Speaker
Description
Exclusive processes in Ultra Peripheral Collisions (UPCs) at the LHC and in the future EIC will provide access to the spatial distribution of small-x partons in nuclei at high energies. In particular, the transverse momentum of the produced particle, such as vector meson, is Fourier conjugate to the impact parameter.
In this talk, we focus on vector meson production in UPCs and show how non-linear saturation effects change the density profile of a heavy nucleus, and that such modifications are necessary to obtain a good description of the exclusive J/psi production as measured by the ALICE and LHCb collaborations in Pb+Pb UPCs at the LHC [1]. We employ the joint impact parameter and transverse momentum-dependent cross-section framework developed in [2] to incorporate the finite photon transverse momentum and the interference between the cases for which the role of photon emitter and target are interchanged between the nuclei. We show that these effects are comparable to the experimental precision for pT differential cross sections and must be included when comparing to LHC data.
[1] Heikki Mäntysaari, Farid Salazar and Björn Schenke.
Phys.Rev.D 106 (2022) 7, 074019. e-Print: 2207.03712 [hep-ph]
[2] Hongxi Xing, Cheng Zhang, Jian Zhou, Ya-Jin Zhou.
JHEP 10 (2020) 064 • e-Print: 2006.06206 [hep-ph]
