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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 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.
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.
Search for the standard model Higgs boson decaying into two photons 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.3
A search for a Higgs boson decaying into two photons is described. The analysis is performed using a dataset recorded by the CMS experiment at the LHC from pp collisions at a center-of-mass energy of 7 TeV, which corresponds to an integrated luminosity of 4.8 fb<SUP>-1</SUP>. Limits are set on the cross section of the standard model Higgs boson decaying to two photons. The expected exclusion limit at 95% confidence level is between 1.4 and 2.4 times the standard model cross section in the mass range between 110 and 150 GeV. The analysis of the data excludes, at 95% confidence level, the standard model Higgs boson decaying into two photons in the mass range 128 to 132 GeV. The largest excess of events above the expected standard model background is observed for a Higgs boson mass hypothesis of 124 GeV with a local significance of 3.1σ. The global significance of observing an excess with a local significance ≥3.1σ anywhere in the search range 110-150 GeV is estimated to be 1.8σ. More data are required to ascertain the origin of this 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.,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.
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.714 No.2
The Λ<SUB>b</SUB> differential production cross section and the cross section ratio σ(Λ@?<SUB>b</SUB>)/σ(Λ<SUB>b</SUB>) are measured as functions of transverse momentum p<SUB>T</SUB><SUP>Λ'b</SUP> and rapidity |y<SUP>Λ'b</SUP>| in pp collisions at s=7 TeV using data collected by the CMS experiment at the LHC. The measurements are based on Λ<SUB>b</SUB> decays reconstructed in the exclusive final state J/ψΛ, with the subsequent decays J/ψ→μ<SUP>+</SUP>μ<SUP>-</SUP> and Λ→pπ, using a data sample corresponding to an integrated luminosity of 1.9 fb<SUP>-1</SUP>. The product σ(Λ<SUB>b</SUB>)xB(Λ<SUB>b</SUB>→J/ψΛ) versus p<SUB>T</SUB><SUP>Λ'b</SUP> falls faster than that of b mesons. The measured value of σ(Λ<SUB>b</SUB>)xB(Λ<SUB>b</SUB>→J/ψΛ) for p<SUB>T</SUB><SUP>Λ'b</SUP>>10 GeV and |y<SUP>Λ'b</SUP>|<2.0 is 1.16+/-0.06+/-0.12 nb, and the integrated σ(Λ@?<SUB>b</SUB>)/σ(Λ<SUB>b</SUB>) ratio is 1.02+/-0.07+/-0.09, where the uncertainties are statistical and systematic, respectively.
Search for heavy narrow dilepton resonances in pp collisions at s=7 TeV and s=8 TeV
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.,Hormann, N.,Hrubec, North-Holland Pub. Co 2013 Physics letters: B Vol.720 No.1
An updated search for heavy narrow resonances decaying to muon or electron pairs using the CMS detector is presented. Data samples from pp collisions at s=7 TeV and 8 TeV at the LHC, with integrated luminosities of up to 5.3 and 4.1 fb<SUP>-1</SUP>, respectively, are combined. No evidence for a heavy narrow resonance is observed. The analysis of the combined data sets excludes, at 95% confidence level, a Sequential Standard Model Z<SUB>SSM</SUB><SUP>'</SUP> resonance lighter than 2590 GeV, a superstring-inspired Z<SUB>ψ</SUB><SUP>'</SUP> lighter than 2260 GeV, and Kaluza-Klein gravitons lighter than 2390 (2030) GeV, assuming that the coupling parameter k/M@?<SUB>Pl</SUB> is 0.10 (0.05). These are the most stringent limits to date.
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.,Hormann, N.,Hrubec, North-Holland Pub. Co 2012 Physics letters: B Vol.716 No.2
A search is presented for physics beyond the standard model (BSM) in events with a Z boson, jets, and missing transverse energy (E<SUB>T</SUB><SUP>miss</SUP>). This signature is motivated by BSM physics scenarios, including supersymmetry. The study is performed using a sample of proton-proton collision data collected at s=7 TeV with the CMS experiment at the LHC, corresponding to an integrated luminosity of 4.98 fb<SUP>-1</SUP>. The contributions from the dominant standard model backgrounds are estimated from data using two complementary strategies, the jet-Z balance technique and a method based on modeling E<SUB>T</SUB><SUP>miss</SUP> with data control samples. In the absence of evidence for BSM physics, we set limits on the non-standard-model contributions to event yields in the signal regions and interpret the results in the context of simplified model spectra. Additional information is provided to facilitate tests of other BSM physics models.