Constraints on light dark matter particles using white dwarf stars

We report constraints on the nucleon-dark matter particle cross section using the internal luminosity of observed white dwarf stars in the globular cluster Messier 4. Our results cover the parameter space corresponding to relatively light dark matter particles, in the mass range $0.1~GeV-5~GeV$, which is known to be very difficult to be probed by direct dark matter searches. The additional luminosity coming from self-annihilations of dark matter particles captured inside the stars must not exceed the observed luminosity. Imposing that condition, we obtain for the spin independent cross section of light dark matter particles on baryons $\sigma_{N\chi}$ the upper bound: $\sigma_{N\chi} < 4 \times 10^{-41}{\rm cm^2}$.