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Observation of Z decays to four leptons with the CMS detector at the LHC

Chatrchyan, S. and Apresyan, A. and Bornheim, A. and Chen, Y. and Di Marco, E. and Duarte, J. and Gataullin, M. and Ma, Y. and Mott, A. and Newman, H. B. and Rogan, C. and Spiropulu, M. and Timciuc, V. and Traczyk, P. and Veverka, J. and Wilkinson, R. and Yang, Y. and Zhu, R. Y. and Dias, F. A. and Dubinin, M. (2012) Observation of Z decays to four leptons with the CMS detector at the LHC. Journal of High Energy Physics, 2012 (12). Art. No. 034. ISSN 1126-6708. http://resolver.caltech.edu/CaltechAUTHORS:20130326-103727958

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Abstract

The first observation of the Z boson decaying to four leptons in proton-proton collisions is presented. The analyzed data set corresponds to an integrated luminosity of 5.02 fb^(−1) at s√=7 TeV collected by the CMS detector at the Large Hadron Collider. A pronounced resonance peak, with a statistical significance of 9.7 σ, is observed in the distribution of the invariant mass of four leptons (electrons and/or muons) with mass and width consistent with expectations for Z boson decays. The branching fraction and cross section reported here are defined by phase space restrictions on the leptons, namely, 80 < m_(4ℓ) < 100 GeV, where m_(4ℓ) is the invariant mass of the four leptons, and m_(ℓℓ) > 4 GeV for all pairs of leptons, where m_(ℓℓ) is the two-lepton invariant mass. The measured branching fraction is B(Z→4ℓ)= 4.2^(+0.9)_(−0.8)(stat.)±0.2(syst.))×10^(−6) and agrees with the standard model prediction of 4.45 × 10^(−6). The measured cross section times branching fraction is σ(pp→Z)B(Z→4ℓ)=112^(+23)_(−20)(stat.)^(+7)_(−5)(syst.)^(+3)_(−2)(lumi.) fb, also consistent with the standard model prediction of 120 fb. The four-lepton mass peak arising from Z → 4ℓ decays provides a calibration channel for the Higgs boson search in the H → ZZ → 4ℓ decay mode.


Item Type:Article
Related URLs:
URLURL TypeDescription
http://dx.doi.org/10.1007/JHEP12(2012)034DOIUNSPECIFIED
http://link.springer.com/article/10.1007/JHEP12%282012%29034PublisherUNSPECIFIED
http://arxiv.org/abs/1210.3844arXivUNSPECIFIED
Additional Information:© 2012 CERN for the benefit of the CMS collaboration. Received: October 14, 2012. Accepted: November 19, 2012. Published: December 7, 2012. 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 source are credited. We congratulate our colleagues in the CERN accelerator departments for the excellent performance of the LHC machine. We thank the technical and administrative staff at CERN and other CMS institutes, and acknowledge support from 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 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); MSI (New Zealand); PAEC (Pakistan); MSHE and NSC (Poland); FCT (Portugal); JINR (Armenia, Belarus, Georgia, Ukraine, Uzbekistan); MON, RosAtom, RAS and RFBR (Russia); MSTD (Serbia); SEIDI and CPAN (Spain); Swiss Funding Agencies (Switzerland); NSC (Taipei); ThEP, IPST and NECTEC (Thailand); TUBITAK and TAEK (Turkey); NASU (Ukraine); STFC (United Kingdom); DOE and NSF (USA).
Group:CMS@Caltech
Funders:
Funding AgencyGrant Number
BMWF and FWF (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
MoERSF0690030s09
ERDF (Estonia)UNSPECIFIED
Academy of FinlandUNSPECIFIED
MEC (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 (Mexico)UNSPECIFIED
UASLP-FAI (Mexico)UNSPECIFIED
MSI (New Zealand)UNSPECIFIED
PAEC (Pakistan)UNSPECIFIED
MSHE and NSC (Poland)UNSPECIFIED
FCT (Portugal)UNSPECIFIED
JINR (Armenia, Belarus, Georgia, Ukraine, Uzbekistan)UNSPECIFIED
MONUNSPECIFIED
RosAtom UNSPECIFIED
RAS and RFBR (Russia)UNSPECIFIED
MSTD (Serbia)UNSPECIFIED
SEIDI and CPAN (Spain)UNSPECIFIED
Swiss Funding Agencies (Switzerland)UNSPECIFIED
NSC (Taipei)UNSPECIFIED
ThEPUNSPECIFIED
IPST and NECTEC (Thailand)UNSPECIFIED
TUBITAK and TAEK (Turkey) UNSPECIFIED
NASU (Ukraine)UNSPECIFIED
STFC (United Kingdom)UNSPECIFIED
Department of Energy (DOE)UNSPECIFIED
NSFUNSPECIFIED
Subject Keywords:Hadron-Hadron Scattering
Record Number:CaltechAUTHORS:20130326-103727958
Persistent URL:http://resolver.caltech.edu/CaltechAUTHORS:20130326-103727958
Official Citation:Observation of Z decays to four leptons with the CMS detector at the LHC S. Chatrchyan, V. Khachatryan, A. M. Sirunyan…
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:37626
Collection:CaltechAUTHORS
Deposited By: Ruth Sustaita
Deposited On:26 Mar 2013 18:13
Last Modified:29 Aug 2014 14:25

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