Abstract
We study the production of γ rays via LSP annihilations in the core of the Galaxy as a possible experimental signature of the constrained minimal supersymmetric extension of the Standard Model (CMSSM), in which supersymmetry-breaking parameters are assumed to be universal at the GUT scale, assuming also that the LSP is the lightest neutralino χ. The part of the CMSSM parameter space that is compatible with the measured astrophysical density of cold dark matter is known to include a {τ̃1}−χ coannihilation strip, a focus-point strip where χ has an enhanced Higgsino component, and a funnel at large tan β where the annihilation rate is enhanced by the poles of nearby heavy MSSM Higgs bosons, A/H. We calculate the total annihilation rates, the fractions of annihilations into different Standard Model final states and the resulting fluxes of γ rays for CMSSM scenarios along these strips. We observe that typical annihilation rates are much smaller in the coannihilation strip for tan β = 10 than along the focus-point strip or for tan β = 55, and that the annihilation branching ratios differ greatly between the different dark matter strips. Whereas the current Fermi-LAT data are not sensitive to any of the CMSSM scenarios studied, and the calculated γ-ray fluxes are probably unobservably low along the coannihilation strip for tan β = 10, we find that substantial portions of the focus-point strips and rapid-annihilation funnel regions could be pressured by several more years of Fermi-LAT data, if understanding of the astrophysical background and/or systematic uncertainties can be improved in parallel.
Highlights
Soon after the realization that the lightest supersymmetric particle (LSP), in particular the lightest neutralino χ, could naturally provide the astrophysical dark matter in models in which R-parity is conserved [1], it was suggested that LSP dark matter annihilations might be detectable via features in the γ-ray spectrum [2]
Connecting the accelerator and astroparticle experiments requires interpreting them within a common model framework, and in this paper we choose to compare their sensitivities within the framework of the CMSSM, assuming that R-parity is conserved and that the LSP is the lightest neutralino χ
In this paper we study the likely sensitivity of searches for γ rays from the galactic centre to LSP annihilations in the CMSSM, taking as examples the (m1/2, m0) planes shown in Fig. 1 and focusing on the dark blue WMAP strips, in particular
Summary
Soon after the realization that the lightest supersymmetric particle (LSP), in particular the lightest neutralino χ, could naturally provide the astrophysical dark matter in models in which R-parity is conserved [1], it was suggested that LSP dark matter annihilations might be detectable via features in the γ-ray spectrum [2]. Along the focus-point WMAP strip it is not possible to achieve the required amount of degeneracy between the LSP and lightest chargino and, on the other hand, along the stau coannihilation strip the effect of the Sommerfeld enhancement is known not to be important [42] The total S-wave annihilation cross section is much larger along the other WMAP strips shown, with typically σv ∼ (1 − 2) × 10−26 cm3/s 1 This difference immediately suggests that detecting dark matter annihilations will be easier along the funnel for tan β = 55 as well as the focus-point strip for tan β = 10, or for tan β = 55. We do not consider the possible effects due to the presence of a massive black hole, or any other source that might enhance the γ-ray flux arising from annihilations of neutralinos in the dark matter halo
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
