Observation of forward neutron multiplicity dependence of dimuon acoplanarity in ultraperipheral Pb-Pb collisions at sqrt[s_{NN}]=5.02 TeV
File(s)PhysRevLett.127.122001.pdf (433.51 KB)
Published version
Author(s)
Type
Journal Article
Abstract
The first measurement of the dependence of γγ→μ^{+}μ^{-} production on the multiplicity of neutrons emitted very close to the beam direction in ultraperipheral heavy ion collisions is reported. Data for lead-lead interactions at sqrt[s_{NN}]=5.02 TeV, with an integrated luminosity of approximately 1.5 nb^{-1}, are collected using the CMS detector at the LHC. The azimuthal correlations between the two muons in the invariant mass region 8<m_{μμ}<60 GeV are extracted for events including 0, 1, or at least 2 neutrons detected in the forward pseudorapidity range |η|>8.3. The back-to-back correlation structure from leading-order photon-photon scattering is found to be significantly broader for events with a larger number of emitted neutrons from each nucleus, corresponding to interactions with a smaller impact parameter. This observation provides a data-driven demonstration that the average transverse momentum of photons emitted from relativistic heavy ions has an impact parameter dependence. These results provide new constraints on models of photon-induced interactions in ultraperipheral collisions. They also provide a baseline to search for possible final-state effects on lepton pairs caused by traversing a quark-gluon plasma produced in hadronic heavy ion collisions.
Date Issued
2021-09-17
Date Acceptance
2021-07-21
Citation
Physical Review Letters, 2021, 127 (12)
ISSN
0031-9007
Publisher
American Physical Society
Journal / Book Title
Physical Review Letters
Volume
127
Issue
12
Copyright Statement
© 2021 CERN, for the CMS Collaboration. Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI. Funded by SCOAP3.
License URL
Identifier
https://www.ncbi.nlm.nih.gov/pubmed/34597080
Subjects
CMS Collaboration
hep-ex
hep-ex
nucl-ex
General Physics
01 Mathematical Sciences
02 Physical Sciences
09 Engineering
Publication Status
Published
Coverage Spatial
United States
Article Number
ARTN 122001