Measurement of the Upsilon(1S) Production Cross Section in Proton-Proton Collisions at Center of Mass Energy 7 TeV PDF Download
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Author: Maxwell Ian Scherzer
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Category :
Languages : en
Pages : 262
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A measurement of the cross section for upsilon(1S) production in proton-proton collisions at center of mass energy 7 TeV is presented. The measurement uses the upsilon(1S) 2!mu + mu decay mode and covers up to a transverse momentum of 26 GeV in two bins of rapidity; upsilon(1S) upsilon(1S) -1, collected with the ATLAS detector at the Large Hadron Collider. Templates derived from data are used to model the continuum background. In order to eliminate theoretical uncertainties due to the unknown polarization, the measurement is restricted to the case where both muons have a transverse momentum of p mu T> 4 GeV and a pseudorapidit
Author: Maxwell Ian Scherzer
Publisher:
ISBN:
Category :
Languages : en
Pages : 262
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Book Description
A measurement of the cross section for upsilon(1S) production in proton-proton collisions at center of mass energy 7 TeV is presented. The measurement uses the upsilon(1S) 2!mu + mu decay mode and covers up to a transverse momentum of 26 GeV in two bins of rapidity; upsilon(1S) upsilon(1S) -1, collected with the ATLAS detector at the Large Hadron Collider. Templates derived from data are used to model the continuum background. In order to eliminate theoretical uncertainties due to the unknown polarization, the measurement is restricted to the case where both muons have a transverse momentum of p mu T> 4 GeV and a pseudorapidit
Author: Maxwell Ian Scherzer
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ISBN:
Category :
Languages : en
Pages : 0
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Author: Puneeth D. Kalavase
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ISBN: 9781124885476
Category :
Languages : en
Pages : 167
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The first measurement of the cross section for top-quark pair production in proton-proton collisions at the Large Hadron Collider at center-of-mass energy of 7 TeV has been performed using a data sample corresponding to an integrated luminosity of 3 pb-1 recorded by the CMS detector. This result utilizes the final state with two isolated, highly energetic charged leptons, large missing transverse energy, and two or more jets. Backgrounds from Drell-Yan and non-W/Z boson production are estimated from data. Eleven events are observed in the data with 2.1+/-1.0 events expected from background. The measured cross section is 194+/-72 (statistical) +/-24 (systematic) +/-21 (luminosity) pb. The result is consistent with next-to-leading order theoretical predictions.
Author:
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ISBN:
Category :
Languages : en
Pages : 26
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Book Description
The first measurement of the cross section for top-quark pair production in pp collisions at the LHC at center-of-mass energy sqrt(s)= 7 TeV has been performed using 3.1 {\pm} 0.3 inverse pb of data recorded by the CMS detector. This result utilizes the final state with two isolated, highly energetic charged leptons, large missing transverse energy, and two or more jets. Backgrounds from Drell-Yan and non-W/Z boson production are estimated from data. Eleven events are observed in the data with 2.1 {\pm} 1.0 events expected from background. The measured cross section is 194 {\pm} 72 (stat.) {\pm} 24 (syst.) {\pm} 21 (lumi.) pb, consistent with next-to-leading order predictions.
Author: Jun Gao
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ISBN:
Category :
Languages : en
Pages : 0
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The Standard Model (SM), actual fundamental theory for particle physics, provides a description of the elementary particles and the fundamental interactions: the electromagnetic, weak and strong forces. At the European Organization for Nuclear Research (CERN), physicists and engineers from all over the world are searching to understand the fundamental laws of the universe. It is at CERN that the world's largest and most sophisticated experimental instruments have been built, to accelerate particles at the energy of 3.5-4 TeV with the Large Hadron Collider (LHC). A Toroidal LHC ApparatuS (ATLAS), one of the four main detectors at LHC. In ATLAS, di-boson production is one of the most important electro-weak processes.The electro-weak sector of the SM, as well as the strong interactions, can be tested through the precision measurements of the W+W− production cross section. A measurement of the W+W− production cross section in 8 TeV center of mass proton-proton collisions is presented here from data collected with the ATLAS detector at the LHC for a total integrated luminosity of 20.3 fb−1. The W+W− events are selected with 3 final states: ee, eμ, and μμ. In order to suppress the background contamination, mainly from the Drell-Yan and ttbar processes, a cut on missing transverse energy is applied and events with hadronic jets satisfying appropriate selection criteria are rejected. The major backgrounds, mainly including W +jets, top and Z+jets, are estimated by data driven technique. The measured cross section is 71.0+1⋅1−1⋅1(stat)+5⋅7−5⋅0(syst)+2⋅1−2⋅0(lumi) pb, which is consistent with SM Next-to-Next-Leading-Order prediction of 63.2+2⋅0−1⋅8 pb.
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 38
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Book Description
The integrated and differential cross sections for the production of pairs of isolated photons is measured in proton-proton collisions at a centre-of-mass energy of 7 TeV with the CMS detector at the LHC. A data sample corresponding to an integrated luminosity of 36 inverse picobarns is analysed. A next-to-leading-order perturbative QCD calculation is compared to the measurements. A discrepancy is observed for regions of the phase space where the two photons have an azimuthal angle difference, $\Delta(\phi)$, less than approximately 2.8.
Author:
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ISBN:
Category :
Languages : en
Pages : 223
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This paper presents a measurement of the inclusive 3-jet production differential cross section at a proton-proton centre-of-mass energy of 7 TeV using data corresponding to an integrated luminosity of 5 fb$^{-1}$ collected with the CMS detector. The analysis is based on the three jets with the highest transverse momenta. The cross section is measured as a function of the invariant mass of the three jets in a range of 445-3270 GeV and in two bins of the maximum rapidity of the jets up to a value of 2. A comparison between the measurement and the prediction from perturbative QCD at next-to-leading order is performed. Within uncertainties, data and theory are in agreement. The sensitivity of the observable to parameters of the theory such as the parton distribution functions of the proton and the strong coupling constant $\alpha_S$ is studied. A fit to all data points with 3-jet masses larger than 664 GeV gives a value of the strong coupling constant of $\alpha_S(M_\mathrm{Z})$ = 0.1171 $\pm$ 0.0013 (exp) $^{+0.0073}_{-0.0047}$ (theo).
Author:
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ISBN:
Category :
Languages : en
Pages : 54
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Book Description
The inclusive cross section for top quark pair production is measured in proton-proton collisions at √s = 7 and 8 TeV, corresponding to 5.0 and 19.7 fb-1, respectively, with the CMS experiment at the LHC. The cross sections are measured in the electron-muon channel using a binned likelihood fit to multi-differential final state distributions related to identified b quark jets and other jets in the event. The measured cross section values are 173.6 ± 2.1 (stat)+4.5-4.0 (syst) ± 3.8 (lumi) pb at √s = 7 TeV, and 244.9 ± 1.4 (stat)+6.3-5.5 (syst) ± 6.4 (lumi) pb at √s = 8 TeV, in good agreement with QCD calculations at next-to-next-to-leading-order accuracy. The ratio of the cross sections measured at 7 and 8 TeV is determined, as well as cross sections in the fiducial regions defined by the acceptance requirements on the two charged leptons in the final state. The cross section results are used to determine the top quark pole mass via the dependence of the theoretically predicted cross section on the mass, giving a best result of 173.8+1.7-1.8 GeV. Furthermore, the data at √s = 8 TeV are also used to set limits, for two neutralino mass values, on the pair production of supersymmetric top squarks with masses close to the top quark mass.
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ISBN: 9781303634567
Category :
Languages : en
Pages : 141
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Dijet production is measured in proton--proton collisions with a center-of-mass energy of 7 TeV at the LHC. Double-differential dijet cross sections are presented as functions of the dijet mass and rapidity separation of the two highest-transverse-momentum jets in an event. The data sample collected in 2011 by the ATLAS detector is considered, corresponding to an integrated luminosity of 4.5 fb -1. Jets are defined using the anti-kt algorithm, with two choices of the jet radius parameter, R = 0.4 and R = 0.6. The results are compared with next-to-leading-order (NLO) perturbative calculations, as well as NLO Monte Carlo generator predictions. In both cases, electroweak effects are accounted for. A method for the quantitative comparison of theory predictions with data is presented, employing a frequentist technique. This allows for strong statements on which sets of parton distribution functions best describe the data. A theory of quark compositeness modeled by contact interactions is confronted by the unfolded data using the CLs technique, an example of the versatility of the measurement.
Author:
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ISBN:
Category :
Languages : en
Pages : 33
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Book Description
Measurements of the ZZ production cross sections in proton-proton collisions at center-of-mass energies of 7 and 8 TeV are presented. We found that candidate events for the leptonic decay mode ZZ 2!2l2[nu], where l denotes an electron or a muon, are reconstructed and selected from data corresponding to an integrated luminosity of 5.1 (19.6)fb-1 at 7 (8) TeV collected with the CMS experiment. The measured cross sections, [sigma](pp 2!ZZ)=5.1+1.5-1.4(stat)+1.4-1.1(syst)"0.1(lumi)pb at 7 TeV, and 7.2+0.8-0.8(stat)+1.9-1.5(syst)"0.2(lumi)pb at 8 TeV, are in good agreement with the standard model predictions with next-to-leading-order accuracy. Furthermore, the selected data are analyzed to search for anomalous triple gauge couplings involving the ZZ final state. In the absence of any deviation from the standard model predictions, limits are set on the relevant parameters. As a result, these limits are then combined with the previously published CMS results for ZZ in 4l final states, yielding the most stringent constraints on the anomalous couplings.
