Intermediate-Mass Higgs Searches in Weak Boson Fusion

Abstract

Weak boson fusion is a copious source of intermediate mass Higgs bosons at the LHC. The additional very energetic forward jets in these events are powerful background suppression tools. I analyze the decays H -> gamma gamma and H -> W^(*)W^(*) -> e mu pTmiss, with the latter a potential discovery channel, and the decay H -> tau tau -> lep had pTmiss as a method for achieving the first direct measurement of a Higgs-fermion coupling. I perform parton level analyses of the signal and dominant backgrounds for each decay mode, and demonstrate kinematic cuts and other important tools neccessary to achieve an S/B > 1/1 rate in all cases. I also perform cross section calculations with additional gluon emission which provide an estimate of a minijet veto probability. I show that a 5 sigma H -> gamma gamma observation can be made for 110 GeV < M_H < 150 GeV with modest luminosity, order 40-50 fb^-1, overlapping the region explored by the CERN LEP and Fermilab Tevatron. For 130 GeV < M_H < 200 GeV, I show that H -> WW can achieve a 5 sigma observation with S/B much greater than 1/1 with extremely low luminosity, about 2-10 fb^-1 over almost the entire range. This is the most promising search channel in the 130-200 GeV mass range. It overlaps the H -> gamma gamma region and nicely complements the H -> WW measurement that can be made with very low luminosity in inclusive gg -> H production. I further show that a Higgs-fermion coupling can be directly measured via the H -> tau tau decay with only about 60 fb^-1.