A High Level Trigger Selection of WH->mu nu b b-bar using the Tracker and b-jets

This note describes the use of the CMS Tracker to select Higgs decays into bjet pairs. The channel under study is the associate production of a Higgs and a W boson, followed by the decay into mu nu b b-bar. This final state can be triggered on low luminosity conditions. A fast algorithm has been developed to be used at high-level trigger. Starting from muon and calorimetric hardware-based Level-1 trigger, events with muons with P_T>15 GeV/c and jets with E_T>20 GeV are selected in the central pseudorapidity region. Tracks are reconstructed within the Tracker using a regional approach. An isolated muon is then searched for using the Tracker alone. The initial Level-1 trigger rate (340+-20 Hz) can be lowered to 1.6+-0.5 Hz by applying btagging criteria to the jets in the event. The signal selection efficiency for a 115 GeV/c^2 Higgs mass is 13%, corresponding to 340+-22 events per year at 2x10^33 cm^-2s^-1 luminosity. The response time of the software trigger described here is about 350 ms.