A light dilaton at the LHC

TL;DR

This paper investigates the potential of a light dilaton as an early indicator of new physics at the LHC, analyzing its phenomenology, mixing with the Higgs, and role as a portal to dark sectors.

Contribution

It provides a detailed phenomenological study of a light dilaton in the 10-300 GeV range, including its mixing with the Higgs and implications for dark sector portals.

Findings

Dilaton can produce detectable signals at the LHC within the studied mass range.

Mixing with the Higgs affects the dilaton's production and decay signatures.

Dark photon scenarios lead to significant missing energy signatures.

Abstract

In this paper, we explore the possibility that a light dilaton can be the first sign of new physics at the LHC. The dilaton could emerge in approximate scale invariant UV completions of the SM as the Goldstone boson associated with the spontaneous breaking of the scale invariance. We study in detail the phenomenology of the dilaton at the LHC in the mass range of [$10-300$] GeV including the case where the dilaton can mix with the SM Higgs boson, leading to an interesting interplay between direct and indirect constraints. A possibility that the dilaton acts as a portal to a dark sector is also considered. As a minimal realization, the dark sector includes a dark photon lighter than the dilaton implying sizeable missing energy signatures. Several simplified benchmark models that can encode different UV completions are discussed, for which we scrutinize the current and future LHC reach.