Probing the Dark Sector with Dark Matter Bound States

A model of the dark sector where $O(\text{few}\text{ }\text{ }\mathrm{GeV})$ mass dark matter particles $\ensuremath{\chi}$ couple to a lighter dark force mediator $V$, ${m}_{V}\ensuremath{\ll}{m}_{\ensuremath{\chi}}$, is motivated by the recently discovered mismatch between simulated and observed shapes of galactic halos. Such models, in general, provide a challenge for direct detection efforts and collider searches. We show that for a large range of coupling constants and masses, the production and decay of the bound states of $\ensuremath{\chi}$, such as ${0}^{\ensuremath{-}+}$ and ${1}^{\ensuremath{-}\ensuremath{-}}$ states, ${\ensuremath{\eta}}_{D}$ and ${\mathrm{\ensuremath{\Upsilon}}}_{D}$, is an important search channel. We show that ${e}^{+}{e}^{\ensuremath{-}}\ensuremath{\rightarrow}{\ensuremath{\eta}}_{D}+V$ or ${\mathrm{\ensuremath{\Upsilon}}}_{D}+\ensuremath{\gamma}$ production at $B$ factories for ${\ensuremath{\alpha}}_{D}>0.1$ is sufficiently strong to result in multiple pairs of charged leptons and pions via ${\ensuremath{\eta}}_{D}\ensuremath{\rightarrow}2V\ensuremath{\rightarrow}2({l}^{+}{l}^{\ensuremath{-}})$ and ${\mathrm{\ensuremath{\Upsilon}}}_{D}\ensuremath{\rightarrow}3V\ensuremath{\rightarrow}3({l}^{+}{l}^{\ensuremath{-}})$ $(l=e,\ensuremath{\mu},\ensuremath{\pi})$. The absence of such final states in the existing searches performed at BABAR and Belle sets new constraints on the parameter space of the model. We also show that a search for multiple bremsstrahlung of dark force mediators, ${e}^{+}{e}^{\ensuremath{-}}\ensuremath{\rightarrow}\ensuremath{\chi}\overline{\ensuremath{\chi}}+nV$, resulting in missing energy and multiple leptons, will further improve the sensitivity to self-interacting dark matter.

Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.