Observation of nuclear modifications in W±boson production in pPb collisions at √sNN=8.16 TeV
The CMS Collaboration: et al. ; The production of W±bosons is studied in proton-lead (pPb) collisions at a nucleon-nucleon centre-of-mass energy of √sNN=8.16 TeV. Measurements are performed in the W±→μ±νμchannel using a data sample corresponding to an integrated luminosity of 173.4 ±6.1nb−1, collected by the CMS Collaboration at the LHC. The number of positively and negatively charged W bosons is determined separately in the muon pseudorapidity region in the laboratory frame |ημlab| 25 GeV/c. The W±boson differential cross sections, muon charge asymmetry, and the ratios of W±boson yields for the proton-going over the Pb-going beam directions are reported as a function of the muon pseudorapidity in the nucleon-nucleon centre-of-mass frame. The measurements are compared to the predictions from theoretical calculations based on parton distribution functions (PDFs) at next-to-leading-order. The results favour PDF calculations that include nuclear modifications and provide constraints on the nuclear PDF global fits. ; Individuals have received support from the Marie-Curie pro-gramme and the European Research Council and Horizon 2020 Grant, contract Nos. 675440 and 765710 (European Union); the Leventis Foundation; the Alfred P. Sloan Foundation; the Alexan-der von Humboldt Foundation; the Belgian Federal Science Pol-icy 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 Sci-ence – EOS" – be.h project n. 30820817; the Beijing Municipal Science & Technology Commission, No. Z181100004218003; the Ministry of Education, Youth and Sports (MEYS) of the Czech Re-public; the Lendület ("Momentum") Programme and the János Bolyai Research Scholarship of the Hungarian Academy of Sci-ences, 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 In-dustrial 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 Re-search Program by Qatar National Research Fund; the Programa Estatal de Fomento de la Investigación Científica y Técnica de Excelencia María de Maeztu, grant MDM-2015-0509 and the Pro-grama 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, Chula-longkorn University and the Chulalongkorn Academic into Its 2nd Century Project Advancement Project (Thailand); The Welch Foun-dation, contract C-1845; and the Weston Havens Foundation (USA) ; Funded by SCOAP3. ; Peer reviewed