String-gauge dual description of deep inelastic scattering at small-x

Abstract

The AdS/CFT correspondence in principle gives a new approach to deep inelastic scattering as formulated by Polchinski and Strassler. Subsequently Brower, Polchinski, Strassler and Tan (BPST) computed the strong coupling kernel for the vacuum (or Pomeron) contribution to total cross sections. By identifying deep inelastic scattering with virtual photon total cross section, this allows a self consistent description at small-x where the dominant contribution is the vacuum exchange process. Here we formulate this contribution and compare it with HERA small-x DIS scattering data. We find that the BPST kernel along with a very simple local approximation to the proton and current "wave functions" gives a remarkably good fit not only at large Q 2 dominated by conformal symmetry but also extends to small Q 2 , supplemented by a hard-wall cut-off of the AdS in the IR. We suggest that this is a useful phenomenological parametrization with implications for other diffractive processes, such as double diffractive Higgs production.

Hadronic structure of the photon at smallxin holographic QCD

“…At Q 2 ≥ 8.9 GeV 2 , the conformal kernel results are more consistent with the experimental data than those of the modified kernel with z 0 = 4.25 GeV −1 , although it is known that the modified kernel can reproduce the nucleon structure function F 2 better compared to the conformal kernel [4][5][6]. We find that the modified kernel results can be improved by considering the relationship between the model parameter z 0 and the number of active quark flavors f .…”

“…This can be understood via the results of Q 2 dependencies of the Pomeron intercept with the two kernels, which were shown in Refs. [4][5][6]. In those results, it is seen that the Q 2 dependence of the conformal kernel results is obviously weaker than that of the modified kernel results.…”

“…Brower, Polchinski, Strassler, and Tan (BPST) focused on the small x region, and proposed the Pomeron exchange kernel [3], which gives a contribution of the Pomeron exchange to the total cross section. Utilizing the BPST kernel, various phenomenological investigations have been done [1,[4][5][6], and their successes support further applications for high energy scattering processes in the kinematic region, where the Pomeron exchange gives a dominant contribution.…”

Pomeron Physics at the LHC

“…Single Pomeron exchange is predictive of a power-law rise in the total cross section 3 σ tot ∼ s α0−1 Since the beginning of Pomeron physics, fits to p-p total cross section data have shown some power-law behavior. 4 In these proceedings we review progress in using Pomeron exchange to describe LHC data.…”

Deeply virtual Compton scattering from gauge/gravity duality

“…In this research programme, deep inelastic scattering (DIS) in QCD is among the processes that have been extensively studied using the AdS/CFT duality . In particular, there has been progress in reproducing experimental data from HERA in the regime of low Bjorken x, where the gluons dominate the partonic distribution of the target proton [7,24]. This regime corresponds to the high energy Regge limit where the interaction between the probe and the target is dominated by pomeron exchange [29].…”