[Triumf-seminars] TRIUMF Colloquium today at 14:00

[postmaster at admin.triumf.ca]

Date/Time: Thu 2008-09-18 at 14:00

Location:  Auditorium          

Speaker:   Geoff Grinyer (NSCL, Michigan State University)

Title:     Superallowed Fermi Beta Decay: Nuclear Structure and Fundamental Symmetries

Abstract: High-precision measurements of the ft values for superallowed Fermi beta decays between isobaric analogue states have, for decades, provided some of the most demanding tests of the Standard Model description of electroweak interactions.  Owing to their relative insensitivity to the effects of nuclear structure, these decays confirm the conserved vector current (CVC) hypothesis at the level of 1.3×10-4, limit the existence of possible scalar interactions to 1.3×10-3, and provide the most precise value (by nearly an order of magnitude) for the up-down element Vud of the CKM matrix.  Ironically, the present limit in expanding the precision frontier is not experimental in nature, but rather, comes from a systematic discrepancy between theoretical calculations used to correct these decays for nuclear structure effects.   
 
A summary of the present world data on superallowed Fermi beta decay, and why these decays are so important to our understanding of the electroweak interaction will be discussed.  The ever increasing role that nuclear structure is playing, and the interplay between experiment and structure theory for these decays, will be highlighted using several key experimental results recently obtained at TRIUMF-ISAC.

Stimulants available 15 minutes before the talk.

______________________________

Subscription information available at http://admin.triumf.ca/netdata/seminars/list