Using an amplitude analysis to measure the photon polarisation in decays

Area of Science:

• High-energy particle physics
• Quantum chromodynamics
• Hadron spectroscopy

Background:

• Precise measurement of fundamental parameters in particle physics is crucial for testing theoretical models.
• Photon polarization in B meson decays offers a sensitive probe of underlying dynamics.
• Existing methods may have limitations in precision or model dependence.

Purpose of the Study:

• To propose and validate a novel method for measuring the photon polarization parameter in B meson decays.
• To demonstrate the feasibility of this measurement using amplitude analysis.
• To assess the potential precision achievable with current and future collider experiments.

Main Methods:

• Utilized amplitude analysis of B meson decays (both charged and neutral systems).
• Employed simplified models to simulate B -> X gamma and B -> X ll decays.
• Validated the amplitude analysis technique and assessed model independence.

Main Results:

• Demonstrated the feasibility of measuring the photon polarization parameter irrespective of model parameters.
• Obtained similar sensitivities to the parameter from both charged and neutral hadronic systems.
• Estimated statistical uncertainties of 0.009 for LHCb (9 fb^-1) and 0.018 for Belle II (5 fb^-1) under ideal conditions.

Conclusions:

• The proposed amplitude analysis method is a viable approach for precise photon polarization measurements.
• Future experiments at LHCb and Belle II can achieve high precision in determining this parameter.
• These measurements will provide stringent tests of the Standard Model and probe New Physics.