Inclusive search for a highly boosted Higgs boson decaying to a bottom quark-antiquark pair

TL;DR

This paper reports a search for a highly boosted Higgs boson decaying to bottom quarks using CMS data, employing jet substructure techniques, and observes the Z to b-bbar process in a single-jet topology for the first time.

Contribution

It introduces a novel inclusive method for detecting boosted Higgs bosons decaying to bottom quarks using jet substructure and b-tagging, validated with Z decays, and measures the production cross section consistent with the Standard Model.

Findings

First observation of Z→bar{b} in single-jet topology with 5.1σ significance.

Measured Higgs production cross section times branching ratio aligns with Standard Model predictions.

Evidence of Higgs boson decay at high transverse momentum with a 1.5σ local significance.

Abstract

An inclusive search for the standard model Higgs boson ($\mathrm{H}$) produced with large transverse momentum ($p_\mathrm{T}$) and decaying to a bottom quark-antiquark pair ($\mathrm{b}\overline{\mathrm{b}}$) is performed using a data set of pp collisions at $\sqrt{s}=$ 13 TeV collected with the CMS experiment at the LHC. The data sample corresponds to an integrated luminosity of 35.9 fb$^{-1}$. A highly Lorentz-boosted Higgs boson decaying to $\mathrm{b}\overline{\mathrm{b}}$ is reconstructed as a single, large radius jet and is identified using jet substructure and dedicated $\mathrm{b}$ tagging techniques. The method is validated with $\mathrm{Z}\to\mathrm{b}\overline{\mathrm{b}}$ decays. The $\mathrm{Z}\to\mathrm{b}\overline{\mathrm{b}}$ process is observed for the first time in the single-jet topology with a local significance of 5.1 standard deviations (5.8 expected). For a Higgs boson mass of 125 GeV, an excess of events above the expected background is observed (expected) with a local significance of 1.5 (0.7) standard deviations. The measured cross section times branching fraction for production via gluon fusion of $\mathrm{H} \rightarrow \mathrm{b}\overline{\mathrm{b}}$ with $p_\mathrm{T} > $450 GeV and in the pseudorapidity range $-$2.5 $< \eta <$ 2.5 is 74 $\pm$ 48 (stat) $_{-10}^{+17}$ (syst) fb, which is consistent within uncertainties with the standard model prediction.