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

Please use this identifier to cite or link to this item: https://ir.lib.ncu.edu.tw/handle/987654321/105547

Title:	Observation of Z decays to four leptons with the CMS detector at the LHC
Authors:	張元翰;Apresyan, Artur;Bagliesi, Giuseppe;Velkovska, Julia;Varelas, Nikos;Innocente, Vincenzo;Hadjiiska, Roumyana;Gascon, Susan;Geiser, Achim;Spalding, William J;Markina, Anastasia;Chang, Yuan-Hann;Shukla, Prashant;Colaleo, Anna;Piotrzkowski, Krzysztof;Steinbrück, Georg;Avetisyan, Aram;Elliott-Peisert, Anna;Farrell, Chris;Pant, Lalit Mohan;Tricomi, Alessia;Martinez, German;Cockerill, David JA;Nappi, Aniello;Ferencek, Dinko;Haas, Jeff;Ekmedzic, Marko;Lu, Ying;Hollingsworth, Matthew;Brooke, James John;Thomsen, Jan;Mott, Alexander;Rommerskirchen, Tanja;Mohanty, Ajit Kumar;Spiropulu, Maria;De Moraes Gregores, Eduardo;Malcles, Julie;Jain, Shilpi;Luyckx, Sten;Danielson, Thomas;Fabbri, Fabrizio;Berry, Edmund;Chwalek, Thorsten;Dupont-Sagorin, Niels;Paktinat Mehdiabadi, Saeid;Szillasi, Zoltan;Bauer, Gerry;Hatakeyama, Kenichi;Kazana, Malgorzata;Dumanoglu, Isa;Frueboes, Tomasz;Segoni, Ilaria;Bachtis, Michail;Costa, Salvatore;Letts, James;Kim, Tae Jeong;Saka, Halil;Piparo, Danilo;Van Mechelen, Pierre;Vanini, Sara;Fulcher, Jonathan;West, Christopher;Gomez, Gervasio;Gninenko, Sergei;Dinardo, Mauro Emanuele;Ptochos, Fotios;Timciuc, Vladlen;Wilken, Rachel;Ford, William T;Grachov, Oleg;Kovalskyi, Dmytro;Damgov, Jordan;Boimska, Bozena;Chao, Yuan;Beri, Suman Bala;Cankocak, Kerem;Van Remortel, Nick;Rodozov, Mircho;Halkiadakis, Eva;Navarria, Francesco;Girgis, Semiray;Bellan, Riccardo;Kim, Gui Nyun;Sanders, Stephen;Chang, Sunghyun;Kalavase, Puneeth;De La Cruz, Begona;Laasanen, Alvin T;Goldstein, Joel;Naumann-Emme, Sebastian;Mehta, Pourus;Vavilov, Sergey;Mavrommatis, Charalampos;Dugad, Shashikant;Snow, Gregory R;Gilbert, Andrew;de Trocóniz, Jorge F;Kayis Topaksu, Aysel;Zhokin, Alexander;Mccartin, Joseph;Kreuzer, Peter
Contributors:	理學院物理學系
Keywords:	Classical and Quantum Gravitation;Cross-sections;Decay;Elementary Particles;Experiment;Higgs bosons;High energy physics;High Energy Physics - Experiment;Invariants;Large Hadron Collider;Leptons;Luminosity;Muons;Particle collisions;Particle Physics;Physics;Physics and Astronomy;Protons;Quantum Field Theories;Quantum Field Theory;Quantum Physics;Quarks;Relativity Theory;Solenoids;String Theory
Date:	2012-01-01
Issue Date:	2026-04-23 12:35:18 (UTC+8)
Publisher:	Berlin/Heidelberg: Springer-Verlag
Abstract:	摘要： 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 inverse femtobarns at $\sqrt{s}$ = 7 TeV collected by the CMS detector at the Large Hadron Collider. A pronounced resonance peak, with a statistical significance of 9.7 $\sigma$, 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 $\to$ 4l) = (4.2$^{+0.9}_{-0.8}$ (stat.) $\pm$ 0.2 (syst.)) 10E-6 and agrees with the standard model prediction of 4.45 10E-6. The measured cross section times branching fraction is $\sigma$(pp $\to$ Z) B(Z $\to$ 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 $\to$ 4l decays provides a calibration channel for the Higgs boson search in the H $\to$ ZZ $\to$ 4l decay mode. 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 inverse femtobarns at sqrt(s) = 7 TeV collected by the CMS detector at the Large Hadron Collider. A pronounced resonance peak, with a statistical significance of 9.7 sigma, 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 to 4l) = (4.2 /+0.9/-0.8 (stat.) +/- 0.2 (syst.)) 10E-6 and agrees with the standard model prediction of 4.45 10E-6. The measured cross section times branching fraction is sigma(pp to Z) B(Z to 4 l) = 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 to 4 l decays provides a calibration channel for the Higgs boson search in the H to ZZ to 4 l decay mode. 其他題名： J. High Energ. Phys 出版者： Berlin/Heidelberg: Springer-Verlag 出版日期： 2012-12-01 出處： Journal of High Energy Physics (Online), 2012-12, Vol.2012 (12), Article 34 資源來源： Publicly Available Content Database (Proquest) 版權： CERN for the benefit of the CMS collaboration 2012 版權： CERN for the benefit of the CMS collaboration 2012. 版權： CC0 1.0 - Universal 識別號： ISSN: 1029-8479 識別號： ISSN: 1126-6708 識別號： ISSN: 1127-2236 識別號： EISSN: 1029-8479 識別號： DOI: 10.1007/JHEP12(2012)034
Appears in Collections:	[Department of Physics] journal & Dissertation

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