Exclusive $\pi^{+}\pi^{-}\pi^{+}\pi^{-}$ and $\pi^{+}\pi^{0}\pi^{-} \pi^{0}$ production in two photon collisions at L3

Exclusive rho /sup 0/ rho /sup 0/ and rho /sup +/ rho /sup -/ production in two-photon collisions for quasi-real photons and rho /sup 0/ rho /sup 0/ production, involving highly virtual photons, was measured by the L3 experiment at LEP. The spin-parity-helicity analysis of rho /sup 0/ rho /sup 0/ and rho /sup +/ rho /sup -/ systems at Q/sup 2/ approximately= 0 was performed. A dominance of J /sup P/ = 2/sup +/ and helicity 2 is observed. The cross sections of the process gamma gamma * to rho /sup 0/ rho /sup 0/ for 1.2 < Q/sup 2/ < 30 GeV/sup 2/ and for 1.1 < W/sub gamma gamma / < 3.0 GeV are determined as a function of photon virtuality Q/sup 2/ and as a function of the two-photon center-of-mass energy W/sub gamma gamma /. (14 refs).