A model of the dark sector where O(few GeV) mass dark matter particles χ couple to a lighter dark force mediator V, mVmχ, 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 χ, such as 0-+ and 1 - states, ηD and D, is an important search channel. We show that e+e-→ηD+V or D+γ production at B factories for αD>0.1 is sufficiently strong to result in multiple pairs of charged leptons and pions via ηD→2V→2(l+l-) and D→3V→3(l+l-) (l=e,μ,π). 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-→χχ+nV, resulting in missing energy and multiple leptons, will further improve the sensitivity to self-interacting dark matter.
Bibliographical noteFunding Information:
We would like to thank Clifford Cheung, Ying Fan, Ming Liu, Mark Wise, and Hai-bo Yu for useful discussions. H. A. is supported by the Walter Burke Institute at Caltech and by DOE Grant No. de-sc0011632. B. E. is supported by the U.S. Department of Energy (DOE) under Grants No. DE-FG02-92ER40701 and No. DE-SC0011925. The work of M. P. is supported in part by NSERC, Canada, and research at the Perimeter Institute is supported in part by the Government of Canada through NSERC and by the Province of Ontario through MEDT. Y. Z. is supported by the Gordon and Betty Moore Foundation through Grant No. 776 to the Caltech Moore Center for Theoretical Cosmology and Physics, and by the DOE Grant No. DE-FG02-92ER40701, and also by a DOE Early Career Award under Grant No. DE-SC0010255. H. A., M. P., and Y. Z. acknowledge the hospitality from the Aspen Center for Physics and the support from NSF Grant No. PHY-1066293.
© 2016 American Physical Society.