Chiral-symmetry realization for even- and odd-parity baryon resonances

Area of Science:

• Nuclear Physics
• Particle Physics
• Quantum Chromodynamics

Background:

• Baryon resonances are fundamental to understanding the strong nuclear force.
• Chiral symmetry (ChS) is a key principle in quantum chromodynamics, governing the behavior of hadrons.
• Existing models struggle to consistently describe baryon resonances with both even and odd parities.

Purpose of the Study:

• To collectively investigate even and odd parity baryon resonances using chiral symmetry.
• To propose a new quartet scheme for classifying these resonances.
• To derive parameter-free predictions for baryon masses and decay properties.

Main Methods:

• Theoretical investigation based on chiral symmetry principles.
• Development of a quartet scheme grouping Delta and N(*) resonances.
• Derivation of mass constraints and one-pion decay selection rules.

Main Results:

• The proposed quartet scheme successfully unifies even and odd parity baryon resonances.
• Parameter-free mass constraints derived from the scheme align with experimentally observed masses for spin 1/2, 3/2, and 5/2 states.
• The scheme predicts specific selection rules for one-pion decays, such as the absence of N(1720)-->piDelta(1232) decay.

Conclusions:

• The quartet scheme provides a consistent framework for understanding baryon resonances within chiral symmetry.
• Experimental confirmation of the predicted decay selection rules is crucial for validating the role of chiral symmetry.
• This work offers a new perspective on the structure and interactions of baryon resonances.