[Paper Review] Measurements of inclusive and differential cross sections for the Higgs boson production and decay to four-leptons in proton-proton collisions at $ \sqrt{s} $ = 13 TeV

Hayrapetyan, Aram, Tumasyan, Armen+2318 more|arXiv (Cornell University)|Jan 1, 2023

Particle physics theoretical and experimental studies2 citations

TL;DR

This paper presents the most precise measurements to date of the inclusive and differential fiducial cross sections for Higgs boson production in the H →ZZ →4ℓ decay channel using 138 fb⁻¹ of proton-proton collision data at √s = 13 TeV collected by the CMS experiment at the LHC. The measured inclusive fiducial cross section of 2.73 ± 0.26 fb agrees with the Standard Model prediction of 2.86 ± 0.1 fb, and differential distributions are used to constrain the Higgs boson trilinear self-coupling and coupling modifiers to bottom and charm quarks.

ABSTRACT

Measurements of the inclusive and differential fiducial cross sections for the Higgs boson production in the H $ o$ ZZ $ o$ 4$\ell$ ($\ell$ = e,$\mu$) decay channel are presented. The results are obtained from the analysis of proton-proton collision data recorded by the CMS experiment at the CERN LHC at a center-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 138 fb$^{-1}$. The measured inclusive fiducial cross section is 2.73$\pm$0.26 fb, in agreement with the standard model expectation of 2.86$\pm$0.1 fb. Differential cross sections are measured as a function of several kinematic observables sensitive to the Higgs boson production and decay to four leptons. A set of double-differential measurements is also performed, yielding a comprehensive characterization of the four leptons final state. Constraints on the Higgs boson trilinear coupling and on the bottom and charm quark coupling modifiers are derived from its transverse momentum distribution. All results are consistent with theoretical predictions from the standard model.

Motivation & Objective

• To measure the inclusive and differential fiducial cross sections for Higgs boson production in the H →ZZ →4ℓ decay channel using 138 fb⁻¹ of 13 TeV proton-proton collision data.
• To provide a model-independent characterization of the Higgs boson production and decay in the four-lepton final state by unfolding detector effects.
• To constrain the Higgs boson trilinear self-coupling and coupling modifiers to bottom and charm quarks using the transverse momentum distribution of the Higgs boson.
• To test the Standard Model predictions with high precision using fiducial cross sections in multiple kinematic observables and double-differential measurements.

Proposed method

• The analysis uses data from the CMS detector at the CERN LHC during 2016–2018, corresponding to 138 fb⁻¹ of integrated luminosity at √s = 13 TeV.
• Fiducial cross sections are measured within a phase space region closely matching experimental acceptance and reconstruction-level selection criteria to reduce model dependence.
• Kinematic observables such as the Higgs boson transverse momentum (pH_T), invariant mass of the four-lepton system, and angular distributions are used to measure differential cross sections.
• Double-differential cross sections are measured in bins of multiple kinematic variables to comprehensively characterize the four-lepton final state.
• Matrix element kinematic discriminants are used to probe potential anomalous couplings of the Higgs boson to vector bosons.
• Constraints on the Higgs trilinear self-coupling and coupling modifiers to b and c quarks are derived from the pT distribution of the Higgs boson, using a method complementary to the STXS framework.

Experimental results

Research questions

• RQ1 What is the inclusive fiducial cross section for Higgs boson production in the H →ZZ →4ℓ decay channel at 13 TeV?
• RQ2 How do the differential cross sections vary as functions of key kinematic observables such as Higgs boson transverse momentum and four-lepton invariant mass?
• RQ3 To what extent do the measured distributions constrain the Higgs boson trilinear self-coupling and its couplings to bottom and charm quarks?
• RQ4 Are the observed cross sections consistent with Standard Model predictions across the full fiducial phase space, including double-differential distributions?
• RQ5 Can the data reveal deviations indicative of new physics beyond the Standard Model through anomalous coupling probes?

Key findings

• The measured inclusive fiducial cross section is 2.73 ± 0.26 fb, in excellent agreement with the Standard Model prediction of 2.86 ± 0.1 fb.
• Differential cross sections are measured as functions of the Higgs boson transverse momentum (pH_T), four-lepton invariant mass, and other kinematic variables, providing a comprehensive characterization of the final state.
• Six double-differential cross sections are measured, offering enhanced sensitivity to the underlying physics and improved resolution of the Higgs boson production dynamics.
• Constraints on the Higgs boson trilinear self-coupling and coupling modifiers for bottom and charm quarks are derived from the pH_T distribution, with results consistent with Standard Model expectations.
• All measurements, including those sensitive to anomalous couplings via matrix element discriminants, are consistent with Standard Model predictions.
• The analysis achieves a ∼40% reduction in the leading systematic uncertainty related to lepton reconstruction and selection efficiencies compared to previous measurements.