Evgeniya Cheremushkina
@desy.de
ATLAS group
Desy (Zeuthen)
Scopus Publications
Scopus Publications
, G. Aad, B. Abbott, K. Abeling, N. J. Abicht, S. H. Abidi, A. Aboulhorma, H. Abramowicz, H. Abreu, Y. Abulaiti,et al.
Springer Science and Business Media LLC
AbstractCharged particle reconstruction in the presence of many simultaneous proton–proton ($$p {} p $$ p p ) collisions in the LHC is a challenging task for the ATLAS experiment’s reconstruction software due to the combinatorial complexity. This paper describes the major changes made to adapt the software to reconstruct high-activity collisions with an average of 50 or more simultaneous $$p {} p $$ p p interactions per bunch crossing (pile-up) promptly using the available computing resources. The performance of the key components of the track reconstruction chain and its dependence on pile-up are evaluated, and the improvement achieved compared to the previous software version is quantified. For events with an average of $$60~p {} p $$ 60 p p collisions per bunch crossing, the updated track reconstruction is twice as fast as the previous version, without significant reduction in reconstruction efficiency and while reducing the rate of combinatorial fake tracks by more than a factor two.
G. Aad, B. Abbott, K. Abeling, N. J. Abicht, S. H. Abidi, A. Aboulhorma, H. Abramowicz, H. Abreu, Y. Abulaiti, B. S. Acharya,et al.
American Physical Society (APS)
This Letter presents the first study of Higgs boson production in association with a vector boson (V=W or Z) in the fully hadronic qqbb final state using data recorded by the ATLAS detector at the LHC in proton-proton collisions at sqrt[s]=13 TeV and corresponding to an integrated luminosity of 137 fb^{-1}. The vector bosons and Higgs bosons are each reconstructed as large-radius jets and tagged using jet substructure techniques. Dedicated tagging algorithms exploiting b-tagging properties are used to identify jets consistent with Higgs bosons decaying into bb[over ¯]. Dominant backgrounds from multijet production are determined directly from the data, and a likelihood fit to the jet mass distribution of Higgs boson candidates is used to extract the number of signal events. The VH production cross section is measured inclusively and differentially in several ranges of Higgs boson transverse momentum: 250-450, 450-650, and greater than 650 GeV. The inclusive signal yield relative to the standard model expectation is observed to be μ=1.4_{-0.9}^{+1.0} and the corresponding cross section is 3.1±1.3(stat)_{-1.4}^{+1.8}(syst) pb.
G. Aad, B. Abbott, K. Abeling, N. J. Abicht, S. H. Abidi, A. Aboulhorma, H. Abramowicz, H. Abreu, Y. Abulaiti, B. S. Acharya,et al.
American Physical Society (APS)
ATLAS measured the centrality dependence of the dijet yield using 165 nb^{-1} of p+Pb data collected at sqrt[s_{NN}]=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, R_{CP}, is evaluated, and the results are presented as a function of variables that reflect the kinematics of the initial hard parton scattering process. The R_{CP} shows a scaling with the Bjorken x of the parton originating from the proton, x_{p}, while no such trend is observed as a function of x_{Pb}. 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 x_{p}∼10^{-3} and x_{Pb}∼4×10^{-4}.
, G. Aad, B. Abbott, K. Abeling, N. J. Abicht, S. H. Abidi, A. Aboulhorma, H. Abramowicz, H. Abreu, Y. Abulaiti,et al.
Springer Science and Business Media LLC
AbstractThis paper presents for the first time a precise measurement of the production properties of the Z boson in the full phase space of the decay leptons. This is in contrast to the many previous precise unfolded measurements performed in the fiducial phase space of the decay leptons. The measurement is obtained from proton–proton collision data collected by the ATLAS experiment in 2012 at $$\\sqrt{s} = 8$$ s = 8 TeV at the LHC and corresponding to an integrated luminosity of 20.2 fb$$^{-1}$$ - 1 . The results, based on a total of 15.3 million Z-boson decays to electron and muon pairs, extend and improve a previous measurement of the full set of angular coefficients describing Z-boson decay. The double-differential cross-section distributions in Z-boson transverse momentum $$p_{\\text {T}}$$ p T and rapidity $$y$$ y are measured in the pole region, defined as $$80< m^{\\ell \\ell }< 100$$ 80 < m ℓ ℓ < 100 GeV, over the range $$|y| < 3.6$$ | y | < 3.6 . The total uncertainty of the normalised cross-section measurements in the peak region of the $$p_{\\text {T}}$$ p T distribution is dominated by statistical uncertainties over the full range and increases as a function of rapidity from 0.5–1.0% for $$|y| < 2.0$$ | y | < 2.0 to $$2-7\\%$$ 2 - 7 % at higher rapidities. The results for the rapidity-dependent transverse momentum distributions are compared to state-of-the-art QCD predictions, which combine in the best cases approximate N$$^4$$ 4 LL resummation with N$$^3$$ 3 LO fixed-order perturbative calculations. The differential rapidity distributions integrated over $$p_{\\text {T}}$$ p T are even more precise, with accuracies from 0.2–0.3% for $$|y| < 2.0$$ | y | < 2.0 to 0.4–0.9% at higher rapidities, and are compared to fixed-order QCD predictions using the most recent parton distribution functions. The agreement between data and predictions is quite good in most cases.
G. Aad, B. Abbott, K. Abeling, N.J. Abicht, S.H. Abidi, A. Aboulhorma, H. Abramowicz, H. Abreu, Y. Abulaiti, B.S. Acharya,et al.
Elsevier BV
G. Aad, B. Abbott, K. Abeling, N. J. Abicht, S. H. Abidi, A. Aboulhorma, H. Abramowicz, H. Abreu, Y. Abulaiti, A. C. Abusleme Hoffman,et al.
American Physical Society (APS)
Searches for new resonances are performed using an unsupervised anomaly-detection technique. Events with at least one electron or muon are selected from 140 fb^{-1} of pp collisions at sqrt[s]=13 TeV recorded by ATLAS at the Large Hadron Collider. The approach involves training an autoencoder on data, and subsequently defining anomalous regions based on the reconstruction loss of the decoder. Studies focus on nine invariant mass spectra that contain pairs of objects consisting of one light jet or b jet and either one lepton (e,μ), photon, or second light jet or b jet in the anomalous regions. No significant deviations from the background hypotheses are observed. Limits on contributions from generic Gaussian signals with various widths of the resonance mass are obtained for nine invariant masses in the anomalous regions.
, G. Aad, B. Abbott, K. Abeling, N. J. Abicht, S. H. Abidi, A. Aboulhorma, H. Abramowicz, H. Abreu, Y. Abulaiti,et al.
Springer Science and Business Media LLC
AbstractA search for the associated production of a heavy resonance with a top-quark or a top-antitop-quark pair, and decaying into a $$t{\\bar{t}}$$ t t ¯ pair is presented. The search uses the data recorded by the ATLAS detector in pp collisions at $$\\sqrt{s}= 13$$ s = 13 $$\\text {TeV}$$ TeV at the Large Hadron Collider during the years 2015–2018, corresponding to an integrated luminosity of 139 $$\\text {fb}^{-1}$$ fb - 1 . Events containing exactly one electron or muon are selected. The two hadronically decaying top quarks from the resonance decay are reconstructed using jets clustered with a large radius parameter of $$R=1$$ R = 1 . The invariant mass spectrum of the two top quark candidates is used to search for a resonance signal in the range of 1.0 $$\\text {TeV}$$ TeV to 3.2 $$\\text {TeV}$$ TeV . The presence of a signal is examined using an approach with minimal model dependence followed by a model-dependent interpretation. No significant excess is observed over the background expectation. Upper limits on the production cross section times branching ratio at 95% confidence level are provided for a heavy $$Z^\\prime $$ Z ′ boson based on a simplified model, for $$Z^\\prime $$ Z ′ mass between 1.0 $$\\text {TeV}$$ TeV and 3.0 $$\\text {TeV}$$ TeV . The observed (expected) limits range from 21 (14) fb to 119 (86) fb depending on the choice of model parameters.
, G. Aad, B. Abbott, K. Abeling, N. J. Abicht, S. H. Abidi, A. Aboulhorma, H. Abramowicz, H. Abreu, Y. Abulaiti,et al.
Springer Science and Business Media LLC
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 $$ \\sqrt{s} $$ s = 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 $$ {\\ell}^{+}{\\ell}^{-}t\\overline{t} $$ ℓ + ℓ − t t ¯ and $$ \\nu \\overline{\\nu}b\\overline{b} $$ ν ν ¯ b b ¯ 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 m($$ t\\overline{t} $$ t t ¯ ) and m($$ b\\overline{b} $$ b b ¯ ) distributions in the $$ {\\ell}^{+}{\\ell}^{-}t\\overline{t} $$ ℓ + ℓ − t t ¯ and $$ \\nu \\overline{\\nu}b\\overline{b} $$ ν ν ¯ b b ¯ channels, respectively. In addition, the results are interpreted in the context of two-Higgs-doublet models.
, G. Aad, B. Abbott, K. Abeling, N. J. Abicht, S. H. Abidi, A. Aboulhorma, H. Abramowicz, H. Abreu, Y. Abulaiti,et al.
Springer Science and Business Media LLC
Abstract A search for non-resonant Higgs boson pair (HH) production is presented, in which one of the Higgs bosons decays to a b-quark pair ($$ b\\overline{b} $$ b b ¯ ) and the other decays to WW*, ZZ*, or τ+τ−, with in each case a final state with ℓ+ℓ−+ neutrinos (ℓ = e, μ). The analysis targets separately the gluon-gluon fusion and vector boson fusion production modes. Data recorded by the ATLAS detector in proton-proton collisions at a centre-of-mass energy of 13 TeV at the Large Hadron Collider, corresponding to an integrated luminosity of 140 fb−1, are used in this analysis. Events are selected to have exactly two b-tagged jets and two leptons with opposite electric charge and missing transverse momentum in the final state. These events are classified using multivariate analysis algorithms to separate the HH events from other Standard Model processes. No evidence of the signal is found. The observed (expected) upper limit on the cross-section for non-resonant Higgs boson pair production is determined to be 9.7 (16.2) times the Standard Model prediction at 95% confidence level. The Higgs boson self-interaction coupling parameter κλ and the quadrilinear coupling parameter κ2V are each separately constrained by this analysis to be within the ranges [−6.2, 13.3] and [−0.17, 2.4], respectively, at 95% confidence level, when all other parameters are fixed.
, G. Aad, B. Abbott, K. Abeling, N. J. Abicht, S. H. Abidi, A. Aboulhorma, H. Abramowicz, H. Abreu, Y. Abulaiti,et al.
Springer Science and Business Media LLC
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 $$ \\sqrt{s} $$ s = 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.
, G. Aad, B. Abbott, K. Abeling, N. J. Abicht, S. H. Abidi, A. Aboulhorma, H. Abramowicz, H. Abreu, Y. Abulaiti,et al.
Springer Science and Business Media LLC
Abstract A search for pair production of squarks or gluinos decaying via sleptons or weak bosons is reported. The search targets a final state with exactly two leptons with same-sign electric charge or at least three leptons without any charge requirement. The analysed data set corresponds to an integrated luminosity of 139 fb−1 of proton-proton collisions collected at a centre-of-mass energy of 13 TeV with the ATLAS detector at the LHC. Multiple signal regions are defined, targeting several SUSY simplified models yielding the desired final states. A single control region is used to constrain the normalisation of the WZ + jets background. No significant excess of events over the Standard Model expectation is observed. The results are interpreted in the context of several supersymmetric models featuring R-parity conservation or R-parity violation, yielding exclusion limits surpassing those from previous searches. In models considering gluino (squark) pair production, gluino (squark) masses up to 2.2 (1.7) TeV are excluded at 95% confidence level.
G. Aad, B. Abbott, D. C. Abbott, A. Abed Abud, K. Abeling, D. K. Abhayasinghe, S. H. Abidi, O. S. AbouZeid, N. L. Abraham, H. Abramowicz,et al.
American Physical Society (APS)
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 $\\sqrt{s}$ = 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-sections 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.
, G. Aad, B. Abbott, K. Abeling, N. J. Abicht, S. H. Abidi, A. Aboulhorma, H. Abramowicz, H. Abreu, Y. Abulaiti,et al.
Springer Science and Business Media LLC
G. Aad, B. Abbott, K. Abeling, N.J. Abicht, S.H. Abidi, A. Aboulhorma, H. Abramowicz, H. Abreu, Y. Abulaiti, B.S. Acharya,et al.
IOP Publishing
Abstract This paper presents the electron and photon energy calibration obtained with the ATLAS detector using 140 fb-1 of LHC proton-proton collision data recorded at √(s) = 13 TeV between 2015 and 2018. Methods for the measurement of electron and photon energies are outlined, along with the current knowledge of the passive material in front of the ATLAS electromagnetic calorimeter. The energy calibration steps are discussed in detail, with emphasis on the improvements introduced in this paper. The absolute energy scale is set using a large sample of Z-boson decays into electron-positron pairs, and its residual dependence on the electron energy is used for the first time to further constrain systematic uncertainties. The achieved calibration uncertainties are typically 0.05% for electrons from resonant Z-boson decays, 0.4% at E T ∼ 10 GeV, and 0.3% at E T ∼ 1 TeV; for photons at E T ∼ 60 GeV, they are 0.2% on average. This is more than twice as precise as the previous calibration. The new energy calibration is validated using J/ψ → ee and radiative Z-boson decays.
G. Aad, B. Abbott, D.C. Abbott, K. Abeling, S.H. Abidi, A. Aboulhorma, H. Abramowicz, H. Abreu, Y. Abulaiti, A.C. Abusleme Hoffman,et al.
Elsevier BV
G. Aad, B. Abbott, K. Abeling, N.J. Abicht, S.H. Abidi, A. Aboulhorma, H. Abramowicz, H. Abreu, Y. Abulaiti, B.S. Acharya,et al.
IOP Publishing
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 TeV proton–proton collision data with an integrated luminosity of 140 fb 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.
G. Aad, B. Abbott, K. Abeling, N. J. Abicht, S. H. Abidi, A. Aboulhorma, H. Abramowicz, H. Abreu, Y. Abulaiti, A. C. Abusleme Hoffman,et al.
American Physical Society (APS)
This Letter reports the observation of WZγ production and a measurement of its cross section using 140.1±1.2 fb^{-1} of proton-proton collision data recorded at a center-of-mass energy of 13 TeV by the ATLAS detector at the Large Hadron Collider. The WZγ production cross section, with both the W and Z bosons decaying leptonically, pp→WZγ→ℓ^{'}^{±}νℓ^{+}ℓ^{-}γ (ℓ^{(^{'})}=e, μ), is measured in a fiducial phase-space region defined such that the leptons and the photon have high transverse momentum and the photon is isolated. The cross section is found to be 2.01±0.30(stat)±0.16(syst) fb. The corresponding standard model predicted cross section calculated at next-to-leading order in perturbative quantum chromodynamics and at leading order in the electroweak coupling constant is 1.50±0.06 fb. The observed significance of the WZγ signal is 6.3σ, compared with an expected significance of 5.0σ.
G. Aad, B. Abbott, K. Abeling, N. J. Abicht, S. H. Abidi, A. Aboulhorma, H. Abramowicz, H. Abreu, Y. Abulaiti, B. S. Acharya,et al.
American Physical Society (APS)
G. Aad, B. Abbott, K. Abeling, N.J. Abicht, S.H. Abidi, A. Aboulhorma, H. Abramowicz, H. Abreu, Y. Abulaiti, A.C. Abusleme Hoffman,et al.
Elsevier BV
G. Aad, B. Abbott, K. Abeling, N.J. Abicht, S.H. Abidi, A. Aboulhorma, H. Abramowicz, H. Abreu, Y. Abulaiti, B.S. Acharya,et al.
Elsevier BV
, G. Aad, B. Abbott, K. Abeling, N. J. Abicht, S. H. Abidi, A. Aboulhorma, H. Abramowicz, H. Abreu, Y. Abulaiti,et al.
Springer Science and Business Media LLC
AbstractThe inclusive Higgs boson production cross-section is measured in the di-photon and the $$ZZ^* \\rightarrow 4 \\ell $$ Z Z ∗ → 4 ℓ decay channels using 31.4 and 29.0 fb$$^{-1}$$ - 1 of pp collision data respectively, collected with the ATLAS detector at a centre-of-mass energy of $$\\sqrt{s}=13.6$$ s = 13.6 $$\\text {TeV}$$ 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 $$\\sigma _{\\textrm{fid},\\gamma \\gamma } = $$ σ fid , γ γ = $$76^{+14}_{-13}$$ 76 - 13 + 14 fb, and $$\\sigma _{\\textrm{fid},4 \\ell } =$$ σ fid , 4 ℓ = $$2.80\\, \\pm \\, 0.74$$ 2.80 ± 0.74 fb, in agreement with the corresponding Standard Model predictions of $$67.6 \\pm 3.7 $$ 67.6 ± 3.7 fb and $$3.67 \\pm 0.19 $$ 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 $$\\sigma (pp \\rightarrow H) = 67^{+12}_{-11}$$ σ ( p p → H ) = 67 - 11 + 12 pb and $$46 \\pm 12$$ 46 ± 12 pb at 13.6 $$\\text {TeV}$$ TeV from the di-photon and $$ZZ^* \\rightarrow 4 \\ell $$ Z Z ∗ → 4 ℓ measurements respectively. The two measurements are combined into a total cross-section measurement of $$\\sigma (pp \\rightarrow H)= 58.2 \\pm 8.7$$ σ ( p p → H ) = 58.2 ± 8.7 pb, to be compared with the Standard Model prediction of $$\\sigma (pp \\rightarrow H)_\\textrm{SM} = 59.9 \\pm 2.6 $$ σ ( p p → H ) SM = 59.9 ± 2.6 pb.
G. Aad, B. Abbott, K. Abeling, N.J. Abicht, S.H. Abidi, A. Aboulhorma, H. Abramowicz, H. Abreu, Y. Abulaiti, B.S. Acharya,et al.
Elsevier BV
G. Aad, B. Abbott, K. Abeling, N.J. Abicht, S.H. Abidi, A. Aboulhorma, H. Abramowicz, H. Abreu, Y. Abulaiti, A.C. Abusleme Hoffman,et al.
Elsevier BV
G. Aad, B. Abbott, K. Abeling, N. J. Abicht, S. H. Abidi, A. Aboulhorma, H. Abramowicz, H. Abreu, Y. Abulaiti, A. C. Abusleme Hoffman,et al.
American Physical Society (APS)
G. Aad, B. Abbott, K. Abeling, N. J. Abicht, S. H. Abidi, A. Aboulhorma, H. Abramowicz, H. Abreu, Y. Abulaiti, B. S. Acharya,et al.
American Physical Society (APS)