Nuclear and Particle Physics Colloquium

77

(核与粒子物理学术报告会77)

Place:Room 316, Main Building, Beihang University

Time:14:00-15:40,April 4th, 2019

Title:Compton Scattering: A Poster Child to Link Chiral EFT and Experiment

with Reliable Uncertainties

Speaker:Dr. Harald W. Griesshammer

Abstract:

Compton scattering on one- and few-nucleon systems continues to be an excellent tool to probe the symmetries and strengths of nucleonic and nuclear interactions and provides a natural bridge between data and lattice-QCD computations of fundamental hadronic properties. The spin polarisabilities are particularly interesting since they parametrise the stiffness of the spin in external electro-magnetic fields (nucleonic bi-refringence/Faraday effect) and probe the spin-dependent component of the pion-nucleon interaction, as dictated by chiral symmetry. I review the formalism and how to quantify the residual theoretical uncertainties by Bayesian techniques. I then discuss tests and extractions of the polarisabilities of the proton and neutron with data. Their pion-mass dependence allows one to confront them with lattice-QCD computations, and explore their potential impact on the neutron-proton mass difference and the Anthropic Principle. Comprehensive studies show how sensitive observables for each nucleon, the deuteron and ${}^3$He are on the individual scalar and spin polarisabilities, and to their combinations. This facilitates planning and analysis of the new generation of Compton experiments.

About speaker:

Griesshammer is an Associate Professor of Physics at George Washington University who studies Theoretical Nuclear Physics, with a focus on one- and few-nucleon systems at low energies. He works on universality in nuclear systems, Chiral and Pion-less Effective Field Theories, and Compton scattering as a tool to learn about hadron binding.