Scope and limitations of a string theory dual description of the proton structure

Abstract

Symmetric and antisymmetric structure functions from electromagnetic deep inelastic scattering of charged leptons off spin-1/2 hadrons are investigated in the framework of a top-down holographic dual description. We consider the Brower-Polchinski-Strassler-Tan Pomeron, type IIB superstring theory scattering amplitudes, and type IIB supergravity on AdS5×S5. In all cases, the hard-wall prescription is used. Different kinematic regions of the Bjorken variable x, as well as the squared momentum of the virtual photon Q2, are studied in detail for F2P and g1P structure functions of the proton. Also, the virtual Compton scattering asymmetry of the proton A1P is investigated. Comparison with data from several experimental collaborations is presented. In addition, the holographic Pomeron leads to predictions for the mentioned observables for very small x values. In particular, we present predictions for g1P at Q2 around 10 GeV2, for data expected to be measured in a future electron-ion collider. Limitations of this holographic dual approach are discussed.