Reviving the interference: framework and proof-of-principle for the anomalous gluon self-interaction in the SMEFT

TL;DR

This paper introduces a method to enhance the measurement of interference effects in particle physics, specifically targeting the anomalous gluon interactions in the SMEFT, by quantifying an observable's ability to distinguish positive and negative contributions.

Contribution

It proposes a novel framework to revive interference effects in experimental measurements and demonstrates its application to constrain the anomalous gluon operator in the SMEFT.

Findings

First constraints on the anomalous gluon operator from interference effects.

Method effectively distinguishes positive and negative interference contributions.

Constraints comparable to those from quadratic amplitude terms.

Abstract

Interferences are not positive-definite and can change sign over the phase space. If the contributions of the regions where they are positive and negative nearly cancel each other, their effects can be hard to measure. In this paper, we propose a method to quantify the ability of an observable to separate these opposite contributions and therefore to revive the interference effects at experiments. We apply this strategy to the anomalous gluon operator in the SMEFT, for which the linear-term suppression is well known. We show that we can get, for the first time, constraints on its coefficient from the interference only that are similar to those from the square of the new-physics amplitude.