Long-range rapidity correlations between mean transverse momenta

Vladimir Vechernin

doi:10.1051/epjconf/201713803010

Abstract

The forward-backward correlation strength between event-mean transverse momenta of particles produced in separated rapidity intervals in high energy hadronic collisions is analyzed in the simple model with the string fusion on a transverse lattice. The coefficient of long-range rapidity p t - p t correlation is obtained using the negative binomial distribution for the number of strings, which is closer to reality than the poissonian one. The results demonstrate good agreement with the asymptotes of the correlation coefficient analytically calculated earlier at large string density. It is observed that at LHC energy the p t - p t correlation coefficient reveals the drop for most central collisions. The model calculations show that the physical reason for this decrease is the attenuation of color field fluctuations due to the string fusion at large string density, whereas at RHIC energy the string density is not enough to provide a decline of the correlation coefficient for most central collisions.

Highlights

As expected, the experimental studies of long-range rapidity correlations can give us the information about the initial stage of high energy hadronic interactions [1]
We obtain the coefficient of long-range e-mail: v.vechernin@spbu.ru rapidity pt-pt correlation, bpp, using the negative binomial distribution (NBD) for the fluctuation in number of strings, which is closer to reality than the poissonian one, which was exploited in the previous works [9, 11]
We present the value of the correlation coefficient bpp, (3), between event-mean transverse momenta as a function of η, calculated by MC simulations using the formulae (10)-(12) and by simplified MC simulations based on the formulae (15)

Summary

Introduction

The experimental studies of long-range rapidity correlations can give us the information about the initial stage of high energy hadronic interactions [1]. In [2] the study of the long-range forward-backward (FB) correlations between multiplicities in two separated rapidity windows to find a signature of the string fusion and percolation phenomenon [3,4,5] in ultrarelativistic heavy ion collisions has been proposed Later it was realized [6,7,8,9,10,11,12] that the investigations of the FB correlations involving intensive observables, such e.g. as the event-mean transverse momentum, enable to obtain clearer signal about the initial stage of hadronic interaction, including the process of string fusion, compared to usual FB multiplicity correlations. We discuss the impact of the obtained results on the bpp correlation coefficient centrality dependence at RHIC and LHC energies

Definitions

The model

Correlation between event-mean transverse momenta

Concluding remarks