Author
Armen Tumasyan
Other affiliations: CERN, Austrian Academy of Sciences, University of Antwerp
Bio: Armen Tumasyan is an academic researcher from Yerevan Physics Institute. The author has contributed to research in topics: Large Hadron Collider & Lepton. The author has an hindex of 128, co-authored 1189 publications receiving 79408 citations. Previous affiliations of Armen Tumasyan include CERN & Austrian Academy of Sciences.
Topics: Large Hadron Collider, Lepton, Standard Model, Higgs boson, Boson
Papers
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Albert M. Sirunyan1, Robin Erbacher2, C. A. Carrillo Montoya3, Wagner Carvalho4 +2307 more•Institutions (156)
TL;DR: In this paper, a search for new physics in events with two low-momentum, oppositely charged leptons (electrons or muons) and missing transverse momentum in proton-proton collisions at a centre-of-mass energy of 13.9 fb − 1.
111 citations
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14 Aug 2012
TL;DR: In this paper, a search for high-mass resonances decaying to electron or muon pairs has been performed using pp collision data collected at 7 TeV by the CMS experiment in 2011, and the event yields observed in the signal regions are consistent with predictions of the standard model backgrounds.
Abstract: A search for narrow, high-mass resonances decaying to electron or muon pairs has been performed using pp collision data collected at sqrt(s)=7 TeV by the CMS experiment in 2011. The data sample corresponds to an integrated luminosity of approximately 5 inverse femtobarns. The event yields observed in the signal regions are consistent with predictions of the standard model backgrounds, and upper limits on the cross section times branching fraction for a resonance decaying to dileptons are extracted from a shape analysis of the dilepton invariant mass distribution. The resulting mass limits at 95% confidence level are 2330 GeV for the Z' in the Sequential Standard Model, 2000 GeV for the superstring-inspired Z'(psi) resonance, 890 (540) GeV for the Stueckelberg extension Z'(St) with the mass parameter epsilon=0.06 (0.04), and 2140 (1810) GeV for Kaluza--Klein gravitons with the coupling parameter k/Mbar(Pl) of 0.10 (0.05). These limits are the most stringent to date.
110 citations
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TL;DR: In this paper, a search for a new resonance decaying into a lighter resonance and a Z boson was performed, targeting the decay of the lighter resonance into either a pair of oppositely charged tau leptons or a b-bbar pair.
109 citations
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Vardan Khachatryan1, Albert M. Sirunyan1, Armen Tumasyan1, Wolfgang Adam2 +2178 more•Institutions (179)
TL;DR: In this paper, searches for supersymmetry (SUSY) are performed using a sample of hadronic events produced in 8 TeV pp collisions at the CERN LHC, which are based on the MT2 variable, which is a measure of the transverse momentum imbalance in an event.
Abstract: Searches for supersymmetry (SUSY) are performed using a sample of hadronic events produced in 8 TeV pp collisions at the CERN LHC. The searches are based on the MT2 variable, which is a measure of the transverse momentum imbalance in an event. The data were collected with the CMS detector and correspond to an integrated luminosity of 19.5 inverse femtobarns. Two related searches are performed. The first is an inclusive search based on signal regions defined by the value of the MT2 variable, the hadronic energy in the event, the jet multiplicity, and the number of jets identified as originating from bottom quarks. The second is a search for a mass peak corresponding to a Higgs boson decaying to a bottom quark-antiquark pair, where the Higgs boson is produced as a decay product of a SUSY particle. For both searches, the principal backgrounds are evaluated with data control samples. No significant excess over the expected number of background events is observed, and exclusion limits on various SUSY models are derived.
109 citations
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TL;DR: In this article, a search for new phenomena is performed using events with jets and significant transverse momentum imbalance, as inferred through the $M_{\mathrm {T2}}$ variable.
Abstract: A search for new phenomena is performed using events with jets and significant transverse momentum imbalance, as inferred through the $M_{\mathrm {T2}}$ variable The results are based on a sample of proton–proton collisions collected in 2016 at a center-of-mass energy of 13 $\,\text {TeV}$ with the CMS detector and corresponding to an integrated luminosity of 359 $\,\text {fb}^\text {-1}$ No excess event yield is observed above the predicted standard model background, and the results are interpreted as exclusion limits at 95% confidence level on the masses of predicted particles in a variety of simplified models of R-parity conserving supersymmetry Depending on the details of the model, 95% confidence level lower limits on the gluino (light-flavor squark) masses are placed up to 2025 (1550) $\,\text {GeV}$ Mass limits as high as 1070 (1175) $\,\text {GeV}$ are set on the masses of top (bottom) squarks Information is provided to enable re-interpretation of these results, including model-independent limits on the number of non-standard model events for a set of simplified, inclusive search regions
109 citations
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TL;DR: There is, I think, something ethereal about i —the square root of minus one, which seems an odd beast at that time—an intruder hovering on the edge of reality.
Abstract: There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality.
Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …
33,785 citations
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TL;DR: In this article, a search for the Standard Model Higgs boson in proton-proton collisions with the ATLAS detector at the LHC is presented, which has a significance of 5.9 standard deviations, corresponding to a background fluctuation probability of 1.7×10−9.
9,282 citations
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TL;DR: In this paper, results from searches for the standard model Higgs boson in proton-proton collisions at 7 and 8 TeV in the CMS experiment at the LHC, using data samples corresponding to integrated luminosities of up to 5.8 standard deviations.
8,857 citations
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TL;DR: MadGraph5 aMC@NLO as discussed by the authors is a computer program capable of handling all these computations, including parton-level fixed order, shower-matched, merged, in a unified framework whose defining features are flexibility, high level of parallelisation and human intervention limited to input physics quantities.
Abstract: We discuss the theoretical bases that underpin the automation of the computations of tree-level and next-to-leading order cross sections, of their matching to parton shower simulations, and of the merging of matched samples that differ by light-parton multiplicities. We present a computer program, MadGraph5 aMC@NLO, capable of handling all these computations — parton-level fixed order, shower-matched, merged — in a unified framework whose defining features are flexibility, high level of parallelisation, and human intervention limited to input physics quantities. We demonstrate the potential of the program by presenting selected phenomenological applications relevant to the LHC and to a 1-TeV e + e − collider. While next-to-leading order results are restricted to QCD corrections to SM processes in the first public version, we show that from the user viewpoint no changes have to be expected in the case of corrections due to any given renormalisable Lagrangian, and that the implementation of these are well under way.
6,509 citations