Mass-concentration relation of clusters of galaxies from CFHTLenS
  Based on weak lensing data from the Canada-France-Hawaii Telescope Lensing
Survey (CFHTLenS), in this paper we study the mass-concentration ($M$-$c$)
relation for $\sim 200$ redMaPPer clusters in the fields. We extract the
$M$-$c$ relation by measuring the density profiles of individual clusters
instead of using stacked weak lensing signals. By performing Monte Carlo
simulations, we demonstrate that although the signal-to-noise ratio for each
individual cluster is low, the unbiased $M$-$c$ relation can still be reliably
derived from a large sample of clusters by carefully taking into account the
impacts of shape noise, cluster center offset, dilution effect from member or
foreground galaxies, and the projection effect. Our results show that within
error bars the derived $M$-$c$ relation for redMaPPer clusters is in agreement
with simulation predictions. There is a weak deviation in that the halo
concentrations calibrated by Monte Carlo simulations are somewhat higher than
that predicted from ${\it Planck}$ cosmology.
