A lower limit on the neutralino mass in the MSSM with non-universal gaugino masses

TL;DR

The paper addresses the problem of establishing a robust lower bound on the lightest neutralino mass in the MSSM with non-universal gaugino masses by focusing on the gaugino/slepton sector. It employs two model classes, M0 and LR, scans a wide parameter space with the non-universality ratio $r_{12}=M_1/M_2$, and combines LEP direct limits with relic density calculations from micrOMEGAs and constraints from $(g-2)_ ext{μ}$ and $b\to s\gamma$. The main finding is a conservative lower bound on $m_{ ilde{ eutralino}^0_1}$ of roughly $12$–$18$ GeV for $M_1\ll M_2$, with tighter or looser bounds ($ ext{~}18$–$27$ GeV) depending on slepton masses, $ an\beta$, and the sign of $ e$, including possible cancellations that allow $ ext{~}20$ GeV in some regions. The results have implications for invisible Higgs decays and inform future linear-collider studies that probe light-LSP MSSM scenarios.

Abstract

We discuss constraints on SUSY models with non-unified gaugino masses. We concentrate on the slepton/gaugino sector and obtain a lower limit on the neutralino mass combining direct limits, indirect limits as well as relic density measurements.

Figures (2)

• Figure 1: Lower limit on neutralino mass vs $r_{12}$ from $\Omega h^2$, direct LEP limits as well as $\delta a_\mu>-21(-3)\times10^{-10}$ for a) $\tan\beta=10,50$ and $\mu>0$ b) $\tan\beta=10,\mu<0$.
• Figure 2: Impact of the $\delta a_\mu=-21\times 10^{-10}$ constraint (crosses,dark grey) on the allowed region (circles,light grey) in the a) $M_0-M_2$ plane b) $m_\chi^+-m_{\tilde{\chi}_1^0}$ plane for $\mu<0,r_{12}=.1,\tan\beta=10$. Contours for $\delta a_\mu=-21,-11,-3\times 10^{-10}$ are displayed.