New measurements on diffractive vector mesons

TL;DR

This paper reviews recent experimental measurements of diffractive vector meson photoproduction at high energies from LHC experiments, highlighting new differential data, studies of nuclear dependence, and potential for exotic state searches.

Contribution

It compiles and discusses recent high-precision measurements from ALICE and LHCb, including the first studies of certain differential cross sections and nuclear dependencies in vector meson production.

Findings

First measurement of |t|-dependence of coherent J/ψ in PbPb

First study of A dependence of coherent ρ0 photoproduction

Observation of vector meson production in peripheral PbPb collisions

Abstract

Vector meson photoproduction at high energies has attracted increased interest in recent years due to the unique kinematical ranges offered by the LHC experiments. The ALICE and LHCb collaborations have provided measurements of vector meson photoproduction on nuclear and proton targets, i.e. off p, Pb and Xe targets. The large data sets available from LHC Run 2 allow for more differential measurements. The ALICE and LHCb collaborations have recently provided measurements of coherent \jpsi in \PbPb ultra-peripheral collisions (UPC). In addition, the former also reports the first measurement of the $|t|$-dependence of coherent \jpsi in \PbPb, and has also recently measured coherent \rhozero photoproduction off Pb and Xe targets, thus providing the first study of the A dependence of coherent \rhozero photoproduction. Vector meson photoproduction in peripheral \PbPb collisions has also been observed by ALICE and LHCb, thus providing a viable technique to extract photonuclear cross sections at a low Bjorken-$x$ of around $10^{-5}$. Lastly, the potential of UPC for tetraquark searches is briefly discussed.