Lecturer: Prof. Micheal Kohl
Affiliation: Hampton university
and the Thomas Jefferson national lab
Abstract:
The electromagnetic form factors of the
proton have been under intensive studies
over the last two decades revealing
unexpected anomalies. Two-photon
exchange (TPE) effects have been a favorable
explanation for the differing measurements
of the proton electric-to-magnetic form
factor ratio with polarized and unpolarized
methods. As a dedicated experiment to test
the TPE hypothesis, OLYMPUS at DESY has
quantified the size of TPE effects at four-
momentum transfers up to about 2 (GeV/c)^{^2}
by comparing electron and positron
scattering with high precision. Among other
explanations, two-photon exchange effects
have been considered also at low
momentum transfer to explain a famous
anomaly in the proton electric form factor
known as the proton radius puzzle. This
possibility, along with new physics scenarios
will be stringently probed with the MUSE
experiment at PSI by comparing muon and
electron scattering. Results from OLYMPUS
and the present status of MUSE will be
presented.
This talk will focus on the recently developed
method that is constructed by bridging the
microscopic framework provided by the
nuclear density functional theory and
algebraic theory of interacting bosons. The
method has opened up many new
possibilities of analyzing complex nuclear
shapes and collective excitations in an
accurate, systematic and computationally
feasible manner. I will present the basic
notions of the method and highlight the
interesting applications, including the studies
of reflection asymmetric (or pear-shaped)
nuclei and nuclei with odd number of
nucleons, which are hot topics in nuclear
structure research in recent years.