Color-octet scalars in Dirac gaugino models with broken $R$ symmetry

TL;DR

This paper investigates the collider phenomenology of color-octet scalars (sgluons) in supersymmetric models with Dirac gaugino masses and broken R symmetry, highlighting new decay features and collider constraints.

Contribution

It constructs R-symmetry breaking models, computes decay rates, and analyzes collider constraints, revealing how R-breaking alters sgluon phenomenology and experimental limits.

Findings

R symmetry breaking enhances decay rates and introduces new decay channels.

Existing collider limits are affected, potentially closing or opening mass windows for light sgluons.

Scenarios with light sgluons below 1 TeV remain compatible with current searches.

Abstract

In this work we study the collider phenomenology of color-octet scalars (sgluons) in supersymmetric models with Dirac gaugino masses that feature an explicitly broken $R$ symmetry ($R$-broken models). We construct such models by augmenting minimal $R$-symmetric models with a fairly general set of supersymmetric and softly supersymmetry-breaking operators that explicitly break $R$ symmetry. We then compute the rates of all significant two-body decays and highlight new features that appear as a result of $R$ symmetry breaking, including enhancements to extant decay rates, novel tree- and loop-level decays, and improved cross sections of single sgluon production. We demonstrate in some detail how the familiar results from minimal $R$-symmetric models can be obtained by restoring $R$ symmetry. In parallel to this discussion, we explore constraints on these models from the Large Hadron Collider. We find that, in general, $R$ symmetry breaking quantitatively affects existing limits on color-octet scalars, perhaps closing loopholes for light CP-odd (pseudoscalar) sgluons while opening one for a light CP-even (scalar) particle. Qualitatively, however, we find that -- much as for minimal $R$-symmetric models, despite stark differences in phenomenology -- scenarios with broken $R$ symmetry and two sgluons below the TeV scale can be accommodated by existing searches.