Thursday, May 11, 2017, 16:00
WHGA Auditorium
Frank Deppisch, University College London
Abstract:
Neutrinos are the least understood of all known matter particles. Their
most puzzling property is that they have tiny yet finite masses; even
though the Higgs mechanism has now been largely confirmed by the LHC as
the source of fundamental masses in the Standard Model, the lightness of
neutrinos remains a mystery. A crucial probe to determine the scale and
nature of neutrino masses is neutrinoless double beta decay. Already
hypothesised in 1939, this nuclear process involves the simultaneous
decay of two protons into neutrons within a nucleus under the emission
of two electrons. If observed, neutrinoless double beta decay would be a
definite sign of new physics beyond the Standard Model. Specifically, it
would mean that neutrinos are Majorana fermions and it would most likely
point to a very high mass scale of new physics where lepton number
symmetry is broken. In my talk, I will outline the theory of
neutrinoless double beta and associated processes as a probe of physics
beyond the Standard Model. I will attempt to motivate the importance and
consequences of this process and discuss the intricate problems in
dealing with its nuclear nature. Furthermore, I will sketch the
underlying physics connections with other searches, such as for lepton
flavour violating decays, and explain what we can learn from
neutrinoless double beta decay about the matter-antimatter asymmetry of
the Universe.