Search for the Decay B+-->K+ tau-/+ mu+/-

Area of Science:

• Particle Physics
• High-Energy Physics
• Experimental Physics

Background:

• Lepton flavor violation (LFV) is a key signature of physics beyond the Standard Model.
• The B+ meson system provides a sensitive probe for new physics due to its rich decay modes.

Purpose of the Study:

• To search for the lepton flavor violating decay B+ -> K+ tau mu.
• To constrain new physics models by setting limits on the branching fraction of this decay.

Main Methods:

• Analysis of 383 x 10^6 BBbar events collected by the BABAR detector.
• Full reconstruction of the signal B+ meson candidate in hadronic decay modes.
• Reconstruction of tau lepton kinematics from its decay products and other event information.

Main Results:

• Observed no significant excess of events beyond the expected background.
• Set an upper limit on the branching fraction B(B+ -> K+ tau mu) < 7.7 x 10^-5 at 90% confidence level.
• Improved model-independent bounds on the energy scale of flavor-changing new physics.

Conclusions:

• The absence of signal is consistent with the Standard Model but places stringent constraints on new physics scenarios.
• This search contributes to the ongoing effort to uncover new fundamental particles and interactions.