Physics

Will we see unknown physics in interactions between Higgs particles?

Secondary particle trajectories recorded during proton collisions in the ATLAS detector indicate that a single Higgs boson was present in this event. Credit: IFJ PAN / CERN / ATLAS experiment

Since the launch of the Large Hadron Collider, it has continued to study the Higgs boson and search for traces of physics beyond existing models of elementary particles. Scientists working with the ATLAS detector combined both goals. The latest analysis has expanded our knowledge of Higgs particle interactions and revealed stronger constraints on the phenomenon of “new physics”.

The undisputed success of the Large Hardon Collider (LHC) was the discovery of the last missing ingredient in the Standard Model: the Higgs boson, which is responsible for the origin of mass in elementary particles. There is also the disappointment that there is no trace of physics beyond this model.

Scientists at the European Organization for Nuclear Research (CERN) facility in Geneva will therefore carry out their current research in a way that combines more precise measurements of the properties of the Higgs boson with a further search for “new physics”. It is said that

A study just published in the Journal of High Energy Physics is an example of this approach. In it, physicists from the ATLAS experiment focused on the events that led to the creation of two Higgs bosons, which then decayed into multiple particles of the leptonic family (mainly electrons and muons). said.

The production of Higgs boson pairs can occur within the Standard Model itself. The process here is so rare that it has not been possible to observe it in the data collected so far. However, theoretical models exist that describe phenomena beyond the Standard Model and predict the production of Higgs boson pairs with higher probability.

Observing examples of this type of production using data already collected confirms the existence of a previously unknown class of physical phenomena. It is therefore not surprising for the scientists who participated in the ATLAS experiment that this very process served as the starting point for the above analysis.

“Experimental studies of Higgs boson interactions face a fundamental problem: Higgs boson pairs appear very infrequently in proton collisions at the LHC, At first glance, this seems absolutely necessary if we want to observe interactions between these particles; Can we study it?” asked Dr Bartolomie Zabinski, a physicist at the Institute of Physics of the Polish Academy of Sciences (IPJ PAN), who coordinated the international team responsible for the analysis.

Within the standard model, increasingly accurate predictions can be made about the probabilities of various known processes. The rationale for suggesting the existence of unexpected properties and new physics of the Higgs boson would be the discrepancy between theoretical predictions and actual data from the LHC detector.

The physicists of the ATLAS experiment therefore worked exclusively within the framework of the Standard Model, simulating the signal (along with the background) that would appear on the detector if two Higgs events occurred, and normalizing the results according to expectations. I did. Amount of data obtained from the detector. The final step was to compare the values ​​thus obtained with those obtained from previous observations. The use of decision tree-based machine learning has helped explore these rare processes.

“Our analysis of double Higgs boson production events in final states containing multiple leptons complements work already conducted on other final states. So far, we have However, this result does not exclude the possibility of the existence of “new physical” phenomena, and their possible influence on the production of Higgs boson pairs. “It simply signals that the effects of the virus remain too weak to be confirmed by the data collected so far,” he concludes. Zabinski.

Over the next few years, the LHC is scheduled to undergo significant upgrades. The intensity of the beam is then increased by a factor of 10, resulting in a significant increase in the number of proton collisions recorded.

Due to the limitations imposed by current analyzes on the parameters describing Higgs production and interactions, perhaps at the beginning of the next decade it will be possible to select the first event of double Higgs production from more data and to investigate the phenomenon. Verify today’s predictions by observing directly.

More information: Search for non-resonant Higgs particle pair production in leptonic, Taus, and photon final states in pp collisions at √s = 13 TeV using the ATLAS detector, Journal of High Energy Physics (2024). DOI: 10.1007/JHEP08(2024)164

Provided by Polish Academy of Sciences

Citation: Are unknown physics seen in interactions between Higgs bosons? (November 7, 2024) https://phys.org/news/2024-11-unknown-physics-interactions-higgs-bosons. Retrieved November 8, 2024 from html

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