D. Buskulic et al., MEASUREMENT OF THE D-ASTERISK(+ -) CROSS-SECTION IN 2-PHOTON COLLISIONS AT LEP/, Physics letters. Section B, 355(3-4), 1995, pp. 595-605
The inclusive production of D(+/-) mesons in photon-photon collisions
has been measured by the Aleph experiment at LEP with a beam energy o
f 45 GeV. The D(+) are detected in their decay to D-0 pi(+) with the
D-0 observed in three separate decay modes: (1) K(-)pi(+), (2) K(-)pi(
+)pi(0) and (3) K(-)pi(+)pi(-)pi(+), and analagously for the D(-) mod
es. A total of 33 events was observed from an integrated luminosity of
73 pb(-1) which corresponds to a cross section for sigma(e(+)e(-) -->
e(+)e(-)D(+/-)X) of 155+/-33+/-21 pb, This result is compatible with
both the direct production gamma gamma --> <c(c)over bar> in the Born
approximation and with a more complete calculation which includes bot
h radiative QCD corrections and contributions in which one of the phot
ons is first resolved into its quark and gluon constituents. The shape
s of distributions for events containing a D(+) are found to be bette
r described by the latter.