93 research outputs found
Measurement of the top-quark mass in all-jets events in pp collisions at = 7 TeV
No full textThe mass of the top quark is measured using a sample of candidate events with at least six jets in the final state. The sample is selected from data collected with the CMS detector in pp collisions at = 7 TeV in 2011 and corresponds to an integrated luminosity of 3.54 . The mass is reconstructed for each event employing a kinematic fit of the jets to a hypothesis. The top-quark mass is measured to be 173.49 0.69(stat.) 1.21(syst.) GeV. A combination with previously published measurements in other decay modes by CMS yields a mass of 173.54 0.33(stat.) 0.96(syst.) GeV
Study of the production of charged pions, kaons, and protons in pPb collisions at sqrt(sNN) = 5.02 TeV
No full textSpectra of identified charged hadrons are measured in pPb collisions with the CMS detector at the LHC at sqrt(sNN) = 5.02 TeV. Charged pions, kaons, and protons in the transverse-momentum range pt approximately 0.1-1.7 GeV and laboratory rapidity abs(y) < 1 are identified via their energy loss in the silicon tracker. The average pt increases with particle mass and the charged multiplicity of the event. The increase of the average pt with charged multiplicity is greater for heavier hadrons. Comparisons to Monte Carlo event generators reveal that EPOS LHC, which incorporates additional hydrodynamic evolution of the created system, is able to reproduce most of the data features, unlike HIJING and AMPT. The pt spectra and integrated yields are also compared to those measured in pp and PbPb collisions at various energies. The average transverse momentum and particle ratio measurements indicate that particle production at LHC energies is strongly correlated with event particle multiplicity
Studies of dijet transverse momentum balance and pseudorapidity distributions in pPb collisions at √sNN=5.02 TeV
No full textOpen Access This article is distributed under the terms of the Creative Commons Attribution License which permits any use, distribution, and reproduction in any medium, provided the original author(s) and the
source are credited. Funded by SCOAP3 / License Version CC BY 4.0.Dijet production has been measured in pPb collisions at a nucleon–nucleon centre-of-mass energy of 5.02 TeV . A data sample corresponding to an integrated luminosity of 35 nb −1 was collected using the Compact Muon Solenoid detector at the Large Hadron Collider. The dijet transverse momentum balance, azimuthal angle correlations, and pseudorapidity distributions are studied as a function of the transverse energy in the forward calorimeters ( E 4<|η|<5.2 T ). For pPb collisions, the dijet transverse momentum ratio and the width of the distribution of dijet azimuthal angle difference are comparable to the same quantities obtained from a simulated pp reference and insensitive to E 4<|η|<5.2 T . In contrast, the mean value of the dijet pseudorapidity is found to change monotonically with increasing E 4<|η|<5.2 T , indicating a correlation between the energy emitted at large pseudorapidity and the longitudinal motion of the dijet frame. The pseudorapidity distribution of the dijet system in minimum bias pPb collisions is compared with next-to-leading-order perturbative QCD predictions obtained from both nucleon and nuclear parton distribution functions, and the data more closely match the latter
Probing color coherence effects in pp collisions at √s = 7 TeV
No full textOpen Access This article is distributed under the terms of the Creative Commons Attribution License which permits any use, distribution, and reproduction in any medium, provided the original author(s) and the
source are credited. Funded by SCOAP3 / License Version CC BY 4.0.A study of color coherence effects in pp collisions at a center-of-mass energy of 7TeV is presented. The data used in the analysis were collected in 2010 with the CMS detector at the LHC and correspond to an integrated luminosity of 36 pb-1. Events are selected that contain at least three jets and where the two jets with the largest transverse momentum exhibit a back-to-back topology. The measured angular correlation between the second- and third-leading jet is shown to be sensitive to color coherence effects, and is compared to the predictions of Monte Carlo models with various implementations of color coherence. None of the models describe the data satisfactorily.BMWF and FWF (Austria); FNRS and FWO(Belgium); CNPq, CAPES, FAPERJ, and FAPESP (Brazil);MES
(Bulgaria); CERN; CAS, MoST, and NSFC (China); COLCIENCIAS (Colombia); MSES (Croatia); RPF(Cyprus); MoER, SF0690030s09 and ERDF (Estonia); Academy of Finland, MEC, and HIP (Finland);
CEA and CNRS/IN2P3 (France); BMBF, DFG, and HGF (Germany); GSRT (Greece); OTKA and NIH (Hungary); DAE and DST (India); IPM (Iran); SFI (Ireland); INFN (Italy); NRF and WCU (Republic of
Korea); LAS (Lithuania); CINVESTAV, CONACYT, SEP, andUASLPFAI (Mexico); MBIE (New Zealand); PAEC (Pakistan); MSHE and NSC (Poland); FCT (Portugal); JINR (Dubna); MON, RosAtom, RAS and RFBR(Russia);MESTD (Serbia); SEIDI and CPAN(Spain); Swiss Funding Agencies (Switzerland); NSC (Taipei); ThEPCenter, IPST, STAR and NSTDA (Thailand); TUBITAK and TAEK (Turkey); NASU (Ukraine); STFC (United Kingdom); DOE and NSF (USA)
Manutenibilidade da semântica de modelos de dados de produtos compartilhados em rede interoperável
No full textTese (doutorado) - Universidade Federal de Santa Catarina, Centro Tecnológico.Os dados manipulados por aplicações de engenharia têm sido tratados usando sistemas de gerência de banco de dados ou mecanismos dedicados embutidos em sistemas CAx. As tendências atuais de competitividade industrial apontam para a necessidade de integrar as aplicações de engenharia. Duas demandas principais se manifestam: o uso de um mecanismo para o acesso interoperável em rede aos dados, e a necessidade de manipular modelos de dados baseados em diferentes paradigmas. Esta tese de doutorado apresenta uma revisão sobre tecnologia de banco de dados com ênfase em aplicações de engenharia, introduz os problemas de intercâmbio de dados de produtos e interoperabilidade de aplicações, e discute o problema de perda semântica na tradução de modelos de dados de produtos compartilhados em rede e baseados em formatos padrão. Uma análise dos problemas que emergem nesta tradução, com o objetivo de avaliar a manutenibilidade da semântica dos dados ao longo de uma rede interoperável, é executada e comentada
Measurement of WZ and ZZ production in pp collisions at √s = 8 TeV in final states with b-tagged jets
No full textOpen Access This article is distributed under the terms of the Creative
Commons Attribution License which permits any use, distribution, and
reproduction in any medium, provided the original author(s) and the
source are credited.
Funded by SCOAP3 / License Version CC BY 4.0.Measurements are reported of the WZ and ZZ production cross sections in proton-proton collisions at s √ =8 TeV in final states where one Z boson decays to b-tagged jets. The other gauge boson, either W or Z, is detected through its leptonic decay (either W→eν , μν or Z→e + e − , μ + μ − , or νν ¯ ). The results are based on data corresponding to an integrated luminosity of 18.9 fb −1 collected with the CMS detector at the Large Hadron Collider. The measured cross sections, σ(pp→WZ)=30.7±9.3(stat.)±7.1(syst.)±4.1(th.)±1.0(lum.)pb and σ(pp→ZZ)=6.5±1.7(stat.)±1.0(syst.)±0.9(th.)±0.2(lum.)pb , are consistent with next-to-leading order quantum chromodynamics calculationsBMWF and FWF (Austria); FNRS and FWO (Belgium); CNPq, CAPES, FAPERJ, and FAPESP (Brazil);
MES (Bulgaria); CERN; CAS, MoST, and NSFC (China); COLCIENCIAS (Colombia); MSES and CS (Croatia); RPF (Cyprus); MoER, SF0690030s09 and ERDF (Estonia); Academy of Finland, MEC, and HIP (Finland); CEA and CNRS/IN2P3 (France); BMBF, DFG, and HGF(Germany);GSRT(Greece);OTKAand NIH(Hungary);DAEand DST (India); IPM (Iran); SFI (Ireland); INFN (Italy); NRF and WCU (Republic of Korea); LAS (Lithuania);MOE and UM(Malaysia); CINVESTAV, CONACYT, SEP, and UASLP-FAI (Mexico); MBIE (New Zealand); PAEC (Pakistan); MSHE and NSC (Poland); FCT (Portugal); JINR (Dubna); MON, RosAtom, RAS and RFBR (Russia); MESTD (Serbia); SEIDI and CPAN (Spain); Swiss Funding Agencies (Switzerland);
NSC (Taipei); ThEPCenter, IPST, STAR and NSTDA(Thailand); TUBITAK and TAEK (Turkey); NASU and SFFR (Ukraine); STFC (United Kingdom); DOE and NSF (USA)
Measurement of the inelastic proton–proton cross-section at √s=7 TeV with the ATLAS Detector
No full textA first measurement of the inelastic cross-section is presented for proton-proton collisions at a center of mass energy √ =7 TeV using the ATLAS detector at the Large Hadron Collider. In a dataset corresponding to an integrated luminosity of 20 µb<sup>-1</sup>, events are selected by requiring hits on scintillation counters mounted in the forward region of the detector. An inelastic cross-section of 60.3 ± 2.1 mb is measured for ξ>5x10<sup>-6</sup>, where ξ=M<sup>2</sup><sub>X</sub>/s is calculated from the invariant mass, M<sub>X</sub>, of hadrons selected using the largest rapidity gap in the event. For diffractive events this corresponds to requiring at least one of the dissociation masses to be larger than 15.7 GeV
Search for heavy vector-like quarks coupling to light quarks in proton–proton collisions at √s = 7 TeV with the ATLAS detector
No full text<p>This Letter presents a search for singly produced vector-like quarks, Q, coupling to light quarks, <i>q</i>. The search is sensitive to both charged current (CC) and neutral current (NC) processes, <i>pp→Qq→Wqq′</i> and <i>pp→Qq→Zqq′</i> with a leptonic decay of the vector gauge boson. In 1.04 fb<sup>−1</sup> of data taken in 2011 by the ATLAS experiment at a center-of-mass energy √s = 7 TeV, no evidence of such heavy vector-like quarks is observed above the expected Standard Model background. Limits on the heavy vector-like quark production cross section times branching ratio as a function of mass mQ are obtained. For a coupling <sub>κq</sub>Q=v/mQ, where <i>v</i> is the Higgs vacuum expectation value, 95% C.L. lower limits on the mass of a vector-like quark are set at 900 GeV and 760 GeV from CC and NC processes, respectively.</p>
Search for stable hadronising squarks and gluinos with the ATLAS experiment at the LHC
No full textHitherto unobserved long-lived massive particles with electric and/or colour charge are predicted by a range of theories which extend the Standard Model. In this Letter a search is performed at the ATLAS experiment for slow-moving charged particles produced in proton–proton collisions at 7 TeV centre-of-mass energy at the LHC, using a data-set corresponding to an integrated luminosity of 34 pb−1. No deviations from Standard Model expectations are found. This result is interpreted in a framework of supersymmetry models in which coloured sparticles can hadronise into long-lived bound hadronic states, termed R-hadrons, and 95% CL limits are set on the production cross-sections of squarks and gluinos. The influence of R-hadron interactions in matter was studied using a number of different models, and lower mass limits for stable sbottoms and stops are found to be 294 and 309 GeV respectively. The lower mass limit for a stable gluino lies in the range from 562 to 586 GeV depending on the model assumed. Each of these constraints is the most stringent to date
Measurement of the WW cross section in √s = 7 TeV pp collisions with the ATLAS detector and limits on anomalous gauge couplings
No full textThis Letter reports a measurement of the WW production cross section in
√
s = 7 TeV pp collisions
using data corresponding to an integrated luminosity of 1.02 fb−1 collected with the ATLAS detector.
Using leptonic decays of oppositely charged W bosons, the total measured cross section is σ(pp →
WW) = 54.4 ± 4.0 (stat.) ± 3.9 (syst.) ± 2.0 (lumi.) pb, consistent with the Standard Model prediction
of σ(pp→WW) = 44.4±2.8 pb. Limits on anomalous electroweak triple-gauge couplings are extracted
from a fit to the transverse-momentum distribution of the leading charged lepton in the even
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