Collaborative Research: Studying the Nature of the Higgs Boson and Searching for New Physics at the Large Hadron Collider with the ATLAS Experiment.

ATLAS is a multi-purpose particle physics detector situated around the Large Hadron Collider (LHC) located at CERN, the European Organization for Nuclear Research, just outside of Geneva, Switzerland. The goal of the ATLAS Collaboration’s physics program is to explore the fundamental nature of the universe at the smallest distance scales and highest energies achieved in a controlled environment.

In July of 2022, the LHC restarted operations at a record center of mass energy of 13.6 TeV for proton-proton collisions, marking the beginning of Run 3 where more than 200 fb−1 of data is expected to be collected. This award will explore this new energy regime and the large dataset will allow for precision testing of the Standard Model of particle physics (SM), measurement of the properties of the Higgs Boson and its couplings, and the search for undiscovered particles and phenomena such as heavy bosons, gravitons, dark matter, and leptoquarks.

At the end of 2025, the LHC will enter the next long shutdown where it will be upgraded to the High-Luminosity LHC (HL-LHC) that will provide record numbers of proton-proton collisions at a design center of mass energy of 14 TeV. During this shutdown, the work of this award will contribute to the replacement of the entire inner tracking detector with the Inner Tracker Upgrade (ITk) so that ATLAS is able to provide precision track information for the more than 200 simultaneous collisions expected every 25ns.

This award supports the research of the California State University (CSU) ATLAS group, including PIs at CSU Sacramento and CSU East Bay along with a diverse student population of undergraduate researchers in the CSU system. The group will collect and analyze data during Run 3 and study the Higgs boson by examining events which produce pairs of Higgs bosons (HH).

This process can be used as a precision test of the SM, in particular probing the nature of electroweak symmetry breaking. Additionally Higgs pair production can be used to search for new scalar particles, predicted in a number of Beyond the Standard Model theories. In preparation for the HL-LHC, the CSU ATLAS group will work as members of the ATLAS ITk group to design, build, and install components of the Inner Pixel tracker that will be integrated into ATLAS in 2028.

The focus of the ITk work will be on the production and integration of the ITk Inner Pixel modules and the Detector Control System (DCS) which includes the development of software and user interfaces. Undergraduates will be involved in all aspects of the proposed CSU ATLAS research program and will participate in collaborative science, data analysis, and in instrumentation testing at the campus laboratories as well as at SLAC and CERN.

Supporting CSU students on their paths to physics graduate school and careers in science will have a significant impact on diversifying the physics workforce of the future.

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.