Nuclear and Particle Physics Colloquium77

(核与粒子物理学术报告会77)

Place:Room 316, Main Building, Beihang University

Title:Compton Scattering: A Poster Child to Link Chiral EFT andExperiment

withReliable Uncertainties

Speaker:Dr. Harald W. Griesshammer

Abstract:

Comptonscattering on one- and few-nucleon systems continues to be an excellent tool toprobe the symmetries and strengths of nucleonic and nuclear interactions andprovides a natural bridge between data and lattice-QCD computations offundamental hadronic properties. The spin polarisabilities are particularlyinteresting since they parametrise the stiffness of the spin in externalelectro-magnetic fields (nucleonic bi-refringence/Faraday effect) and probe thespin-dependent component of the pion-nucleon interaction, as dictated by chiralsymmetry. I review the formalism and how to quantify the residual theoreticaluncertainties by Bayesian techniques. I then discuss tests andextractions of the polarisabilities of the proton and neutron with data. Their pion-mass dependence allows one to confront them with lattice-QCDcomputations, and explore their potential impact on the neutron-proton massdifference and the Anthropic Principle. Comprehensive studies show howsensitive observables for each nucleon, the deuteron and ${}^3$He are on theindividual scalar and spin polarisabilities, and to their combinations. Thisfacilitates planning and analysis of the new generation of Compton experiments.

About speaker:

Griesshammeris an Associate Professor of Physics at George Washington University whostudies Theoretical Nuclear Physics, with a focus on one- and few-nucleonsystems at low energies. He works on universality in nuclear systems, Chiraland Pion-less Effective Field Theories, and Compton scattering as a tool tolearn about hadron binding.