Measurements of properties of the Higgs boson decaying into the four-lepton final state in pp collisions at sqrt(s) = 13 TeV

Abstract: Properties of the Higgs boson are measured in the H to ZZ to 4l (l= e, mu) decay channel. A data sample of proton-proton collisions at sqrt(s) = 13 TeV, collected with the CMS detector at the LHC and corresponding to an integrated luminosity of 35.9 inverse femtobarns is used. The signal strength modifier mu, defined as the ratio of the observed Higgs boson rate in the H to ZZ to 4l decay channel to the standard model expectation, is measured to be mu = 1.05 +0.19/-0.17 at m[H ]= 125.09 GeV, the combined ATLAS and CMS measurement of the Higgs boson mass. The signal strength modifiers for the individual Higgs boson production modes are also measured. The cross section in the fiducial phase space defined by the requirements on lepton kinematics and event topology is measured to be 2.92 +0.48/-0.44 (stat) +0.28/-0.24 (syst) fb, which is compatible with the standard model prediction of 2.76 +/- 0.14 fb. Differential cross sections are reported as a function of the transverse momentum of the Higgs boson, the number of associated jets, and the transverse momentum of the leading associated jet. The Higgs boson mass is measured to be m[H] = 125.26 +/- 0.21 GeV and the width is constrained using on-shell production to be Gamma[H] < 1.10 GeV, at 95% confidence level.

• The paper reports a precise measurement of the signal strength modifier (μ = 1.05) with uncertainties that confirm Standard Model expectations.
• The analysis determines the fiducial cross section to be 2.92 fb and provides differential distributions in transverse momentum and associated jets.
• The study constrains the Higgs boson mass to 125.26 GeV and its width to below 1.10 GeV at 95% confidence, highlighting high experimental precision.

Overview of the Measurements of Higgs Boson Properties in the Four-Lepton Final State at CMS

The paper presents an analysis conducted by the CMS collaboration focusing on the properties of the Higgs boson, particularly its decay into a four-lepton final state. This analysis utilizes data from proton-proton collisions at a center-of-mass energy of 13 TeV, collected during Run 2 of the LHC, corresponding to an integrated luminosity of 35.9 fb$^{-1}$.

Key Findings

• Signal Strength Modifier: The paper reports a measurement of the signal strength modifier $\mu$ for the $\PH\to\Z\Z\to4\ell$ decay channel, found to be $\mu = 1.05^{+0.19}_{-0.17}$, which is close to the Standard Model (SM) expectation. This includes both statistical and systematic uncertainties, suggesting that the observed Higgs boson production rate is consistent with the SM predictions.
• Cross Section Measurement: The fiducial cross section of the Higgs boson is measured to be $2.92^{+0.48}_{-0.44}$ (stat.) $^{+0.28}_{-0.24}$ (syst.) fb, aligning well with the SM prediction of $2.76\pm0.14$ fb. The analysis includes differential cross sections related to the Higgs boson's transverse momentum, the number of associated jets, and the transverse momentum of the leading jet.
• Higgs Boson Mass and Width: The Higgs boson mass is measured to be $125.26 \pm 0.21$ GeV. The paper also constrains the Higgs boson width to be less than 1.10 GeV at a 95% confidence level, indicating high precision in the measurement.

Experimental Methodology

The study utilizes the CMS detector's comprehensive data capabilities to conduct in-depth analyses of events containing four leptons. This particular decay channel is valued for its high signal-to-background ratio and the precision it enables in reconstructing the Higgs boson's properties.

Implications and Future Prospects

This study reaffirms the SM's robustness in predicting Higgs boson characteristics, which is crucial in the broader verification of particle physics theories. As further data becomes available with higher luminosities and energies, such precise measurements can probe potential deviations from the SM, indicative of new physics. Additionally, advancements in experimental techniques and data analysis will likely tighten constraints on the Higgs properties and potentially uncover subtle effects not currently observable.

The results also underscore the importance of continued work in precision measurements of the Higgs boson, aiming to further elucidate its role within the SM and its interactions, which are fundamental to our understanding of particle physics. Future research might focus on exploring rare decay channels or investigating the Higgs in conjunction with other particles to gain a more comprehensive picture of its properties and interactions.