Analysis Tools for Discovering Strong Parity Violation at Hadron Colliders

TL;DR

This paper introduces new analysis tools based on group representations to detect parity violation in high-energy hadron collisions, enabling the identification of previously unmeasured parity-violating and conserving observables across various collider experiments.

Contribution

It develops a group-theoretic framework for analyzing azimuthal distributions, revealing new parity-violating observables and methods for separating event handedness in collider data.

Findings

Identification of new parity-violating observables

Distinction of previously lumped parity-conserving observables

Applicability to multiple collider experiments

Abstract

Several arguments suggest parity violation may be observable in high energy strong interactions. We introduce new analysis tools for describing the azimuthal dependence of multi-particle distributions, or "azimuthal flow." Analysis uses the representations of the orthogonal group O(2) and dihedral groups $D_{N}$ necessary to define parity correctly in two dimensions. Classification finds that collective angles used in event-by-event statistics represent inequivalent tensor observables that cannot generally be represented by a single "reaction plane". Many new parity-violating observables exist that have never been measured, while many new parity-conserving observables formerly lumped together are now distinguished. We use the concept of "event shape sorting" to suggest separating right- and left-handed events, and we discuss the effects of transverse and longitudinal spin. The analysis tools are statistically robust, and can be applied equally to low or high multiplicity events at the Tevatron, $RHIC$ or $RHIC\, Spin$, and the $LHC$.