Thermal production of light Dirac right-handed sneutrino dark matter

TL;DR

This paper investigates how light right-handed sneutrinos can be produced as dark matter in the early universe through thermal scatterings and decays, considering their non-thermal origin due to tiny Yukawa couplings.

Contribution

It introduces a scenario where thermal scatterings significantly contribute to right-handed sneutrino dark matter production, expanding beyond decay-based mechanisms.

Findings

Thermal scatterings can dominate sneutrino production.

Non-thermal production is significant with light sneutrinos and sleptons.

Cosmological implications of the scenario are discussed.

Abstract

We consider the production of right-handed (RH) sneutrino dark matter in a model of Dirac neutrino where neutrino Yukawa coupling constants are very small. Dark matter RH sneutrinos are produced by scatterings and decays of thermal particles in the early Universe without reaching thermal equilibrium due to the small Yukawa couplings. We show that not only decays of thermal particles but also the thermal scatterings can be a dominant source as well as non-thermal production in a scenario with light sneutrinos and charged sleptons while other supersymmetric particles are heavy. We also discuss the cosmological implications of this scenario.