Charged planckian interacting dark matter

Abstract

A minimal model of Cold Dark Matter (CDM) is a very massive particle with only gravitational interactions, also called Planckian Interacting Dark Matter (PIDM). Here we consider an extension of the PIDM framework by an unbroken U (1) gauge symmetry under which the PIDM is charged, but remains only gravitationally coupled to the Standard Model (SM). Contrary to "hidden charged dark matter", the charged PIDM never reaches thermal equilibrium with the SM. The dark sector is populated by freeze-in via gravitational interactions at reheating. If the dark fine-structure constant α D is larger than about 10 −3 , the dark sector thermalizes within itself, and the PIDM abundance is further modified by freeze-out in the dark sector. Interestingly, this largely reduces the dependence of the final abundance on the reheating temperature, as compared to an uncharged PIDM. Thermalization within the dark sector is driven by inelastic radiative processes, and affected by the Landau-Pomeranchuk-Migdal (LPM) effect. The observed CDM abundance can be obtained over a wide mass range from the weak to the GUT scale, and for phenomenologically interesting couplings α D ∼ 10 −2 . Due to the different thermal history, the charged PIDM can be discriminated from "hidden charged dark matter" by more precise measurements of the effective number of neutrino species N eff . 1 mathias.garny@tum.de 2

Dark matter and naturalness

“…It is possible the scalar is so heavy that it is unable to be produced directly during reheating, in which case its primordial abundance could be negligible (excepting the interesting possibility of freeze-in [61]). On the other hand, suppose the scalar mass m ϕ is large, in accord with naturalness, but not so large that in cannot be produced during reheating after inflation; for example, its mass may be m ϕ ∼ 10 13 GeV or so.…”

Gravitational production of superheavy dark matter and associated cosmological signatures

“…There are many models for gravitationally produced dark matter with different mass ranges and different types of interactions [50][51][52][53][54][55][56][57]. One may ask if it is possible to determine some properties of such dark matter independently of the details of these models.…”

Leak-in dark matter

“…However, inelastic scattering, χX → χX + Z D , is more effective than elastic scattering at thermalizing the hidden sector over much of the parameter space of interest. The importance of inelastic scattering in thermalizing a sector containing gauge interactions is well-known [112][113][114][115]. While the inelastic scattering process is higher-order in α D , it can be sufficiently enhanced by the region of low momentum transfer to more than compensate for the additional α D suppression.…”

“…While the inelastic scattering process is higher-order in α D , it can be sufficiently enhanced by the region of low momentum transfer to more than compensate for the additional α D suppression. Our estimate of thermalization through this inelastic process will be parametric, and largely follows the related treatment in [115].…”