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Observation of Forward Neutron Multiplicity Dependence of Dimuon Acoplanarity in Ultraperipheral Pb-Pb Collisions at $\sqrt{sNN}$ =5.02 TeV

CMS Collaboration; Sirunyan, A. M.; Tumasyan, A.; Adam, W.; Bergauer, T.; Dragicevic, M.; Erö, J.; Escalante Del Valle, A.; Frühwirth, R.; Jeitler, M.; Krammer, N.; Lechner, L.; Liko, D.; Madlener, T.; Mikulec, I.; Pitters, F. M.; Rad, N.; Schieck, J.; Schöfbeck, R.; ... mehr


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 1.5nb$^{-1}$, 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.

Verlagsausgabe §
DOI: 10.5445/IR/1000138030
Veröffentlicht am 01.10.2021
DOI: 10.1103/PhysRevLett.127.122001
Zitationen: 8
Web of Science
Zitationen: 2
Zitationen: 5
Cover der Publikation
Zugehörige Institution(en) am KIT Institut für Theoretische Teilchenphysik (TTP)
Publikationstyp Zeitschriftenaufsatz
Publikationsjahr 2021
Sprache Englisch
Identifikator ISSN: 0031-9007, 1079-7114, 1092-0145
KITopen-ID: 1000138030
Erschienen in Physical Review Letters
Verlag American Physical Society (APS)
Band 127
Heft 12
Seiten Art.-Nr.: 122001
Bemerkung zur Veröffentlichung Gefördert durch SCOAP3
Nachgewiesen in Dimensions
Web of Science
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