Prospects for Higgs Boson Searches in the Channel WH -> lnbb

TL;DR

The paper evaluates the feasibility of observing the light Higgs in the WH associated production with H -> bb at the HL-LHC using CMS, emphasizing pile-up mitigation, b-tagging performance, and Higgs mass resolution. It demonstrates that with $L_{int}\approx300\,\mathrm{fb}^{-1}$ the SM Higgs discovery reach in this channel is limited to $m_H\lesssim123$ GeV, but the $WWH$ coupling can be measured to about 8–10% once backgrounds are controlled. In the MSSM, extrapolations show substantial parameter-space coverage at high luminosity, though some regions remain difficult. Overall, the channel provides valuable Higgs-coupling information and MSSM coverage, but requires very high integrated luminosity and robust reconstruction to be effective.

Abstract

We present a method how to detect the WH -> lnbb in the high luminosity LHC environment with the CMS detector. This study is performed with fast detector response simulation including high luminosity event pile up. The main aspects of reconstruction are pile up jet rejection, identification of b-jets and improvement of Higgs mass resolution. The detection potential in the SM for m(H) < 130 GeV and in the MSSM is only encouraging for high integrated luminosity. Nevertheless it is possible to extract important Higgs parameters which are useful to elucidate the nature of the Higgs sector. In combination with other channels, this channel provides valuable information on Higgs boson couplings.

Figures (8)

• Figure 1: $W^\pm H^0 \rightarrow l^\pm \nu b\bar{b}$ signal event at LO.
• Figure 2: $b$-tagging performances of $Z^0 \rightarrow jj$ events by FATSIM (bright) and CMSIM (dark). The tagging rates of $b$- and $u$-jets were determined with the following algorithm: 2 tracks in a cone of 0.4 around the jet ($E_T >$ 20 GeV, $|\eta| <$ 2.4) axis with $p_T >$ 0.9 GeV/c, min. 6 hits including 2 pixel hits (in the case of CMSIM) , $ip < 2$ mm and the signed transverse impact parameter significance $\sigma(ip) >$ 0.0 ... 4.5 (various cuts).
• Figure 3: Example of bunch crossing spread in z direction: 21 spikes indicate the primary $pp$ collision vertices due to one hard interaction (marked with a triangle) and twenty superimposed pile up events. The bin width of 250 $\mu m$ corresponds to ten times the resolution of the z coordinate of the primary vertex $V^0_Z$. The shaded area is a measure of the expected frequency distribution of primary vertices.
• Figure 4: $W^\pm H^0$ signal (white or dark shaded) plus resonant $W^\pm Z^0$ background (shaded) plus non resonant background (light shaded). The crosses are signal plus background with statistical error bars and are well above the background in the signal region. Simulated Higgs mass is $m_{H^0} =$ 115 $GeV/c^2$ with $L_{int} =$ 300 $fb^{-1}$.
• Figure 5: Left: signal plus background after subtraction of non resonant background. The simulated data points are fitted with two Gaussians. Right: signal plus background after subtraction of all backgrounds. The simulated data points are fitted with a Gaussian which describes the pure $W^\pm H^0$ signal (shaded) well.