Polarization Measurements of the Recoil Proton in $\pi^{0}$ Photoprodcution

Perturbative QCD theory predicts that the polarization components above the baryon resonance region should have a smooth dependence of $E_{\gamma}$ and approaching limits established by hadron helicity conservation in absence of baryon resonance. Published data show strong variation of polarization variables above $2 \mbox{ GeV}$ which could be a sign of high-mass resonance. We present preliminary results of $\pi^{0}$ photoproduction in $p(\vec{\gamma},\vec{p})\pi^0$ reaction from the Jefferson Lab Hall C experiments E04-108, E04-019, E07-002 and Hall A experiment E99-114 which all measured the polarization observables of proton using recoil polarization method with high statistics. Our data extends the polarization measurement of $\pi^{0}$ photoproduction up to $E_{\gamma}=5.7 \mbox{ GeV}$ with high four momentum transfer. The results show good agreement in the overlap region with previous experiment in Hall A that $E_{\gamma}$ up to $4.1 \mbox{ GeV}$. We will discuss the interpretation of these observations.