Why Unparticle Models with Mass Gaps are Examples of Hidden Valleys

TL;DR

This paper explores how unparticle models with added mass gaps transition into hidden valley models, highlighting unique collider signatures and the limitations of unparticle propagator predictions.

Contribution

It demonstrates that unparticle models with mass gaps are effectively hidden valley models and discusses novel signatures and effects of strong dynamics on collider observables.

Findings

Unparticle models with mass gaps behave as hidden valley models.

Spectacular collider signatures include displaced vertices and multi-particle final states.

Strong dynamics influence hidden valley signals beyond unparticle predictions.

Abstract

Hidden valleys, hidden sectors with multi-particle dynamics and a mass gap, can produce striking and unusual final states at the LHC. Unparticle models, hidden-sectors with conformal dynamics and no (or a very small) mass gap, can result in unusual kinematic features that indirectly reflect the conformal dynamics. When sufficiently large mass gaps are added to unparticle models, they become hidden valley models. Predictions using unparticle propagators alone overlook the most striking signals, which are typically of hidden-valley type. Inclusive signatures often cannot be predicted from unparticle dimensions, and exclusive signatures are often visible and can be spectacular. Among possible signatures are: Higgs decays to pairs of particles that in turn decay to two quarks, leptons or gauge bosons, possibly with displaced vertices; Higgs, top, and neutralino decays to more than six particles; resonances below an ``unparticle'' continuum which produce multi-body final states; etc. The Stephanov model is deconstructed, reconstructed, and shown to be a hidden valley model. Some effects of strong dynamics on hidden valley observables, not predictable using unparticle methods, are discussed, including resonances, reduced flavor symmetry breaking, reduced supersymmetry breaking, and a strongly enhanced hidden parton shower.