scalesquarks

Scalesquark is a hypothetical elementary fermion proposed in certain beyond-Standard-Model theories that extend the Standard Model with a new confining interaction tied to scale invariance. In these frameworks, a new gauge sector enforces or emerges from approximate scale symmetry, and scalesquarks act as the fermionic matter content of that sector. The name reflects their quark-like character and their association with scaling transformations rather than color charge.

In typical implementations, scalesquarks carry no Standard Model color and may transform under a new scale-color gauge group. They are usually assumed to be heavy, with masses at the TeV scale, and to couple to Standard Model fields primarily through portal interactions such as mixing with the Higgs or via a dilaton—the pseudo-Goldstone boson of broken scale invariance. Depending on the model, scalesquarks can be stable or decay to Standard Model particles plus hidden-sector states.

Phenomenology and experiments: If produced at high-energy colliders, scalesquarks would be created in pairs and decay to jets, leptons, or missing energy signatures. Their decays could yield unusual kinematic distributions or displaced vertices if lifetimes are appreciable. Current LHC searches have not observed scalesquarks; analyses place lower bounds on their masses that are model-dependent but often reach the TeV scale for strongly coupled variants.

Status and outlook: Scalesquarks remain speculative and model-dependent. They feature in discussions of scale symmetry and its breaking, conformal technicolor, and other approaches to naturalness. Ongoing theoretical work seeks to clarify their spectra and interactions, while collider experiments continue to probe the parameter space of scale-symmetric theories. See also: scale invariance, dilaton, technicolor, beyond-Standard-Model physics.