Diffractive vector meson photoproduction from dual string theory

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}{sub V}{approx}s{sup 2{epsilon}}{sup -2{alpha}{sub P}{sup '}}{sup /B}, where from the string theory model of [arXiv:hep-th/0501039], {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{sup -4M{}sub V}{sup /T{}sub 0}, with T{sub 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{sub 0} of aboutmore » 1.3 GeV, i.e. the gauge theory ''Planck scale,'' as expected. The ratio of the experimental soft Pomeron onset scale E-circumflex{sub R}{approx}9 GeV and of the gauge theory Planck scale, T{sub 0}{approx}1.3 GeV, conforms to the theoretical prediction of N{sub c}{sup 2}/N{sub c}{sup 1/4}.« less