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Prospects for the Search for a Standard Model Higgs Boson in ATLAS using Vector Boson Fusion

S. Asai, G. Azuelos, C. Buttar, V. Cavasinni, D. Costanzo, K. Cranmer, R. Harper, K. Jakobs, J. Kanzaki, M. Klute, R. Mazini, B. Mellado, W. Quayle, E. Richter-Was, T. Takemoto, I. Vivarelli, Sau Lan Wu

TL;DR

The study evaluates ATLAS's potential to discover a Standard Model Higgs via vector boson fusion, focusing on the H→WW(*) and H→ττ decay modes in the low-to-intermediate mass range. By employing forward jet tagging and central jet veto, it demonstrates significant background suppression and robust discovery prospects, especially in the H→WW(*) channel, with complementary sensitivity in H→ττ around 120 GeV. Using realistic detector simulations and detailed background modeling (tt̄, Wt, WW+jets, Z/γ*+jets, ττ, ZZ, etc.), the work shows that, with integrated luminosities as low as 10–30 fb⁻¹, ATLAS could achieve 5σ discovery coverage across substantial portions of the mass range, and that combining VBF channels with other production modes extends reach down to near 120 GeV. The results emphasize the complementary nature of VBF channels, their relative resilience to systematics, and their crucial role in Higgs coupling measurements and non-standard-model sensitivity.

Abstract

The potential for the discovery of a Standard Model Higgs boson in the mass range m_H < 2 m_Z in the vector boson fusion mode has been studied for the ATLAS experiment at the LHC. The characteristic signatures of additional jets in the forward regions of the detector and of low jet activity in the central region allow for an efficient background rejection. Analyses for the H -> WW and H -> tau tau decay modes have been performed using a realistic simulation of the expected detector performance. The results obtained demonstrate the large discovery potential in the H -> WW decay channel and the sensitivity to Higgs boson decays into tau-pairs in the low-mass region around 120 GeV.

Prospects for the Search for a Standard Model Higgs Boson in ATLAS using Vector Boson Fusion

TL;DR

The study evaluates ATLAS's potential to discover a Standard Model Higgs via vector boson fusion, focusing on the H→WW(*) and H→ττ decay modes in the low-to-intermediate mass range. By employing forward jet tagging and central jet veto, it demonstrates significant background suppression and robust discovery prospects, especially in the H→WW(*) channel, with complementary sensitivity in H→ττ around 120 GeV. Using realistic detector simulations and detailed background modeling (tt̄, Wt, WW+jets, Z/γ*+jets, ττ, ZZ, etc.), the work shows that, with integrated luminosities as low as 10–30 fb⁻¹, ATLAS could achieve 5σ discovery coverage across substantial portions of the mass range, and that combining VBF channels with other production modes extends reach down to near 120 GeV. The results emphasize the complementary nature of VBF channels, their relative resilience to systematics, and their crucial role in Higgs coupling measurements and non-standard-model sensitivity.

Abstract

The potential for the discovery of a Standard Model Higgs boson in the mass range m_H < 2 m_Z in the vector boson fusion mode has been studied for the ATLAS experiment at the LHC. The characteristic signatures of additional jets in the forward regions of the detector and of low jet activity in the central region allow for an efficient background rejection. Analyses for the H -> WW and H -> tau tau decay modes have been performed using a realistic simulation of the expected detector performance. The results obtained demonstrate the large discovery potential in the H -> WW decay channel and the sensitivity to Higgs boson decays into tau-pairs in the low-mass region around 120 GeV.

Paper Structure

This paper contains 11 sections, 2 figures, 2 tables.

Table of Contents

  1. Introduction
  2. Signal and Backgrounds
  3. Experimental Issues
  4. Trigger aspects
  5. Lepton Identification
  6. Jet Tagging
  7. Jet-Veto Efficiencies
  8. Signal Selection Criteria
  9. The $H \rightarrow W W^{(*)}$ decay mode
  10. Di-lepton final states: $\hbox{$H \rightarrow W W^{(*)} \rightarrow \ell \nu \ell \nu$}$
  11. Event selection

Figures (2)

  • Figure 1: a) Pseudorapidity distribution of the tag jets in signal events with $m_H = 160$${\rm{GeV/}c^2}$ and for $t \overline{t}$ background events. The full histograms show the distributions at parton level, the dots represent the reconstructed distributions, after the tagging algorithm has been applied. The corresponding distributions for jets identified as tag jets in $t \overline{t}$ events are superimposed as dashed histograms. All distributions are normalized to unity. b) Separation $\Delta \eta$ between the tag jets for the same types of events.
  • Figure 2: a) Efficiency for reconstructing a tag jet with $\hbox{$P_T$} > 20$${\rm{GeV/}c}$ which originates from a parton with $\hbox{$P_T$} > 20$${\rm{GeV/}c}$ as a function of pseudorapidity $\eta$ of the parton. b) Probability for finding at least one jet from pileup events in central rapidity intervals in the ATLAS detector as a function of the $P_T$ value used in the jet definition. The dashed curves connect the points for pseudorapidity itervals $| \eta |<$1.5 and $| \eta |<$3.0 for low and high LHC luminosities.