Holographic $J/ψ$ production near threshold and the proton mass problem

Abstract

It has been suggested that the production of a heavy quarkonium near threshold in electron-proton scattering can shed light on the origin of the proton mass via the QCD trace anomaly. We study the photoproduction of $J/ψ$ off the proton using gauge/string duality and demonstrate that the $t$-dependence of the differential cross section $dσ/dt$ at small-$t$ is a sensitive probe of the trace anomaly.

17 pages, 7 figures. v2: Eq.(24,27) corrected, minor changes in numerical results