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Search for the standard model Higgs boson decaying to bottom quarks in pp collisions at sqrt(s) = 7 TeV

CMS Collaboration

TL;DR

This study targets the SM Higgs boson in VH production with $H\to b\bar{b}$, using $L=4.7\,\mathrm{fb}^{-1}$ of data from $pp$ collisions at $\sqrt{s}=7$ TeV collected by CMS. The analysis employs five VH channels and a boosted-decision-tree discriminator, complemented by a cross-check using the $m(\mathrm{jj})$ distribution, to extract a potential signal from large SM backgrounds such as $V+$jets, $t\bar{t}$, dibosons, and QCD multijet processes. No significant excess is observed, and 95% CL upper limits are set on $\sigma(pp\to VH)\times\mathcal{B}(H\to b\bar{b})$ for $m_H=110$–$135$ GeV, with observed limits ranging from approximately $3.4$ to $7.5$ times the SM expectation and expected limits from $2.7$ to $6.7$; the $BDT$-based VH search provides the primary sensitivity. These results constitute the first LHC upper limits in these VH channels for $H\to b\bar{b}$, underpinning progress toward measuring the Higgs coupling to bottom quarks. The methodology integrates data-driven background control, precise jet $b$-tagging, and boosted kinematic selections to mitigate challenging QCD backgrounds in the low-mass Higgs region.

Abstract

A search for the standard model Higgs boson (H) decaying to a b-quark pair when produced in association with weak vector bosons (V) is reported for the following modes: W(mu,nu)H, W(e,nu)H, Z(mu,mu)H, Z(e,e)H and Z(nu,nu)H. The search is performed in a data sample corresponding to an integrated luminosity of 4.7 inverse femtobarns, recorded by the CMS detector in proton-proton collisions at the LHC with a center-of-mass energy of 7 TeV. No significant excess of events above the expectation from background is observed. Upper limits on the VH production cross section times the H to b-quark pair branching ratio, with respect to the expectations for a standard model Higgs boson, are derived for a Higgs boson in the mass range 110-135 GeV. In this range, the observed 95% confidence level upper limits vary from 3.4 to 7.5 times the standard model prediction; the corresponding expected limits vary from 2.7 to 6.7.

Search for the standard model Higgs boson decaying to bottom quarks in pp collisions at sqrt(s) = 7 TeV

TL;DR

This study targets the SM Higgs boson in VH production with , using of data from collisions at TeV collected by CMS. The analysis employs five VH channels and a boosted-decision-tree discriminator, complemented by a cross-check using the distribution, to extract a potential signal from large SM backgrounds such as jets, , dibosons, and QCD multijet processes. No significant excess is observed, and 95% CL upper limits are set on for – GeV, with observed limits ranging from approximately to times the SM expectation and expected limits from to ; the -based VH search provides the primary sensitivity. These results constitute the first LHC upper limits in these VH channels for , underpinning progress toward measuring the Higgs coupling to bottom quarks. The methodology integrates data-driven background control, precise jet -tagging, and boosted kinematic selections to mitigate challenging QCD backgrounds in the low-mass Higgs region.

Abstract

A search for the standard model Higgs boson (H) decaying to a b-quark pair when produced in association with weak vector bosons (V) is reported for the following modes: W(mu,nu)H, W(e,nu)H, Z(mu,mu)H, Z(e,e)H and Z(nu,nu)H. The search is performed in a data sample corresponding to an integrated luminosity of 4.7 inverse femtobarns, recorded by the CMS detector in proton-proton collisions at the LHC with a center-of-mass energy of 7 TeV. No significant excess of events above the expectation from background is observed. Upper limits on the VH production cross section times the H to b-quark pair branching ratio, with respect to the expectations for a standard model Higgs boson, are derived for a Higgs boson in the mass range 110-135 GeV. In this range, the observed 95% confidence level upper limits vary from 3.4 to 7.5 times the standard model prediction; the corresponding expected limits vary from 2.7 to 6.7.

Paper Structure

This paper contains 12 sections, 3 figures, 4 tables.

Table of Contents

  1. Introduction
  2. CMS Detector and Simulations
  3. Triggers and Event Reconstruction
  4. Triggers
  5. Event reconstruction
  6. Event Selection
  7. Background Control Regions
  8. Yield Uncertainties
  9. Results
  10. Summary
  11. Acknowledgements
  12. The CMS Collaboration

Figures (3)

  • Figure 1: Distributions of the bdt output, for $m_{H}\xspace$=115$\,\text{Ge\spaceV}$, for each mode after all selection criteria are applied. The solid histograms for the backgrounds and the signal are summed cumulatively. The line histogram for signal is also shown superimposed. The data is represented by points with error bars.
  • Figure 2: Dijet invariant mass distribution, combined for all channels, for events that pass the $m(\mathrm{jj})$ analysis selection. The solid histograms for the backgrounds and the signal are summed cumulatively. The line histogram for signal and for $V$$V$ backgrounds are also shown superimposed. The data is represented by points with error bars.
  • Figure 3: Expected and observed $95\%$ CL upper limits on the product of the $V{H}\xspace$ production cross section times the ${H}\xspace\to {b}\overline{{b}}\xspace$ branching ratio, with respect to the expectations for a standard model Higgs boson, for the bdt analysis.