Abstract

We consider the possible existence of a SM-neutral and light dark sector coupled to the visible sector through irrelevant portal interactions. Scenarios of this kind are motivated by dark matter and arise in various extensions of the Standard Model. We characterize the dark dynamics in terms of one ultraviolet scale Λuv, at which the exchange of heavy mediator fields generates the portal operators, and by one infrared scale ΛIR, setting the mass gap. At energies ΛIR « E « Λuv the dark sector behaves like a conformal field theory and its phenomenology can be studied model independently. We derive the constraints set on this scenario by high- and low-energy laboratory experiments and by astrophysical observations. Our results are conservative and serve as a minimum requirement that must be fulfilled by the broad class of models satisfying our assumptions, of which we give several examples. The experimental constraints are derived in a manner consistent with the validity of the effective field theory used to define the portal interactions. We find that high-energy colliders give the strongest bounds and exclude UV scales up to a few TeV, but only in specific ranges of the IR scale. The picture emerging from current searches can be taken as a starting point to design a future experimental strategy with broader sensitivity.

Highlights

  • Introduction and motivationsNew physics beyond the Standard Model (SM) of particle physics is well motivated from several considerations, one of the most appealing being the requirement of a Dark Matter (DM) candidate

  • The models discussed above provide concrete realizations of dark sectors with portal interactions of the type considered in eq (1.3)

  • A DM candidate might reside in the dark sector or be part of the UV dynamics, and its abundance may be thermal or arise from a different production mechanism

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Summary

Introduction

Introduction and motivationsNew physics beyond the Standard Model (SM) of particle physics is well motivated from several considerations, one of the most appealing being the requirement of a Dark Matter (DM) candidate. Sector, coupled to the SM only through portal interactions formed by the product of one SM and one dark singlet operator. Scenarios of this kind are predicted in various extensions of the SM and have been intensively studied under the assumption that the portal operators have dimension 4 or less, see for example [1,2,3,4] and references therein. In this work we analyze the more elusive dark sectors where the portal operators are higher-dimensional and are generated at some ultraviolet (UV) scale ΛUV by heavy mediator fields. The DM candidate might reside in the dark sector (DS) or be part of the UV dynamics. The portal interactions can be written in terms of SU(3)c × SU(2)L × U(1)Y invariant operators

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