Neutrinoless double beta decay is a key probe of physics beyond the Standard Model, whose interpretation relies on accurate nuclear matrix elements. These matrix elements are strongly influenced by both the decay operator and nuclear many-body correlations. In this talk, I present recent progress based on relativistic approaches. On the operator side, a Lorentz-invariant chiral framework is developed, showing that the leading-order transition amplitude can be renormalized without unknown short-range contributions, providing a model-independent basis for nuclear-structure calculations. On the many-body side, relativistic configuration-interaction density functional theory is developed to incorporate triaxial deformation. Applications to 76Ge show that triaxiality can significantly enhance the neutrinoless double beta decay matrix element. Combining the relativistic decay operator with relativistic many-body wavefunctions, nuclear matrix elements for 48Ca, 76Ge, 82Se, 100Mo, and 136Xe are calculated with substantially reduced short-range uncertainties.
Bio:
Pengwei Zhao received his Ph.D. in Physics from Peking University in 2012. He held research positions at the Yukawa Institute for Theoretical Physics (YITP), Kyoto University, Japan, and at Argonne National Laboratory, USA. In 2018, he joined the School of Physics at Peking University as a faculty member. His research interests focus on relativistic quantum many-body theory, relativistic effective field theory, exotic nuclear structure, and fundamental symmetries and their breaking mechanisms. He has published over 120 refereed papers, receiving more than 5,000 citations, with an h-index of 39.
Ziyu Wang