[Triumf-seminars] TRIUMF Colloquium today at 11:00

[postmaster at admin.triumf.ca]

Date/Time: Mon 2009-03-02 at 11:00

Location:  Auditorium          

Speaker:   Daniel Phillips (Ohio University)

Title:     Symmetry breaking, nuclear dynamics, and neutrons

Abstract: I will discuss two examples of ongoing efforts that use experiments with neutrons to elucidate key aspects of nuclear forces. First, I will present an effective field theory of the strong interaction that is based only on confinement and isospin symmetry and describes nucleon-nucleon scattering at very low energies. I will show how this effective field theory facilitates analysis of parity violation in neutron-proton scattering, and thereby explain how measurements of parity-violating asymmetries in np scattering provide significantly more information on the weak nuclear force than can be obtained in the analogous proton-proton scattering experiments.

I will then move to higher energies, where chiral symmetry is an important counterpart to isospin symmetry. Chiral effective field theories of QCD can be used to propagate the consequences of both these symmetries---and the pattern of their breaking---through to neutron dynamics. I will use these theories to discuss what neutron electromagnetic polarizabilities teach us about the pattern of chiral-symmetry breaking in QCD, and give an update on the status of efforts to extract these quantities from Compton scattering experiments on light nuclei.

Stimulants will be available 15 minutes before the talk.

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