Light Neutralinos with Large Scattering Cross Sections in the Minimal Supersymmetric Standard Model

TL;DR

This paper examines collider constraints on light neutralino dark matter in the MSSM, highlighting how certain Higgs and charged Higgs properties influence direct detection signals and rare decay processes.

Contribution

It identifies the parameter space where light neutralinos with large scattering cross sections are consistent with collider and decay constraints.

Findings

Cross sections below 2 x 10^-41 cm^2 are compatible with constraints.

A slight local dark matter over-density may explain CoGeNT excess.

Light charged Higgs impacts rare decay processes.

Abstract

Motivated by recent data from CoGeNT and the DAMA annual modulation signal, we discuss collider constraints on MSSM neutralino dark matter with mass in the 5-15 GeV range. Such an LSP would be a Bino with a small Higgsino admixture. Maximization of the DM-nucleon scattering cross section for such a WIMP requires a light Higgs boson with tan beta enhanced couplings. Limits on the invisible width of the Z boson, when combined with Tevatron constraints on Higgs bosons at large tan beta, and the rare decay $B^{\pm} \to \tau \nu$ constrain cross sections to be below $\sigma_n \lesssim 2 \times 10^{-41} {cm}^2$. This indicates a slight local Dark Matter over-density would be necessary to explain the CoGeNT excess. This scenario also requires a light charged Higgs boson, which can give substantial contributions to rare decays such as $b \to s \gamma$ and $t \to b H^+$.