Missing particle associated with two bottom quarks at the LHC: Mono-b versus 2b with razor variables

摘要

The extended Higgs sector, such as by a second Higgs doublet of type Ⅱ, provides portals to the dark sector which contain missing particles at the LHC, e.g., dark matter particles. In this paper, working in the simplified model and taking into consideration the wide decay-width effect of the mediator, we analyze the characteristic signatures of mono-b + MET and 2b + MET at the LHC. The latter signature was believed to be ineffective, while we found that, with the aid of razor shape analysis, it should be as important as the mono-b signature. In the region of relatively low mediator mass (below a few hundred GeV), by requiring a signal-to-background ratio greater than a few percent, the 2b-tagged razor analysis has comparable sensitivity to the mono-b search, it is even better for a mediator lighter than ～200 GeV.