Measurement of the groomed jet mass in PbPb and pp collisions at root s(NN)=5:02 TeV

Abstract

WOS:000449259100001 ; A measurement of the groomed jet mass in PbPb and pp collisions at a nucleon-nucleon center-of-mass energy of 5.02 TeV with the CMS detector at the LHC is presented. Jet grooming is a recursive procedure which sequentially removes soft constituents of a jet until a pair of hard subjets is found. The resulting groomed jets can be used to study modifications to the parton shower evolution in the presence of the hot and dense medium created in heavy ion collisions. Predictions of groomed jet properties from the pythia and herwig++ event generators agree with the measurements in pp collisions. When comparing the results from the most central PbPb collisions to pp data, a hint of an increase of jets with large jet mass is observed, which could originate from additional medium-induced radiation at a large angle from the jet axis. However, no modification of the groomed mass of the core of the jet is observed for all PbPb centrality classes. The PbPb results are also compared to predictions from the jewel and q-pythia event generators, which predict a large modification of the groomed mass not observed in the data. ; BMWFW (Austria); FWF (Austria)Austrian Science Fund (FWF); FNRS (Belgium)Fonds de la Recherche Scientifique - FNRS; FWO (Belgium)FWO; CNPq (Brazil)National Council for Scientific and Technological Development (CNPq); CAPES (Brazil)CAPES; FAPERJ (Brazil)Carlos Chagas Filho Foundation for Research Support of the State of Rio de Janeiro (FAPERJ); FAPESP (Brazil)Fundacao de Amparo a Pesquisa do Estado de Sao Paulo (FAPESP); MES (Bulgaria); MoST (China)Ministry of Science and Technology, China; NSFC (China)National Natural Science Foundation of China (NSFC); COL-CIENCIAS (Colombia)Departamento Administrativo de Ciencia, Tecnologia e Innovacion Colciencias; CSF (Croatia); SENESCYT (Ecuador); MoER (Estonia); ERDF (Estonia)European Union (EU); Academy of Finland (Finland)Academy of Finland; MEC (Finland); CEA (France)French Atomic Energy Commission; CNRS/IN2P3 (France)Centre National de la Recherche Scientifique (CNRS); BMBF (Germany)Federal Ministry of Education & Research (BMBF); DFG (Germany)German Research Foundation (DFG); HGF (Germany); GSRT (Greece)Greek Ministry of Development-GSRT; NKFIA (Hungary); DAE (India)Department of Atomic Energy (DAE); DST (India)Department of Science & Technology (India); IPM (Iran); SFI (Ireland)Science Foundation Ireland; INFN (Italy)Istituto Nazionale di Fisica Nucleare (INFN); NRF (Republic of Korea); MOE (Malaysia); UM (Malaysia); BUAP (Mexico); CONACYT (Mexico)Consejo Nacional de Ciencia y Tecnologia (CONACyT); UASLP-FAI (Mexico); MBIE (New Zealand); PAEC (Pakistan); MSHE (Poland); FCT (Portugal)Portuguese Foundation for Science and Technology; JINR (Dubna); RosAtom (Russia); RFBR (Russia)Russian Foundation for Basic Research (RFBR); MESTD (Serbia); SEIDI (Spain); FEDER (Spain)European Union (EU); Swiss Funding Agencies (Switzerland); NSTDA (Thailand); TUBITAK (Turkey)Turkiye Bilimsel ve Teknolojik Arastirma Kurumu (TUBITAK); TAEK (Turkey)Ministry of Energy & Natural Resources - Turkey; NASU (Ukraine); SFFR (Ukraine)State Fund for Fundamental Research (SFFR); DOE (U.S.A.)United States Department of Energy (DOE); NSF (U.S.A.)National Science Foundation (NSF); Marie-Curie programmeEuropean Union (EU); European Research CouncilEuropean Research Council (ERC); European UnionEuropean Union (EU) [675440]; Leventis Foundation; A.P. Sloan FoundationAlfred P. Sloan Foundation; Alexander von Humboldt FoundationAlexander von Humboldt Foundation; Belgian Federal Science Policy OfficeBelgian Federal Science Policy Office; Fonds pour la Formation a la Recherche dans l'Industrie et dans l'Agriculture (FRIA-Belgium)Fonds de la Recherche Scientifique - FNRS; Agentschap voor Innovatie door Wetenschap en Technologie (IWT-Belgium)Institute for the Promotion of Innovation by Science and Technology in Flanders (IWT); FWO (Belgium) under the "Excellence of Science - EOSFWO [30820817]; Ministry of Education, Youth and Sports (MEYS) of the Czech RepublicMinistry of Education, Youth & Sports - Czech Republic; NKFIA (Hungary) [123842, 123959, 124845, 124850, 125105]; Council of Science and Industrial Research, IndiaCouncil of Scientific & Industrial Research (CSIR) - India; HOMING PLUS programme of the Foundation for Polish Science; European Union, Regional Development FundEuropean Union (EU); Mobility Plus programme of the Ministry of Science and Higher Education, the National Science Center (Poland) [Harmonia 2014/14/M/ST2/00428, Opus 2014/13/B/ST2/02543, 2014/15/B/ST2/03998, 2015/19/B/ST2/02861, Sonata-bis 2012/07/E/ST2/01406]; National Priorities Research Program by Qatar National Research Fund; Programa Severo Ochoa del Principado de Asturias; Thalis programme - EU-ESF; Aristeia programme - EU-ESF; Greek NSRFGreek Ministry of Development-GSRT; Rachadapisek Sompot Fund for Postdoctoral Fellowship, Chulalongkorn University (Thailand); Welch FoundationThe Welch Foundation [C-1845]; Weston Havens Foundation (U.S.A.); CERN; CAS (China)Chinese Academy of Sciences; MSES (Croatia); RPF (Cyprus); ERC IUT (Estonia)Estonian Research Council; HIP (Finland); MSIP (Republic of Korea); LAS (Lithuania); CINVESTAV (Mexico); LNS (Mexico); SEP (Mexico); MON (Russia); RAS (Russia)Russian Academy of Sciences; PCTI (Spain); CPAN (Spain); ThEPCenter (Thailand); IPST (Thailand); STFC (United Kingdom)Science & Technology Facilities Council (STFC); Lendulet ("Momentum") Programme (Hungary); Janos Bolyai Research Scholarship of the Hungarian Academy of Sciences (Hungary); New National Excellence Program UNKP (Hungary); F.R.S.-FNRS (Belgium)Fonds de la Recherche Scientifique - FNRS; Programa Estatal de Fomento de la Investigacion Cientffica y Tecnica de Excelencia Maria de Maeztu [MDM-2015-0509]; Chulalongkorn Academic into Its 2nd Century Project Advancement Project (Thailand); Science and Technology Facilities CouncilScience & Technology Facilities Council (STFC) [ST/J005479/1, ST/N001273/1, ST/J004871/1, ST/I003622/1, ST/I505580/1, ST/K003542/1, ST/F007434/1, ST/L005603/1, ST/K003542/1 GRID PP, ST/M004775/1] Funding Source: researchfish ; 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 centers 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: BMWFW and FWF (Austria); FNRS and FWO (Belgium); CNPq, CAPES, FAPERJ, and FAPESP (Brazil); MES (Bulgaria); CERN; CAS, MoST, and NSFC (China); COL-CIENCIAS (Colombia); MSES and CSF (Croatia); RPF (Cyprus); SENESCYT (Ecuador); MoER, ERC IUT, 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); LAS (Lithuania); MOE and UM (Malaysia); BUAP, CINVESTAV, CONACYT, LNS, SEP, and UASLP-FAI (Mexico); MBIE (New Zealand); PAEC (Pakistan); MSHE and NSC (Poland); FCT (Portugal); JINR (Dubna); MON, RosAtom, RAS and RFBR (Russia); MESTD (Serbia); SEIDI, CPAN, PCTI and FEDER (Spain); Swiss Funding Agencies (Switzerland); MST (Taipei); ThEPCenter, IPST, STAR, and NSTDA (Thailand); TUBITAK and TAEK (Turkey); NASU and SFFR (Ukraine); STFC (United Kingdom); DOE and NSF (U.S.A.).; Individuals have received support from the Marie-Curie programme and the European Research Council and Horizon 2020 Grant, contract No. 675440 (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 a 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 Ministry of Education, Youth and Sports (MEYS) of the Czech Republic; the Lendulet ("Momentum") Programme and the Janos Bolyai Research Scholarship of the Hungarian Academy of Sciences, the New National Excellence Program UNKP, the NKFIA research grants 123842, 123959, 124845, 124850 and 125105 (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 Programa Estatal de Fomento de la Investigacion Cientffica y Tecnica de Excelencia Maria 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 Welch Foundation, contract C-1845; and the Weston Havens Foundation (U.S.A.).