CAREER: Quark and Gluon Structure of Nucleons and Nuclei

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This project seeks to reveal new aspects of the structure of the atomic nuclei that make up more than 99% of the matter on Earth. The classic picture of a nucleus is a collection of protons and neutrons. The Standard Model of particle physics describes the structure of these protons and neutrons in terms of more fundamental constituents, matter particles (quarks) and force-carrier particles (gluons) that bind the quarks together. Revealing the quark and gluon structure of protons, neutrons and nuclei is a fundamental challenge bridging nuclear and particle physics with data science and high-performance computing. In particular, new studies of gluon structure require techniques that will be developed and implemented in supercomputer calculations of the Standard Model theory on the largest computers in the world. Building a new particle collider to measure gluon structure is the highest priority in the long-range plan of the nuclear physics community. This project will provide theory benchmarks for new experimental programs and facilitate new tests of our understanding of the structure of matter and of the emergence of the complexities of nuclear structure in nature. This project will focus on new aspects of the fundamental structure of nature through Lattice Quantum Chromodynamics (QCD) calculations of the gluon composition of the nucleon and of the modification of nucleon structure in nuclei. The results will provide essential information for current and future nuclear and particle physics experimental programs, such as the planned electron-ion collider (EIC) designed to measure the gluon structure of nucleons and nuclei with unprecedented precision over the next decade. In particular, the three-dimensional gluon structure of the nucleon will be cleanly measured for the first time at the planned EIC. A main goal of this project is the first calculation of the gluon generalised form factors describing this structure. Another goal is the first determination of exotic glue in nuclei through the gluon transversity structure function. Finally, first calculations of QCD constraints on several muti-body nuclear effects will be undertaken. These are increasingly important theory inputs to the interpretation of the results of next-generation intensity frontier experiments. For example, these calculations will constrain the modification of the strange quark nucleon sigma term in nuclei, which provides an important correction to theory cross-sections for the direct detection of particle dark matter candidates.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.