Orateur
Description
Summary
In summary, we have shown that generally large Electroweak scalar multiplet with half-integer isospin provides larger Sommerfeld enhanced dark matter (DM) annihilation cross section to WW, ZZ, $\gamma\gamma$ and $\gamma Z$ compared to scalar doublet. We have also shown that the Sommerfeld enhancement can be reduced by increasing the mass splitting between DM state and other charged scalars of the multiplet where maximal splitting is allowed by the Electroweak Precision constraints. Therefore, Large scalar multiplet in the scotogenic model can have suppressed annihilation rate in contrast to the case of minimal dark matter model. Moreover, we have pointed out that large off-diagonal potential matrix element due to group theoretical factor associated with the multiplet leads to the suppression (resonance dips) for S-wave DM-DM annihilation cross section for certain mass of the DM. We have illustrated it in detail with two-level system of square-well potential. Finally, by comparing the calculated annihilation cross sections with current bounds from H.E.S.S. and future sensitivity limits of CTA, we point out that large scalar multiplets of the scotogenic model are more likely to be constraints by the current and upcoming Imaging Atmospheric Cherenkov Telescope observatories.
