Measurement of exclusive di-pion electroproduction with ZEUS at HERA 

The exclusive electoproduction of dipions was measured with the ZEUS
detector at HERA using an integrated luminosity of 363 pb-1.
The measurement was performed in the kinematic range of photon virtualities 
Q^2 > 5 GeV^2, photon proton centre-of-mass energies 40 < W < 160 GeV and
invariant masses of the dipion system between 1.2 and 5 GeV. The cross section 
is presented as a function of Q^2, W, the four-momentum transfer,t, and the 
longitudinal momentum fraction, u. The results are compared to determiantions 
based on measurements of vector mesons and to theoretical predictions for the
light-cone wave function of the photon.