A portrait of the Higgs boson by the CMS experiment ten years after the discovery (2207.00043v3)

Abstract: In July 2012, the ATLAS and CMS Collaborations at the CERN Large Hadron Collider announced the observation of a Higgs boson at a mass of around 125 GeV. Ten years later, and with the data corresponding to the production of 30 times larger number of Higgs bosons, we have learnt much more about the properties of the Higgs boson. The CMS experiment has observed the Higgs boson in numerous fermionic and bosonic decay channels, established its spin-parity quantum numbers, determined its mass and measured its production cross sections in various modes. Here the CMS Collaboration reports the most up-to-date combination of results on the properties of the Higgs boson, including the most stringent limit on the cross section for the production of a pair of Higgs bosons, on the basis of data from proton-proton collisions at a centre-of-mass energy of 13 TeV. Within the uncertainties, all these observations are compatible with the predictions of the standard model of elementary particle physics. Much evidence points to the fact that the standard model is a low-energy approximation of a more comprehensive theory. Several of the standard model issues originate in the sector of Higgs boson physics. An order of magnitude larger number of Higgs bosons, expected to be examined over the next fifteen years, will help deepen our understanding of this crucial sector.

• The paper reports precise measurements of Higgs boson properties, including a mass of 125.38 ± 0.14 GeV and production cross sections consistent with SM expectations.
• The study employs advanced methodologies such as gluon-gluon fusion and vector boson fusion to achieve statistically robust measurements across key decay channels.
• The paper outlines future prospects with planned LHC upgrades aimed at refining Higgs self-coupling constraints and exploring potential physics beyond the Standard Model.

Overview of the Higgs Boson Analysis by the CMS Experiment

The paper discusses a comprehensive analysis by the CMS collaboration at CERN, detailing the accumulated knowledge about the Higgs boson ten years after its initial discovery. This analysis is based on extensive data collection and observations conducted at the Large Hadron Collider (LHC) with proton-proton collision data at a center-of-mass energy of 13 TeV, further expanding our understanding of the Higgs sector in the context of the Standard Model (SM) of particle physics.

Theoretical and Experimental Context

The Standard Model is a successful and fundamental theory of particle physics, describing electromagnetic, weak, and strong interactions through spin-1 bosons. The discovery of the Higgs boson validated the BEH (Brout–Englert–Higgs) mechanism, which explains the electroweak symmetry breaking necessary for the mass acquisition by W and Z bosons as well as fermions through Yukawa couplings. Despite the success of the SM, it is widely believed to be an effective low-energy approximation of a more complete theory.

The paper outlines how the CMS experiment at the LHC has contributed empirical evidence supporting the SM predictions. It describes the observation and measurement of various Higgs boson properties, such as its mass, spin-parity quantum numbers, and production cross sections in different channels. The paper also discusses the capability of future LHC operations to enhance understanding by increasing the number of Higgs bosons observed.

Experimental Analysis and Results

The paper systematically details the production and decay channels of the Higgs boson. The CMS collaboration employed sophisticated detector equipment and methodologies for precise measurements. A significant portion of the analysis includes gluon-gluon fusion, vector boson fusion (VBF), and associated production processes involving weak gauge bosons or top quarks. The experimental results align with theoretical predictions, showcasing the SM's robustness in describing Higgs boson interactions and decay processes with high accuracy.

Key results presented include:

• A measured Higgs boson mass of 125.38 ± 0.14 GeV
• Observed decay channels such as Higgs to WW, ZZ, and γγ with distinct statistical significance levels
• Signal strength parameter (μ) for combined data, yielding 1.002 ± 0.057, illustrating strong consistency with SM expectations

Future Prospects and Impact

The paper highlights the importance of planned upgrades to the LHC and CMS detector systems, which will facilitate enhanced precision in Higgs boson studies. These upgrades are anticipated to potentially uncover discrepancies with the SM predictions, thus offering insights into new physics beyond the SM. Moreover, by expanding the data acquisition capabilities, the LHC aims to provide tighter constraints on Higgs self-coupling—a critical parameter for testing the electroweak phase transition and its implications for cosmology.

Conclusion

This extensive analysis conducted by the CMS collaboration represents a robust evaluation of the Higgs boson properties compatible with the SM framework. It provides a crucial reference for ongoing and future efforts in particle physics research. The implications of this paper suggest a promising path forward for experimental particle physics, with future data poised to refine our understanding of the fundamental interactions governing our universe.