Isospin Symmetry Breaking in the ^{71}Kr and ^{71}Br Mirror System

Area of Science:

• Nuclear Physics
• Nuclear Structure
• Quantum Chromodynamics

Background:

• Isospin symmetry is a fundamental principle in nuclear physics, stating that protons and neutrons are interchangeable in the nucleus.
• While generally approximate, deviations from isospin symmetry offer insights into nuclear forces and structure.
• Mirror nuclei, differing by one proton and one neutron, are expected to share similar ground-state spins and parities due to this symmetry.

Purpose of the Study:

• To investigate potential violations of isospin symmetry in the ^{71}Br and ^{71}Kr mirror nuclei system.
• To explore the nuclear structure of isotopes near the N=Z line.
• To search for exotic nuclear states, such as coexisting 0+ states, using advanced decay spectroscopy.

Main Methods:

• High-statistics beta decay study of ^{71}Kr.
• Advanced nuclear shell model calculations.
• Analysis of beta-delayed proton emission.

Main Results:

• Evidence for a broken isospin symmetry in the ground states of the ^{71}Br and ^{71}Kr mirror pair.
• Observation of a new state in ^{70}Se populated through beta-delayed proton emission.
• The newly observed state in ^{70}Se is interpreted as a potential coexisting 0+ state.

Conclusions:

• The findings challenge the assumption of perfect isospin symmetry in certain nuclear systems.
• The identified state in ^{70}Se provides new data for understanding nuclear structure phenomena like state coexistence.
• This research highlights the importance of studying symmetry breaking for a comprehensive understanding of nuclear physics.