Aaboud, M.Aad, G.Abbott, B.Abbott, D.C.Abdinov, O.Abeloos, B.Abhayasinghe, D.K.Abidi, S.H.AbouZeid, O.S.Abraham, N.L.Abramowicz, H.Abreu, H.Abulaiti, Y.Acharya, B.S.Adachi, S.Adam, L.Adamczyk, L.Adamek, L.Adelman, J.Adersberger, M.et al.2020-02-272020-02-272019Physics Letters B, 2019; 796:230-2520370-26931873-2445http://hdl.handle.net/2440/123479The inclusive production rates of isolated, prompt photons in p + Pb collisions at √sNN=8.16TeV are studied with the ATLAS detector at the Large Hadron Collider using a dataset with an integrated luminosity of 165nb⁻¹ recorded in 2016. The cross-section and nuclear modification factor RpPbare measured as a function of photon transverse energy from 20GeV to 550GeV and in three nucleon–nucleon centre-of-mass pseudorapidity regions, (−2.83, −2.02), (−1.84, 0.91), and (1.09, 1.90). The cross-section and RpPb values are compared with the results of a next-to-leading-order perturbative QCD calculation, with and without nuclear parton distribution function modifications, and with expectations based on a model of the energy loss of partons prior to the hard scattering. The data disfavour a large amount of energy loss and provide new constraints on the parton densities in nuclei.en©2019 The Author. Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/). Funded by SCOAP³.Journal article003013117510.1016/j.physletb.2019.07.0310004834262000312-s2.0-85069881218463385Jackson, P. [0000-0002-0847-402X]Oliver, J.L. [0000-0002-0713-6627]White, M. [0000-0001-5474-4580]