  We combine the latest observations of disk galaxy photometry and rotation
curves at moderate redshift from the FORS Deep Field (FDF) with simple models
of chemical enrichment. Our method describes the buildup of the stellar
component through infall of gas and allows for gas and metal outflows. In this
framework, we keep a minimum number of constraints and we search a large volume
of parameter space, looking for the models which best reproduce the photometric
observations in the observed redshift range (0.5<z<1). We find the star
formation efficiency to correlate well with vMAX so that massive disks are more
efficient in the formation of stars and have a smaller spread in stellar ages.
This trend presents a break at around vMAX 140km/s. Galaxies on either side of
this threshold have significantly different age distributions. This break has
been already suggested by several authors in connection with the contribution
from either gravitational instabilities or supernova-driven turbulence to star
formation. No clear trend is seen between galaxy mass and infall timescale or
gas outflows. The model presented in this paper suggests massive disks have
formation histories resembling those of early-type galaxies, with highly
efficient and short-lived bursts, in contrast with low-mass disks, which have a
more extended star formation history. One option to explain the observed
shallow slope of the Tully-Fisher relation at intermediate redshift could be
small episodes of star formation in low-mass disks.
