Measuring the Photon Polarization in [Formula presented]

We propose a way of measuring the photon polarization in radiative [Formula presented] decays into [Formula presented] resonance states decaying to [Formula presented], which can test the standard model and probe new physics. The photon polarization is shown to be measured by the up-down asymmetry of the photon direction relative to the [Formula presented] decay plane in the [Formula presented] resonance rest frame. The integrated asymmetry in [Formula presented], calculated to be [Formula presented] in the standard model, is measurable at currently operating [Formula presented] factories.