Forward-backward multiplicity fluctuations in ultrarelativistic nuclear collisions with wounded quarks and fluctuating strings

Abstract

We analyze a generic model where wounded quarks are amended with strings in which both endpoint positions fluctuate in spatial rapidity. With the assumption that the strings emit particles independently of one another and with a uniform distribution in rapidity, we are able to analyze the model semi-analytically, which allows for its detailed understanding. Using as a constraint the one-body string emission functions obtained from the experimental data for collisions at √ sNN = 200 GeV, we explore the two-body correlations for various scenarios of string fluctuations. We find that the popular measures used to quantify the longitudinal fluctuations (anm coefficients) are limited with upper and lower bounds. These measures can be significantly larger in the model where both end-point are allowed to fluctuate, compared to the model with single end-point fluctuations.

Longitudinal correlations from fluctuating strings in Pb-Pb, p -Pb, and p−p collisions

“…In this section we proceed in analogy to our earlier work [1]. However, in contrast to the description used therein, in this article we pass from the profile functions in pseudorapidity η, obtained in the previous section, to…”

“…The reason is technical but relevant. The method of [1] works for profile functions with are unimodal (have a single maximum), as this is what follows from strings continuously stretched between fluctuating end-points. Unimodality is not the case in the present analysis, as can be seen from Fig.…”

“…since the Jacobian factors dη/dy cancel out between the numerator and denominator. In analogy to the profile for the emission of individual particles from a single string, a two-particle profile for the emission of particle pairs from single strings is [1]…”

“…In our recent paper [1] we have presented an analysis of the longitudinal hadronic correlations at the highest RHIC energy of √ s NN = 200 GeV in the framework of a simple model, where emission proceeds from strings with fluctuating end-points [2]. The model is, up to emission profiles extracted from the data, analytic, which allows us for a simple understanding of generic production features present in various string or fluxtube approaches.…”

“…Then, the one-body emission profile f (y) can be written as [1] f (y) = ∞ −∞ dy 1 ∞ −∞ dy 2 g 1 (y 1 )g 2 (y 2 )s(y; y 1 , y 2 )…”