  We use public data from the CMS experiment to study the 2-prong substructure
of jets. The CMS Open Data is based on 31.8/pb of 7 TeV proton-proton
collisions recorded at the Large Hadron Collider in 2010, yielding a sample of
768,687 events containing a high-quality central jet with transverse momentum
larger than 85 GeV. Using CMS's particle flow reconstruction algorithm to
obtain jet constituents, we extract the 2-prong substructure of the leading jet
using soft drop declustering. We find good agreement between results obtained
from the CMS Open Data and those obtained from parton shower generators, and we
also compare to analytic jet substructure calculations performed to modified
leading-logarithmic accuracy. Although the 2010 CMS Open Data does not include
simulated data to help estimate systematic uncertainties, we use track-only
observables to validate these substructure studies.
