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Чадеева, Марина Валентиновна

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Цель ИЯФиТ и стратегия развития - создание и развитие научно-образовательного центра мирового уровня в области ядерной физики и технологий, радиационного материаловедения, физики элементарных частиц, астрофизики и космофизики.

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Чадеева

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Марина Валентиновна

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Теперь показываю 1 - 10 из 172

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Strange hadron production in pp and pPb collisions at root(NN)-N-s=5.02 TeV
(2020) Sirunyan, A. M.; Tumasyan, A.; Adam, W.; Ambrogi, F.; Matveev, V.; Chistov, R.; Danilov, M.; Parygin, P.; Philippov, D.; Polikarpov, S.; Tarkovskii, E.; Azarkin, M.; Dremin, I.; Kirakosyan, M.; Newbold, D. M.; Chadeeva, M.; Popova, E.; Rusinov, V.; Матвеев, Виктор Анатольевич; Чистов, Руслан Николаевич; Данилов, Михаил Владимирович; Поликарпов, Сергей Михайлович; Чадеева, Марина Валентиновна; Русинов, Владимир Юрьевич
The transverse momentum (pT) distributions of Lambda, Xi(-), and Omega(-) baryons, their antiparticles, and K-S(0) mesons are measured in proton-proton (pp) and proton-lead (pPb) collisions at a nucleon-nucleon center-of-mass energy of 5.02 TeV over a broad rapidity range. The data, corresponding to integrated luminosities of 40.2 nb(-1) and 15.6 mu b(-1) for pp and pPb collisions, respectively, were collected by the CMS experiment. The nuclear modification factor R-pPb, which is defined as the ratio of the particle yield in pPb collisions and a scaled pp reference, is measured for each particle. A strong dependence on particle species is observed in the pT range from 2 to 7 GeV, where R-pPb for K-S(0) is consistent with unity, while an enhancement ordered by strangeness content and/or particle mass is observed for the three baryons. In pPb collisions, the strange hadron production is asymmetric about the nucleon-nucleon center-of-mass rapidity. Enhancements, which depend on the particle type, are observed in the direction of the Pb beam. The results are compared with predictions from EPOS LHC, which includes parametrized radial flow. The model is in qualitative agreement with the R-pPb data, but fails to describe the dependence on particle species in the yield asymmetries measured away from midrapidity in pPb collisions.
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A search for pair production of new light bosons decaying into muons in proton-proton collisions at 13  TeV
(2019) Sirunyan, A. M.; Tumasyan, A.; Adam, W.; Ambrogi, F.; Matveev, V.; Chadeeva, M.; Parygin, P.; Philippov, D.; Polikarpov, S.; Popova, E.; Rusinov, V.; Dremin, I.; Матвеев, Виктор Анатольевич; Чадеева, Марина Валентиновна; Поликарпов, Сергей Михайлович; Русинов, Владимир Юрьевич
© 2019 The Author(s)A search for new light bosons decaying into muon pairs is presented using a data sample corresponding to an integrated luminosity of 35.9fb−1 of proton-proton collisions at a center-of-mass energy s=13TeV, collected with the CMS detector at the CERN LHC. The search is model independent, only requiring the pair production of a new light boson and its subsequent decay to a pair of muons. No significant deviation from the predicted background is observed. A model independent limit is set on the product of the production cross section times branching fraction to dimuons squared times acceptance as a function of new light boson mass. This limit varies between 0.15 and 0.39 fb over a range of new light boson masses from 0.25 to 8.5 GeV. It is then interpreted in the context of the next-to-minimal supersymmetric standard model and a dark supersymmetry model that allows for nonnegligible light boson lifetimes. In both cases, there is significant improvement over previously published limits.
Только метаданные
Nuclear modification of Y states in pPb collisions at sNN=5.02TeV
(2022) Tumasyan, A.; Adam, W.; Ambrogi, F.; Bergauer, T.; Chadeeva, M.; Parygin, P.; Philippov, D.; Popova, E.; Rusinov, V.; Matveev, V.; Чадеева, Марина Валентиновна; Русинов, Владимир Юрьевич; Матвеев, Виктор Анатольевич
Production cross sections of [Formula presented], [Formula presented], and [Formula presented] states decaying into [Formula presented] in proton-lead (pPb) collisions are reported using data collected by the CMS experiment at sNN=5.02TeV. 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 [Formula presented] is found to be [Formula presented]. Similar results for the excited states indicate a sequential suppression pattern, such that [Formula presented]. The suppression of all states is much less pronounced in pPb than in PbPb collisions, and independent of transverse momentum [Formula presented] and center-of-mass rapidity [Formula presented] of the individual [Formula presented] state in the studied range [Formula presented] and [Formula presented]. 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. © 2022 The Author(s)
Открытый доступ
Search for low-mass resonances decaying into bottom quark-antiquark pairs in proton-proton collisions at s =13 TeV
(2019) Sirunyan, A. M.; Tumasyan, A.; Adam, W.; Ambrogi, F.; Matveev, V.; Chadeeva, M.; Parygin, P.; Philippov, D.; Polikarpov, S.; Popova, E.; Rusinov, V.; Dremin, I.; Матвеев, Виктор Анатольевич; Чадеева, Марина Валентиновна; Поликарпов, Сергей Михайлович; Русинов, Владимир Юрьевич
© 2019 CERN, for the CMS Collaboration. Published by the American Physical Society under the terms of the »https://creativecommons.org/licenses/by/4.0/» Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI. Funded by SCOAP3. A search for narrow, low-mass, scalar, and pseudoscalar resonances decaying to bottom quark-antiquark pairs is presented. The search is based on events recorded in s=13 TeV proton-proton collisions with the CMS detector at the LHC, collected in 2016, and corresponding to an integrated luminosity of 35.9 fb-1. The search selects events in which the resonance would be produced with high transverse momentum because of the presence of initial- or final-state radiation. In such events, the decay products of the resonance would be reconstructed as a single large-radius jet with high mass and two-prong substructure. A potential signal would be identified as a narrow excess in the jet invariant mass spectrum. No evidence for such a resonance is observed within the mass range from 50 to 350 GeV, and upper limits at 95% confidence level are set on the product of the cross section and branching fraction to a bottom quark-antiquark pair. These constitute the first constraints from the LHC on exotic bottom quark-antiquark resonances with masses below 325 GeV.
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Search for high-mass resonances decaying to a jet and a Lorentz-boosted resonance in proton-proton collisions at s=13TeV
(2022) Chadeeva, M.; Oskin, A.; Popova, E.; Parygin, P.; Matveev, V.; Bychkova, O.; Polikarpov, S.; Чадеева, Марина Валентиновна; Матвеев, Виктор Анатольевич; Поликарпов, Сергей Михайлович
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 s=13TeV, corresponding to an integrated luminosity of 138fb−1. 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. © 2022 The Author(s)
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Evidence for WW/WZ vector boson scattering in the decay channel ℓνqq produced in association with two jets in proton-proton collisions at s=13 TeV
(2022) Tumasyan, A.; Adam, W.; Andrejkovic, J.W.; Bergauer, T.; Chadeeva, M.; Oskin, A.; Parygin, P.; Popova, E.; Selivanova, D.; Matveev, V.; Zhemchugov, E.; Чадеева, Марина Валентиновна; Матвеев, Виктор Анатольевич
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Search for charged Higgs bosons in the H± ? t ± ?t decay channel in proton-proton collisions at √s=13 TeV
(2019) Sirunyan, A. M.; Tumasyan, A.; Adam, W.; Ambrogi, F.; Matveev, V.; Chadeeva, M.; Polikarpov, S.; Popova, E.; Rusinov, V.; Dremin, I.; Матвеев, Виктор Анатольевич; Чадеева, Марина Валентиновна; Поликарпов, Сергей Михайлович; Русинов, Владимир Юрьевич
© 2019, The Author(s).A search is presented for charged Higgs bosons in the H± ? t±?t decay mode in the hadronic final state and in final states with an electron or a muon. The search is based on proton-proton collision data recorded by the CMS experiment in 2016 at a center-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 35.9 fb-1. The results agree with the background expectation from the standard model. Upper limits at 95% confidence level are set on the production cross section times branching fraction to t±?t for an H± in the mass range of 80GeV to 3TeV, including the region near the top quark mass. The observed limit ranges from 6 pb at 80 GeV to 5 fb at 3 TeV. The limits are interpreted in the context of the minimal supersymmetric standard model mh hod - scenario.[Figure not available: see fulltext.].
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Evidence for light-by-light scattering and searches for axion-like particles in ultraperipheral PbPb collisions at sNN=5.02TeV
(2019) Sirunyan, A. M.; Tumasyan, A.; Adam, W.; Ambrogi, F.; Matveev, V.; Chadeeva, M.; Parygin, P.; Philippov, D.; Polikarpov, S.; Popova, E.; Rusinov, V.; Матвеев, Виктор Анатольевич; Чадеева, Марина Валентиновна; Поликарпов, Сергей Михайлович; Русинов, Владимир Юрьевич
© 2019 The Author(s)Evidence for the light-by-light scattering process, γγ→γγ, in ultraperipheral PbPb collisions at a centre-of-mass energy per nucleon pair of 5.02TeV is reported. The analysis is conducted using a data sample corresponding to an integrated luminosity of 390μb−1 recorded by the CMS experiment at the LHC. Light-by-light scattering processes are selected in events with two photons exclusively produced, each with transverse energy ET γ>2GeV, pseudorapidity |ηγ|<2.4, diphoton invariant mass mγγ>5GeV, diphoton transverse momentum pT γγ<1GeV, and diphoton acoplanarity below 0.01. After all selection criteria are applied, 14 events are observed, compared to expectations of 9.0±0.9(theo) events for the signal and 4.0±1.2(stat) for the background processes. The excess observed in data relative to the background-only expectation corresponds to a significance of 3.7 standard deviations, and has properties consistent with those expected for the light-by-light scattering signal. The measured fiducial light-by-light scattering cross section, σfid(γγ→γγ)=120±46(stat)±28(syst)±12(theo)nb, is consistent with the standard model prediction. The mγγ distribution is used to set new exclusion limits on the production of pseudoscalar axion-like particles, via the (Figure presented.) process, in the mass range (Figure presented.).
Открытый доступ
Measurements of the pp WZ inclusive and differential production cross sections and constraints on charged anomalous triple gauge couplings at s=13 TeV
(2019) Sirunyan, A. M.; Tumasyan, A.; Adam, W.; Ambrogi, F.; Matveev, V.; Parygin, P.; Philippov, D.; Polikarpov, S.; Dremin, I.; Chadeeva, M.; Popova, E.; Rusinov, V.; Матвеев, Виктор Анатольевич; Поликарпов, Сергей Михайлович; Чадеева, Марина Валентиновна; Русинов, Владимир Юрьевич
The WZ production cross section is measured in proton-proton collisions at a centre-of-mass energy = 13 TeV using data collected with the CMS detector, corresponding to an integrated luminosity of 35.9 fb(-1). The inclusive cross section is measured to be sigma(tot)(ppWZ)=48.0) pb, resulting in a total uncertainty of -2.78/+2.98 pb. Fiducial cross section and ratios of charge-dependent cross section measurements are provided. Differential cross section measurements are also presented with respect to three variables: the Z boson transverse momentum p(T), the leading jet p(T), and the M(WZ) variable, defined as the invariant mass of the system composed of the three leptons and the missing transverse momentum. Differential measurements with respect to the W boson p(T), separated by charge, are also shown. Results are consistent with standard model predictions, favouring next-to-next-to-leading-order predictions over those at next-to-leading order. Constraints on anomalous triple gauge couplings are derived via a binned maximum likelihood fit to the M(WZ) variable.
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W+ W- boson pair production in proton-proton collisions at root s=13 TeV
(2020) Sirunyan, A. M.; Tumasyan, A.; Adam, W.; Ambrogi, F.; Matveev, V.; Chadeeva, M.; Oskin, A.; Parygin, P.; Popova, E.; Rusinov, V.; Матвеев, Виктор Анатольевич; Чадеева, Марина Валентиновна; Русинов, Владимир Юрьевич
A measurement of the W+W- boson pair production cross section in proton-proton collisions at root s = 13 TeV is presented. The data used in this study are collected with the CMS detector at the CERN LHC and correspond to an integrated luminosity of 35.9 fb(-1). The W+W- candidate events are selected by requiring two oppositely charged leptons (electrons or muons). Two methods for reducing background contributions are employed. In the first one, a sequence of requirements on kinematic quantities is applied allowing a measurement of the total production cross section, 117.6 +/- 6.8 pb, which agrees well with the theoretical prediction. Fiducial cross sections are also reported for events with zero or one jet, and the change in the zero-jet fiducial cross section with the jet transverse momentum threshold is measured. Normalized differential cross sections are reported within the fiducial region. A second method for suppressing background contributions employs two random forest classifiers. The analysis based on this method includes a measurement of the total production cross section and also a measurement of the normalized jet multiplicity distribution in W+W- events. Finally, a dilepton invariant mass distribution is used to probe for physics beyond the standard model in the context of an effective field theory, and constraints on the presence of dimension-6 operators are derived.