Threshold $\pi^0$ photoproduction in relativistic chiral perturbation theory

Understand

We present a calculation of $\pi^0$ photoproduction on the proton in manifestly Lorentz-invariant baryon chiral perturbation theory up to and including chiral order $q^4$.

• With the results we analyze the latest $\pi^0$ photoproduction data in the threshold region obtained at the Mainz Microtron.
• In the calculation of observables and the fit of the low-energy constants, we take $S$, $P$, and $D$ waves into account.
• We compare the results for the multipoles with the corresponding single-energy analysis.