- #1

BOAS

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## Homework Statement

A ##\pi^0## meson decays predominantly to two photons. Suppose the energies (E1, E2) and angle (##\theta##) between the emitted photons are measured. Find an expression for the ##\pi^0## mass in terms of E1, E2, and ##\theta##.

## Homework Equations

## The Attempt at a Solution

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In the pion rest frame, by momentum conservation, I know that the two photons are emitted with equal but opposite momenta.

##E'_{\pi} = m_{\pi}##

##E'_{\gamma} = p'_{\gamma}##

##E'_{\gamma 1} = p'_{\gamma 1} = E'_{\gamma 2} = p'_{\gamma 2} = \frac{E'_{\pi}}{2} = \frac{m_{\pi}}{2}##

I know how to transform the photon energies into the lab frame, but I don't understand how to include the angular dependency.

Thanks for any help you can give!