The first measurement of the inclusive cross section for top quark pairs (tt‾) produced in association with two additional charm jets is presented. The analysis uses the dileptonic final states of tt‾ events produced in proton-proton collisions at a centre-of-mass energy of 13 TeV. The data correspond to an integrated luminosity of 41.5fb−1, recorded by the CMS experiment at the LHC. A new charm jet identification algorithm provides input to a neural network that is trained to distinguish among tt‾ events with two additional charm (tt‾cc‾), bottom (tt‾bb‾), and light-flavour or gluon (tt‾LL) jets. By means of a template fitting procedure, the inclusive tt‾cc‾, tt‾bb‾, and tt‾LL cross sections are simultaneously measured, together with their ratios to the inclusive tt‾ + two jets cross section. This provides measurements of the tt‾cc‾ and tt‾bb‾ cross sections of 10.1±1.2(stat)±1.4(syst)pb and 4.54±0.35(stat)±0.56(syst)pb, respectively, in the full phase space. The results are compared and found to be consistent with predictions from two different matrix element generators with next-to-leading order accuracy in quantum chromodynamics, interfaced with a parton shower simulation.
|Journal||Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics|
|Publication status||Published - 2021 Sept 10|
Bibliographical noteFunding Information:
Individuals have received support from the Marie-Curie programme and the European Research Council and Horizon 2020 Grant, contract Nos. 675440 , 724704 , 752730 , and 765710 (European Union); the Leventis Foundation ; the A.P. Sloan Foundation ; the Alexander von Humboldt Foundation ; the Belgian Federal Science Policy Office ; the Fonds pour la Formation à la Recherche dans l'Industrie et dans l'Agriculture (FRIA-Belgium); the Agentschap voor Innovatie door Wetenschap en Technologie (IWT-Belgium); the F.R.S.-FNRS and FWO (Belgium) under the “Excellence of Science – EOS” – be.h project n. 30820817 ; the Beijing Municipal Science & Technology Commission , No. Z191100007219010 ; the Ministry of Education, Youth and Sports (MEYS) of the Czech Republic; the Deutsche Forschungsgemeinschaft (DFG) under Germany's Excellence Strategy – EXC 2121 “Quantum Universe” – 390833306 ; the Lendület (“Momentum”) Programme and the János Bolyai Research Scholarship of the Hungarian Academy of Sciences , the New National Excellence Program ÚNKP , the NKFIA research grants 123842 , 123959 , 124845 , 124850 , 125105 , 128713 , 128786 , and 129058 (Hungary); the Council of Science and Industrial Research, India ; the HOMING PLUS programme of the Foundation for Polish Science , cofinanced from European Union, Regional Development Fund, the Mobility Plus programme of the Ministry of Science and Higher Education , the National Science Center (Poland), contracts Harmonia 2014/14/M/ST2/00428 , Opus 2014/13/B/ST2/02543 , 2014/15/B/ST2/03998 , and 2015/19/B/ST2/02861 , Sonata-bis 2012/07/E/ST2/01406 ; the National Priorities Research Program by Qatar National Research Fund ; the Ministry of Science and Higher Education , project no. 0723-2020-0041 (Russia); the Tomsk Polytechnic University Competitiveness Enhancement Program; the Programa Estatal de Fomento de la Investigación Científica y Técnica de Excelencia María de Maeztu , grant MDM-2015-0509 and the Programa Severo Ochoa del Principado de Asturias ; the Thalis and Aristeia programmes cofinanced by EU-ESF and the Greek NSRF ; the Rachadapisek Sompot Fund for Postdoctoral Fellowship, Chulalongkorn University and the Chulalongkorn Academic into Its 2nd Century Project Advancement Project (Thailand); the Kavli Foundation ; the Nvidia Corporation; the SuperMicro Corporation ; the Welch Foundation , contract C-1845 ; and the Weston Havens Foundation (USA).
We congratulate our colleagues in the CERN accelerator departments for the excellent performance of the LHC and thank the technical and administrative staffs at CERN and at other CMS institutes for their contributions to the success of the CMS effort. In addition, we gratefully acknowledge the computing centres and personnel of the Worldwide LHC Computing Grid for delivering so effectively the computing infrastructure essential to our analyses. Finally, we acknowledge the enduring support for the construction and operation of the LHC and the CMS detector provided by the following funding agencies: BMBWF and FWF (Austria); FNRS and FWO (Belgium); CNPq , CAPES , FAPERJ , FAPERGS , and FAPESP (Brazil); MES (Bulgaria); CERN ; CAS , MOST , and NSFC (China); COLCIENCIAS (Colombia); MSES and CSF (Croatia); RIF (Cyprus); SENESCYT (Ecuador); MoER , ERC PUT and ERDF (Estonia); Academy of Finland , MEC , and HIP (Finland); CEA and CNRS/IN2P3 (France); BMBF , DFG , and HGF (Germany); GSRT (Greece); NKFIA (Hungary); DAE and DST (India); IPM (Iran); SFI (Ireland); INFN (Italy); MSIP and NRF (Republic of Korea); MES (Latvia); LAS (Lithuania); MOE and UM (Malaysia); BUAP , CINVESTAV , CONACYT , LNS , SEP , and UASLP-FAI (Mexico); MOS (Montenegro); MBIE (New Zealand); PAEC (Pakistan); MSHE and NSC (Poland); FCT (Portugal); JINR (Dubna); MON , ROSATOM , RAS , RFBR , and NRC KI (Russia); MESTD (Serbia); SEIDI , CPAN , PCTI , and FEDER (Spain); MoSTR (Sri Lanka); Swiss Funding Agencies (Switzerland); MST (Taipei); ThEPCenter , IPST , STAR , and NSTDA (Thailand); TUBITAK and TAEK (Turkey); NASU (Ukraine); STFC (United Kingdom); DOE and NSF (USA).
© 2021 The Author(s)
All Science Journal Classification (ASJC) codes
- Nuclear and High Energy Physics