Neutrino Mass, Sneutrino Dark Matter and Signals of Lepton Flavor Violation in the MRSSM

TL;DR

This paper explores mixed-sneutrino dark matter within the MRSSM, showing it can account for dark matter relic abundance, satisfy detection constraints, generate small neutrino masses, and produce observable lepton flavor violation signals at the LHC.

Contribution

It demonstrates the viability of mixed sneutrinos as dark matter candidates in the MRSSM and links neutrino mass generation with collider signals of lepton flavor violation.

Findings

Relic abundance of sneutrino dark matter matches observed values.

Parameter space can satisfy direct detection constraints.

Sneutrino flavor composition leads to detectable lepton flavor violation signals.

Abstract

We study the phenomenology of mixed-sneutrino dark matter in the Minimal R-Symmetric Supersymmetric Standard Model (MRSSM). Mixed sneutrinos fit naturally within the MRSSM, as the smallness (or absence) of neutrino Yukawa couplings singles out sneutrino A-terms as the only ones not automatically forbidden by R-symmetry. We perform a study of randomly generated sneutrino mass matrices and find that (i) the measured value of $\Omega_{DM}$ is well within the range of typical values obtained for the relic abundance of the lightest sneutrino, (ii) with small lepton-number-violating mass terms $m_{nn}^{2} {\tilde n} {\tilde n}$ for the right-handed sneutrinos, random matrices satisfying the $\Omega_{DM}$ constraint have a decent probability of satisfying direct detection constraints, and much of the remaining parameter space will be probed by upcoming experiments, (iii) the $m_{nn}^{2} {\tilde n} {\tilde n}$ terms radiatively generate appropriately small Majorana neutrino masses, with neutrino oscillation data favoring a mostly sterile lightest sneutrino with a dominantly mu/tau-flavored active component, and (iv) a sneutrino LSP with a significant mu component can lead to striking signals of e-mu flavor violation in dilepton invariant-mass distributions at the LHC.