Lattice QCD and Higgs Models

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This award funds the research activities of Professors James Hetrick and Kieran Holland at the University of the Pacific.The Standard Model (SM) is the name given to our current understanding of what matter is and how it behaves at the most fundamental level that can currently be probed by experiments. This theoretical framework describes the forces between different types of quarks, electrons, and neutrinos, fundamental entities that are at the heart of the model, and further predicts a rather mysterious Higgs particle that pervades the universe and is responsible for profound intricacies of the SM. This Higgs particle was observed at the Large Hadron Collider in 2012, opening the door to understanding the SM at a deeper level. The research of Professors Hetrick and Holland uses supercomputer modeling to explore different scenarios to explain the origin of Higgs particle and thereby advance our understanding of matter beyond the SM. This work is in the national interest because it furthers the development of fundamental science in the United States and develops expertise in high-performance computing for scientific modeling in undergraduate students. Working at a predominantly undergraduate institution, Professors Hetrick and Holland will involve undergraduates in their research, thereby exposing them to advanced research methods very early in their careers. This research program also involves the creation and maintainence of a large-scale publicly available data archive for researchers in this field, thereby leveraging the work of other groups in the US and multiplying the impact of their research. Professors Hetrick and Holland will also continue to deliver public lectures and engage in other community outreach efforts to enhance the public's understanding of particle physics. More technically, the activities supported by this grant involve theoretical particle physics models that could dynamically explain the properties of the Higgs boson and the underlying cause of electroweak symmetry breaking. One such model involves four-dimensional strongly-interacting gauge theories, similar to the theory of Quantum Chromodynamics of quarks and gluons. In this scenario, the Higgs boson emerges as a composite scalar state, and the fundamental theory reveals itself through Higgs dynamics and a rich spectrum of additional composite states. Another model explored in this research program involves five-dimensional gauge theory with fermions in the adjoint representation of the gauge group. The compactification of the fifth dimension with periodic fermion boundary conditions leads to an emergent Higgs state. In both models, lattice simulations using Monte-Carlo techniques on medium- to large-scale computer clusters are the state-of-the-art tools to probe such theories. An additional aspect of these activities is the continuing development of "The Gauge Connection", a big data archive developed to share large ensembles of valuable and costly data produced by research groups across the US. These data sets can be repurposed for new projects with much reduced cost. This is an important activity which benefits many researchers in the particle-physics community. Professors Hetrick and Holland will also continue to mentor undergraduate students who will develop important technical and analytical skills.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.