  Higher-pseudospin fermions, associated with multiple band-crossings in
topological semimetals, are the condensed matter analogues of higher-spin
fermions in high-energy physics. In this paper, we demonstrate that analyzing
the response of a circular drive is an effective way to detect the topology of
the lowest-energy Bloch band, as it can be connected to a frequency-dependent
probe. The dichroic response exhibits circular dichroism due to the
differential excitation rates by the left- and right-circular orientations of a
time-periodic drive, induced on a filled band, because of the geometrical
properties of the Bloch bands. Our analytical approximation reveals that the
dichroic response is quantized for isotropic systems, when the frequency of the
drive is above a critical value, and thus correctly infers the ground-state
Chern number. We demonstrate this through explicit numerical computations by
considering three kinds of semimetals with pseudospin values of 1/2, 1, and
3/2, respectively, and all having linear dispersions. Furthermore, we
investigate the effects of tilt and anisotropy on the systems, and find that
although tilt does not have any effect on the response, the presence of
anisotropy can drastically hamper the quantization. Our scheme thus provides an
important methodology for designing future experiments to detect the topology
of band structures.
