intervals for the coupling modifiers are −1.4 < κλ < 6.9 and −0.5 < κ2V < 2.7, assuming all other Higgs boson couplings except the one under study are fixed to the Standard Model predictions. The results are interpreted in the Standard Model effective field theory and Higgs effective field theory frameworks in terms of constraints on the couplings of anomalous Higgs boson (self-)interactions.
19.	Andrean, Stefio Y., 1991-, et al. (författare) Comparison of inclusive and photon-tagged jet suppression in 5.02 TeV Pb+Pb collisions with ATLAS 2023 Ingår i: Physics Letters B. - : Elsevier BV. - 0370-2693 .- 1873-2445. ; 846 Tidskriftsartikel (refereegranskat)abstract 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.
20.	Mullier, Geoffrey A., et al. (författare) Differential cross-section measurements of the production of four charged leptons in association with two jets using the ATLAS detector 2024 Ingår i: Journal of High Energy Physics (JHEP). - : Springer Nature. - 1126-6708 .- 1029-8479. ; 2024:1 Tidskriftsartikel (refereegranskat)abstract Differential cross-sections are measured for the production of four charged leptons in association with two jets. These measurements are sensitive to final states in which the jets are produced via the strong interaction as well as to the purely-electroweak vector boson scattering process. The analysis is performed using proton-proton collision data collected by ATLAS at √s = 13 TeV and with an integrated luminosity of 140 fb−1. The data are corrected for the effects of detector inefficiency and resolution and are compared to state-of-the-art Monte Carlo event generator predictions. The differential cross-sections are used to search for anomalous weak-boson self-interactions that are induced by dimension-six and dimension-eight operators in Standard Model effective field theory.
21.	Mullier, Geoffrey A., et al. (författare) Measurement of the Centrality Dependence of the Dijet Yield in p+Pb Collisions at √sNN=8.16 TeV with the ATLAS Detector 2024 Ingår i: Physical Review Letters. - : American Physical Society. - 0031-9007 .- 1079-7114. ; 132:10 Tidskriftsartikel (refereegranskat)abstract 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.
22.	Mullier, Geoffrey A., et al. (författare) Search for the decay of the Higgs boson to a Z boson and a light pseudoscalar particle decaying to two photons 2024 Ingår i: Physics Letters B. - : Elsevier B.V.. - 0370-2693 .- 1873-2445. ; 850 Tidskriftsartikel (refereegranskat)abstract A search for the decay of the Higgs boson to a Z boson and a light, pseudoscalar particle, a, decaying respectively to two leptons and to two photons is reported. The search uses the full LHC Run 2 proton–proton collision data at √?=13 TeV, corresponding to 139 fb−1 collected by the ATLAS detector. This is one of the first searches for this specific decay mode of the Higgs boson, and it probes unexplored parameter space in models with axion-like particles (ALPs) and extended scalar sectors. The mass of the a particle is assumed to be in the range 0.1–33 GeV. The data are analysed in two categories: a merged category where the photons from the a decay are reconstructed in the ATLAS calorimeter as a single cluster, and a resolved category in which two separate photons are detected. The main background processes are from Standard Model Z boson production in association with photons or jets. The data are in agreement with the background predictions, and upper limits on the branching ratio of the Higgs boson decay to Za times the branching ratio ?→?? are derived at the 95% confidence level and they range from 0.08% to 2% depending on the mass of the a particle. The results are also interpreted in the context of ALP models.
23.	Mullier, Geoffrey A., et al. (författare) Search for vector-boson resonances decaying into a top quark and a bottom quark using pp collisions at √s=13 TeV with the ATLAS detector 2023 Ingår i: Journal of High Energy Physics (JHEP). - : Springer Nature. - 1126-6708 .- 1029-8479. ; 2023:12 Tidskriftsartikel (refereegranskat)abstract A search for a new massive charged gauge boson, W′, is performed with the ATLAS detector at the LHC. The dataset used in this analysis was collected from proton-proton collisions at a centre-of-mass energy of √s = 13 TeV, and corresponds to an integrated luminosity of 139 fb−1. The reconstructed tb invariant mass is used to search for a W′ boson decaying into a top quark and a bottom quark. The result is interpreted in terms of a W′ boson with purely right-handed or left-handed chirality in a mass range of 0.5–6 TeV. Different values for the coupling of the W′ boson to the top and bottom quarks are considered, taking into account interference with single-top-quark production in the s-channel. No significant deviation from the background prediction is observed. The results are expressed as upper limits on the W′ → tb production cross-section times branching ratio as a function of the W′-boson mass and in the plane of the coupling vs the W′-boson mass.
24.	Aad, G., et al. (författare) 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 2023 Ingår i: Journal of High Energy Physics (JHEP). - : Springer Nature. - 1126-6708 .- 1029-8479. ; 2023:7 Tidskriftsartikel (refereegranskat)abstract 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.
25.	Aad, G., et al. (författare) 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 2023 Ingår i: Physical Review D. - : AMER PHYSICAL SOC. - 2470-0010 .- 2470-0029. ; 108:5 Tidskriftsartikel (refereegranskat)abstract 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 √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 , 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 for signals with mY between 1.5 and 6 TeV and mX between 65 and 3000 GeV.

Skapa referenser, mejla, bekava och länka

Länka till träfflistan

Träfflista för sökning "WFRF:(Pereira Sanchez Laura 1995 ) "

Avgränsa träffmängd

År