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The pion-photon transition form factor (TFF) provides strong constraints onthe pion distribution amplitude (DA). We perform an analysis of all existingdata (CELLO, CLEO, BaBar, Belle) on the pion-photon TFF by means of light-conepQCD approach in which we include the next-to-leading order correction to thevalence-quark contribution and estimate the non-valence-quark contribution by aphenomenological model based on the TFF's limiting behavior at both $Q^2\to 0$and $Q^2\to\infty$. At present, the pion DA is not definitely determined, it ishelpful to have a pion DA model that can mimic all the suggested behaviors,especially to agree with the constraints from the pion-photon TFF in wholemeasured region within a consistent way. For the purpose, we adopt theconventional model for pion wavefunction/DA that has been constructed in ourprevious paper \cite{hw1}, whose broadness is controlled by a parameter $B$. Wefix the DA parameters by using the CELLO, CLEO, BABAR and Belle data within thesmaller $Q^2$ region ($Q^2 \leq 15$ GeV$^2$), where all the data are consistentwith each other. And then the pion-photon TFF is extrapolated into larger $Q^2$region. We observe that the BABAR favors $B=0.60$ which has the behavior closeto the Chernyak-Zhitnitsky DA, whereas the recent Belle favors $B=0.00$ whichis close to the asymptotic DA. We need more accurate data at large $Q^2$ regionto determine the precise value of $B$, and the definite behavior of pion DA canbe concluded finally by the consistent data in the coming future.

Information on the Pion Distribution Amplitude from the Pion-Photon Transition Form Factor with the Belle and BaBar Data