Abstract
In this paper, we consider a novel realization of the Dynamical Dark Matter (DDM) framework in which the ensemble of particles which collectively constitute the dark matter are the composite states of a strongly-coupled conformal field theory. Cosmological abundances for these states are then generated through mixing with an additional, elementary state. As a result, the physical fields of the DDM dark sector at low energies are partially composite -- i.e., admixtures of elementary and composite states. Interestingly, we find that the degree of compositeness exhibited by these states varies across the DDM ensemble. We calculate the masses, lifetimes, and abundances of these states -- along with the effective equation of state of the entire ensemble -- by considering the gravity dual of this scenario in which the ensemble constituents are realized as the Kaluza-Klein states associated with a scalar propagating within a slice of five-dimensional anti-de Sitter (AdS) space. Surprisingly, we find that the warping of the AdS space gives rise to parameter-space regions in which the decay widths of the dark-sector constituents vary non-monotonically with their masses. We also find that there exists a maximum degree of AdS warping for which a phenomenologically consistent dark-sector ensemble can emerge. Our results therefore suggest the existence of a potentially rich cosmology associated with partially composite DDM.
Highlights
Dynamical Dark Matter [1,2] (DDM) provides an alternative framework for dark-matter physics in which the notion of dark-matter stability is replaced by something more general and powerful: a balancing of decay widths against cosmological abundances across an ensemble of individual dark-matter constituents
Examples of scenarios which yield a DDM-appropriate set of scaling relations include higher-dimensional theories of an axion or axionlike particle propagating in the bulk [3] in which the Kaluza-Klein (KK) resonances collectively constitute the DDM ensemble [2,4]; theories with additional fields which transform nontrivially under large, spontaneously broken symmetry groups, in which the ensemble constituents are the physical degrees of freedom within the corresponding symmetry multiplets [5]; and theories with strongly coupled hidden-sector gauge groups, in which the ensemble constituents are identified with the “hadrons” which
We have investigated a novel realization of the DDM framework within the context of a strongly coupled conformal field theory (CFT)
Summary
Dynamical Dark Matter [1,2] (DDM) provides an alternative framework for dark-matter physics in which the notion of dark-matter stability is replaced by something more general and powerful: a balancing of decay widths against cosmological abundances across an ensemble of individual dark-matter constituents. By studying the gravity dual of our partially composite DDM scenario we can infer information about the values of these parameters and determine how the lifetimes, abundances, etc., of the individual constituents scale across the ensemble This dual theory involves a scalar propagating in the bulk of a spacetime orbifold which is tantamount to a slice of five-dimensional anti-de Sitter (AdS) space. The gravity dual of our partially composite DDM scenario is useful as a tool for gleaning information about this scenario, but is interesting in its own right It has been shown [2,4] that the KK modes of an axionlike particle propagating in the bulk of a theory with a single, flat extra dimension constitute a phenomenologically viable DDM ensemble with a particular set of scaling relations. III by considering different possible locations for the relevant boundary terms which give rise to the decay widths and abundances for the ensemble constituents
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