  Hot Jupiters (HJs) are short-period giant planets that are observed around ~
1% of solar-type field stars. One possible formation scenario for HJs is
high-eccentricity (high-e) migration, in which the planet forms at much larger
radii, is excited to high eccentricity by some mechanism, and migrates to its
current orbit due to tidal dissipation occurring near periapsis. We consider
high-e migration in dense stellar systems such as the cores of globular
clusters (GCs), in which encounters with passing stars can excite planets to
the high eccentricities needed to initiate migration. We study this process via
Monte Carlo simulations of encounters with a star+planet system including the
effects of tidal dissipation, using an efficient regularized restricted
three-body code. HJs are produced in our simulations over a significant range
of the stellar number density n_*. Assuming the planet is initially on a
low-eccentricity orbit with semimajor axis 1 au, for n_* < 1e3 pc^{-3} the
encounter rate is too low to induce orbital migration, whereas for n_* > 1e6
pc^{-3} HJ formation is suppressed because the planet is more likely ejected
from its host star, tidally disrupted, or transferred to a perturbing star. The
fraction of planets that are converted to HJs peaks at ~ 2% for intermediate
number densities of ~ 4e4 pc^{-3}. Warm Jupiters, giant planets with periods
between 10 and 100 days, are produced in our simulations with an efficiency of
up to ~ 0.5%. Our results suggest that HJs can form through high-e migration
induced by stellar encounters in the centers of of dense GCs, but not in their
outskirts where the densities are lower.
