First observation of the decay B --> J/psistraight phiK

Area of Science:

• Particle Physics
• High Energy Physics
• Quantum Chromodynamics

Background:

• B meson decays are crucial for testing the Standard Model of particle physics.
• Understanding rare B meson decays provides insights into fundamental quark interactions.
• Previous studies have explored various B meson decay modes, but this specific channel was unobserved.

Purpose of the Study:

• To report the first observation of the B-->J/psistraight phiK decay.
• To measure the branching fraction of this newly observed decay.
• To investigate B meson decays involving the creation of an additional quark-antiquark pair.

Main Methods:

• Analysis of 9.6x10^6 B&Bmacr; meson pairs collected using the CLEO detector.
• Identification of ten fully reconstructed B-->J/psistraight phiK candidate events.
• Estimation of background events to ensure the significance of the observation.

Main Results:

• Observed ten candidate events for the B-->J/psistraight phiK decay with an estimated background of 0.5+/-0.2 events.
• Measured the branching fraction B(B-->J/psistraight phiK) = (8.8(+3.5)(-3.0)[stat]+/-1.3[syst])x10^-5.
• This represents the first B meson decay observed that necessitates the creation of an additional s&smacr; quark pair.

Conclusions:

• The first evidence for the B-->J/psistraight phiK decay has been established.
• This observation opens new avenues for studying rare B meson decays and quark dynamics.
• The finding highlights the capability of current experiments to probe complex particle interactions.