The  Vera C. Rubin Legacy Survey of Space and Time (LSST) will be undertaken with  a 3.2 gigapixel camera— the largest CCD camera ever constructed on a telescope—mounted on a 8.4m diameter primary mirror. The survey will be in the ugrizy bands and will scan all of the available sky every few days, for a survey duration of ten years. Multiple (international) science working groups have been formed to work with LSST data; the LSST Dark Energy Science Collaboration (LSST DESC), as its name implies, focuses on dark energy studies with LSST, using weak lensing, galaxy clustering, clusters, and supernovae as the main cosmic probes; cross-correlations across the probes are also a major topic of interest. CPAC is playing a major role in constructing a large-scale synthetic galaxy catalog for LSST DESC Data Challenge 2, as well as a web-based validation framework, called DESCQA. Our research interests span the broad range of LSST DESC science.