We present the X-shooter Lens Survey ( XLENS ) data .
The main goal of XLENS is to disentangle the stellar and dark matter content of massive early-type galaxies ( ETGs ) , through combined strong gravitational lensing , dynamics and spectroscopic stellar population studies .
The sample consists of 11 lens galaxies covering the redshift range from 0.1 to 0.45 and having stellar velocity dispersions between 250 and 380 \mathrm { km } \mathrm { s } ^ { -1 } .
All galaxies have multi-band , high-quality HST imaging .
We have obtained long-slit spectra of the lens galaxies with X-shooter on the VLT .
We are able to disentangle the dark and luminous mass components by combining lensing and extended kinematics data-sets , and we are also able to precisely constrain stellar mass-to-light ratios and infer the value of the low-mass cut-off of the IMF , by adding spectroscopic stellar population information .
Our goal is to correlate these IMF parameters with ETG masses and investigate the relation between baryonic and non-baryonic matter during the mass assembly and structure formation processes .
In this paper we provide an overview of the survey , highlighting its scientific motivations , main goals and techniques .
We present the current sample , briefly describing the data reduction and analysis process , and we present the first results on spatially resolved kinematics .