Stringy (holographic) Pomeron with extrinsic curvature

Abstract

We model the soft pomeron in QCD using a scalar Polyakov string with extrinsic curvature in the bottom-up approach of holographic QCD. The overall dipole-dipole scattering amplitude in the soft pomeron kinematics is shown to be sensitive to the extrinsic curvature of the string for finite momentum transfer. The characteristics of the diffractive peak in the differential elastic pp scattering are affected by a small extrinsic curvature of the string.

Higher order string effects and the properties of the Pomeron

“…There are also some theoretical justifications for a nonzero µ, with a suggested sign. In fact, we already mentioned it in (9): the extrinsic curvature term in the action does indeed produce such a contribution, see [12,13]. One may further ask if lattice studies of the potential can also help to find the magnitude of µ.…”

“…The former are UV sensitive and in dimensional regularization renormalize to zero, as we assume throughout. The latter are not accounted for in the conformal Nambu-Goto string, but arise from the extrinsic curvature term (4) in the form [12][13][14].…”

Regimes of the Pomeron and its intrinsic entropy

“…2, is in the b−ln(s/s 0 ) plane. The transition region in the middle corresponds to the near-critical regime defined by the equation T ≈ T H where T was given in (1) and the intrinsic Hagedorn temperature for the Pomeron in (12). While at LHC energies, indicated by a horizontal dotted line, all three regions are clearly visible, at lower ones (RHIC/ISR colliders) only the "cold" regime is present and the elastic collisions profile is basically Gaussian.…”

“…In the inelastic collision the string bits come out of the critical Pomeron, like beeds coming out of a shattered neckless. Each string bit is a colorless closed string or glueball of typical mass 1/ √ α ∼ 1 GeV, which can break into several pions, for T = 1/β close to T H ∼ 160 MeV as defined in (12). The normalized distribution for the events with large multiplicity N L is therefore thermal…”

“…The highly excited string state has been described in [11,12] in terms of the so called string balls. This notion which originated from the string theory literature, describes a selfinteracting string system that interpolates between a free string at small mass, and a black hole at large mass.…”