Hadron Physics in Tests of Fundamental Symmetries

Low energy precision tests of fundamental symmetries provide excellent probes for the Beyond Standard Model Physics. Theoretical interpretations of these experiments often involve the application of non-perturbative Quantum Chromodynamics in the study of hadronic matrix elements that may either serve as signals of new physics or Standard Model backgrounds. In this work I present a series of studies on different hadronic matrix elements using various low-energy effective approaches to Quantum Chromodynamics, and discuss the impact of these studies on our knowledge of Standard Model and Beyond Standard Model physics

Model-independent determination of nuclear weak form factors and implications for Standard Model precision tests

We analyze the recoil corrections in superallowed beta decays of $T=1$, $J^P=0^+$ nuclei by fixing the mean square charge weak radius model-independently using the data of multiple charge radii across the nuclear isotriplet. By comparing to model estimations, we argue that the existing theory uncertainty in the statistical rate function $f$ might have been substantially underestimated. We discuss the implications of our proposed strategy for precision tests of Standard Model, including a potential alleviation of the first-row CKM unitarity deficit, and motivate new experiments for charge radii measurements.Comment: Version accepted by PR

Effective Field Theory in The Study of Long Range Nuclear Parity Violation on Lattice

A non-zero signal $A_\gamma^\mathrm{np}=(-3.0\pm1.4\pm0.2)\times 10^{-8}$ of the gamma-ray asymmetry in the neutron-proton capture was recently reported by the NPDGamma Collaboration which provides the first determination of the $\Delta I=1$ parity-odd pion-nucleon coupling constant $h_\pi^1=(2.6\pm 1.2\pm 0.2)\times 10^{-7}$. The ability to reproduce this value from first principles serves as a direct test of our current understanding of the interplay between the strong and weak interaction at low energy. To motivate new lattice studies of $h_\pi^1$, we review the current status of the theoretical understanding of this coupling, which includes our recent work that relates it to a nucleon mass-splitting by a soft-pion theorem. We further investigate the possibility of calculating the mass-splitting on the lattice by providing effective field theory parameterizations of all the involved quark contraction diagrams. We show that the lattice calculations of the easier connected diagrams will provide information of the chiral logarithms in the much harder quark loop diagrams and thus help in the chiral extrapolation of the latter.Comment: 43 pages, 3 figures, 1 table. Accepted by EPJ

Towards ab\it{ab}-initio\it{initio} nuclear theory calculations of δC\delta_\mathrm{C}

We propose a new theory framework to study the isospin-symmetry breaking correction $\delta_\text{C}$ in superallowed nuclear beta decays, crucial for the precise determination of $|V_{ud}|$. Based on a general assumptions of the isovector dominance in ISB interactions, we construct a set of functions $F_{T_z}$ which involve nuclear matrix elements of isovector monopole operators and the nuclear Green's function. Via the functions $F_{T_z}$, a connection of $\delta_\text{C}$ to measurable electroweak nuclear radii is established, providing an experimental gauge of the theory accuracy of $\delta_\text{C}$. We outline a strategy to perform ab-initio calculations of $F_{T_z}$ based on the Lanczos algorithm, and discuss its similarity with other nuclear-structure-dependent inputs in nuclear beta decays.Comment: 8 pages, 1 tabl