WhatIsTheNews.press

The CMS experiment has recently conducted its first search for new physics using data from Run 3 of the Large Hadron Collider. This study focuses on the potential production of "dark photons" in the decay of Higgs bosons within the detector. Dark photons are considered exotic and long-lived particles, as they have average lifetimes that exceed a tenth of a billionth of a second, which is significantly longer than most particles produced by the LHC. Moreover, they are not accounted for in the standard model of particle physics, leading to a continued search for phenomena outside of this model. This latest result from CMS establishes more restricted limits on the parameters of Higgs boson decay to dark photons, thereby narrowing down the possible areas where physicists can search for them

In theory, if dark photons exist, they would travel a measurable distance within the CMS detector before decaying into "displaced muons." By retracing the tracks of these muons, scientists have observed that they do not reach the collision point. Instead, they originate from a particle that has already moved some distance away, leaving no trace. Run 3 of the LHC, which commenced in July 2022, boasts a higher instantaneous luminosity compared to previous runs. This means that more collisions are occurring simultaneously, providing researchers with a more extensive dataset to analyze. Given that the LHC generates millions of collisions per second, only a few thousand of them can be stored due to limited data storage capacity

Consequently, CMS employs a real-time data selection algorithm known as the trigger, which determines the relevance of each collision. The trigger is instrumental in not only handling the increased volume of data but also in identifying specific phenomena such as the dark photon. Juliette Alimena from the CMS experiment acknowledged the improvements made in triggering on displaced muons, which has enabled CMS to collect a greater number of events involving muons displaced from the collision point by distances ranging from a few hundred micrometers to several meters. Consequently, if dark photons exist, CMS now has a higher likelihood of detecting them. The CMS trigger was refined significantly between Runs 2 and 3 and played a critical role in this search for exotic, long-lived particles. By using just a third of the data used in previous searches, the collaboration achieved a robust result

This was made possible by the introduction of a new algorithm known as a non-pointing muon algorithm, which considerably increased the number of recorded displaced-muon events in the Run 3 data set compared to the larger Run 2 data set from 2016-2018. The expanded coverage of the triggers has widened the range of muon momentum that can be detected, enabling the team to explore uncharted regions where long-lived particles might be hiding. Moving forward, the CMS team intends to employ the most advanced techniques to analyze all data gathered during the remaining years of Run 3 operations. Their objective is to delve further into physics beyond the standard model and continue the exploration of new phenomena.