Search for associated production of a Z boson with a single top quark and for tZ flavour-changing interactions in pp collisions at √s=8 TeV

被引:0
作者
Sirunyan, A. M. [1 ]
Tumasyan, A. [1 ]
Adam, W. [2 ]
Asilar, E. [2 ]
Bergauer, T. [2 ]
Brandstetter, J. [2 ]
Brondolin, E. [2 ]
Dragicevic, M. [2 ]
Eroe, J. [2 ]
Flechl, M. [2 ]
Friedl, M. [2 ]
Fruehwirth, R. [2 ,201 ]
Ghete, V. M. [2 ]
Hartl, C. [2 ]
Hoermann, N. [2 ]
Hrubec, J. [2 ]
Jeitler, M. [2 ]
Koenig, A. [2 ]
Kraetschmer, I. [2 ]
Liko, D. [2 ]
Matsushita, T. [2 ]
Mikulec, I. [2 ]
Rabady, D. [2 ]
Rad, N. [2 ]
Rahbaran, B. [2 ]
Rohringer, H. [2 ]
Schieck, J. [2 ,201 ]
Strauss, J. [2 ]
Waltenberger, W. [2 ]
Wulzi, C. -E. [2 ]
Dvornikov, O. [3 ]
Makarenko, V. [3 ]
Mossolov, V. [3 ]
Gonzalez, J. Suarez [3 ]
Zykunov, V. [3 ]
Shumeiko, N. [4 ]
Alderweireldt, S. [5 ]
De Wolf, E. A. [5 ]
Janssen, X. [5 ]
Lauwers, J. [5 ]
Van De Klundert, M. [5 ]
Van Haevermaet, H. [5 ]
Van Mechelen, P. [5 ]
Van Remortel, N. [5 ]
Van Spilbeeck, A. [5 ]
Abu Zeid, S. [6 ]
Blekman, F. [6 ]
D'Hondt, J. [6 ]
Daci, N. [6 ]
De Bruyn, I. [6 ]
机构
[1] Yerevan Phys Inst, Yerevan, Armenia
[2] Inst Hochenergiephys, Vienna, Austria
[3] Inst Nucl Problems, Minsk, BELARUS
[4] Natl Ctr Particle & High Energy Phys, Minsk, BELARUS
[5] Univ Antwerp, Antwerp, Belgium
[6] Vrije Univ Brussel, Brussels, Belgium
[7] Univ Libre Bruxelles, Brussels, Belgium
[8] Univ Ghent, Ghent, Belgium
[9] Catholic Univ Louvain, Louvain La Neuve, Belgium
[10] Univ Mons, Mons, Belgium
[11] Ctr Brasileiro Pesquisas Fis, Rio De Janeiro, Brazil
[12] Univ Estado Rio de Janeiro, Rio De Janeiro, Brazil
[13] Univ Estadual Paulista, Sao Paulo, Brazil
[14] Univ Fed ABC, Sao Paulo, Brazil
[15] Inst Nucl Energy Res, Sofia, Bulgaria
[16] Univ Sofia, Sofia, Bulgaria
[17] Beihang Univ, Beijing, Peoples R China
[18] Inst High Energy Phys, Beijing, Peoples R China
[19] Peking Univ, State Key Lab Nucl Phys & Technol, Beijing, Peoples R China
[20] Univ Los Andes, Bogota, Colombia
[21] Univ Split, Fac Elect Engn Mech Engn & Naval Architecture, Split, Croatia
[22] Univ Split, Fac Sci, Split, Croatia
[23] Inst Rudjer Boskov, Zagreb, Croatia
[24] Univ Cyprus, Nicosia, Cyprus
[25] Charles Univ Prague, Prague, Czech Republic
[26] Univ San Francisco Quito, Quito, Ecuador
[27] Egyptian Network High Energy Phys, Acad Sci Res & Technol Arab Republ Egypt, Cairo, Egypt
[28] NICPB, Tallinn, Estonia
[29] Univ Helsinki, Dept Phys, Helsinki, Finland
[30] Helsinki Inst Phys, Helsinki, Finland
[31] Lappeenranta Univ Technol, Lappeenranta, Finland
[32] Univ Paris Saclay, CEA, IRFU, Gif Sur Yvette, France
[33] CNRS, Ecole Polytech, Lab LeprinceRinguet, IN2P3, Palaiseau, France
[34] Univ Strasbourg, CNRS, Inst Pluridisciplinaire Hubert Curien, IN2P3, Strasbourg, France
[35] CNRS, Ctr Calcul Inst Natl Phys Nucl & Phys Particulars, IN2P3, Villeurbanne, France
[36] Univ Claude Bernard Lyon 1, Univ Lyon, CNRS, Inst Phys Nucl Lyon,IN2P3, Villeurbanne, France
[37] Georgian Tech Univ, Tbilisi, Georgia
[38] Tbilisi State Univ, Tbilisi, Georgia
[39] Rhein Westfal TH Aachen, Phys Inst 1, Aachen, Germany
[40] Rhein Westfal TH Aachen, Phys Inst A 3, Aachen, Germany
[41] Rhein Westfal TH Aachen, Phys Inst B 3, Aachen, Germany
[42] Deutsch Elekt Synchrotron, Hamburg, Germany
[43] Univ Hamburg, Hamburg, Germany
[44] Inst Expt Kernphys, Karlsruhe, Germany
[45] NCSR Demokritos, Inst Nucl & Particle Phys, Aghia Paraskevi, Greece
[46] Natl & Kapodistrian Univ Athens, Athens, Greece
[47] Univ Ioannina, Ioannina, Greece
[48] Eotvos Lorand Univ, MTA ELTE Lendulet CMS Particle & Nucl Phys Grp, Budapest, Hungary
[49] Wigner Res Ctr Phys, Budapest, Hungary
[50] Inst Nucl Res ATOMKI, Debrecen, Hungary
来源
JOURNAL OF HIGH ENERGY PHYSICS | 2017年 / 07期
基金
美国国家科学基金会; 新加坡国家研究基金会; 巴西圣保罗研究基金会; 欧洲研究理事会; 芬兰科学院; 奥地利科学基金会; 俄罗斯基础研究基金会; 中国国家自然科学基金; 英国科学技术设施理事会;
关键词
Flavour Changing Neutral Currents; Hadron-Hadron scattering (experiments); Top physics; COUPLINGS; DECAYS;
D O I
10.1007/JHEP07(2017)003
中图分类号
O412 [相对论、场论]; O572.2 [粒子物理学];
学科分类号
摘要
A search for the production of a single top quark in association with a Z boson is presented, both to identify the expected standard model process and to search for flavour changing neutral current interactions. The data sample corresponds to an integrated luminosity of 19.7 fb(-1) recorded by the CMS experiment at the LHC in proton-proton collisions at root s = 8 TeV. Final states with three leptons (electrons or muons) and at least one jet are investigated. An events yield compatible with tZq standard model production is observed, and the corresponding cross section is measured to be sigma(pp -> tZq -> lvbl(+)l(-) q) = 10(-7)(+8) fb with a significance of 2.4 standard deviations. No presence of flavour-changing neutral current production of tZq is observed. Exclusion limits at 95% confidence level on the branching fractions of a top quark decaying to a Z boson and an up or a charm quark are found to be B(t -> Zu) < 0.022% and B(t -> Zc) < 0.049%.
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