Level 1 b-tagging Trigger Proposal for CMS

A study of $b$-tagging in CMS Level-1 triggers by simulated data is presented. Two muon momentum cuts, loose and tight, are proposed, which give a Level-1 $b$-tagging efficiency of 7.9\% for jet $|\eta|<2.5$, and 7.3\% for jet $|\eta|<2.0$ respectively. For an instantaneous luminosity of $L=2 \times 10^{33}$ cm$^{-2}$s$^{-1}$and the jet $p_T$ cut of 20 GeV jet pT cut 20GeV, we obtain an integrated background rate 3.8kHz for tight cut, and 5.7kHz for loose, which is a hundred times lower than 210kHz rate of a non-b-tag L1 trigger with the same jet threshold. The proposed trigger is now under consideration by the CMS collaboration.