  We present a study of Ks band luminosity evolution of the asymptotic giant
branch (AGB) population in simple stellar systems using star clusters in the
Large Magellanic Cloud (LMC). We determine physical parameters of LMC star
clusters including center coordinates, radii, and foreground reddenings. Ages
of 83 star clusters are derived from isochrone fitting with the Padova models,
and those of 19 star clusters are taken from the literature. The AGB stars in
102 star clusters with log(age) = 7.3 - 9.5 are selected using near-infrared
color magnitude diagrams based on 2MASS photometry. Then we obtain the Ks band
luminosity fraction of AGB stars in these star clusters as a function of ages.
The Ks band luminosity fraction of AGB stars increases, on average, as age
increases from log(age) ~ 8.0, reaching a maximum at log(age) ~ 8.5, and it
decreases thereafter. There is a large scatter in the AGB luminosity fraction
for given ages, which is mainly due to stochastic effects. We discuss this
result in comparison with five simple stellar population models. The maximum Ks
band AGB luminosity fraction for bright clusters is reproduced by the models
that expect the value of 0.7 - 0.8 at log(age) = 8.5 - 8.7. We discuss the
implication of our results with regard to the study of size and mass evolution
of galaxies.
