Composite Leptoquarks at the LHC

TL;DR

This paper explores the theoretical possibility of composite leptoquarks arising from strong sector physics, their potential masses, and prospects for detection at the LHC, within models that address flavor suppression and unification.

Contribution

It introduces a model where composite leptoquarks emerge naturally in strongly-coupled theories with flavor suppression, and discusses their phenomenology and detection prospects at the LHC.

Findings

Composite leptoquarks can be light pseudo-Nambu-Goldstone bosons.

Flavor suppression mechanisms may evade current experimental constraints.

LHC has promising prospects for discovering these leptoquarks.

Abstract

If electroweak symmetry breaking arises via strongly-coupled physics, the observed suppression of flavour-changing processes suggests that fermion masses should arise via mixing of elementary fermions with composite fermions of the strong sector. The strong sector then carries colour charge, and may contain composite leptoquark states, arising either as TeV scale resonances, or even as light, pseudo-Nambu-Goldstone bosons. The latter, since they are coupled to colour, get a mass of the order of several hundred GeV, beyond the reach of current searches at the Tevatron. The same generic mechanism that suppresses flavour-changing processes suppresses leptoquark-mediated rare processes, making it conceivable that the many stringent constraints may be evaded. The leptoquarks couple predominantly to third-generation quarks and leptons, and the prospects for discovery at LHC appear to be good. As an illustration, a model based on the Pati-Salam symmetry is described, and its embedding in models with a larger symmetry incorporating unification of gauge couplings, which provide additional motivation for leptoquark states at or below the TeV scale, is discussed.