Photo-nuclear jet production in ultra-peripheral Pb+Pb collisions at $\sqrt{s}_\text{NN} = 5.02$ TeV with the ATLAS detector

Results are presented from a measurement by ATLAS of photo-nuclear production of dijet and multi-jet final states in ultra-peripheral Pb+Pb collisions at $\sqrt{s}_\text{NN} = 5.02$ TeV. The measurement is performed using a data set recorded in 2018 with an integrated luminosity of 1.72 nb$^{-1}$. Photo-nuclear events are selected by requiring no breakup of one of the incident nuclei and using a rapidity gap requirement in the photon-going direction. Particle-flow jets are reconstructed using the anti-$k_t$ algorithm with radius parameter, $R = 0.4$. The hard-scattering kinematics are reconstructed from the mass and rapidity of the jet system. Triple-differential cross-sections are measured as a function of the nuclear and photon parton momentum fractions, $x_A$ and $z_\gamma$, respectively, and the total transverse momentum in the jet system, $H_T$. The cross-sections, unfolded for detector response, are compared to results from the Pythia 8 event generator. Also presented are results for measured rapidity, $H_T$, and $\Delta\phi$ distributions of dijet/multi-jet final states in events for which both nuclei remain intact.