A detailed map of Higgs boson interactions by the ATLAS experiment ten years after the discovery

Abstract: The Standard Model of particle physics describes the known fundamental particles and forces that make up our universe, with the exception of gravity. One of the central features of the Standard Model is a field that permeates all of space and interacts with fundamental particles. The quantum excitation of this field, known as Higgs field, manifests itself as the Higgs boson, the only fundamental particle with no spin. In 2012, a particle with properties consistent with the Higgs boson of the Standard Model was observed by the ATLAS and CMS experiments at the Large Hadron Collider at CERN. Since then, more than 30 times as many Higgs bosons have been recorded by the ATLAS experiment, allowing much more precise measurements and new tests of the theory. Here, on the basis of this larger dataset, we combine an unprecedented number of production and decay processes of the Higgs boson to scrutinize its interactions with elementary particles. Interactions with gluons, photons, and $W$ and $Z$ bosons -- the carriers of the strong, electromagnetic, and weak forces -- are studied in detail. Interactions with three third-generation matter particles (bottom ($b$) and top ($t$) quarks, and tau leptons ($\tau$)) are well measured and indications of interactions with a second-generation particle (muons, $\mu$) are emerging. These tests reveal that the Higgs boson discovered ten years ago is remarkably consistent with the predictions of the theory and provide stringent constraints on many models of new phenomena beyond the Standard Model.

• The paper presents a detailed mapping of Higgs boson interactions using 139 fb–1 of Run 2 data to validate the Standard Model's mass-dependent coupling predictions.
• It employs rigorous analyses of gluon fusion and vector-boson fusion channels to precisely measure production rates and decay constants across multiple channels.
• The findings bolster our understanding of the Higgs mechanism while paving the way for probing rare decay modes and exploring potential new physics.

Overview of "A Detailed Map of Higgs Boson Interactions by the ATLAS Experiment Ten Years After the Discovery"

The paper "A Detailed Map of Higgs Boson Interactions by the ATLAS Experiment Ten Years After the Discovery" presents a comprehensive analysis of the Higgs boson properties as derived from data obtained by the ATLAS experiment at CERN. The findings are derived from the large dataset collected during the Run 2 data-taking period from 2015 to 2018, marking a decade since the Higgs boson's initial observation. This period enabled the collection of approximately 139 inverse femtobarns (fb$^{-1}$) of data, which is translatable into millions of Higgs boson events. This unprecedented statistic allows for a finer resolution in examining the nuances of Higgs boson behaviors, including production and decay channels, and provides stringent tests for the Standard Model (SM) consilience.

Detailed Examination of Higgs Boson Couplings

The analysis centers on the exploration of Higgs boson couplings to various fundamental particles and examines whether these couplings align with the mass-dependent predictions of the Standard Model. The dominant production mechanism at the Large Hadron Collider (LHC) is gluon-gluon fusion (ggF), constituting about 87% of Higgs production, with significant contributions also from vector-boson fusion (VBF), and associated production with vector bosons and top quarks.

The paper expounds on the decay paths of the Higgs boson, which typically decay instantaneously into various SM particles. Key decays include those into pairs of W and Z bosons, photons, and third-generation matter particles like b quarks, tau leptons, and, importantly, into particles that could indicate physics beyond the SM, such as potentially invisible particles linked with dark matter postulations.

Results and Findings

The ATLAS Collaboration reports that the collected data exhibits a remarkable agreement with the SM predictions for Higgs boson interactions. The decay rates and coupling constants observed align closely with expectations across multiple decay channels and production mechanisms:

• The inclusive Higgs boson production rate relative to the SM prediction is determined to be 1.05 ± 0.06, with the precision enhanced through copious data allowing reduced experimental and theoretical uncertainties.
• Higgs boson decay into fermions, particularly tau leptons, b-quarks, and the seldom-measured muon channel, were in consistency with SM expectations, with some indications towards interactions with the second-generation particles, such as muons.
• The SM's prediction that the Higgs couples proportionally to particle masses received further validation through these measurements. The comparative sizes of the uncertainties highlighted that experimental control and theoretical predictions of related processes have advanced considerably, yielding greater precision.

Implications and Future Prospects

The outcomes of the ATLAS experiment reaffirm the robustness of the SM in describing fundamental particles' interactions but stress-test our understanding, opening pathways for scrutinizing rare Higgs processes. Despite the apparent convergence with SM predictions, emphasis remains on scrutinizing self-coupling properties of the Higgs boson and rare decay pathways (such as Higgs decays into potential dark matter candidates).

The results accentuate the continuity of investigations in high-energy physics and guide future experiments, including those planned for LHC's Run 3 and the High-Luminosity LHC upgrades. With further improvements in detector technology and theoretical frameworks, augmented datasets will be pivotal, potentially unveiling new physics phenomena and evaluating deviations from the SM that could signal the presence of new, as yet unobserved, particles or interactions.

In total, this paper solidifies our understanding of the Higgs mechanism and its integration into the quantum field framework of the universe, setting a thorough empirical groundwork essential for theoretical explorations and upcoming experimental inquiries in particle physics.