Experimental Particle Physics

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This award will provide support to a group working on the ATLAS experiment at the Large Hadron Collider (LHC) at CERN, a particle physics laboratory in Geneva, Switzerland. The LHC machine and ATLAS, a large particle detector facility, were built as basic science tools using funds from NSF and other agencies around the world. One of their primary objectives was to find the Higgs Boson, the last particle in the historically successful "Standard Model" (SM) that accounts for so much of the existence of, and forces between, known particles forming the matter in the universe. This effort has been successful. The next step in the experiments is to look for evidence for physics Beyond the Standard Model (BSM) that might, for instance, account for the presence of the mysterious "Dark Matter" that makes up so much of the mass of the universe. The LHC is currently in the midst of Run 2, at almost twice the energy explored earlier and with significantly increased event samples. It is possible that evidence for BSM physics could emerge at this higher energy and with the higher event statistics. Analytically, the New Mexico group is searching for BSM physics using the ATLAS detector. These studies include a definitive ATLAS measurement of the branching ratio of the rare decay of the neutral Bs meson into two muons. This measurement is interesting because the early data from LHC yielded a value in tension with predictions of the Standard Model, and any significant deviations are a harbinger of new BSM physics. In the upcoming data run which begins in 2021, the group is working on software infrastructure to probe for hints of lepton flavor anomaly. Technically, the New Mexico group leads a study of the ATLAS Pixel tracking detector that characterizes the performance capabilities of this detector through the end of the next run and yields guidelines for Pixel operations in this era. The pixel detector is critical to the studies of particles with short lifetimes such as the neutral Bs mesons of interest to the group, as well as for the broader ATLAS program of discovery science.The broader impacts of the New Mexico group's research activities include advances in machine learning. The development of such analytical tools is intrinsic to the New Mexico data analyses, and the group's junior members are becoming authoritative in this domain and will be able to train others. Machine learning has applications in virtual assistants, medical diagnosis, DNA classification, and other research domains where weak signals must be sensitively separated from extensive background. The group's research serves as a springboard for QuarkNet projects that they sponsor, including LHC masterclasses, laboratory research for teachers, and technical tours of New Mexico scientific facilities.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.