Diffractive Vector Meson Photoproduction from Dual String Theory

TL;DR

This paper models diffractive vector meson photoproduction using string theory and AdS/CFT, revealing a dominant soft Pomeron behavior and confirming the presence of Boltzmann factors in experimental data, with implications for understanding high-energy scattering.

Contribution

It introduces a string theory-based model for vector meson photoproduction, linking black hole production in dual gravity to observable cross-section behaviors and temperature-dependent factors.

Findings

Soft Pomeron dominates at high energies with specific power-law behavior.

Experimental data supports the presence of Boltzmann factors involving the black hole temperature.

The gauge theory Planck scale is estimated at about 1.3 GeV, consistent with theoretical predictions.

Abstract

We study diffractive vector meson photoproduction using string theory via AdS/CFT. The large $s$ behavior of the cross sections for the scattering of the vector meson $V$ on a proton is dominated by the soft Pomeron, $\sigma_V\sim s^{2\epsilon-2\alpha'_P/B}$, where from the string theory model of \cite{nastase2}, $\epsilon$ is approximately 1/7 below 10 GeV, and 1/11 for higher, but still sub-Froissart, energies. This is due to the production of black holes in the dual gravity. In $\phi$-photoproduction the mesonic Regge poles do not contribute, so that we deal with a pure Pomeron contribution. This allows for an experimental test. At the gauge theory "Planck scale" of about 1-2 GeV, the ratios of the soft Pomeron contributions to the photoproduction cross-sections of different vector mesons involve not only the obvious quark model factors, but also the Boltzmann factors $e^{-4 M_V/T_0}$, with $T_0$ the temperature of the dual black hole. The presence of these factors is confirmed in the experimental data for $\rho, \omega, \phi, J/\psi,$ and $\psi(2S)$ photoproduction and is compatible with the meager $\Upsilon$ photoproduction data. Throughout, we use vector meson dominance, and from the data we obtain $T_0$ of about $1.3 GeV$, i.e. the gauge theory "Planck scale," as expected. The ratio of the experimental soft Pomeron onset scale $\hat{E}_R\sim 9$ GeV and of the gauge theory Planck scale, $T_0 \sim 1.3$ GeV conforms to the theoretical prediction of $N_c^2/N_c^{1/4}$.