  We show that the intensity of pumped states near Weyl point is different when
pumped with left- and right-handed circular polarized light, which leads to a
special circular dichroism (CD) in time-dependent angle resolved photoemission
spectra (ARPES). We derive the expression for the CD of time-dependent ARPES,
which is directly related to the chirality of Weyl fermions. Based on the above
derivation, we further propose a method to determine the chirality for a given
Weyl point from the CD of time-dependent ARPES. The corresponding CD spectra
for TaAs has then been calculated from the first principle, which can be
compared with the future experiments.
