Testing universality of the color glass condensate descriptions

Abstract

Perturbative Quantum Chromodynamics (pQCD) predicts that the small-x gluons in a hadron wavefunction should form a Color Glass Condensate (CGC), which has universal properties, which are the same for all hadrons or nuclei. Assuming this property, in this paper we cross relate the current CGC descriptions of the ep HERA data and dAu RHIC data. In particular, we use the quark dipole scattering amplitude recently proposed by Kharzeev, Kovchegov and Tuchin (KKT) to explain the high pT particle suppression observed in dAu collisions at RHIC in our calculations of the proton and longitudinal structure functions. We present a detailed comparison between this parameterization and those proposed to describe the ep HERA data. We find out that, due to its peculiar dependence on the energy and dipole separation, the KKT parameterization is able to describe the experimental ep data only in a limited kinematical range of photon virtualities.

Exclusive vector meson production in electron-ion collisions

“…In a previous paper we have performed a more systematic comparison between different dipole models [56]. Based on this comparison, we believe that using other scattering amplitudes would slightly change the normalization of our predictions for the cross sections.…”

Saturation physics at HERA and RHIC: An unified description

“…1 in Ref. [27]). Consequently, one can expect to be possible to cross relate these experiments in this respect and gain a clear understanding of the CGC in high energy experiments.…”

“…[27], based on the universality of the hadronic wave function predicted by the CGC formalism, we might expect that the KKT and DHJ parameterizations would also describe the HERA data on proton structure functions in the kinematical region where the saturation effects should be present (small x and low Q 2 ). However, this expectation fails when the KKT model is applied, as verified in [27].…”

Saturation and the Ratio sigmadiff/sigmatot in an electron-ion collider

“…Since the dipole cross section is universal, i.e., the same for γp and pp scatterings, a better procedure would be to fit simultaneously HERA and RHIC data. The determination of a dipole cross section compatible with both sets of data was discussed in [20,21].…”