Observation of B decays to two kaons

Area of Science:

• High-energy physics
• Particle physics
• Hadron spectroscopy

Background:

• The Belle experiment collected 449 million BB[over ] pairs at the KEKB asymmetric-energy electron-positron collider.
• Understanding B meson decays provides insights into the Standard Model of particle physics and CP violation.

Purpose of the Study:

• To observe and measure the branching fractions and partial-rate asymmetries of B(+)-->K[over ](0)K(+) and B(0)-->K[over ](0)K(0) decays.
• To search for B(0)-->K(+)K(-) decays and set an upper limit on its branching fraction.
• To measure branching fractions and asymmetries for B(+)-->K(0)pi(+) decays.

Main Methods:

• Analysis of 449 million BB[over ] pairs collected by the Belle detector.
• Statistical analysis to determine signal significance, branching fractions, and asymmetries.
• Simultaneous fit to extract decay parameters.

Main Results:

• Clear signals observed for B(+)-->K[over ](0)K(+) (5.3 sigma) and B(0)-->K[over ](0)K(0) (6.0 sigma) decays.
• Measured branching fractions: B(B(+)-->K[over ](0)K(+))=(1.22(-0.28-0.16)(+0.32+0.13))x10(-6) and B(B(0)-->K[over ](0)K(0))=(0.87(-0.20)(+0.25)+/-0.09)x10(-6).
• Measured partial-rate asymmetries: A(CP)(B(+)-->K[over ](0)K(+))=0.13(-0.24)(+0.23)+/-0.02 and A(CP)(B(0)-->K[over ](0)K(0))=-0.58(-0.66)(+0.73)+/-0.04.
• Branching fraction for B(+)-->K(0)pi(+) measured as (22.8(-0.7)(+0.8)+/-1.3)x10(-6) with A(CP)(B(+)-->K(0)pi(+))=0.03+/-0.03+/-0.01.
• Upper limit set for B(0)-->K(+)K(-) branching fraction at 4.1x10(-7) (90% CL).

Conclusions:

• The study successfully observed and quantified key B meson decays involving kaons.
• The measurements provide valuable data for testing theoretical models of particle physics.
• The absence of a significant B(0)-->K(+)K(-) signal and its upper limit further constrain new physics scenarios.