Strong Signatures of Right-Handed Compositeness

TL;DR

This work analyzes collider signatures of right-handed quark compositeness within partial compositeness and MFV, focusing on a color-octet gluon resonance and heavy quark partners. It combines simulations with existing ATLAS/CMS dijet and ttbar searches to derive bounds on the color octet mass and the masses/mixings of light-generation quark partners, highlighting that dijet data robustly constrain the gluon resonance while left-handed partners face strong single-production limits and right-handed partners yield predominantly multi-jet final states. The study shows that MFV-based scenarios yield sizable production rates for light quark partners, but bounds are highly spectrum-dependent; dedicated multi-jet searches could substantially improve sensitivity, especially for 2+1 and 3+1 jet topologies. Overall, the results indicate that MFV-inspired composite models remain viable but increasingly constrained, motivating new experimental strategies beyond conventional SUSY-like multijet searches, including jet-tagging and optimized jet-ordering techniques. The findings underscore the need for tailored LHC analyses to probe the distinctive jet-rich signatures of right-handed compositeness and to test the naturalness implications of these models.

Abstract

Right-handed light quarks could be significantly composite, yet compatible with experimental searches at the LHC and precision tests on Standard Model couplings. In these scenarios, that are motivated by flavor physics, one expects large cross sections for the production of new resonances coupled to light quarks. We study experimental strong signatures of right-handed compositeness at the LHC, and constrain the parameter space of these models with recent results by ATLAS and CMS. We show that the LHC sensitivity could be significantly improved if dedicated searches were performed, in particular in multi-jet signals.

Figures (24)

• Figure 1: Above couplings of the color octet to SM quarks and their heavy partners. Below couplings to electroweak gauge bosons.
• Figure 2: The heavy color octet is dominantly produced from a quark anti-quark pair and then decays into any kinematically accessible combination of light and heavy quarks.
• Figure 3: Typical behavior of the color octet width as a function of the octet mass, for $g_\rho = 3$. The width increases significantly as the decay channels to the quark partners open up, these qualitative features hold independently of the mixings.
• Figure 4: Exclusion plot for a color octet with $g_\rho=3$. In blue, region excluded by compositeness bounds. In red (ATLAS) and green (CMS) exclusion from direct production. The different regions correspond to $95$% confidence level exclusion for two hypothetical scenarios where the quark partners are light ($m_Q = 1$ TeV, solid contour) or heavy ($m_Q = 2$ TeV, dashed contour).
• Figure 5: Ratio of $\sigma(pp \to \rho \to t {\bar{t}})$ in MFV models compared to the experimental benchmark Randall-Sundrum model. The blue region corresponds to a width greater than $0.2 \; m_\rho$ where the experimental bounds are not be applicable. In this comparison the assumption is made that the decay to heavy fermions is kinematically forbidden.