First symmetry tests in polarized Z0 decays to bbg

Area of Science:

• Particle Physics
• High Energy Physics
• Quantum Chromodynamics

Background:

• The Standard Model (SM) of particle physics successfully describes fundamental particles and forces.
• Symmetry tests in particle decays provide crucial probes for physics beyond the Standard Model.
• Polarized Z0 boson decays offer a unique laboratory for precise measurements of fundamental interactions.

Purpose of the Study:

• To conduct the first direct symmetry tests in polarized Z0 boson decays into bbg (bottom quark-antiquark-gluon) final states.
• To search for parity violation at the bbg vertex.
• To investigate T-odd, CP-even, or CP-odd final-state interactions.

Main Methods:

• Analysis of fully identified bbg states from polarized Z0 boson decays collected by the SLD experiment at SLAC.
• Studying asymmetries in b-quark polar and azimuthal angle distributions to probe parity violation.
• Measuring angular correlations between the three-jet plane and Z0 polarization to search for final-state interactions.

Main Results:

• Experimental results are consistent with the predictions of the Standard Model.
• No significant evidence for parity violation at the bbg vertex was observed.
• No evidence for anomalous T-odd, CP-even, or CP-odd final-state interactions was found.

Conclusions:

• The study sets 95% confidence level (C.L.) limits on potential anomalous contributions to Z0 boson decays.
• These findings strengthen the validation of the Standard Model in the context of heavy quark and gluon interactions.
• The performed symmetry tests provide stringent constraints for future theoretical and experimental investigations in particle physics.