Theory and Phenomenology of Planckian Interacting Massive Particles as Dark Matter

TL;DR

This paper explores the theoretical framework and phenomenology of Planckian Interacting Massive Particles (PIDM) as a minimal dark matter candidate, emphasizing gravitational production mechanisms and potential observational tests.

Contribution

It generalizes the scalar PIDM model to fermion, vector, and tensor cases, showing similar phenomenology across spins, and discusses specific string theory realizations and indirect detection prospects.

Findings

PIDM can be produced gravitationally after inflation in a wide mass range.

Phenomenology is nearly identical for scalar, fermion, vector, and tensor PIDMs.

Future measurements of primordial tensor modes can test the GUT scale PIDM hypothesis.

Abstract

Planckian Interacting Dark Matter (PIDM) is a minimal scenario of dark matter assuming only gravitational interactions with the standard model and with only one free parameter, the PIDM mass. PIDM can be successfully produced by gravitational scattering in the thermal plasma of the Standard Model sector after inflation in the PIDM mass range from TeV up to the GUT scale, if the reheating temperature is sufficiently high. The minimal assumption of a GUT scale PIDM mass can be tested in the future by measurements of the primordial tensor-to-scalar ratio. While large primordial tensor modes would be in tension with the QCD axion as dark matter in a large mass range, it would favour the PIDM as a minimal alternative to WIMPs. Here we generalise the previously studied scalar PIDM scenario to the case of fermion, vector and tensor PIDM scenarios, and show that the phenomenology is nearly identical, independent of the spin of the PIDM. We also consider the specific realisation of the PIDM as the Kaluza Klein excitation of the graviton in orbifold compactifications of string theory, as well as in models of monodromy inflation and in Higgs inflation. Finally we discuss the possibility of indirect detection of PIDM through non-perturbative decay.