  We report the measurement of a new observable of jet quenching in central
Pb-Pb collisions at $\sqrt{s_{\rm NN}} = 2.76$ TeV, based on the semi-inclusive
rate of charged jets recoiling from a high transverse momentum (high-$p_{\rm
T}$) charged hadron trigger. Jets are measured using collinear-safe jet
reconstruction with infrared cutoff for jet constituents of 0.15 GeV/$c$, for
jet resolution parameters $R = 0.2$, 0.4 and 0.5. Underlying event background
is corrected at the event-ensemble level, without imposing bias on the jet
population. Recoil jet spectra are reported in the range
$20<p_\mathrm{T,jet}^\mathrm{ch}<100$ GeV/$c$. Reference distributions for pp
collisions at $\sqrt{s} = 2.76$ TeV are calculated using Monte Carlo and NLO
pQCD methods, which are validated by comparing with measurements in pp
collisions at $\sqrt{s} = 7$ TeV. The recoil jet yield in central Pb-Pb
collisions is found to be suppressed relative to that in pp collisions. No
significant medium-induced broadening of the intra-jet energy profile is
observed within 0.5 radians relative to the recoil jet axis. The angular
distribution of the recoil jet yield relative to the trigger axis is found to
be similar in central Pb-Pb and pp collisions, with no significant
medium-induced acoplanarity observed. Large-angle jet deflection, which may
provide a direct probe of the nature of the quasi-particles in hot QCD matter,
is explored.
