Publications
1265 results found
Tumasyan A, Adam W, Andrejkovic JW, et al., 2023, Search for Higgs boson decays to a Z boson and a photon in proton-proton collisions at √s=13 TeV, JOURNAL OF HIGH ENERGY PHYSICS, ISSN: 1029-8479
Tumasyan A, Adam W, Andrejkovic JW, et al., 2023, Search for heavy resonances and quantum black holes in eμ, eτ, and μτ final states in proton-proton collisions at √<i>s</i>=13 TeV, JOURNAL OF HIGH ENERGY PHYSICS, ISSN: 1029-8479
Tumasyan A, Adam W, Andrejkovic JW, et al., 2023, Strange hadron collectivity in pPb and PbPb collisions, JOURNAL OF HIGH ENERGY PHYSICS, ISSN: 1029-8479
Tumasyan A, Adam W, Andrejkovic JW, et al., 2023, Publisher Correction: Observation of triple J/ψ meson production in proton-proton collisions (Nature Physics, (2023), 19, 3, (338-350), 10.1038/s41567-022-01838-y), Nature Physics, Vol: 19, ISSN: 1745-2473
Correction to: Nature Physics. Published online 19 January 2023. In the version of this article initially published, the first affiliation—Yerevan Physics Institute, Yerevan, Armenia—was missing from the list of author affiliations and has now been inserted in the HTML and PDF versions of the article.
Sirunyan AM, Tumasyan A, Adam W, et al., 2023, Measurement of prompt and nonprompt charmonium suppression in PbPb collisions at 5.02 TeV (vol 78, 509, 2018), EUROPEAN PHYSICAL JOURNAL C, Vol: 83, ISSN: 1434-6044
Tumasyan A, Adam W, Andrejkovic JW, et al., 2023, Observation of triple J/ψ meson production in proton-proton collisions, NATURE PHYSICS, ISSN: 1745-2473
Tumasyan A, Adam W, Andrejkovic JW, et al., 2023, Publisher Correction: Observation of triple J/ψ meson production in proton-proton collisions (Nature Physics, (2023), 19, 3, (338-350), 10.1038/s41567-022-01838-y), Nature Physics, ISSN: 1745-2473
Correction to: Nature Physics, published online 19 January 2023. In the version of the article initially published, the second affiliation of T. Elkafrawy was incorrect and is now shown as Ain Shams University, Cairo, Egypt in the HTML and PDF versions of the article.
Tumasyan A, Adam W, Andrejkovic JW, et al., 2023, Azimuthal correlations in Z +jets events in proton-proton collisions at s=13TeV., Eur Phys J C Part Fields, Vol: 83, ISSN: 1434-6044
The production of Z bosons associated with jets is measured in pp collisions at s=13TeV with data recorded with the CMS experiment at the LHC corresponding to an integrated luminosity of 36.3fb-1. The multiplicity of jets with transverse momentum pT>30GeV is measured for different regions of the Z boson's pT(Z), from lower than 10GeV to higher than 100GeV. The azimuthal correlation Δϕ between the Z boson and the leading jet, as well as the correlations between the two leading jets are measured in three regions of pT(Z). The measurements are compared with several predictions at leading and next-to-leading orders, interfaced with parton showers. Predictions based on transverse-momentum dependent parton distributions and corresponding parton showers give a good description of the measurement in the regions where multiple parton interactions and higher jet multiplicities are not important. The effects of multiple parton interactions are shown to be important to correctly describe the measured spectra in the low pT(Z) regions.
Tumasyan A, Adam W, Andrejkovic JW, et al., 2023, Measurement of the differential tt¯ production cross section as a function of the jet mass and extraction of the top quark mass in hadronic decays of boosted top quarks., Eur Phys J C Part Fields, Vol: 83, ISSN: 1434-6044
A measurement of the jet mass distribution in hadronic decays of Lorentz-boosted top quarks is presented. The measurement is performed in the lepton + jets channel of top quark pair production (tt¯) events, where the lepton is an electron or muon. The products of the hadronic top quark decay are reconstructed using a single large-radius jet with transverse momentum greater than 400GeV. The data were collected with the CMS detector at the LHC in proton-proton collisions and correspond to an integrated luminosity of 138fb-1. The differential tt¯ production cross section as a function of the jet mass is unfolded to the particle level and is used to extract the top quark mass. The jet mass scale is calibrated using the hadronic W boson decay within the large-radius jet. The uncertainties in the modelling of the final state radiation are reduced by studying angular correlations in the jet substructure. These developments lead to a significant increase in precision, and a top quark mass of 173.06±0.84GeV.
Tumasyan A, Adam W, Andrejkovic JW, et al., 2023, CMS pythia 8 colour reconnection tunes based on underlying-event data., Eur Phys J C Part Fields, Vol: 83, ISSN: 1434-6044
New sets of parameter tunes for two of the colour reconnection models, quantum chromodynamics-inspired and gluon-move, implemented in the pythia 8 event generator, are obtained based on the default CMS pythia 8 underlying-event tune, CP5. Measurements sensitive to the underlying event performed by the CMS experiment at centre-of-mass energies s=7 and 13TeV, and by the CDF experiment at 1.96TeV are used to constrain the parameters of colour reconnection models and multiple-parton interactions simultaneously. The new colour reconnection tunes are compared with various measurements at 1.96, 7, 8, and 13TeV including measurements of the underlying-event, strange-particle multiplicities, jet substructure observables, jet shapes, and colour flow in top quark pair (tt¯) events. The new tunes are also used to estimate the uncertainty related to colour reconnection modelling in the top quark mass measurement using the decay products of tt¯ events in the semileptonic channel at 13TeV.
Tumasyan A, Adam W, Andrejkovic JW, et al., 2023, Search for light Higgs bosons from supersymmetric cascade decays in pp collisions at s=13TeV., Eur Phys J C Part Fields, Vol: 83, ISSN: 1434-6044
A search is reported for pairs of light Higgs bosons (H1) produced in supersymmetric cascade decays in final states with small missing transverse momentum. A data set of LHC pp collisions collected with the CMS detector at s=13TeV and corresponding to an integrated luminosity of 138fb-1 is used. The search targets events where both H1 bosons decay into pairs that are reconstructed as large-radius jets using substructure techniques. No evidence is found for an excess of events beyond the background expectations of the standard model (SM). Results from the search are interpreted in the next-to-minimal supersymmetric extension of the SM, where a "singlino" of small mass leads to squark and gluino cascade decays that can predominantly end in a highly Lorentz-boosted singlet-like H1 and a singlino-like neutralino of small transverse momentum. Upper limits are set on the product of the squark or gluino pair production cross section and the square of the branching fraction of the H1 in a benchmark model containing almost mass-degenerate gluinos and light-flavour squarks. Under the assumption of an SM-like branching fraction, H1 bosons with masses in the range 40-120GeV arising from the decays of squarks or gluinos with a mass of 1200-2500GeV are excluded at 95% confidence level.
Tumasyan A, Adam W, Andrejkovic JW, et al., 2023, A search for decays of the Higgs boson to invisible particles in events with a top-antitop quark pair or a vector boson in proton-proton collisions at s=13TeV., Eur Phys J C Part Fields, Vol: 83, ISSN: 1434-6044
A search for decays to invisible particles of Higgs bosons produced in association with a top-antitop quark pair or a vector boson, which both decay to a fully hadronic final state, has been performed using proton-proton collision data collected at s=13TeV by the CMS experiment at the LHC, corresponding to an integrated luminosity of 138fb-1. The 95% confidence level upper limit set on the branching fraction of the 125GeV Higgs boson to invisible particles, B(H→inv), is 0.54 (0.39 expected), assuming standard model production cross sections. The results of this analysis are combined with previous B(H→inv) searches carried out at s=7, 8, and 13TeV in complementary production modes. The combined upper limit at 95% confidence level on B(H→inv) is 0.15 (0.08 expected).
Tumasyan A, Adam W, Andrejkovic JW, et al., 2023, Measurements of jet multiplicity and jet transverse momentum in multijet events in proton-proton collisions at s=13TeV., Eur Phys J C Part Fields, Vol: 83, ISSN: 1434-6044
Multijet events at large transverse momentum (pT) are measured at s=13TeV using data recorded with the CMS detector at the LHC, corresponding to an integrated luminosity of 36.3fb-1. The multiplicity of jets with pT>50GeV that are produced in association with a high-pT dijet system is measured in various ranges of the pT of the jet with the highest transverse momentum and as a function of the azimuthal angle difference Δϕ1,2 between the two highest pT jets in the dijet system. The differential production cross sections are measured as a function of the transverse momenta of the four highest pT jets. The measurements are compared with leading and next-to-leading order matrix element calculations supplemented with simulations of parton shower, hadronization, and multiparton interactions. In addition, the measurements are compared with next-to-leading order matrix element calculations combined with transverse-momentum dependent parton densities and transverse-momentum dependent parton shower.
Tumasyan A, Adam W, Ambrogi F, et al., 2022, Nuclear modification of Y states in pPb collisions at √sNN = 5.02 TeV, Physics Letters B, Vol: 835, ISSN: 0370-2693
Production cross sections of Υ(1S), Υ(2S), and Υ(3S) states decaying into μ+μ− in proton-lead (pPb) collisions are reported using data collected by the CMS experiment at √sNN = 5.02 TeV. A comparison is made with corresponding cross sections obtained with pp data measured at the same collision energy and scaled by the Pb nucleus mass number. The nuclear modification factor for Υ(1S) is found to be RpPb(Υ(1S)) = 0.806±0.024 (stat)±0.059 (syst). Similar results for the excited states indicate a sequentialsuppression pattern, such that RpPb(Υ(1S)) > RpPb(Υ(2S)) > RpPb(Υ(3S)). The suppression of all states is much less pronounced in pPb than in PbPb collisions, and independent of transverse momentum pΥT and center-of-mass rapidity yΥCM of the individual Υ state in the studied range pΥT < 30 GeV/c and |yΥCM| <1.93. Models that incorporate final-state effects of bottomonia in pPb collisions are in better agreement with the data than those which only assume initial-state modifications.
Tumasyan A, Adam W, Andrejkovic JW, et al., 2022, Search for new particles in an extended Higgs sector with four b quarks in the final state at √s=13 TeV, PHYSICS LETTERS B, Vol: 835, ISSN: 0370-2693
Tumasyan A, Adam W, Andrejkovic JW, et al., 2022, Addendum: Measurement and QCD analysis of double-differential inclusive jet cross sections in proton-proton collisions at √s=13 TeV, JOURNAL OF HIGH ENERGY PHYSICS, ISSN: 1029-8479
Tumasyan A, Adam W, Bergauer T, et al., 2022, Measurements of the associated production of a W boson and a charm quark in proton-proton collisions at √<i>s</i>=8TeV, EUROPEAN PHYSICAL JOURNAL C, Vol: 82, ISSN: 1434-6044
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- Citations: 5
Tumasyan A, Adam W, Andrejkovic JW, et al., 2022, Search for new particles in an extended Higgs sector with four b quarks in the final state at <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si1.svg"><mml:msqrt><mml:mrow><mml:mi>s</mml:mi></mml:mrow></mml:msqrt><mml:mo linebreak="goodbreak" linebreakstyle="after">=</mml:mo><mml:mn>13</mml:mn><mml:mrow><mml:mspace width="0.20em" /><mml:mtext>TeV</mml:mtext></mml:mrow></mml:math>, Physics Letters B, Vol: 835, Pages: 137566-137566, ISSN: 0370-2693
Chatrchyan S, Khachatryan V, Sirunyan AM, et al., 2022, Searches for long-lived charged particles in pp collisions at √s = 7 and 8 TeV (vol 07, 122, 2013), JOURNAL OF HIGH ENERGY PHYSICS, ISSN: 1029-8479
Tumasyan A, Adam W, Andrejkovic JW, et al., 2022, Evidence for WW/WZ vector boson scattering in the decay channelνqq produced in association with two jets in proton-proton collisionsat √s = 13 TeV, Physics Letters B, Vol: 834, Pages: 1-28, ISSN: 0370-2693
Evidence is reported for electroweak (EW) vector boson scattering in the decay channel νqq of twoweak vector bosons WV (V = W or Z), produced in association with two parton jets. The search usesa data set of proton-proton collisions at 13 TeV collected with the CMS detector during 2016–2018with an integrated luminosity of 138 fb−1. Events are selected requiring one lepton (electron or muon),moderate missing transverse momentum, two jets with a large pseudorapidity separation and a large dijetinvariant mass, and a signature consistent with the hadronic decay of a W/Z boson. The cross section iscomputed in a fiducial phase space defined at parton level requiring all parton transverse momentapT > 10 GeV and at least one pair of outgoing partons with invariant mass mqq > 100 GeV. The measuredand expected EW WV production cross sections are 1.90+0.53−0.46 pb and 2.23+0.08−0.11(scale) ± 0.05(PDF) pb,respectively, where PDF is the parton distribution function. The observed EW signal strength is μEW =0.85 ± 0.12 (stat)+0.19−0.17 (syst), corresponding to a signal significance of 4.4 standard deviations with 5.1expected, and it is measured keeping the quantum chromodynamics (QCD) associated diboson productionfixed to the standard model prediction. This is the first evidence of vector boson scattering in the νqqdecay channel at LHC. The simultaneous measurement of the EW and QCD associated diboson productionagrees with the standard model prediction.
Tumasyan A, Adam W, Andrejkovic JW, et al., 2022, Measurement of the Higgs boson width and evidence of its off-shell contributions to ZZ production, Nature Physics, Vol: 18, Pages: 1329-1334, ISSN: 1745-2473
Since the discovery of the Higgs boson in 2012, detailed studies of its properties have been ongoing. Besides its mass, its width—related to its lifetime—is an important parameter. One way to determine this quantity is to measure its off-shell production, where the Higgs boson mass is far away from its nominal value, and relating it to its on-shell production, where the mass is close to the nominal value. Here we report evidence for such off-shell contributions to the production cross-section of two Z bosons with data from the CMS experiment at the CERN Large Hadron Collider. We constrain the total rate of the off-shell Higgs boson contribution beyond the Z boson pair production threshold, relative to its standard model expectation, to the interval [0.0061, 2.0] at the 95% confidence level. The scenario with no off-shell contribution is excluded at a p-value of 0.0003 (3.6 standard deviations). We measure the width of the Higgs boson as ΓH=3.2+2.4−1.7MeV, in agreement with the standard model expectation of 4.1 MeV. In addition, we set constraints on anomalous Higgs boson couplings to W and Z boson pairs.
Tumasyan A, Adam W, Andrejkovic JW, et al., 2022, earch for a W′ boson decaying to a vector-like quark and a top or bottom quark in the all-jets final state at s√ = 13 TeV, The Journal of High Energy Physics, Vol: 2022, Pages: 1-46, ISSN: 1029-8479
A search is presented for a heavy W′ boson resonance decaying to a B or T vector-like quark and a t or a b quark, respectively. The analysis is performed using proton-proton collisions collected with the CMS detector at the LHC. The data correspond to an integrated luminosity of 138 fb−1 at a center-of-mass energy of 13 TeV. Both decay channels result in a signature with a t quark, a Higgs or Z boson, and a b quark, each produced with a significant Lorentz boost. The all-hadronic decays of the Higgs or Z boson and of the t quark are selected using jet substructure techniques to reduce standard model backgrounds, resulting in a distinct three-jet W′ boson decay signature. No significant deviation in data with respect to the standard model background prediction is observed. Upper limits are set at 95% confidence level on the product of the W′ boson cross section and the final state branching fraction. A W′ boson with a mass below 3.1 TeV is excluded, given the benchmark model assumption of democratic branching fractions. In addition, limits are set based on generalizations of these assumptions. These are the most sensitive limits to date for this final state.
Tumasyan A, Adam W, Andrejkovic JW, et al., 2022, Search for a W' boson decaying to a vector-like quark and a top or bottom quark in the all-jets final state at root s=13 TeV, The Journal of High Energy Physics, Vol: 2022, Pages: 1-46, ISSN: 1029-8479
A search is presented for a heavy W′ boson resonance decaying to a B or T vector-like quark and a t or a b quark, respectively. The analysis is performed using proton-proton collisions collected with the CMS detector at the LHC. The data correspond to an integrated luminosity of 138 fb−1 at a center-of-mass energy of 13 TeV. Both decay channels result in a signature with a t quark, a Higgs or Z boson, and a b quark, each produced with a significant Lorentz boost. The all-hadronic decays of the Higgs or Z boson and of the t quark are selected using jet substructure techniques to reduce standard model backgrounds, resulting in a distinct three-jet W′ boson decay signature. No significant deviation in data with respect to the standard model background prediction is observed. Upper limits are set at 95% confidence level on the product of the W′ boson cross section and the final state branching fraction. A W′ boson with a mass below 3.1 TeV is excluded, given the benchmark model assumption of democratic branching fractions. In addition, limits are set based on generalizations of these assumptions. These are the most sensitive limits to date for this final state.
Tumasyan A, Adam W, Andrejkovic JW, et al., 2022, Search for high-mass resonances decaying to a jet and a Lorentz-boosted resonance in proton-proton collisions at √<i>s</i>=13 TeV, Publisher: ELSEVIER
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Tumasyan A, Adam W, Andrejkovic JW, et al., 2022, Search for high-mass resonances decaying to a jet and aLorentz-boosted resonance in proton-proton collisions at √s = 13 TeV, Physics Letters B, Vol: 832, Pages: 1-24, ISSN: 0370-2693
A search is reported for high-mass hadronic resonances that decay to a parton and a Lorentz-boosted resonance, which in turn decays into a pair of partons. The search is based on data collected with the CMS detector at the LHC in proton-proton collisions at , corresponding to an integrated luminosity of 138. The boosted resonance is reconstructed as a single wide jet with substructure consistent with a two-body decay. The high-mass resonance is thus considered as a dijet system. The jet substructure information and the kinematic properties of cascade resonance decays are exploited to disentangle the signal from the large quantum chromodynamics multijet background. The dijet mass spectrum is analyzed for the presence of new high-mass resonances, and is found to be consistent with the standard model background predictions. Results are interpreted in a warped extra dimension model where the high-mass resonance is a Kaluza–Klein gluon, the boosted resonance is a radion, and the final state partons are all gluons. Limits on the production cross section are set as a function of the Kaluza–Klein gluon and radion masses. These limits exclude at 95% confidence level models with Kaluza–Klein gluon masses in the range 2.0 to 4.3 TeV and radion masses in the range 0.20 to 0.74 TeV. By exploring a novel experimental signature, the observed limits on the Kaluza–Klein gluon mass are extended by up to about 1 TeV compared to previous searches.
Tumasyan A, Adam W, Andrejkovic JW, et al., 2022, Search for Higgs boson pair production in the four b quark final state in proton-proton collisions at sqrt[s]=13 TeV, Physical Review Letters, Vol: 129, ISSN: 0031-9007
A search for pairs of Higgs bosons produced via gluon and vector boson fusion is presented, focusing on the four b quark final state. The data sample consists of proton-proton collisions at a center-of-mass energy of 13 TeV, collected with the CMS detector at the LHC, and corresponds to an integrated luminosity of 138 fb^{-1}. No deviation from the background-only hypothesis is observed. A 95% confidence level upper limit on the Higgs boson pair production cross section is observed at 3.9 times the standard model prediction for an expected value of 7.8. Constraints are also set on the modifiers of the Higgs field self-coupling, κ_{λ}, and of the coupling of two Higgs bosons to two vector bosons, κ_{2 V}. The observed (expected) allowed intervals at the 95% confidence level are -2.3<κ_{λ}<9.4 (-5.0<κ_{λ}<12.0) and -0.1<κ_{2 V}<2.2 (-0.4<κ_{2 V}<2.5). These are the most stringent observed constraints to date on the HH production cross section and on the κ_{2 V } coupling.
Tumasyan A, Adam W, Andrejkovic JW, et al., 2022, Strategies and performance of the CMS silicon tracker alignment during LHC Run 2, Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors, and Associated Equipment, Vol: 1037, ISSN: 0168-9002
The strategies for and the performance of the CMS silicon tracking system alignment during the 2015–2018 data-taking period of the LHC are described. The alignment procedures during and after data taking are explained. Alignment scenarios are also derived for use in the simulation of the detector response. Systematic effects, related to intrinsic symmetries of the alignment task or to external constraints, are discussed and illustrated for different scenarios.
Tumasyan A, Adam W, Andrejkovic JW, et al., 2022, Measurement of the Drell-Yan forward-backward asymmetry at high dilepton masses in proton-proton collisions at root s=13 TeV, The Journal of High Energy Physics, Vol: 2022, Pages: 1-58, ISSN: 1029-8479
A measurement of the forward-backward asymmetry of pairs of oppositely charged leptons (dimuons and dielectrons) produced by the Drell-Yan process in proton-proton collisions is presented. The data sample corresponds to an integrated luminosity of 138 fb−1 collected with the CMS detector at the LHC at a center-of-mass energy of 13 TeV. The asymmetry is measured as a function of lepton pair mass for masses larger than 170 GeV and compared with standard model predictions. An inclusive measurement across both channels and the full mass range yields an asymmetry of 0.612 ± 0.005 (stat) ± 0.007 (syst). As a test of lepton flavor universality, the difference between the dimuon and dielectron asymmetries is measured as well. No statistically significant deviations from standard model predictions are observed. The measurements are used to set limits on the presence of additional gauge bosons. For a Z′ boson in the sequential standard model the observed (expected) 95% confidence level lower limit on the Z′ mass is 4.4 TeV (3.7 TeV).
Tumasyan A, Adam W, Andrejkovic JW, et al., 2022, Search for flavor-changing neutral current interactions of the top quark and Higgs Boson in final states with two photons in proton-proton collisions at sqrt[s]=13 TeV., Physical Review Letters, Vol: 129, Pages: 1-20, ISSN: 0031-9007
Proton-proton interactions resulting in final states with two photons are studied in a search for the signature of flavor-changing neutral current interactions of top quarks (t) and Higgs bosons (H). The analysis is based on data collected at a center-of-mass energy of 13 TeV with the CMS detector at the LHC, corresponding to an integrated luminosity of 137 fb^{-1}. No significant excess above the background prediction is observed. Upper limits on the branching fractions (B) of the top quark decaying to a Higgs boson and an up (u) or charm (c) quark are derived through a binned fit to the diphoton invariant mass spectrum. The observed (expected) 95% confidence level upper limits are found to be 0.019% (0.031%) for B(t→Hu) and 0.073% (0.051%) for B(t→Hc). These are the strictest upper limits yet determined.
Tumasyan A, Adam W, Andrejkovic JW, et al., 2022, Search for long-lived heavy neutral leptons with displaced vertices in proton-proton collisions at root s=13 TeV, The Journal of High Energy Physics, Vol: 2022, ISSN: 1029-8479
A search for heavy neutral leptons (HNLs), the right-handed Dirac or Majorana neutrinos, is performed in final states with three charged leptons (electrons or muons) using proton-proton collision data collected by the CMS experiment at s√ = 13 TeV at the CERN LHC. The data correspond to an integrated luminosity of 138 fb−1. The HNLs could be produced through mixing with standard model neutrinos ν. For small values of the HNL mass (<20 GeV) and the square of the HNL-ν mixing parameter (10−7–10−2), the decay length of these particles can be large enough so that the secondary vertex of the HNL decay can be resolved with the CMS silicon tracker. The selected final state consists of one lepton emerging from the primary proton-proton collision vertex, and two leptons forming a displaced, secondary vertex. No significant deviations from the standard model expectations are observed, and constraints are obtained on the HNL mass and coupling strength parameters, excluding previously unexplored regions of parameter space in the mass range 1–20 GeV and squared mixing parameter values as low as 10−7.
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