Bound State Theory and High Precision QED: Muonium, Positronium, Hydrogen, and Pentaquarks

University Of Kentucky Research Foundation, Lexington KY

Investigators

Abstract

An area of active fundamental research in physics is the study of the hydrogen-like atoms and exotic atoms, atoms where one particle such as an electron is replaced by another such as a muon. Theoretical research of the properties of these systems represents the main goal of this project. In recent years, experiments in this area have reached an unprecedented level of accuracy, challenging the theory at a stronger and stronger level. Responding to this challenge, this project will provide theoretical input to the determination with higher precision of many fundamental physical constants, such as the electron-muon and electron-proton mass ratios, the proton charge radius, and the Rydberg constant. The new theoretical understanding developed here will be used in the next CODATA analysis of the fundamental physical constants. CODATA compilations of the fundamental constants are used in every science classroom, as well as in numerous fields of science and engineering, from fundamental research to consumer electronics. This project will also provide theoretical insight in the properties of pentaquarks, the bound states of five quarks recently discovered by the LHCb Collaboration at the European Organization for Nuclear Research (CERN). Graduate and undergraduate students participating in this research will acquire research, computer, problem solving, and presentation skills. High precision quantum electrodynamics of hydrogen-like bound states is an active field of theoretical research motivated both by the spectacular experimental progress achieved in recent years and the intrinsic intellectual challenge. Despite significant progress in the theory of light hydrogen-like bound states, a number of challenging problems remain and will be addressed in this research: 1) Complete calculation of all three-loop radiative-recoil corrections to hyperfine splitting in muonium, 2) Complete calculation of hard three-loop corrections to hyperfine splitting in positronium due to two-loop radiative insertions in the fermion lines in two-photon exchange nonannihilation diagrams, 3) Complete calculation of all relevant three-loop nonrecoil corrections to the Lamb shift in hydrogen and muonium. The above represent the largest unknown contributions to the Lamb shift in atomic physics. Respective three-loop nonrecoil corrections to hyperfine splitting in hydrogen and muonium will be calculated also. The PI will further develop the hadrocharmomium interpretation of pentaquarks. The project will provide quantitative description of their properties.