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Forward energy flow, central charged-particle multiplicities, and pseudorapidity gaps in W and Z boson events from pp collisions at √s =7 TeV

Chatrchyan, S. and Apresyan, A. and Bornheim, A. and Bunn, J. and Chen, Y. and Gataullin, M. and Ma, Y. and Mott, A. and Newman, H. B. and Rogan, C. and Shin, K. and Timciuc, V. and Traczyk, P. and Veverka, J. and Wilkinson, R. and Yang, Y. and Zhu, R. Y. and Spiropulu, M. and Dubinin, M. (2012) Forward energy flow, central charged-particle multiplicities, and pseudorapidity gaps in W and Z boson events from pp collisions at √s =7 TeV. European Physical Journal C, 72 (1). Art. No. 1839. ISSN 1434-6044. http://resolver.caltech.edu/CaltechAUTHORS:20120326-105151343

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Abstract

A study of forward energy flow and central charged-particle multiplicity in events with W and Z bosons decaying into leptons is presented. The analysis uses a sample of 7 TeV pp collisions, corresponding to an integrated luminosity of 36 pb^(−1), recorded by the CMS experiment at the LHC. The observed forward energy depositions, their correlations, and the central charged-particle multiplicities are not well described by the available non-diffractive soft-hadron production models. A study of about 300 events with no significant energy deposited in one of the forward calorimeters, corresponding to a pseudorapidity gap of at least 1.9 units, is also presented. An indication for a diffractive component in these events comes from the observation that the majority of the charged leptons from the W(Z) decays are found in the hemisphere opposite to the gap. When fitting the signed lepton pseudorapidity distribution of these events with predicted distributions from an admixture of diffractive (pompyt) and non-diffractive (pythia) Monte Carlo simulations, the diffractive component is determined to be (50.0 ± 9.3 (stat.) ± 5.2 (syst.))%.


Item Type:Article
Related URLs:
URLURL TypeDescription
http://dx.doi.org/10.1140/epjc/s10052-011-1839-3DOIUNSPECIFIED
http://www.springerlink.com/content/706682283061141t/PublisherUNSPECIFIED
Additional Information:© 2012 CERN for the benefit of the CMS collaboration. This article is distributed under the terms of the Creative Commons Attribution Noncommercial License which permits any noncommercial use, distribution, and reproduction in any medium, provided the original author(s) and source are credited. Received: 2 October 2011. Revised: 2 November 2011. Published online: 20 January 2012. We wish to congratulate our colleagues in the CERN accelerator departments for the excellent performance of the LHC machine.We would like to thank P. Skands for many explanations and discussions concerning the different underlying event tunes. We would also like to thank the technical and administrative staff at CERN and other CMS institutes, and acknowledge support from: FMSR (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); Academy of Sciences and NICPB (Estonia); Academy of Finland, ME, and HIP (Finland); CEA and CNRS/IN2P3 (France); BMBF, DFG, and HGF (Germany); GSRT (Greece); OTKA and NKTH (Hungary); DAE and DST (India); IPM (Iran); SFI (Ireland); INFN (Italy); NRF and WCU (Korea); LAS (Lithuania); CINVESTAV, CONACYT, SEP, and UASLP-FAI (Mexico); PAEC (Pakistan); SCSR (Poland); FCT (Portugal); JINR (Armenia, Belarus, Georgia, Ukraine, Uzbekistan); MST and MAE (Russia); MSTDS (Serbia); MICINN and CPAN (Spain); Swiss Funding Agencies (Switzerland); NSC (Taipei); TUBITAK and TAEK (Turkey); STFC (United Kingdom); DOE and NSF (USA). Individuals have received support from the Marie-Curie IEF program (European Union); the Leventis Foundation; the A. P. Sloan Foundation; the Alexander von Humboldt Foundation; and the Associazione per lo Sviluppo Scientifico e Tecnologico del Piemonte (Italy).
Group:CMS@Caltech
Funders:
Funding AgencyGrant Number
FMSR (Austria)UNSPECIFIED
FNRS and FWO (Belgium) UNSPECIFIED
CNPq (Brazil)UNSPECIFIED
CAPES (Brazil)UNSPECIFIED
FAPERJ (Brazil)UNSPECIFIED
FAPESP (Brazil)UNSPECIFIED
MES (Bulgaria)UNSPECIFIED
CERNUNSPECIFIED
CASUNSPECIFIED
MoST (China)UNSPECIFIED
NSFC (China)UNSPECIFIED
COLCIENCIAS (Colombia)UNSPECIFIED
MSES (Croatia)UNSPECIFIED
RPF (Cyprus) UNSPECIFIED
Academy of Sciences and NICPB (Estonia) UNSPECIFIED
Academy of FinlandUNSPECIFIED
ME (Finland)UNSPECIFIED
HIP (Finland)UNSPECIFIED
CEA and CNRS/IN2P3 (France)UNSPECIFIED
BMBF (Germany)UNSPECIFIED
DFG (Germany)UNSPECIFIED
HGF (Germany)UNSPECIFIED
GSRT (Greece)UNSPECIFIED
OTKA and NKTH (Hungary) UNSPECIFIED
DAE and DST (India) UNSPECIFIED
IPM (Iran)UNSPECIFIED
SFI (Ireland)UNSPECIFIED
INFN (Italy)UNSPECIFIED
NRF and WCU (Korea)UNSPECIFIED
LAS (Lithuania)UNSPECIFIED
CINVESTAV (Mexico)UNSPECIFIED
CONACyT (Mexico)UNSPECIFIED
SEP and UASLP-FAI (Mexico)UNSPECIFIED
PAEC (Pakistan)UNSPECIFIED
SCSR (Poland)UNSPECIFIED
FCT (Portugal)UNSPECIFIED
JINR (Armenia, Belarus, Georgia, Ukraine, Uzbekistan)UNSPECIFIED
MST and MAE (Russia) UNSPECIFIED
MSTDS (Serbia)UNSPECIFIED
MICINN and CPAN (Spain) UNSPECIFIED
Swiss Funding Agencies (Switzerland)UNSPECIFIED
NSC (Taipei)UNSPECIFIED
TUBITAK and TAEK (Turkey) UNSPECIFIED
STFC (United Kingdom)UNSPECIFIED
Department of Energy (DOE)UNSPECIFIED
NSFUNSPECIFIED
Marie Curie EIF (European Union)UNSPECIFIED
Leventis Foundation UNSPECIFIED
A.P. Sloan FoundationUNSPECIFIED
Alexander von Humboldt FoundationUNSPECIFIED
Associazione per lo Sviluppo Scientifico e Tecnologico del Piemonte (Italy) UNSPECIFIED
Record Number:CaltechAUTHORS:20120326-105151343
Persistent URL:http://resolver.caltech.edu/CaltechAUTHORS:20120326-105151343
Official Citation:Forward energy flow, central charged-particle multiplicities, and pseudorapidity gaps in W and Z boson events from pp collisions at s=7 TeV The CMS Collaboration, S. Chatrchyan, V. Khachatryan, A. M. Sirunyan and A. Tumasyan, et al. DOI: 10.1140/epjc/s10052-011-1839-3
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:29843
Collection:CaltechAUTHORS
Deposited By: Ruth Sustaita
Deposited On:26 Mar 2012 18:20
Last Modified:25 Feb 2013 23:29

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