Meson resonances in forward-angle $\pi^+\pi^-$ photoproduction

Assuming that the $\pi^+\pi^-$ photoproduction at forward angles and high energies is dominated by one pion exchange we calculate the $\pi^+\pi^-$ mass distributions for low partial waves. Predictions of the model agree well Assuming that the $\pi^+\pi^-$ photoproduction at forward angles and high energies is dominated by one pion exchange we calculate the $\pi^+\pi^-$ mass distributions for low partial waves. Predictions of the model agree well with the experimental data which indicate that the $S$, $P$ and $D$ waves are dominated by the $f_0(980)$, $\rho(770)$ and $f_2(1270)$, resonances respectively.