TY - JOUR
T1 - Measurement of light-by-light scattering and the Breit-Wheeler process, and search for axion-like particles in ultraperipheral PbPb collisions at √sNN = 5.02 TeV
AU - the CMS Collaboration
AU - Anthony, David B
AU - Brooke, Jim
AU - Bundock, Aaron
AU - Bury, Florian J J
AU - Clement, Emyr J
AU - Cussans, David G
AU - Flächer, H.
AU - Glowacki, Maciej
AU - Goldstein, Joel
AU - Heath, Helen F
AU - Holmberg, Mei-Li
AU - Kreczko, Lukasz
AU - Paramesvaran, Sudarshan
AU - Robertshaw, Liam
AU - Seif El Nasr, Sarah A
AU - Smith, Vincent J
AU - Stylianou, Nicolas
AU - Walkingshaw Pass, Katie L M R
AU - al , et
N1 - Publisher Copyright:
© The Author(s) 2025.
PY - 2025/8/1
Y1 - 2025/8/1
N2 - Measurements of light-by-light scattering (LbL, γγ → γγ) and the Breit-Wheeler process (BW, γγ → e+e−) are reported in ultraperipheral PbPb collisions at a centre-of-mass energy per nucleon pair of 5.02 TeV. The data sample, corresponding to an integrated luminosity of 1.7 nb−1, was collected by the CMS experiment at the CERN LHC in 2018.Events with an exclusively produced γγ or e+e−pair with invariant masses mγγ,ee > 5 GeV, along with other fiducial criteria, are selected. The measured BW fiducial production cross section, σfid(γγ → e+e−) = 263.5 ± 1.8(stat) ± 17.8(syst) µb, as well as the differential distributions for various kinematic observables, are in agreement with leading-order quantum electrodynamics predictions complemented with final-state photon radiation. The measured differential BW cross sections allow discrimination between different theoretical descriptions of the photon flux of the lead ion. In the LbL final state, 26 exclusive diphoton candidate events are observed compared with 12.0 ± 2.9 expected for the background. Combined with previous results, the observed significance of the LbL signal with respect to the background only hypothesis is above five standard deviations. The measured fiducial LbL scattering cross section, σfid(γγ → γγ) = 107 ± 24(stat) ± 13(syst) nb, is in agreement with next-to-leading-order predictions. Limits on the production of axion-like particles coupled to photons are set over the mass range 5–100 GeV, including the most stringent limits to date in the range of 5–10 GeV.
AB - Measurements of light-by-light scattering (LbL, γγ → γγ) and the Breit-Wheeler process (BW, γγ → e+e−) are reported in ultraperipheral PbPb collisions at a centre-of-mass energy per nucleon pair of 5.02 TeV. The data sample, corresponding to an integrated luminosity of 1.7 nb−1, was collected by the CMS experiment at the CERN LHC in 2018.Events with an exclusively produced γγ or e+e−pair with invariant masses mγγ,ee > 5 GeV, along with other fiducial criteria, are selected. The measured BW fiducial production cross section, σfid(γγ → e+e−) = 263.5 ± 1.8(stat) ± 17.8(syst) µb, as well as the differential distributions for various kinematic observables, are in agreement with leading-order quantum electrodynamics predictions complemented with final-state photon radiation. The measured differential BW cross sections allow discrimination between different theoretical descriptions of the photon flux of the lead ion. In the LbL final state, 26 exclusive diphoton candidate events are observed compared with 12.0 ± 2.9 expected for the background. Combined with previous results, the observed significance of the LbL signal with respect to the background only hypothesis is above five standard deviations. The measured fiducial LbL scattering cross section, σfid(γγ → γγ) = 107 ± 24(stat) ± 13(syst) nb, is in agreement with next-to-leading-order predictions. Limits on the production of axion-like particles coupled to photons are set over the mass range 5–100 GeV, including the most stringent limits to date in the range of 5–10 GeV.
U2 - 10.1007/JHEP08(2025)006
DO - 10.1007/JHEP08(2025)006
M3 - Article (Academic Journal)
SN - 1029-8479
VL - 2025
JO - Journal of High Energy Physics
JF - Journal of High Energy Physics
IS - 8
M1 - 6
ER -