Cross section measurement of $\tau$ pairs in two photon collisions with the L3 detector at LEP 2

The production of tau pairs in gamma gamma collisions is studied with the L3 detector at LEP. Data were collected at square root =189-202 GeV for a total integrated luminosity of 393.0 pb/sup -1/. An exclusive decay channel is considered, with tau /sup +or-/ to e/sup +or-/ nu /sub tau / nu /sub e/ and tau /sup -or+/ to rho /sup -or+/ nu /sub tau /, with rho /sup -or+/ to pi /sup -or+/ pi /sup 0/. The cross section sigma (e/sup +/e/sup -/ to e/sup +/e/sup -/ tau /sup +/ tau /sup -/) is compared to O( alpha /sup 4/) QED calculations. The cross section of tau production is measured in gamma gamma collisions for the first time at LEP 2. (9 refs).