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Soumya Rao

Publications and source records attributed to Soumya Rao.

20 records · Page 2Linked to original sources

A simple model for magnetic inelastic dark matter (MiDM)

A simple model for magnetic inelastic dark matter (MiDM), which is a minimal extension of the standard model with right-handed neutrinos ($N_R$), a singly charged scalar ($S$) and a vector-like charged fermion ($E$), has been presented. In this framework in which dark matter inelastically scatters off nuclei through a magnetic dipole interaction by making a transition to a nearly degenerate state with a mass splitting ($δ$) of 100 keV. The model is constrained from Direct detection experiments, DAMA and COGENT. In our analysis we do not find any parameter space using the recent annual modulation data from COGENT, where DAMA and COGENT are consistent with each other. The bound from relic density provides a much stronger constraint. We find that this minimal extension of SM incorporates a DM candidate which can explain the indirect detection results while being consistent with relic density measurements. The right handed neutrino and the charged particles responsible for the right-handed neutrino magnetic moments could be produced at the Large Hadron Collider.

hep-ph↗

Dipolar Dark Matter

If dark matter (DM) has non-zero direct or transition, electric or magnetic dipole moment then it can scatter nucleons electromagnetically in direct detection experiments. Using the results from experiments like XENON, CDMS, DAMA and COGENT we put bounds on the electric and magnetic dipole moments of DM. If DM consists of Dirac fermions with direct dipole moments, then DM of mass less than 10 GeV is consistent with the DAMA signal and with null results of other experiments. If on the other hand DM consists of Majorana fermions then they can have only non-zero transition moments between different mass eigenstates. We find that Majorana fermions with mass m_χ> 38 GeV and mass splitting of the order of (50-200) keV can explain the DAMA signal and the null observations from other experiments and in addition give the observed relic density of DM by dipole-mediated annihilation. This parameter space for the mass and for dipole moments is allowed by limits from L3 but may have observable signals at LHC.

hep-ph↗