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
titanium (darmstadtium)



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


Zhongbo Kang (L)


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)


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

Presentation Materials