In a groundbreaking endeavor, the CMS (Compact Muon Solenoid) experiment at the Large Hadron Collider (LHC) has conducted its first search for new physics using data from Run 3. This study delves into the possibility of “dark photon” production in the decay of Higgs bosons, offering a glimpse into a realm of exotic particles that lie beyond the Standard Model of particle physics. Dark photons, distinguished by their long lifetimes and non-conformity to the Standard Model, present an exciting avenue for physicists to explore unanswered questions. Through rigorous analysis and utilization of advanced technological enhancements, the CMS experiment has managed to define more stringent limits on the parameters of Higgs boson decay to dark photons, effectively narrowing down the search space for these elusive particles.
Dark photons, unlike their ordinary counterparts, defy the confines of the Standard Model. With an average lifetime exceeding a tenth of a billionth of a second, they possess an extraordinary longevity among particles produced in the LHC. Additionally, these particles deviate from the known building blocks of the Universe, beckoning scientists to investigate phenomena that lie beyond the Standard Model. The CMS experiment’s pursuit of dark photons aims to shed light on these exotic particles by detecting their production in the Higgs boson’s decay within the detector.
A key feature of dark photon detection lies in tracing the tracks of muons that result from the decay of dark photons. Displaced muons, originating from dark photons, exhibit a peculiar characteristic whereby their tracks terminate before reaching the collision point. This peculiar phenomenon arises from the fact that the particle producing the muons has travelled a significant distance away, leaving no observable trace at the point of collision. The CMS experiment’s comprehensive search involves retracing these enigmatic tracks within the CMS detector, hoping to find evidence of the existence of dark photons.
Run 3 of the LHC, which commenced in July 2022, offers a higher instantaneous luminosity compared to previous runs. The increased luminosity translates to a greater number of collisions occurring at any given moment, providing researchers with an abundance of data to analyze. The LHC generates tens of millions of collisions every second, but only a fraction of them can be stored for further investigation, necessitating a real-time data selection mechanism known as the trigger. This crucial algorithm determines the level of interest of a particular collision, allowing scientists to focus their analysis on the most promising events.
The CMS experiment’s success in the search for dark photons owes much to the refinement of the trigger system between Runs 2 and 3. The CMS team introduced a novel algorithm, the non-pointing muon algorithm, which played a pivotal role in detecting exotic long-lived particles, including dark photons. The improved trigger system enabled the collection of a higher number of displaced-muon events with just four to five months of data from Run 3, surpassing the quantity recorded in the considerably larger Run 2 dataset spanning from 2016 to 2018. By continuously fine-tuning the trigger system and harnessing the power of advanced techniques, the CMS experiment strives to analyze all data obtained during the remaining years of Run 3 operations, propelling the investigation into physics beyond the Standard Model.
The CMS experiment’s pioneering search for dark photons using data from Run 3 heralds a new frontier in the quest for physics beyond the Standard Model. Through meticulous analysis and the reimagining of the trigger system, the collaboration has achieved significant progress in narrowing down the possible parameters of Higgs boson decay to dark photons. The profound nature of these findings showcases the cutting-edge capabilities of the CMS experiment, providing impetus for further exploration and discovery in the fascinating realm of particle physics. As we delve deeper into the mysteries of the Universe, the elusive dark photons stand as a testament to the enduring curiosity and ingenuity of scientific exploration.