Forward-Backward Correlations and Event Shapes as probes of Minimum-Bias Event Properties

TL;DR

This paper investigates how forward-backward correlations and event-shape observables can enhance understanding of minimum-bias events at the LHC, analyzing their sensitivity to theoretical uncertainties and model tuning.

Contribution

It introduces the use of forward-backward correlations and event-shape variables as probes for minimum-bias event properties, assessing their sensitivity to various theoretical effects.

Findings

FB correlations and event shapes are sensitive to multiple parton interactions.

Comparisons of PYTHIA tunes reveal differences in model predictions.

Event-shape observables can constrain Monte Carlo models effectively.

Abstract

Measurements of inclusive observables, such as particle multiplicities and momentum spectra, have already delivered important information on soft-inclusive ("minimum-bias") physics at the Large Hadron Collider. In order to gain a more complete understanding, however, it is necessary to include also observables that probe the structure of the studied events. We argue that forward-backward (FB) correlations and event-shape observables may be particulary useful first steps in this respect. We study the sensitivity of several different types of FB correlations and two event shape variables - transverse thrust and transverse thrust minor - to various sources of theoretical uncertainty: multiple parton interactions, parton showers, colour (re)connections, and hadronization. The power of each observable to furnish constraints on Monte Carlo models is illustrated by including comparisons between several recent, and qualitatively different, PYTHIA 6 tunes, for pp collisions at sqrt(s) = 900 GeV.