Measurement of inclusive J/ψ polarization in p+p collisions at s =200 GeV by the STAR experiment

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We report on new measurements of inclusive J/ψ polarization at midrapidity in p+p collisions at s=200 GeV by the STAR experiment at the Relativistic Heavy Ion Collider. The polarization parameters, λθ, λφ, and λθφ, are measured as a function of transverse momentum (pT) in both the helicity and Collins-Soper (CS) reference frames within pT<10 GeV/c. Except for λθ in the CS frame at the highest measured pT, all three polarization parameters are consistent with 0 in both reference frames without any strong pT dependence. Several model calculations are compared with data, and the one using the Color Glass Condensate effective field theory coupled with nonrelativistic QCD gives the best overall description of the experimental results, even though other models cannot be ruled out due to experimental uncertainties.

Original languageEnglish
Article number092009
JournalPhysical Review D
Issue number9
StatePublished - Nov 20 2020

Bibliographical note

Funding Information:
We thank the RHIC Operations Group and RCF at BNL, the NERSC Center at LBNL, and the Open Science Grid consortium for providing resources and support. This work was supported in part by the Office of Nuclear Physics within the U.S. DOE Office of Science; the U.S. National Science Foundation; the Ministry of Education and Science of the Russian Federation; National Natural Science Foundation of China; Chinese Academy of Science; the Ministry of Science and Technology of China and the Chinese Ministry of Education; the Higher Education Sprout Project by Ministry of Education at NCKU; the National Research Foundation of Korea; Czech Science Foundation and Ministry of Education, Youth and Sports of the Czech Republic; Hungarian National Research, Development and Innovation Office; New National Excellency Programme of the Hungarian Ministry of Human Capacities; Department of Atomic Energy and Department of Science and Technology of the Government of India; the National Science Centre of Poland; the Ministry of Science Education and Sports of the Republic of Croatia; RosAtom of Russia and German Bundesministerium fur Bildung, Wissenschaft, Forschung and Technologie (BMBF); Helmholtz Association; Ministry of Education, Culture, Sports, Science, and Technology (MEXT); and Japan Society for the Promotion of Science (JSPS).

Publisher Copyright:
© 2020 authors.

ASJC Scopus subject areas

  • Nuclear and High Energy Physics


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