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Search for three-jet resonances in pp collisions at s=7TeV
CMS Collaboration,Chatrchyan, S.,Khachatryan, V.,Sirunyan, A.M.,Tumasyan, A.,Adam, W.,Aguilo, E.,Bergauer, T.,Dragicevic, M.,Ero, J.,Fabjan, C.,Friedl, M.,Fruhwirth, R.,Ghete, V.M.,Hammer, J.,Hormann, North-Holland Pub. Co 2012 Physics letters: B Vol.718 No.2
<P>Results are reported from a search for the production of three-jet resonances in pp collisions at a center-of-mass energy root s = 7 TeV. The study uses the data sample collected by the CMS experiment at the LHC in 2011, corresponding to an integrated luminosity of 5.0 fb(-1). Events with high jet multiplicity and a large scalar sum of jet transverse momenta are analyzed for the presence of resonances in the three-jet invariant mass spectrum. No evidence for a narrow resonance is found in the data, and limits are set on the cross section for gluino pair production in an R-parity-violating supersymmetry model, for gluino masses greater than 280 GeV. Assuming a branching fraction for gluino decay into three jets of 100%, gluino masses below 460 GeV are excluded at 95% confidence level. These results significantly extend the range of previous limits. (C) 2012 CERN. Published by Elsevier By. All rights reserved.</P>
Search for supersymmetry in pp collisions at 7 TeV in events with jets and missing transverse energy
CMS Collaboration,Khachatryan, V.,Sirunyan, A.M.,Tumasyan, A.,Adam, W.,Bergauer, T.,Dragicevic, M.,Ero, J.,Fabjan, C.,Friedl, M.,Fruhwirth, R.,Ghete, V.M.,Hammer, J.,Hansel, S.,Hartl, C.,Hoch, M.,Horm North-Holland Pub. Co 2011 Physics letters: B Vol.698 No.3
A search for supersymmetry with R-parity conservation in proton-proton collisions at a centre-of-mass energy of 7 TeV is presented. The data correspond to an integrated luminosity of 35 pb<SUP>-1</SUP> collected by the CMS experiment at the LHC. The search is performed in events with jets and significant missing transverse energy, characteristic of the decays of heavy, pair-produced squarks and gluinos. The primary background, from standard model multijet production, is reduced by several orders of magnitude to a negligible level by the application of a set of robust kinematic requirements. With this selection, the data are consistent with the standard model backgrounds, namely tt@?, W+jet and Z+jet production, which are estimated from data control samples. Limits are set on the parameters of the constrained minimal supersymmetric extension of the standard model. These limits extend those set previously by experiments at the Tevatron and LEP colliders.
CMS Collaboration,Chatrchyan, S.,Khachatryan, V.,Sirunyan, A.M.,Tumasyan, A.,Adam, W.,Aguilo, E.,Bergauer, T.,Dragicevic, M.,Ero, J.,Fabjan, C.,Friedl, M.,Fruhwirth, R.,Ghete, V.M.,Hammer, J.,Hormann, North-Holland Pub. Co 2013 Physics letters: B Vol.719 No.1
Many models of new physics, including versions of supersymmetry (SUSY), predict production of events with low missing transverse energy, electroweak gauge bosons, and many energetic final-state particles. The stealth SUSY model yields this signature while conserving R-parity by means of a new hidden sector in which SUSY is approximately conserved. The results of a general search for new physics, with no requirement on missing transverse energy, in events with two photons and four or more hadronic jets are reported. The study is based on a sample of proton-proton collisions at s=7 TeV corresponding to 4.96 fb<SUP>-1</SUP> of integrated luminosity collected with the CMS detector in 2011. Based on good agreement between the data and the standard model expectation, the data are used to determine model-independent cross-section limits and a limit on the squark mass in the framework of stealth SUSY. With this first study of its kind, squark masses less than 1430 GeV are excluded at the 95% confidence level.
Jet momentum dependence of jet quenching in PbPb collisions at s<sub>NN</sub>=2.76 TeV
CMS Collaboration,Chatrchyan, S.,Khachatryan, V.,Sirunyan, A.M.,Tumasyan, A.,Adam, W.,Bergauer, T.,Dragicevic, M.,Ero, J.,Fabjan, C.,Friedl, M.,Fruhwirth, R.,Ghete, V.M.,Hammer, J.,Hormann, N.,Hrubec, North-Holland Pub. Co 2012 Physics letters: B Vol.712 No.3
Dijet production in PbPb collisions at a nucleon-nucleon center-of-mass energy of 2.76 TeV is studied with the CMS detector at the LHC. A data sample corresponding to an integrated luminosity of 150 μb<SUP>-1</SUP> is analyzed. Jets are reconstructed using combined information from tracking and calorimetry, using the anti-k<SUB>T</SUB> algorithm with R=0.3. The dijet momentum balance and angular correlations are studied as a function of collision centrality and leading jet transverse momentum. For the most peripheral PbPb collisions, good agreement of the dijet momentum balance distributions with pp data and reference calculations at the same collision energy is found, while more central collisions show a strong imbalance of leading and subleading jet transverse momenta attributed to the jet-quenching effect. The dijets in central collisions are found to be more unbalanced than the reference, for leading jet transverse momenta up to the highest values studied.
Design of the Advanced Metadata Service System with AMGA for the Belle II Experiment
S. Ahn,K. Cho,S. Hwang,J. Kim,H. Jang,B. K. Kim,H. Yoon,J. Yu,Z. Drasal,T. Hara,Y. Iida,R. Itoh,G. Iwai,N. Katayama,Y. Kawai,S. Nishida,T. Sasaki,Y. Watase,R. Fruhwirth,W. Mitaroff,R. Grzymkowski,M. S 한국물리학회 2010 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.57 No.4
The Belle II experiment is expected to produce 50 times more data than the existing Belle experiment. Such huge data production requires not only scalability with respect to the storage service but also scalability regarding the metadata service. There has already been a metadata service at the Belle experiment, but it is not proper for the Belle II experiment because it has scalability problems and it is not intended to be used in a distributed grid environment. To deal with these issues, we designed an advanced metadata service system based on AMGA, which provides efficient and scalable metadata searching. We have built testbed sites to test the correctness, performance and scalability of the advanced metadata service system, and it has been proved to be able to provide efficient metadata searching for the Belle II experiment.
Search for heavy long-lived charged particles in pp collisions at s=7 TeV
CMS Collaboration,Chatrchyan, S.,Khachatryan, V.,Sirunyan, A.M.,Tumasyan, A.,Adam, W.,Bergauer, T.,Dragicevic, M.,Ero, J.,Fabjan, C.,Friedl, M.,Fruhwirth, R.,Ghete, V.M.,Hammer, J.,Hormann, N.,Hrubec, North-Holland Pub. Co 2012 Physics letters: B Vol.713 No.4
The result of a search for heavy long-lived charged particles produced in pp collisions at s=7 TeV at the LHC is described. The data sample has been collected using the CMS detector and corresponds to an integrated luminosity of 5.0 fb<SUP>-1</SUP>. The inner tracking detectors are used to define a sample of events containing tracks with high momentum and high ionization energy loss. A second sample of events, which have high-momentum tracks satisfying muon identification requirements in addition to meeting high-ionization and long time-of-flight requirements, is analyzed independently. In both cases, the results are consistent with the expected background estimated from data. The results are used to establish cross section limits as a function of mass within the context of models with long-lived gluinos, scalar top quarks and scalar taus. Cross section limits on hyper-meson particles, containing new elementary long-lived hyper-quarks predicted by a vector-like confinement model, are also presented. Lower limits at 95% confidence level on the mass of gluinos (scalar top quarks) are found to be 1098 (737) GeV/c<SUP>2</SUP>. A limit of 928 (626) GeV/c<SUP>2</SUP> is set for a gluino (scalar top quark) that hadronizes into a neutral bound state before reaching the muon detectors. The lower mass limit for a pair produced scalar tau is found to be 223 GeV/c<SUP>2</SUP>. Mass limits for a hyper-kaon are placed at 484, 602, and 747 GeV/c<SUP>2</SUP> for hyper-ρ masses of 800, 1200, and 1600 GeV/c<SUP>2</SUP>, respectively.
Combined results of searches for the standard model Higgs boson in pp collisions at s=7 TeV
CMS Collaboration,Chatrchyan, S.,Khachatryan, V.,Sirunyan, A.M.,Tumasyan, A.,Adam, W.,Bergauer, T.,Dragicevic, M.,Ero, J.,Fabjan, C.,Friedl, M.,Fruhwirth, R.,Ghete, V.M.,Hammer, J.,Hoch, M.,Hormann, N North-Holland Pub. Co 2012 Physics letters: B Vol.710 No.1
Combined results are reported from searches for the standard model Higgs boson in proton-proton collisions at s=7 TeV in five Higgs boson decay modes: γγ, bb, ττ, WW, and ZZ. The explored Higgs boson mass range is 110-600 GeV. The analysed data correspond to an integrated luminosity of 4.6-4.8 fb<SUP>-1</SUP>. The expected excluded mass range in the absence of the standard model Higgs boson is 118-543 GeV at 95% CL. The observed results exclude the standard model Higgs boson in the mass range 127-600 GeV at 95% CL, and in the mass range 129-525 GeV at 99% CL. An excess of events above the expected standard model background is observed at the low end of the explored mass range making the observed limits weaker than expected in the absence of a signal. The largest excess, with a local significance of 3.1σ, is observed for a Higgs boson mass hypothesis of 124 GeV. The global significance of observing an excess with a local significance ≥3.1σ anywhere in the search range 110-600 (110-145) GeV is estimated to be 1.5σ(2.1σ). More data are required to ascertain the origin of the observed excess.
Search for neutral Higgs bosons decaying to tau pairs in pp collisions at s=7 TeV
CMS Collaboration,Chatrchyan, S.,Khachatryan, V.,Sirunyan, A.M.,Tumasyan, A.,Adam, W.,Bergauer, T.,Dragicevic, M.,Ero, J.,Fabjan, C.,Friedl, M.,Fruhwirth, R.,Ghete, V.M.,Hammer, J.,Hoch, M.,Hormann, N North-Holland Pub. Co 2012 Physics letters: B Vol.713 No.2
A search for neutral Higgs bosons decaying to tau pairs at a center-of-mass energy of 7 TeV is performed using a dataset corresponding to an integrated luminosity of 4.6 fb<SUP>-1</SUP> recorded by the CMS experiment at the LHC. The search is sensitive to both the standard model Higgs boson and to the neutral Higgs bosons predicted by the minimal supersymmetric extension of the standard model (MSSM). No excess of events is observed in the tau-pair invariant-mass spectrum. For a standard model Higgs boson in the mass range of 110-145 GeV upper limits at 95% confidence level (CL) on the production cross section are determined. We exclude a Higgs boson with m<SUB>H</SUB>=115 GeV with a production cross section 3.2 times of that predicted by the standard model. In the MSSM, upper limits on the neutral Higgs boson production cross section times branching fraction to tau pairs, as a function of the pseudoscalar Higgs boson mass, m<SUB>A</SUB>, sets stringent new bounds in the parameter space, excluding at 95% CL values of tanβ as low as 7.1 at m<SUB>A</SUB>=160 GeV in the m<SUB>h</SUB><SUP>max</SUP> benchmark scenario.
CMS Collaboration,Chatrchyan, S.,Khachatryan, V.,Sirunyan, A.M.,Tumasyan, A.,Adam, W.,Aguilo, E.,Bergauer, T.,Dragicevic, M.,Ero, J.,Fabjan, C.,Friedl, M.,Fruhwirth, R.,Ghete, V.M.,Hammer, J.,Hormann, North-Holland Pub. Co 2012 Physics letters: B Vol.718 No.2
The results of a search for the pair production of a fourth-generation up-type quark (t<SUP>'</SUP>) in proton-proton collisions at s=7 TeV are presented, using data corresponding to an integrated luminosity of about 5.0 fb<SUP>-1</SUP> collected by the Compact Muon Solenoid experiment at the LHC. The t<SUP>'</SUP> quark is assumed to decay exclusively to a W boson and a b quark. Events with a single isolated electron or muon, missing transverse momentum, and at least four hadronic jets, of which at least one must be identified as a b jet, are selected. No significant excess of events over standard model expectations is observed. Upper limits for the t<SUP>'</SUP>t@?<SUP>'</SUP> production cross section at 95% confidence level are set as a function of t<SUP>'</SUP> mass, and t<SUP>'</SUP>-quark production for masses below 570 GeV is excluded. The search is equally sensitive to nonchiral heavy quarks decaying to Wb. In this case, the results can be interpreted as upper limits on the production cross section times the branching fraction to Wb.
CMS Collaboration,Chatrchyan, S.,Khachatryan, V.,Sirunyan, A.M.,Tumasyan, A.,Adam, W.,Bergauer, T.,Dragicevic, M.,Ero, J.,Fabjan, C.,Friedl, M.,Fruhwirth, R.,Ghete, V.M.,Hammer, J.,Hoch, M.,Hormann, N North-Holland Pub. Co 2012 Physics letters: B Vol.710 No.1
A search for the standard model Higgs boson decaying to W<SUP>+</SUP>W<SUP>-</SUP> in pp collisions at s=7 TeV is reported. The data are collected at the LHC with the CMS detector, and correspond to an integrated luminosity of 4.6 fb<SUP>-1</SUP>. The W<SUP>+</SUP>W<SUP>-</SUP> candidates are selected in events with two charged leptons and large missing transverse energy. No significant excess of events above the standard model background expectations is observed, and upper limits on the Higgs boson production relative to the standard model Higgs expectation are derived. The standard model Higgs boson is excluded in the mass range 129-270 GeV at 95% confidence level.