Time & Place: Nov. 30, 3:00pm, Room 9409

Speaker: Prof. Stephen Lars Olsen,
Center for Underground Physics, Institute for Basic Science (Korea)
University of the Chinese Academy of Science, Beijing (China)


Title:      Neutrinoless double-beta decay
       —the last frontier of the Standard Model—


Abstract: The discovery of the Higgs boson at the LHC in 2012 has often
been characterized as “the completion of the Standard Model.” This
description ignores huge gaps in our understanding of fundamental
properties of neutrinos:

1. it is still not known if neutrinos are Dirac particles with distinct
antiparticles or if they are Majorana particles that are their own
antiparticles;

2. it is not known whether or not the SM requires lepton number
conservation;

3. neither the absolute scale nor the correct hierarchy of neutrino
masses have yet been established;

4. CP violating neutrino-mixing phases, the single Dirac-phase and the
two possible Majorana-phases, remain unexplored.
Current and proposed neutrino oscillation experiments will establish the
mass hierarchy and the possibility of a non-zero Dirac-type CPV phase,
only a sub-set of the remaining issues. They cannot address the more
fundamental issues: i.e., Dirac- vs Majorana-type neutrinos; lepton
number conservation; the absolute mass scale; or the possibility of
nonzero Majorana CPV phases. Measurements of neutrinoless double beta
rates for certain even-even nuclei, while nearly impossibly difficult,
could, in principle, provide unique possibilities for addressing these
remaining issues.

In this talk Prof. Olsen will review the three-neutrino paradigm, with
emphasis on those features that can only be accessed by measurements of
neutrinoless double-beta decay half-lives, and describe some of the very
difficult experimental challenges that are involved. Prof. Olsen will
also briefly describe AMoRE, a new experiment in this field that is
currently underway in South Korea.
*********************************************************************

About Speaker:

Stephen Lars Olsen received a B.S. from the City College of New York in
1963 and a Ph.D. in physics from the University of Wisconsin in 1970.
His research has concentrated mostly on studies of heavy quarks and
their associated hadrons using CLEO at Cornell, AMY and Belle
experiments at KEK in Japan, and the BES experiments at IHEP in Beijing.
Olsen was an Alfred P. Sloan Fellow (1972-1977), a John Simon Guggenheim
Fellow (1986-1987), a Japan Society for the Promotion of Science Fellow
(1987-1988). He was awarded the University of Hawaii Regents Medal for
Excellence in Research in 2002 and was designated as a University of
Wisconsin Distinguished Alumni in 2007. He was elected Fellow of the APS
in 1984. Olsen got the 2016 W.K.H. Panofsky Prize in Experimental
Particle Physics "For leadership in the BaBar and Belle Experiments,
which established the violation of CP symmetry in B-meson decay, and
furthered our understanding of quark mixing and quantum chromodynamics."