Exclusive π+π−π+π− and π+π0π−π0 production in two photon collisions at L3

Abstract Exclusive ϱ 0 ϱ 0 and ϱ + ϱ − production in two-photon collisions for quasi-real photons and ϱ 0 ϱ 0 production, involving highly virtual photons, was measured by the L3 experiment at LEP. The spin-parity-helicity analysis of ϱ 0 ϱ 0 and ϱ + ϱ − systems at Q 2 ≈ 0 was performed. A dominance of J P = 2 + and helicity 2 is observed. The cross sections of the process γγ ∗ → ϱ 0 ϱ 0 for 1.2 Q 2 2 and for 1.1 W γγ Q 2 and as a function of the two-photon center-of-mass energy W γγ .