Diphoton decays of stoponium at the Large Hadron Collider

TL;DR

This paper investigates the potential to detect stoponium, a bound state of top squarks, via its diphoton decay at the LHC, which could allow precise measurements of superpartner masses.

Contribution

It provides an updated and corrected analysis of the prospects for observing stoponium through diphoton decays at the LHC, highlighting conditions for detectability.

Findings

Diphoton decay mode can be observable over background under favorable conditions.

Detection enables precise superpartner mass measurements.

Analysis corrects and updates previous studies.

Abstract

If the lighter top squark has no kinematically allowed two-body decays that conserve flavor, then it will form hadronic bound states. This is required in models that are motivated by the supersymmetric little hierarchy problem and obtain the correct thermal relic abundance of dark matter by top-squark-mediated neutralino annihilations, or by top-squark-neutralino co-annihilations. It is also found in models that can accommodate electroweak-scale baryogenesis within minimal supersymmetry. I study the prospects for detecting scalar stoponium from its diphoton decay mode at the Large Hadron Collider, updating and correcting previous work. Under favorable circumstances, this signal will be observable over background, enabling a uniquely precise measurement of the superpartner masses through a narrow peak in the diphoton invariant mass spectrum, limited by statistics and electromagnetic calorimeter resolutions.