Observation of B(+/-) --> p(-)pK(+/-).

Area of Science:

• High Energy Physics
• Particle Physics
• Quantum Chromodynamics

Background:

• B mesons are crucial for studying CP violation and new physics beyond the Standard Model.
• Understanding rare B meson decays provides stringent tests of the Standard Model.
• Baryonic B decays are less explored but offer unique insights into hadron structure and dynamics.

Purpose of the Study:

• To report the first observation of the B(+/-) --> p(-)pK(+/-) decay mode.
• To measure the branching fraction for this rare decay.
• To investigate the proton-antiproton invariant mass spectrum and set limits on related decays.

Main Methods:

• Analysis of 29.4 fb(-1) of data collected by the Belle detector at the KEKB collider.
• Identification of B(+/-) mesons and their decay products, specifically protons, antiprotons, and kaons.
• Statistical analysis to determine the significance of the signal and measure the branching fraction.

Main Results:

• Observation of the B(+/-) --> p(-)pK(+/-) decay, a novel b --> s transition involving final-state baryons.
• The measured branching fraction is B(B+/--->p(-)pK+/-) = [4.3(+1.1)(-0.9)(stat)+/-0.5(syst)]x 10(-6).
• The p(-)p mass spectrum is peaked at low mass, deviating from phase space expectations.

Conclusions:

• The observed decay provides the first evidence of a b --> s transition with baryons in the final state.
• The results offer new opportunities to study non-leptonic weak decays and hadron spectroscopy.
• Upper limits were set for B(0)-->p(-)pK(S) and B(+/-)-->p(-)p pi(+/-) decays, constraining new physics scenarios.