Establishing CP Violation in b-Baryon Decays.

Area of Science:

• Particle Physics
• High Energy Physics
• Quantum Chromodynamics

Background:

• CP violation (CPV) is a fundamental phenomenon in particle physics, observed in meson decays but not yet definitively established in baryon decays.
• The discrepancy in CPV between meson and baryon systems remains a long-standing puzzle in the Standard Model of particle physics.

Purpose of the Study:

• To investigate the reasons behind the lack of definitive CP violation establishment in baryon decays compared to meson decays.
• To explore the potential for significant CPV in specific partial-wave amplitudes of Lambda_b decays.
• To propose new experimental strategies for probing CPV in baryon systems.

Main Methods:

• Analysis of partial-wave CP violation in Lambda_b -> p pi- and Lambda_b -> p K- decays.
• Investigating the destructive interference between different partial waves.
• Proposing the study of CPV observables in the angular distributions of Lambda_b -> p a1(1260) and Lambda_b -> p K1(1270) decay products.

Main Results:

• Individual partial-wave CPV in Lambda_b -> p pi- and p K- decays can exceed 10%.
• Destructive interference between partial waves suppresses the net direct CPV in these decays to small, currently measured values.
• The dynamics governing CPV in baryon decays differ significantly from those in meson decays.

Conclusions:

• The suppression of net CPV in observed Lambda_b decays is due to destructive interference between partial waves.
• The findings highlight distinct dynamics responsible for CPV in baryon versus meson systems.
• Observables associated with angular distributions in Lambda_b -> p a1(1260) and p K1(1270) decays offer promising avenues for experimentally identifying significant CPV.