Theoretical analysis for the apparent discrepancy between pbarp and pp data in charged particle forward-backward multiplicity correlations

TL;DR

This paper investigates the apparent discrepancy in charged particle forward-backward multiplicity correlations between pbar+p and p+p collisions at 200 GeV, attributing differences to detector acceptance and observing intervals, and introduces a mixed event method to analyze correlation sources.

Contribution

It provides a theoretical analysis explaining the discrepancy between experimental data sets and introduces a mixed event method to separate statistical and dynamical correlations.

Findings

Discrepancy between UA5 and STAR data explained by detector acceptance differences.

Statistical correlations dominate over dynamical correlations in the studied collisions.

PYTHIA simulations fitted with Negative Binomial Distribution agree with mixed event correlation results.

Abstract

The strength of charged particle forward-backward multiplicity correlation in pbar+p and p+p collisions at s^1/2 = 200 GeV is studied by PYTHIA 6.4 and compared to the UA5 and STAR data correspondingly. It is turned out that a factor of 3-4 apparent discrepancy between UA5 and STAR data can be attributed to the differences in detector acceptances and observing bin interval in both experiments. A mixed event method is introduced and used to calculate the statistical correlation strength and the dynamical correlation strengths stemming from the charge conservation, four- momentum conservation, and decay, respectively. It seems that the statistical correlation is much larger than dynamical one and the charge conservation, four-momentum conservation and decay may account for most part of the dynamical correlation. In addition, we have also calculated the correlation strength by fitting the charged particle multiplicity distribution from PYTHIA to the Negative Binomial Distribution and found that the result agrees well with the correlation strength calculated by mixed events.