  The total mass of clusters of galaxies is a key parameter to study massive
halos. It relates to numerous gravitational and baryonic processes at play in
the framework of large scale structure formation, thus rendering its
determination important but challenging. From a sample of the 11 X-ray bright
clusters selected from the excpres sample, we investigate the optical and X-ray
properties of clusters with respect to their total mass derived from weak
gravitational lensing. From multi-color wide field imaging obtained with
MegaCam at CFHT, we derive the shear profile of each individual cluster of
galaxies. We perform a careful investigation of all systematic sources related
to the weak lensing mass determination. The weak lensing masses are then
compared to the X-ray masses obtained from the analysis of XMM observations and
assuming hydrostatic equilibrium. We find a good agreement between the two mass
proxies although a few outliers with either perturbed morphology or poor
quality data prevent to derive robust mass estimates. The weak lensing mass is
also correlated with the optical richness and the total optical luminosity, as
well as with the X-ray luminosity, to provide scaling relations within the
redshift range 0.4<z<0.6. These relations are in good agreement with previous
works at lower redshifts. For the L_X-M relation we combine our sample with two
other cluster and group samples from the literature, thus covering two decades
in mass and X-ray luminosity, with a regular and coherent correlation between
the two physical quantities.

Cosmology and Nongalactic Astrophysics