Rubin-LSST

Research group

Research theme

Sub department

About

J/ψ and ψ (2S) production in pp collisions at √s = 7 TeV

Journal of High Energy Physics 2012:2 (2012)

Authors:

S Chatrchyan, V Khachatryan, AM Sirunyan, A Tumasyan, W Adam, T Bergauer, M Dragicevic, J Erö, C Fabjan, M Friedl, R Frühwirth, VM Ghete, J Hammer, M Hoch, N Hörmann, J Hrubec, M Jeitler, W Kiesenhofer, M Krammer, D Liko, I Mikulec, M Pernicka, B Rahbaran, H Rohringer, R Schöfbeck, J Strauss, A Taurok, F Teischinger, C Trauner, P Wagner, W Waltenberger, G Walzel, E Widl, CE Wulz, V Mossolov, N Shumeiko, J Suarez Gonzalez, S Bansal, L Benucci, EA De Wolf, X Janssen, S Luyckx, T Maes, L Mucibello, S Ochesanu, B Roland, R Rougny, M Selvaggi, H Van Haevermaet, P Van Mechelen, N Van Remortel, F Blekman, S Blyweert, J D'Hondt, R Suarez Gonzalez, A Kalogeropoulos, M Maes, A Olbrechts, W Van Doninck, P Van Mulders, GP Van Onsem, I Villella, O Charaf, B Clerbaux, G De Lentdecker, V Dero, APR Gay, GH Hammad, T Hreus, A Léonard, PE Marage, L Thomas, C Vander Velde, P Vanlaer, J Wickens, V Adler, K Beernaert, A Cimmino, S Costantini, M Grunewald, B Klein, J Lellouch, A Marinov, J McCartin, D Ryckbosch, N Strobbe, F Thyssen, M Tytgat, L Vanelderen, P Verwilligen, S Walsh, N Zaganidis, S Basegmez, G Bruno, J Caudron, L Ceard, E Cortina Gil, J De Favereau De Jeneret, C Delaere, D Favart

Abstract:

A measurement of the J/ ψ and ψ (2S) production cross sections in pp collisions at √s = 7TeV with the CMS experiment at the LHC is presented. The data sample corresponds to an integrated luminosity of 37 pb -1. Using a fit to the invariant mass and decay length distributions, production cross sections have been measured separately for prompt and non-prompt charmonium states, as a function of the meson transverse momentum in several rapidity ranges and integrated in the kinematical regions considered in this study. In addition, cross sections restricted to the acceptance of the CMS detector are given, which are not affected by the polarization of the charmonium states. The ratio of the differential production cross sections of the two states, where systematic uncertainties largely cancel, is also determined. The branching fraction of the inclusive B → ψ (2S)X decay is extracted from the ratio of the non-prompt cross sections to be: B(B → ψ (2S)X) = (3:08 ± 0:12 (stat.+syst.) ± 0:13 (theor.) ± 0:42 (BPDG)) × 10-3: B(B → ψ(2S)X) = (3.08 ± 0.12 (stat.+syst.) ± 0.13 (theor.) ± 0.42 (BPDG)) × 10-3.
More details from the publisher

Jet production rates in association with W and Z bosons in pp collisions at √s = 7 TeV

Journal of High Energy Physics 2012:1 (2012)

Authors:

S Chatrchyan, V Khachatryan, AM Sirunyan, A Tumasyan, W Adam, T Bergauer, M Dragicevic, J Erö, C Fabjan, M Friedl, R Frühwirth, VM Ghete, J Hammer, S Hánsel, M Hoch, N Hörmann, J Hrubec, M Jeitler, W Kiesenhofer, M Krammer, D Liko, I Mikulec, M Pernicka, B Rahbaran, H Rohringer, R Schöfbeck, J Strauss, A Taurok, F Teischinger, C Trauner, P Wagner, W Waltenberger, G Walzel, E Widl, CE Wulz, V Mossolov, N Shumeiko, J Suarez Gonzalez, S Bansal, L Benucci, EA De Wolf, X Janssen, S Luyckx, T Maes, L Mucibello, S Ochesanu, B Roland, R Rougny, M Selvaggi, H Van Haevermaet, P Van Mechelen, N Van Remortel, F Blekman, S Blyweert, J D'Hondt, R Gonzalez Suarez, A Kalogeropoulos, M Maes, A Olbrechts, W Van Doninck, P Van Mulders, GP Van Onsem, I Villella, O Charaf, B Clerbaux, G De Lentdecker, V Dero, APR Gay, GH Hammad, T Hreus, PE Marage, A Raval, L Thomas, G Vander Marcken, C Vander Velde, P Vanlaer, V Adler, A Cimmino, S Costantini, M Grunewald, B Klein, J Lellouch, A Marinov, J McCartin, D Ryckbosch, F Thyssen, M Tytgat, L Vanelderen, P Verwilligen, S Walsh, N Zaganidis, S Basegmez, G Bruno, J Caudron, L Ceard, E Cortina Gil, J De Favereau De Jeneret, C Delaere, D Favart, A Giammanco

Abstract:

Measurements of jet production rates in association with W and Z bosons for jet transverse momenta above 30 GeV are reported, using a sample of proton-proton collision events recorded by CMS at √s = 7TeV, corresponding to an integrated luminosity of 36 pb-1. The study includes the measurement of the normalized inclusive rates of jets σ(V+ ≥ n jets)=σ(V), where V represents either a W or a Z. In addition, the ratio of W to Z cross sections and the W charge asymmetry as a function of the number of associated jets are measured. A test of scaling at √s = 7TeV is also presented. The measurements provide a stringent test of perturbative-QCD calculations and are sensitive to the possible presence of new physics. The results are in agreement with the predictions of a simulation that uses explicit matrix element calculations for final states with jets. © 2012 SISSA.
More details from the publisher

Maintaining and improving of the training program on the analysis software in CMS

Journal of Physics: Conference Series 396:PART 6 (2012)

Authors:

S Malik, F Hoehle, K Lassila-Perini, A Hinzmann, R Wolf, I Shipsey

Abstract:

Since 2009, the CMS experiment at LHC has provided intensive training on the use of Physics Analysis Tools (PAT), a collection of common analysis tools designed to share expertise and maximize productivity in the physics analysis. More than ten one-week courses preceded by prerequisite studies have been organized and the feedback from the participants has been carefully analyzed. This note describes how the training team designs, maintains and improves the course contents based on the feedback, the evolving analysis practices and the software development.
More details from the publisher
More details

Measurement of the W boson polarization in top quark decays with the ATLAS detector

Journal of High Energy Physics 2012:6 (2012)

Authors:

G Aad, B Abbott, J Abdallah, S Abdel Khalek, AA Abdelalim, O Abdinov, B Abi, M Abolins, OS AbouZeid, H Abramowicz, H Abreu, E Acerbi, BS Acharya, L Adamczyk, DL Adams, TN Addy, J Adelman, S Adomeit, P Adragna, T Adye, S Aefsky, JA Aguilar-Saavedra, M Agustoni, M Aharrouche, SP Ahlen, F Ahles, A Ahmad, M Ahsan, G Aielli, T Akdogan, TPA Åkesson, G Akimoto, AV Akimov, A Akiyama, MS Alam, MA Alam, J Albert, S Albrand, M Aleksa, IN Aleksandrov, F Alessandria, C Alexa, G Alexander, G Alexandre, T Alexopoulos, M Alhroob, M Aliev, G Alimonti, J Alison, BMM Allbrooke, PP Allport, SE Allwood-Spiers, J Almond, A Aloisio, R Alon, A Alonso, B Alvarez Gonzalez, MG Alviggi, K Amako, C Amelung, VV Ammosov, A Amorim, N Amram, C Anastopoulos, LS Ancu, N Andari, T Andeen, CF Anders, G Anders, KJ Anderson, A Andreazza, V Andrei, XS Anduaga, P Anger, A Angerami, F Anghinolfi, A Anisenkov, N Anjos, A Annovi, A Antonaki, M Antonelli, A Antonov, J Antos, F Anulli, S Aoun, L Aperio Bella, R Apolle, G Arabidze, I Aracena, Y Arai, ATH Arce, S Arfaoui, JF Arguin, E Arik, M Arik, AJ Armbruster, O Arnaez, V Arnal, C Arnault, A Artamonov

Abstract:

This paper presents measurements of the polarization ofW bosons in top quark decays, derived from tt̄ events with missing transverse momentum, one charged lepton and at least four jets, or two charged leptons and at least two jets. Data from pp collisions at a centre-of-mass energy of 7 TeV were collected with the ATLAS experiment at the LHC and correspond to an integrated luminosity of 1.04 fb-1. The measured fractions of longitudinally, left- and right-handed polarization are F0 = 0.67 ± 0.07, FL = 0.32 ± 0.04 and FR = 0.01 ± 0.05, in agreement with the Standard Model predictions. As the polarization of the W bosons in top quark decays is sensitive to the Wtb vertex Lorentz structure and couplings, the measurements were used to set limits on anomalous contributions to the Wtb couplings. © CERN.
More details from the publisher
More details

Measurement of the Z/γ*+b-jet cross section in pp collisions at √s = 7 TeV

Journal of High Energy Physics 2012:6 (2012)

Authors:

S Chatrchyan, V Khachatryan, AM Sirunyan, A Tumasyan, W Adam, T Bergauer, M Dragicevic, J Erö, C Fabjan, M Friedl, R Frühwirth, VM Ghete, J Hammer, M Hoch, N Hörmann, J Hrubec, M Jeitler, W Kiesenhofer, M Krammer, D Liko, I Mikulec, M Pernicka, B Rahbaran, C Rohringer, H Rohringer, R Schöfbeck, J Strauss, A Taurok, F Teischinger, P Wagner, W Waltenberger, G Walzel, E Widl, CE Wulz, V Mossolov, N Shumeiko, J Suarez Gonzalez, S Bansal, L Benucci, T Cornelis, EA De Wolf, X Janssen, S Luyckx, T Maes, L Mucibello, S Ochesanu, B Roland, R Rougny, M Selvaggi, H Van Haevermaet, P Van Mechelen, N Van Remortel, A Van Spilbeeck, F Blekman, S Blyweert, J D'Hondt, R Gonzalez Suarez, A Kalogeropoulos, M Maes, A Olbrechts, W Van Doninck, P Van Mulders, GP Van Onsem, I Villella, O Charaf, B Clerbaux, G De Lentdecker, V Dero, APR Gay, GH Hammad, T Hreus, A Léonard, PE Marage, L Thomas, C Vander Velde, P Vanlaer, J Wickens, V Adler, K Beernaert, A Cimmino, S Costantini, G Garcia, M Grunewald, B Klein, J Lellouch, A Marinov, J McCartin, AA Ocampo Rios, D Ryckbosch, N Strobbe, F Thyssen, M Tytgat, L Vanelderen, P Verwilligen, S Walsh, E Yazgan, N Zaganidis, S Basegmez, G Bruno, L Ceard

Abstract:

The production of b jets in association with a Z/γ*boson is studied using proton-proton collisions delivered by the LHC at a centre-of-mass energy of 7TeV and recorded by the CMS detector. The inclusive cross section for Z/γ*+b-jet production is measured in a sample corresponding to an integrated luminosity of 2.2 fb-1. The Z/γ*+b-jet cross section with Z/γ*→ℓℓ (where ℓ ℓ = ee or μ μ) for events with the invariant mass 60 < Mℓ ℓ < 120 GeV, at least one b jet at the hadron level with pT > 25 GeV and |η|< 2:1, and a separation between the leptons and the jets of ΔR > 0:5 is found to be 5:84±0:08 (stat:) ±0:72 (syst:) -0:55+0:25 (theory) pb. The kinematic properties of the events are also studied and found to be in agreement with the predictions made by the MadGraph event generator with the parton shower and the hadronisation performed by pythia.
More details from the publisher
More details