Heavy Right-Handed Neutrinos and Dark Matter in the $\nu$CMSSM

TL;DR

This paper investigates how the inclusion of heavy right-handed neutrinos in the $ u$CMSSM affects dark matter relic density predictions, revealing significant shifts in focus point and funnel regions due to neutrino Yukawa couplings.

Contribution

It provides a systematic analysis of the impact of type-I seesaw neutrinos on dark matter predictions within the constrained supersymmetric model, highlighting new effects on focus point and funnel regions.

Findings

Focus point scale can exceed the electroweak scale, eliminating the focus point region.

Right-handed neutrinos influence the funnel region via heavy Higgs s-channel annihilations.

Sneutrino coannihilation regions are affected by neutrino Yukawa coupling, especially at small $m_0,m_{1/2}$.

Abstract

We perform a systematic study of the effects of the type-I seesaw mechanism on the dark matter abundance in the constrained supersymmetric standard model (CMSSM) which includes three right-handed neutrinos (the $\nu$CMSSM). For large values of $m_0,m_{1/2}$, we exploit the effects of large neutrino Yukawa couplings on the renormalization group (RG) evolution of the up-type Higgs. In particular, we show that the focus point scale can greatly exceed the electroweak scale resulting in the absence of a focus point region for which the relic density of neutralinos is within the range determined by WMAP. We also discuss the effects of the right-handed neutrinos on the so-called funnel region, where the relic density is controlled by s-channel annihilations through a heavy Higgs. For small values of $m_0,m_{1/2}$, we discuss the possibility of sneutrino coannihilation regions with an emphasis on the suppression of the left-handed slepton doublet masses due to the neutrino Yukawa coupling. We consider two types of toy models consistent with either the normal or inverted hierarchy of neutrino masses.