Observation of B^{0}→pΛ[over ¯]D^{(*)-}

Area of Science:

• Particle Physics
• High-Energy Physics
• Quantum Chromodynamics

Background:

• B mesons are crucial for testing the Standard Model of particle physics.
• Understanding B meson decays provides insights into fundamental forces and particle interactions.

Purpose of the Study:

• To report the first observation of B0 -> p anti-proton D(-) and B0 -> p anti-proton D*- decays.
• To measure the branching fractions for these newly observed decay modes.
• To investigate the behavior of the dibaryon (p anti-proton) system in B decays.

Main Methods:

• Analysis of a large dataset (711 fb^-1) of B anti-B pairs collected by the Belle detector at the KEKB collider.
• Statistical analysis to establish the significance of the observed decay signals.
• Measurement of branching fractions and comparison with theoretical predictions.

Main Results:

• Observation of B0 -> p anti-proton D- with a statistical significance of 19.8 sigma.
• Observation of B0 -> p anti-proton D*- with a statistical significance of 10.8 sigma.
• Measured branching fractions: (25.1 +/- 2.6 +/- 3.5) x 10^-6 for B0 -> p anti-proton D- and (33.6 +/- 6.3 +/- 4.4) x 10^-6 for B0 -> p anti-proton D*-.
• Results are inconsistent with generalized factorization predictions.
• Observed threshold enhancement in the dibaryon (p anti-proton) system.

Conclusions:

• The observed B0 decays provide new data for studying weak interactions.
• The discrepancy with theoretical models highlights the need for refined theoretical frameworks.
• The dibaryon system's behavior offers clues about multi-hadron interactions.