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Neutron Resonance Widths and the Porter-Thomas Distribution
Alexander Volya1, Hans A Weidenmüller2, Vladimir Zelevinsky3
1Department of Physics, Florida State University, Tallahassee, Florida 32306-4350, USA.
Physical Review Letters
|August 15, 2015
Summary
The Porter-Thomas distribution (PTD) for neutron widths is challenged by new evidence. We found that coupling to decay channels introduces terms violating orthogonal invariance, modifying the PTD significantly.
Area of Science:
- Nuclear physics
- Quantum mechanics
Background:
- The Porter-Thomas distribution (PTD) is a fundamental statistical model for describing partial neutron widths.
- Recent experimental data have raised questions about the validity of the PTD in certain nuclear systems.
Purpose of the Study:
- To investigate the theoretical basis for deviations from the Porter-Thomas distribution.
- To identify the physical mechanisms responsible for the observed modifications of the PTD.
Main Methods:
- Analysis of the effective Hamiltonian in nuclear reactions.
- Identification of terms violating orthogonal invariance.
- Calculation of modifications due to coupling to decay channels.
Main Results:
- Two specific terms in the effective Hamiltonian were identified as violating orthogonal invariance.
- These terms arise from the coupling to decay channels, including the neutron channel and nonstatistical gamma decays.
- Realistic estimates show these couplings significantly alter the PTD, aligning with experimental observations.
Conclusions:
- The deviations from the Porter-Thomas distribution are explained by coupling effects to decay channels.
- The study provides a theoretical framework to understand and predict modifications to the PTD in nuclear physics.
- This work reconciles experimental findings with theoretical predictions, enhancing our understanding of nuclear decay processes.
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