Intermediate-Mass Higgs Searches in Weak Boson Fusion

TL;DR

This paper analyzes weak boson fusion at the LHC for intermediate-mass Higgs bosons, demonstrating promising detection channels and the potential for direct Higgs-fermion coupling measurement with specific decay modes and luminosities.

Contribution

It provides detailed parton level analyses and kinematic strategies for Higgs detection in weak boson fusion, including estimates of signal significance and background suppression techniques.

Findings

5 sigma detection for H -> gamma gamma at 110-150 GeV with 40-50 fb^-1

H -> WW channel achieves 5 sigma detection at 130-200 GeV with 2-10 fb^-1

Direct measurement of Higgs-fermion coupling via H -> tau tau with 60 fb^-1

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.