Title: Measurement of Charm Production in Two-Photon Collisions at LEP
 

Inclusive charm production in  gamma-gamma  collisions
has been studied with the L3 detector at the LEP collider.
Hadronic final states containing charm particles were 
identified by detecting electrons or muons
from their semi-leptonic decays. 
Charm particles in the final state were also identified 
by the reconstruction of charged D* meson decays.
The total cross section for the process 
e+ e- ---> e+ e- c bar(c) X
has been measured at several centre-of-mass
energies between 189 GeV and 202 GeV.
Even including real and virtual gluon emission (NLO QCD) the direct
process  gamma-gamma --> c bar (c) 
is insufficient to describe charm production in gamma-gamma collisions.
 The cross section values and event distributions require resolved processes,
sensitive to the gluon density function of the photon.
Including this contribution good agreement is found with NLO QCD predictions.
The total cross sections 
( e+ e-) --> e+ e- c bar(c) X ) and  
 (gamma-gamma ---> c bar(c) X) are also measured 
as function of the two-photon centre-of-mass energy in the 
interval  W(gamma-gamma)  between 5 GeV and 70 GeV.
 We observe a steeper rise with energy as compared to
hadron-hadron cross sections and 
to  (gamma-gamma --> hadrons).


Parallel sessions: 1, 2, 3, 7 
Plenary sessions: 3, 4, 11, 12