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Mirror-symmetry violation in bound nuclear ground states
D E M Hoff1, A M Rogers2, S M Wang3
1Department of Physics and Applied Physics, University of Massachusetts Lowell, Lowell, MA, USA. dan@demhoff.com.
Nature
|April 3, 2020
Summary
Nuclear mirror symmetry is violated in strontium-73 and bromine-73 ground states. This finding reveals insights into charge-symmetry-breaking forces within atomic nuclei.
Area of Science:
- Nuclear Physics
- Particle Physics
- Quantum Mechanics
Background:
- Conservation laws are intrinsically linked to symmetries in physical systems.
- Nucleons (neutrons and protons) can be viewed as projections of a single fermion with isobaric spin (isospin).
- Mirror nuclei, with exchanged neutron and proton numbers, are expected to exhibit identical nuclear states due to mirror symmetry.
Purpose of the Study:
- To investigate potential violations of mirror symmetry in the ground states of specific mirror nuclei.
- To explore the implications of observed deviations from expected mirror symmetry for nuclear structure and forces.
Main Methods:
- Analysis of proton emission patterns from the T = 3/2 isobaric-analogue state in rubidium-73.
- Comparison of nuclear states between mirror nuclei strontium-73 and bromine-73.
- Determination of spin and parity assignments for nuclear states.
Main Results:
- Evidence for mirror-symmetry violation found in the bound nuclear ground states of strontium-73 and bromine-73.
- A spin assignment of Jπ = 5/2- is required for the isobaric-analogue state in rubidium-73.
- The ground state of strontium-73 differs from its mirror partner bromine-73 (Jπ = 1/2-).
Conclusions:
- The observed violation of mirror symmetry provides direct evidence for charge-symmetry-breaking forces in atomic nuclei.
- This finding challenges the assumption of perfect mirror symmetry in nuclear ground states.
- The study offers new insights into the fundamental forces governing nuclear structure.
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