A unified picture of parton multiple scattering in the small-x regime and forward physics at RHIC and the LHC

19 May 2014, 17:50
20m
titanium (darmstadtium)

titanium

darmstadtium

Schlossgraben 1 64283 Darmstadt Germany
Contributed Talk Initial State Physics Initial state physics

Speaker

Zhongbo Kang (L)

Description

The quest for experimental signatures of small-x gluon saturation has been one of the major goals in p+A (d+A) programs at RHIC and LHC. Experimental measurements of single particle and two-particle correlations in the forward direction have revealed novel nuclear suppression patterns, which might help pinpoint the small-x gluon dynamics. At the moment there are two formalisms which can both describe reasonably well the nuclear suppression observed in these experiments. One is the so-called higher-twist factorization approach, which describes the parton multiple scattering in terms of the power corrections to the differential cross section [1,2]. The other one is the so-called small-x color glass condensate (CGC) approach [3]. So far the precise connection between these two approaches has not been established. In this talk, we demonstrate how the multiple parton scattering picture and the small-x gluon saturation picture are related and show how the transition from a dilute parton system to a dense gluon saturation region occurs. Our work unifies the two approaches in studying the nonlinear small-x parton dynamics. On the example of forward rapidity photon production in p+A collisions, we demonstrate that in the broad transition region between a dilute parton system and a deeply saturated regime the two approaches give identical results. This work also helps understand the constraints on the small-x phenomenological studies. [1] J. Qiu and I. Vitev, Phys. Lett. B632, 507 (2006) [2] Z. B. Kang, I. Vitev and H. Xing, Phys. Rev. D85, 054024 (2012) [3] see, e.g., J. L. Albacete and C. Marquet, Phys. Rev. Lett. 105, 162301 (2010)

Primary author

Zhongbo Kang (L)

Co-authors

Hongxi Xing (Los Alamos National Laboratory) Dr Ivan Vitev (Los Alamos National Laboratory) Jianwei Qiu (Brookhaven National Lab)

Presentation Materials