abstract

• The first measurement of the dependence of γγ→μ%2bμ- 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 sNN=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 88.3. 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. © 2021 CERN, for the CMS Collaboration.

authors

• Morelos Pineda Antonio

publication date

• 2021-01-01

published in

• Physical Review Letters  Journal

keywords

Digital Object Identifier (DOI)

• 10.1103/PhysRevLett.127.122001

PubMed ID

• 34597080

start page

end page

volume

• 127

issue

• 12