Higgs Boson Decay Reveals New Insights into Electroweak Interactions.

The precise measurement of the Higgs boson’s decay pathways continues to refine our understanding of fundamental particle interactions, offering insights into the subtle relationships between the Higgs field and the electroweak force. New research focuses on calculating increasingly accurate theoretical predictions for these decays, accounting for quantum effects beyond the simplest approximations. Gonçalves et al, from the Department of Physics at Oklahoma State University, present a detailed analysis of ‘higher-order corrections’ – refinements to calculations that incorporate more complex quantum interactions – to the angular distribution of the Higgs boson as it decays. Their work, titled ‘Higher-Order Corrections to Quantum Observables’, demonstrates that these corrections, while relatively small, induce measurable shifts in the predicted decay patterns and reveal previously hidden relationships between the intermediate particles produced in the process, offering a more robust framework for interpreting experimental data.

Precision measurements of Higgs boson decay represent a critical avenue for investigating fundamental interactions and rigorously testing the Standard Model of particle physics. Researchers meticulously examine next-to-leading order electroweak corrections to angular coefficients, which characterise the decay process, revealing subtle properties of these interactions and refining theoretical predictions. These corrections, arising from quantum loop effects involving virtual particles, induce shifts of up to 5% in established angular coefficient values, demonstrating the necessity of their inclusion for accurate phenomenological studies. Angular coefficients describe the angular distribution of the decay products, providing information about the spin and parity of the decaying particle and the nature of the interaction.

The (H > ZZ) decay channel, where the Higgs boson decays into two Z bosons, exhibits particular stability under higher-order corrections, in contrast to previously investigated decay modes. This resilience reinforces its potential as a robust probe of physics beyond the Standard Model. Researchers employ advanced perturbative techniques to calculate these electroweak corrections, accounting for the exchange of virtual particles that modify the Higgs boson’s decay. These calculations require careful consideration of loop integrals, complex mathematical expressions arising from the quantum loops, and renormalisation procedures, a process of absorbing infinities to obtain finite, physically meaningful predictions.

Further analysis expands to encompass other Higgs boson decay channels, particularly those involving heavier intermediate bosons, such as the W boson. This broader investigation provides a more comprehensive understanding of the Higgs sector and its interactions with the electroweak gauge bosons, the force carriers of the weak and electromagnetic interactions. Automated computational tools are being developed for calculating higher-order electroweak corrections, facilitating more efficient and accurate studies and enabling exploration of a wider range of theoretical models. Future work focuses on extending these calculations to include next-to-next-leading order corrections, further refining the precision of theoretical predictions and pushing the boundaries of calculational complexity.

Researchers investigate the implications of these findings for precision measurements at future colliders, such as the International Linear Collider, a proposed electron-positron collider, maximising the scientific return from these facilities. They also investigate the sensitivity of these angular coefficients to potential beyond-the-Standard-Model physics, such as modifications to the Higgs self-coupling, which describes how Higgs bosons interact with each other, or the introduction of new particles not accounted for in the Standard Model. A detailed comparison between theoretical predictions and high-precision measurements from the ATLAS and CMS collaborations at the Large Hadron Collider validates the findings and constrains potential new physics scenarios.

The emergence of new structures within these corrections reveals that they alter established angular coefficient values, reinforcing the potential of the (H > ZZ) decay channel as a robust probe of new physics. These subtle alterations provide a sensitive window into potential deviations from the Standard Model, offering a pathway to discover new particles or interactions that may lie beyond our current understanding.