Solar constraints on asymmetric dark matter
The dark matter content of the Universe is likely to be a mixture of matter and antimatter, perhaps comparable to the measured asymmetric mixture of baryons and antibaryons. During the early stages of the Universe, the dark matter particles are produced in a process similar to baryogenesis, and dark matter freeze-out depends on the dark matter asymmetry and the annihilation cross section (s-wave and p-wave annihilation channels). In these η-parametrised asymmetric dark matter models (η-ADM), the dark matter particles have an annihilation cross section close to the weak interaction cross section, and a value of η-dark matter asymmetry close to the baryon asymmetry η_B. Furthermore, we assume that dark matter scattering of baryons, namely, the spin-independent scattering cross section, is of the same order as the range of values suggested by several theoretical particle physics models used to explain the current unexplained events reported in the DAMA/LIBRA, CoGeNT and CRESST experiments. Here, we constrain η-ADM models by investigating the impact of such a type of dark matter on the evolution of the Sun, namely, the flux of solar neutrinos and helioseismology. We find that dark matter particles with a mass smaller than 15 GeV, a spin-independent scattering cross section on baryons of the order of a picobarn, and an η-dark matter asymmetry with a value in the interval 10^{-12}-10^{-10}, would induce a change in solar neutrino fluxes in disagreement with current neutrino flux measurements. A natural consequence of this model is suppressed annihilation, thereby reducing the tension between indirect and direct dark matter detection experiments, but the model also allows a greatly enhanced annihilation cross section. All the cosmological η-asymmetric dark matter scenarios that we discuss are in agreement with the current WMAP measured values.