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$h^0\to W^+W^-\ra \ell^+\ell^{'-}ν_\ell{\bar ν}_{\ell'}$ as the Dominant SM Higgs Search Mode at the LHC for $M_{h^0}$= 155-180 GeV

Michael Dittmar, Herbi Dreiner

TL;DR

The paper argues that for mh in the 155–180 GeV range, the h^0 → W^+W^- → l^+ l^- ν ν decay channel offers superior sensitivity to the SM Higgs compared to ZZ* channels. It employs a detailed, detector-level simulation with novel cuts exploiting the WW system's boost and spin correlations to suppress the irreducible WW background. The results show a pronounced mass-sensitive peak and achieve high signal significance, enabling a potential mh determination with about ±5 GeV precision using only 5 fb^-1. This approach effectively fills the early-LHC luminosity gap and provides a robust path to discovery in this Higgs mass window.

Abstract

We show that the Standard Model Higgs decay $h^0 \to W^+W ^- \to l^+ l^- ν{\barν}$ is the most sensitive mode for SM Higgs searches in the range 155-180 GeV. The previously considered mode $h^0 \to Z^0 Z^{0*} \to l^+ l^- l^+l^-$ has a significantly lower search sensitivity. We place particular emphasis on two new cuts based on (i) the boost and (ii) the spin-correlation of the $W^+W^-$-system. The distribution we obtain from our combined cuts shows a mass sensitive peak which probably allows a mass determination to $\pm$ 5 GeV for 5 fb^{-1}. This contribution complements our earlier published paper.

$h^0\to W^+W^-\ra \ell^+\ell^{'-}ν_\ell{\bar ν}_{\ell'}$ as the Dominant SM Higgs Search Mode at the LHC for $M_{h^0}$= 155-180 GeV

TL;DR

The paper argues that for mh in the 155–180 GeV range, the h^0 → W^+W^- → l^+ l^- ν ν decay channel offers superior sensitivity to the SM Higgs compared to ZZ* channels. It employs a detailed, detector-level simulation with novel cuts exploiting the WW system's boost and spin correlations to suppress the irreducible WW background. The results show a pronounced mass-sensitive peak and achieve high signal significance, enabling a potential mh determination with about ±5 GeV precision using only 5 fb^-1. This approach effectively fills the early-LHC luminosity gap and provides a robust path to discovery in this Higgs mass window.

Abstract

We show that the Standard Model Higgs decay is the most sensitive mode for SM Higgs searches in the range 155-180 GeV. The previously considered mode has a significantly lower search sensitivity. We place particular emphasis on two new cuts based on (i) the boost and (ii) the spin-correlation of the -system. The distribution we obtain from our combined cuts shows a mass sensitive peak which probably allows a mass determination to 5 GeV for 5 fb^{-1}. This contribution complements our earlier published paper.

Paper Structure

This paper contains 7 sections, 5 equations, 6 figures.

Table of Contents

  1. Introduction
  2. Separating the Signal from the Continuum $WW$ Background
  3. Boost of the $W^+W^-$-System
  4. Spin Correlation of the $W^+W^--$System
  5. Remaining Cuts
  6. Conclusion
  7. References

Figures (6)

  • Figure 1: MRRSmrrs structure functions scaled by $x$. $g(x)$ is scaled by $x/10$.
  • Figure 2: Product of the structure functions as a function of $x_1$ for fixed $x_1\cdot x_2=10^{-4}$.
  • Figure 3: Monte Carlo generated distribution of the signal (shaded histogram) and background $WW$ rapidity distributions.
  • Figure 4: Invariant mass distribution for $W$ boson pair production from $q{\bar{q}}$ annihilation at the LHC. L (longitudinal) and T (transverse) refer to the polarization of the $W$ bosons. The differential cross section in Refscott was used.
  • Figure 5: Signal (shaded histogram) and background distribution of events in $\cos\theta_{\ell^+\ell^-}$ for $5\,fb^{-1}$ integrated luminosity.
  • ...and 1 more figures