  Nd2Ir2O7 is a correlated semimetal with the pyrochlore structure, in which
competing spin-orbit coupling and electron-electron interactions are believed
to induce a time-reversal symmetry broken Weyl semimetal phase characterized by
pairs of topologically protected Dirac points at the Fermi energy. However, the
emergent properties in these materials are far from clear, and exotic new
states of matter have been conjectured. Here we demonstrate optically that at
low temperatures the free carrier spectral weight is proportional to T^2 where
T is the temperature, as expected for massless Dirac electrons. However, we do
{\em not} observe the corresponding T^3 term in the specific heat. That the
system is not in a Fermi liquid state is further corroborated by the
"Planckian" T-linear temperature dependence of the momentum relaxation rate and
the progressive opening of a correlation-induced gap at low temperatures. These
observations can not be reconciled within the framework of band theory of
electron-like quasiparticles and point toward the effective decoupling of the
charge transport from the single particle sector.
