V. Khachatryan
A5005250779- Particle physics theoretical and experimental studies
- High-Energy Particle Collisions Research
- Quantum Chromodynamics and Particle Interactions
- Particle Detector Development and Performance
- Dark Matter and Cosmic Phenomena
- Cosmology and Gravitation Theories
- Neutrino Physics Research
- Black Holes and Theoretical Physics
- Computational Physics and Python Applications
- Particle Accelerators and Free-Electron Lasers
- Medical Imaging Techniques and Applications
- Nuclear physics research studies
- Astrophysics and Cosmic Phenomena
- Atomic and Subatomic Physics Research
- Particle accelerators and beam dynamics
- Atomic and Molecular Physics
- Nuclear reactor physics and engineering
- Superconducting Materials and Applications
- Distributed and Parallel Computing Systems
- Stochastic processes and statistical mechanics
- Radiation Detection and Scintillator Technologies
- Advanced NMR Techniques and Applications
- advanced mathematical theories
- Cold Atom Physics and Bose-Einstein Condensates
- Pediatric Urology and Nephrology Studies
Duke University
2021-2025
Indiana University
2024-2025
Indiana University Bloomington
2023-2025
Stony Brook University
2016-2025
Joint Institute for Nuclear Research
2013-2024
COMSATS University Islamabad
2024
Budker Institute of Nuclear Physics
2024
Bhabha Atomic Research Centre
2017-2024
Banaras Hindu University
2016-2024
Augustana University
2016-2024
Results are presented from searches for the standard model Higgs boson in proton-proton collisions at sqrt(s) = 7 and 8 TeV Compact Muon Solenoid experiment LHC, using data samples corresponding to integrated luminosities of up 5.1 inverse femtobarns 5.3 TeV. The search is performed five decay modes: gamma gamma, ZZ, WW, tau tau, b b-bar. An excess events observed above expected background, with a local significance 5.0 deviations, mass near 125 GeV, signalling production new particle. that...
The Compact Muon Solenoid (CMS) detector is described. operates at the Large Hadron Collider (LHC) CERN. It was conceived to study proton-proton (and lead-lead) collisions a centre-of-mass energy of 14 TeV (5.5 nucleon-nucleon) and luminosities up 1034 cm−2 s−1 (1027 s−1). At core CMS sits high-magnetic-field large-bore superconducting solenoid surrounding an all-silicon pixel strip tracker, lead-tungstate scintillating-crystals electromagnetic calorimeter, brass-scintillator sampling hadron...
Results on two-particle angular correlations for charged particles emitted in proton-proton collisions at center-of-mass energies of 0.9, 2.36, and 7 TeV are presented, using data collected with the CMS detector over a broad range pseudorapidity (eta) azimuthal angle (phi). Short-range Delta(eta), which studied minimum bias events, characterized simple "independent cluster" parametrization order to quantify their strength (cluster size) extent eta decay width). Long-range differentially as...
This paper describes the CMS trigger system and its performance during Run 1 of LHC. The consists two levels designed to select events potential physics interest from a GHz (MHz) interaction rate proton-proton (heavy ion) collisions. first level is implemented in hardware, selects containing detector signals consistent with an electron, photon, muon, τ lepton, jet, or missing transverse energy. A programmable menu up 128 object-based algorithms used for subsequent processing. thresholds are...
Properties of the Higgs boson with mass near 125 $$\,\text {GeV}$$ are measured in proton-proton collisions CMS experiment at LHC. Comprehensive sets production and decay measurements combined. The channels include $$\gamma \gamma $$ , $$\mathrm{Z}\mathrm{Z}$$ $$\mathrm{W}\mathrm{W}$$ $$\tau \tau $$\mathrm{b} \mathrm{b} $$\mu \mu pairs. data samples were collected 2011 2012 correspond to integrated luminosities up 5.1 {fb}^\text {-1}$$ 7 {TeV}$$ 19.7 8 . From high-resolution channels, is...
Combined results are reported from searches for the standard model Higgs boson in proton-proton collisions at sqrt(s)=7 TeV five decay modes: gamma pair, b-quark tau lepton W and Z pair. The explored mass range is 110-600 GeV. analysed data correspond to an integrated luminosity of 4.6-4.8 inverse femtobarns. expected excluded absence 118-543 GeV 95% CL. observed exclude 127-600 CL, 129-525 99% An excess events above background low end making limits weaker than a signal. largest excess, with...
Jet production in PbPb collisions at a nucleon-nucleon center-of-mass energy of 2.76 TeV was studied with the CMS detector LHC, using data sample corresponding to an integrated luminosity 6.7 inverse microbarns. Jets are reconstructed deposited calorimeters and as function collision centrality. With increasing centrality, striking imbalance dijet transverse momentum is observed, consistent jet quenching. The observed effect extends from lower cut-off used this study (jet = 120 GeV/c) up...
Results on two-particle angular correlations for charged particles emitted in pPb collisions at a nucleon–nucleon center-of-mass energy of 5.02 TeV are presented. The analysis uses two million collected with the CMS detector LHC. studied over broad range pseudorapidity, η, and full azimuth, ϕ, as function particle multiplicity transverse momentum, pT. In high-multiplicity events, long-range (2<|Δη|<4), near-side (Δϕ≈0) structure emerges Δη–Δϕ correlation functions. This is first observation...
A detailed description is reported of the analysis used by CMS Collaboration in search for standard model Higgs boson pp collisions at LHC, which led to observation a new boson. The data sample corresponds integrated luminosities up 5.1 inverse femtobarns sqrt(s) = 7 TeV, and 5.3 8 TeV. results five decay modes gamma gamma, ZZ, WW, tau tau, bb, show combined local significance 5 deviations near 125 GeV, are reviewed. fit invariant mass two high resolution channels, ZZ 4 ell, gives estimate...
New sets of parameters (“tunes”) for the underlying-event (UE) modelling pythia8, pythia6 and herwig++ Monte Carlo event generators are constructed using different parton distribution functions. Combined fits to CMS UE proton–proton ( $$\mathrm {p}\mathrm {p}$$ ) data at $$\sqrt{s} = 7\,\text {TeV} $$ proton–antiproton {p}\overline{\mathrm{p}} from CDF experiment lower $$\sqrt{s}$$ , used study models constrain their parameters, providing thereby improved predictions collisions 13 $$\,\text...
The performance of muon reconstruction, identification, and triggering in CMS has been studied using 40 inverse picobarns data collected pp collisions at sqrt(s) = 7 TeV the LHC 2010. A few benchmark sets selection criteria covering a wide range physics analysis needs have examined. For all considered selections, efficiency to reconstruct identify with transverse momentum pT larger than GeV is above 95% over whole region pseudorapidity covered by system, abs(eta) < 2.4, while probability...
Improved jet energy scale corrections, based on a data sample corresponding to an integrated luminosity of 19.7 inverse-femtobarns collected by the CMS experiment in proton-proton collisions at center-of-mass 8 TeV, are presented. The corrections as function pseudorapidity eta and transverse momentum pT extracted from simulated events combining several channels methods. They account successively for effects pileup, uniformity detector response, residual data-simulation differences. Further...
The performance and strategies used in electron reconstruction selection at CMS are presented based on data corresponding to an integrated luminosity of 19.7 fb−1, collected proton-proton collisions √s = 8 TeV the CERN LHC. paper focuses prompt isolated electrons with transverse momenta ranging from about 5 a few 100 GeV. A detailed description is given algorithms cluster energy electromagnetic calorimeter reconstruct trajectories tracker. momentum estimated by combining measurement...
Charged-hadron transverse-momentum and pseudorapidity distributions in proton-proton collisions at $\sqrt{s}=7\text{ }\text{ }\mathrm{TeV}$ are measured with the inner tracking system of CMS detector LHC. The charged-hadron yield is obtained by counting number reconstructed hits, hit pairs, fully charged-particle tracks. combination three methods gives a multiplicity per unit...
The properties of a Higgs boson candidate are measured in the $H\ensuremath{\rightarrow}ZZ\ensuremath{\rightarrow}4\ensuremath{\ell}$ decay channel, with $\ensuremath{\ell}=e$, $\ensuremath{\mu}$, using data from $pp$ collisions corresponding to an integrated luminosity $5.1\text{ }\text{ }{\mathrm{fb}}^{\ensuremath{-}1}$ at center-of-mass energy $\sqrt{s}=7\text{ }\mathrm{TeV}$ and $19.7\text{ }{\mathrm{fb}}^{\ensuremath{-}\text{1}}$ $\sqrt{s}=8\text{ }\mathrm{TeV}$, recorded CMS detector...
A joint measurement is presented of the branching fractions $B^0_s\to\mu^+\mu^-$ and $B^0\to\mu^+\mu^-$ in proton-proton collisions at LHC by CMS LHCb experiments. The data samples were collected 2011 a centre-of-mass energy 7 TeV, 2012 8 TeV. combined analysis produces first observation decay, with statistical significance exceeding six standard deviations, best its fraction so far. Furthermore, evidence for decay obtained three deviations. measurements are statistically compatible SM...
The transverse momentum spectra of charged particles have been measured in pp and PbPb collisions at $\sqrt{s_{NN}}=2.76~\mathrm{TeV}$ by the CMS experiment LHC. In range p T=5–10 GeV/c, particle yield most central is suppressed up to a factor 7 compared scaled number incoherent nucleon–nucleon collisions. At higher T, this suppression significantly reduced, approaching roughly 2 for with T T=40–100 GeV/c.
Measurements of two- and four-particle angular correlations for charged particles emitted in pPb collisions are presented over a wide range pseudorapidity full azimuth. The data, corresponding to an integrated luminosity approximately 31 inverse nanobarns, were collected during the 2013 LHC run at nucleon-nucleon center-of-mass energy 5.02 TeV by CMS experiment. results compared 2.76 semi-peripheral PbPb collision 2011 run, covering similar particle multiplicities. observed characterized...
Observation of the diphoton decay mode recently discovered Higgs boson and measurement some its properties are reported. The analysis uses entire dataset collected by CMS experiment in proton-proton collisions during 2011 2012 LHC running periods. data samples correspond to integrated luminosities 5.1[Formula: see text]at [Formula: text] 19.7[Formula: 8[Formula: . A clear signal is observed channel at a mass close 125[Formula: with local significance text], where expected for standard model...
Results are presented from a search for particle dark matter (DM), extra dimensions, and unparticles using events containing jet an imbalance in transverse momentum. The data were collected by the CMS detector proton-proton collisions at LHC correspond to integrated luminosity of 19.7 inverse femtobarns centre-of-mass energy 8 TeV. number observed is found be consistent with standard model prediction. Limits placed on DM-nucleon scattering cross section as function DM mass spin-dependent...
Measurements of two- and multi-particle angular correlations in pp collisions at sqrt(s) = 5, 7, 13 TeV are presented as a function charged-particle multiplicity. The data, corresponding to integrated luminosities 1.0 inverse picobarn (5 TeV), 6.2 picobarns (7 0.7 (13 were collected using the CMS detector LHC. second-order (v[2]) third-order (v[3]) azimuthal anisotropy harmonics unidentified charged particles, well v[2] K0 short Lambda/anti-Lambda extracted from long-range two-particle...
A study is presented of the mass and spin-parity new boson recently observed at LHC a near 125 GeV. An integrated luminosity 17.3 fb(-1), collected by CMS experiment in proton-proton collisions center-of-mass energies 7 8 TeV, used. The measured ZZ channel, where both Z bosons decay to e or μ pairs, 126.2 ± 0.6(stat) 0.2(syst) angular distributions lepton pairs this channel are sensitive boson. Under assumption spin 0, present data consistent with pure scalar hypothesis, while disfavoring...
The study of the spin-parity and tensor structure interactions recently discovered Higgs boson is performed using H to ZZ, Z gamma*, gamma* 4 l, WW l nu nu, gamma decay modes. full dataset recorded by CMS experiment during LHC Run 1 used, corresponding an integrated luminosity up 5.1 inverse femtobarns at a center-of-mass energy 7 TeV 19.7 8 TeV. A wide range spin-two models excluded 99% confidence level or higher, 99.87% for minimal gravity-like couplings, regardless whether assumptions are...
Results are presented from a search for the rare decays ${B}_{s}^{0}\ensuremath{\rightarrow}{\ensuremath{\mu}}^{+}{\ensuremath{\mu}}^{\ensuremath{-}}$ and ${B}^{0}\ensuremath{\rightarrow}{\ensuremath{\mu}}^{+}{\ensuremath{\mu}}^{\ensuremath{-}}$ in $pp$ collisions at $\sqrt{s}=7$ 8 TeV, with data samples corresponding to integrated luminosities of 5 $20\text{ }\text{ }{\mathrm{fb}}^{\ensuremath{-}1}$, respectively, collected by CMS experiment LHC. An unbinned maximum-likelihood fit dimuon...
A bstract search for the standard model Higgs boson decaying to a W-boson pair at LHC is reported. The event sample corresponds an integrated luminosity of 4.9 fb −1 and 19.4 collected with CMS detector in pp collisions $ \sqrt{s} = 7 8 TeV, respectively. candidates are selected events two or three charged leptons. An excess above background observed, consistent expectation from mass around 125 GeV. probability observe equal larger than one seen, under background-only hypothesis,...