@article{10902/24709,
year = {2021},
month = {9},
url = {http://hdl.handle.net/10902/24709},
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 √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 8 < mμμ < 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.},
organization = {We congratulate our colleagues in the CERN accelerator
departments for the excellent performance of the LHC and
thank the technical and administrative staffs at CERN and
at other CMS institutes for their contributions to the success
of the CMS effort. In addition, we gratefully acknowledge
the computing centers and personnel of the Worldwide
LHC Computing Grid for delivering so effectively the
computing infrastructure essential to our analyses. Finally,
we acknowledge the enduring support for the construction
and operation of the LHC and the CMS detector provided
by the following funding agencies: BMBWF and FWF
(Austria); FNRS and FWO (Belgium); CNPq, CAPES,
FAPERJ, FAPERGS, and FAPESP (Brazil); MES
(Bulgaria); CERN; CAS, MoST, and NSFC (China);
COLCIENCIAS (Colombia); MSES and CSF (Croatia);
RIF (Cyprus); SENESCYT (Ecuador); MoER, ERC PUT,
and ERDF (Estonia); Academy of Finland, MEC, and HIP
(Finland); CEA and CNRS/IN2P3 (France); BMBF, DFG,
and HGF (Germany); GSRT (Greece); NKFIA (Hungary);
DAE and DST (India); IPM (Iran); SFI (Ireland); INFN
(Italy); MSIP and NRF (Republic of Korea); MES (Latvia);
LAS (Lithuania); MOE and UM (Malaysia); BUAP,
CINVESTAV, CONACYT, LNS, SEP, and UASLP-FAI
(Mexico); MOS (Montenegro); MBIE (New Zealand);
PAEC (Pakistan); MSHE and NSC (Poland); FCT
(Portugal); JINR (Dubna); MON, RosAtom, RAS,
RFBR, and NRC KI (Russia); MESTD (Serbia); SEIDI,
CPAN, PCTI, and FEDER (Spain); MOSTR (Sri Lanka);
Swiss Funding Agencies (Switzerland); MST (Taipei);
ThEPCenter, IPST, STAR, and NSTDA (Thailand);
TUBITAK and TAEK (Turkey); NASU (Ukraine); STFC(United Kingdom); DOE and NSF (U.S.).},
publisher = {American Physical Society},
publisher = {Physical Review Letters 127(12), 122001 (2021)},
title = {Observation of forward neutron multiplicity dependence of dimuon acoplanarity in ultraperipheral Pb-Pb collisions at √ S-NN=5.02 TeV},
author = {Sirunyan, A. M. and Cabrillo Bartolomé, José Iban and Calderón Tazón, Alicia and Chazin Quero, Bárbara and Duarte Campderros, Jorge and Fernández García, Marcos and Fernández Manteca, Pedro José and Gómez Gramuglio, Gervasio and Martínez Rivero, Celso and Martínez Ruiz del Árbol, Pablo and Matorras Weinig, Francisco and Piedra Gómez, Jonatan and Prieëls, Cedric and Ricci-Tam, Francesca Shun-Ning Annarosa and Rodrigo Anoro, Teresa and Ruiz Jimeno, Alberto and Scodellaro, Luca and Vila Álvarez, Iván  and Vizán García, Jesús Manuel},
}