"Rosenbluth" separation of the $J/\psi$ near-threshold photoproduction -- an access to the gluon Gravitational Form Factors at high $t$

Abstract

We perform analysis of the near-threshold $J/\psi$ photoproduction data off the proton based on two theoretical approaches, GPD [1] and holographic [2], that represent the differential cross sections as powers of the skewness parameter with coefficients that depend only on the momentum transfer $t$. This allows to separate kinematically the corresponding coefficient functions, in much the same way as this is done for the electric and magnetic form factors using the Rosenbluth separation. We examine the independence of the extracted functions with the photon beam energy. These functions, under additional assumptions, are related to the proton's gluon Gravitational Form Factors (gGFFs). We compare the extracted functions with lattice calculations of the gGFFs in the region of $0.5<|t|<2$~GeV${}^2$, where they overlap. Such analysis demonstrates the possibility of extracting some combinations of the gGFFs from the data at high $t$, complementary to the lattice calculations available in the low $t$ region. However, higher statistics are needed to more accurately check the predicted scaling behavior of the data and compare with the lattice results, thus testing and comparing the theoretical assumptions used in the GPD and holographic models.

References in corpus (9)

• QCD Analysis of Near-Threshold Photon-Proton Production of Heavy Quarkonium
• Gluon gravitational structure of hadrons of different spin
• Gravitational form factors of the proton from lattice QCD
• Deciphering the mechanism of near-threshold $J/\psi$ photoproduction
• $J/\psi$ near threshold in holographic QCD: A and D gravitational form factors
• Measurement of the J/$\psi$ photoproduction cross section over the full near-threshold kinematic region
• Perturbative QCD Analysis of Near Threshold Heavy Quarkonium Photoproduction at Large Momentum Transfer
• Updated analysis of near-threshold heavy quarkonium production for probe of proton's gluonic gravitational form factors
• $\varphi$-meson lepto-production near threshold and the strangeness $D$-term