TY - JOUR

T1 - Observation of Forward Neutron Multiplicity Dependence of Dimuon Acoplanarity in Ultraperipheral Pb-Pb Collisions at sNN =5.02 TeV

AU - The CMS collaboration

AU - Sirunyan, A. M.

AU - Tumasyan, A.

AU - Adam, W.

AU - Bergauer, T.

AU - Dragicevic, M.

AU - Erö, J.

AU - Escalante Del Valle, A.

AU - Frühwirth, R.

AU - Jeitler, M.

AU - Krammer, N.

AU - Lechner, L.

AU - Liko, D.

AU - Madlener, T.

AU - Mikulec, I.

AU - Pitters, F. M.

AU - Rad, N.

AU - Schieck, J.

AU - Schöfbeck, R.

AU - Spanring, M.

AU - Templ, S.

AU - Waltenberger, W.

AU - Wulz, C. E.

AU - Zarucki, M.

AU - Chekhovsky, V.

AU - Litomin, A.

AU - Makarenko, V.

AU - Suarez Gonzalez, J.

AU - Darwish, M. R.

AU - De Wolf, E. A.

AU - Di Croce, D.

AU - Janssen, X.

AU - Kello, T.

AU - Lelek, A.

AU - Pieters, M.

AU - Rejeb Sfar, H.

AU - Van Haevermaet, H.

AU - Van Mechelen, P.

AU - Van Putte, S.

AU - Van Remortel, N.

AU - Blekman, F.

AU - Bols, E. S.

AU - Chhibra, S. S.

AU - D'Hondt, J.

AU - De Clercq, J.

AU - Lontkovskyi, D.

AU - Blinov, V.

AU - Dimova, T.

AU - Kardapoltsev, L.

AU - Ovtin, I.

AU - Skovpen, Y.

N1 - Funding Information: 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 Copyright: © 2021 CERN, for the CMS Collaboration.

PY - 2021/9/17

Y1 - 2021/9/17

N2 - 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 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.

AB - 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 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.

UR - http://www.scopus.com/inward/record.url?scp=85115323201&partnerID=8YFLogxK

U2 - 10.1103/PhysRevLett.127.122001

DO - 10.1103/PhysRevLett.127.122001

M3 - Article

C2 - 34597080

AN - SCOPUS:85115323201

VL - 127

JO - Physical Review Letters

JF - Physical Review Letters

SN - 0031-9007

IS - 12

M1 - 122001

ER -