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Title: Suppression of excited Upsilon states relative to the ground state in PbPb collisions at sqrt(sNN) = 5.02 TeV

Abstract

The relative yields of Upsilon mesons produced in pp and PbPb collisions at sqrt(s[NN]) = 5.02 TeV and reconstructed via the dimuon decay channel are measured using data collected by the CMS experiment. Double ratios are formed by comparing the yields of the excited states, Upsilon(2S) and Upsilon(3S), to the ground state, Upsilon(1S), in both PbPb and pp collisions at the same center-of-mass energy. The double ratios, [Upsilon(nS)/Upsilon(1S)](PbPb)/[Upsilon(nS)/Upsilon(1S)](pp), are measured to be 0.308 +/- 0.055 (stat) +/- 0.019 (syst) for the Upsilon(2S) and less than 0.26 at 95% confidence level for the Upsilon(3S). No significant Upsilon(3S) signal is found in the PbPb data. The double ratios are studied as a function of collision centrality, as well as dimuon transverse momentum and rapidity. No significant dependencies are observed.

Authors:
;
Publication Date:
Research Org.:
Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
Sponsoring Org.:
USDOE Office of Science (SC), High Energy Physics (HEP) (SC-25)
OSTI Identifier:
1371591
Report Number(s):
FERMILAB-PUB-17-241-CMS; CMS-HIN-16-008; CERN-EP-2017-080; arXiv:1706.05984
1605750
DOE Contract Number:
AC02-07CH11359
Resource Type:
Journal Article
Resource Relation:
Journal Name: TBD
Country of Publication:
United States
Language:
English
Subject:
73 NUCLEAR PHYSICS AND RADIATION PHYSICS; 72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS

Citation Formats

Sirunyan, Albert M, and et al. Suppression of excited Upsilon states relative to the ground state in PbPb collisions at sqrt(sNN) = 5.02 TeV. United States: N. p., 2017. Web.
Sirunyan, Albert M, & et al. Suppression of excited Upsilon states relative to the ground state in PbPb collisions at sqrt(sNN) = 5.02 TeV. United States.
Sirunyan, Albert M, and et al. 2017. "Suppression of excited Upsilon states relative to the ground state in PbPb collisions at sqrt(sNN) = 5.02 TeV". United States. doi:. https://www.osti.gov/servlets/purl/1371591.
@article{osti_1371591,
title = {Suppression of excited Upsilon states relative to the ground state in PbPb collisions at sqrt(sNN) = 5.02 TeV},
author = {Sirunyan, Albert M and et al.},
abstractNote = {The relative yields of Upsilon mesons produced in pp and PbPb collisions at sqrt(s[NN]) = 5.02 TeV and reconstructed via the dimuon decay channel are measured using data collected by the CMS experiment. Double ratios are formed by comparing the yields of the excited states, Upsilon(2S) and Upsilon(3S), to the ground state, Upsilon(1S), in both PbPb and pp collisions at the same center-of-mass energy. The double ratios, [Upsilon(nS)/Upsilon(1S)](PbPb)/[Upsilon(nS)/Upsilon(1S)](pp), are measured to be 0.308 +/- 0.055 (stat) +/- 0.019 (syst) for the Upsilon(2S) and less than 0.26 at 95% confidence level for the Upsilon(3S). No significant Upsilon(3S) signal is found in the PbPb data. The double ratios are studied as a function of collision centrality, as well as dimuon transverse momentum and rapidity. No significant dependencies are observed.},
doi = {},
journal = {TBD},
number = ,
volume = ,
place = {United States},
year = 2017,
month = 6
}
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  • The production of jets in association with Z bosons, reconstructed via the mu+mu- and e+e- decay channels, is studied in pp and, for the first time, in PbPb collisions. Both data samples were collected by the CMS experiment at the LHC, at a center-of-mass energy of 5.02 TeV. The PbPb collisions were analyzed in the 0-30% centrality range. The back-to-back azimuthal alignment was studied in both pp and PbPb collisions for Z bosons with transverse momentum ptz > 60 GeV/c and a recoiling jet with ptj > 30 GeV/c. The pt imbalance, xjz= ptj/ptz, as well as the average numbermore » of jet partners per Z, rjz, were studied in intervals of ptz, in both pp and PbPb collisions. The rjz is found to be smaller in PbPb than in pp collisions, which suggests that in PbPb collisions a larger fraction of partons, associated with the Z bosons, lose energy and fall below the 30 GeV/c ptj threshold.« less
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