The puzzle of angular momentum conservation in beta decay and related processes.
- Date
- March 21 (Fri) at 14:00 - 15:30, 2025 (JST)
- Speaker
-
- Gordon Baym (Professor Emeritus, University of Illinois, USA)
- Venue
- Seminar Room #359 (Main Venue)
- via Zoom
- Language
- English
- Host
- Tetsuo Hatsuda
This is a iTHEMS-FQSP joint seminar.
We ask the question of how angular momentum is conserved in a number of related processes, from elastic scattering of a circularly polarized photon by an atom, where the scattered photon has a different spin direction than the original photon; to scattering of a fully relativistic spin-1/2 particle by a central potential; to inverse beta decay in which an electron is emitted following the capture of a neutrino on a nucleus, where the final spin is in a different direction than that of the neutrino – an apparent change of angular momentum.
The apparent non-conservation of angular momentum arises in the quantum measurement process in which the measuring apparatus does not have an initially well-defined angular momentum, but is localized in direction in the outside world. We generalize the discussion to massive neutrinos and electrons, and examine nuclear beta decay and electron-positron annihilation processes through the same lens, enabling physically transparent derivations of angular and helicity distributions in these reactions.
Reference
- Gordon Baym, Jen-Chieh Peng, and C. J. Pethick, Understanding the puzzle of angular momentum conservation in beta decay and related processes, doi: https://www.pnas.org/doi/abs/10.1073/pnas.2416768121
This is a closed event for scientists. Non-scientists are not allowed to attend. If you are not a member or related person and would like to attend, please contact us using the inquiry form. Please note that the event organizer or speaker must authorize your request to attend.