Demonstration of cosmic microwave background delensing using the cosmic
  infrared background
  Delensing is an increasingly important technique to reverse the gravitational
lensing of the cosmic microwave background (CMB) and thus reveal primordial
signals the lensing may obscure. We present a first demonstration of delensing
on Planck temperature maps using the cosmic infrared background (CIB).
Reversing the lensing deflections in Planck CMB temperature maps using a linear
combination of the 545 and 857GHz maps as a lensing tracer, we find that the
lensing effects in the temperature power spectrum are reduced in a manner
consistent with theoretical expectations. In particular, the characteristic
sharpening of the acoustic peaks of the temperature power spectrum resulting
from successful delensing is detected at a significance of 16$\rm{\sigma}$,
with an amplitude of $A_{\rm{delens}} = 1.12 \pm 0.07$ relative to the expected
value of unity. This first demonstration on data of CIB delensing, and of
delensing techniques in general, is significant because lensing removal will
soon be essential for achieving high-precision constraints on inflationary
B-mode polarization.
