Measurement of prompt photon production in sNN=8.16 TeV p + Pb collisions with ATLAS

• Autor(a) principal: Santos, S. P. Amor dos
• Data de Publicação: 2019
• Outros Autores: Fiolhais, M. C. N., Galhardo, B., Veloso, F., Wolters, H., ATLAS Collaboration
• Tipo de documento: Artigo
• Idioma: eng
• Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
• Texto Completo: http://hdl.handle.net/10316/107230; https://doi.org/10.1016/j.physletb.2019.07.031

The inclusive production rates of isolated, prompt photons in p +Pbcollisions at √sNN=8.16TeV are studied with the ATLAS detector at the Large Hadron Collider using a dataset with an integrated luminosity of 165nb−1recorded 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 RpPbvalues 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.