LHC Shines on Positivity

TL;DR

This paper demonstrates that the LHC can effectively test the positivity bounds of certain dimension-8 operators involving colored particles through diphoton final state analysis, reaching multi-TeV scales.

Contribution

It introduces a novel method to probe positivity bounds of dimension-8 operators at hadron colliders using differential distributions, extending the reach beyond previous constraints.

Findings

LHC can probe positivity of dimension-8 operators up to 2 TeV at HL-LHC.

Future 100 TeV collider can extend this to over 5 TeV.

Diphoton kinematic distributions enable effective global fits for positivity tests.

Abstract

We show that hadron colliders have an excellent reach for positivity tests on a class of diphoton operators. Due to the helicity selection rules, the relevant dimension-6 operators either do not contribute or are highly constrained by other experimental observables. We show, for the first time, that the LHC can probe the positivity of the dimension-8 operators involving colored particles. The kinematic differential distributions of the diphoton final states are exploited to perform the $\chi^2$ analysis. Through a global fit, the effective scale for these operators can be inclusively probed up to around 2 TeV at HL-LHC and over 5 TeV at future 100 TeV FCC-hh at 95% C.L., providing a powerful test of the positivity bounds up to multi-TeV scale.