Exclusive dipion production.

Justyna Tomaszewska
The exclusive electroproduction of two pions in the mass range \unit{0.4 $ < $ M$_{\pi \pi} < $ 2.5}{\GeV} Ahas been studied with the ZEUS detector at HERA using an integrated luminosity of \unit{82}{\invpb}. AThe two-pion invariant-mass distribution is interpreted in terms of the pion electromagnetic form factor, A$|F(M_{\pi \pi})|$, assuming that the studied mass range includes Athe contributions of the $\rho$, $\rho'$ and $\rho"$ vector-meson states.