We present weak lensing results for 12 distant clusters determined from images obtained with the refurbished Hubble Space Telescope .
We detect the signature of gravitational lensing in 11 of the 12 clusters ; the clusters span nearly an order of magnitude in lensing strength .
The sample thus provides an excellent database for correlating direct mass estimates based on lensing with indirect ones which rely on baryonic tracers .
We examine the correlation between the cluster X-ray luminosities and the mean gravitational shear strengths and develop a model which allows us to predict the relationship expected from the properties of local clusters .
After allowing for various observational effects , we find that the predicted correlation is a reasonable match to the available data , indicating that there has been little evolution in the X-ray luminosity–central mass relationship between z \sim 0.4 and now .
We discuss the implications of this result in the context of the evolution of the X-ray luminosity function found by earlier workers .
The comparison between shear amplitudes and velocity dispersions , estimated from a modest sample of members ( \sim 30 ) , reveals a discrepancy in the sense that these velocity dispersions are typically over-estimated by factors of \sim 50 % .
This supports earlier suggestions that high dispersions measured for distant clusters may be seriously affected by both unidentified substructure and outliers .
Combining our shear-based mass estimates with morphologically-based luminosity estimates , we determine mass/light ratios of M / L _ { V } ^ { all } =180 ^ { +210 } _ { -110 } h ( M/L ) _ { \odot } for the entire population and 620 ^ { +250 } _ { -240 } h for spheroidal population where the evolutionary effects can be best treated .
We argue that this provides an upper bound to the present-day cluster mass/light ratio corresponding to \Omega \sim 0.4 .
Our results demonstrate the important role weak gravitational lensing can play in the study of the evolution of distant clusters , as the most direct and least biased probe of their growth .