Electroweak bremsstrahlung in bino-like dark matter annihilations

Understand

We investigate the effects of electroweak bremsstrahlung on bino-like neutralino dark matter pair annihilations in the minimal supersymmetric standard model (MSSM).

• We calculate the nonrelativistic pair annihilation cross sections via $W$-strahlung from leptonic final states, $\chi\chi$ $\to$ $W\ell\bar{\nu}$, and compare them with the contributions of the relevant two-body final states.
• We explore the case that sleptons lie below the TeV scale, while squarks are extremely heavy.
• It is found that the electroweak bremsstrahlung can give a dominant contribution to the cross section for some parameter regions which include slepton coannihilation regions with the observed relic abundance.