Weak-Lensing Mass Calibration of ACTPol Sunyaev-Zel'dovich Clusters with
  the Hyper Suprime-Cam Survey
  We present weak-lensing measurements using the first-year data from the Hyper
Suprime-Cam Strategic Survey Program on the Subaru telescope for eight galaxy
clusters selected through their thermal Sunyaev-Zel'dovich (SZ) signal measured
at 148 GHz with the Atacama Cosmology Telescope Polarimeter experiment. The
overlap between the two surveys in this work is 33.8 square degrees, before
masking bright stars. The signal-to-noise ratio of individual cluster lensing
measurements ranges from 2.2 to 8.7, with a total of 11.1 for the stacked
cluster weak-lensing signal. We fit for an average weak-lensing mass
distribution using three different profiles, a Navarro-Frenk-White profile, a
dark-matter-only emulated profile, and a full cosmological hydrodynamic
emulated profile. We interpret the differences among the masses inferred by
these models as a systematic error of 10\%, which is currently smaller than the
statistical error. We obtain the ratio of the SZ-estimated mass to the
lensing-estimated mass (the so-called hydrostatic mass bias $1-b$) of
$0.74^{+0.13}_{-0.12}$, which is comparable to previous SZ-selected clusters
from the Atacama Cosmology Telescope and from the {\sl Planck} Satellite. We
conclude with a discussion of the implications for cosmological parameters
inferred from cluster abundances compared to cosmic microwave background
primary anisotropy measurements.
