  Gapped graphene has been proposed to be a good platform to observe the valley
Hall effect, a transport phenomenon involving the flow of electrons that are
characterized by different valley indices. In the present work, we show that
this phenomenon is better described as an instance of the orbital Hall effect,
where the ambiguous "valley" indices are replaced by a physical quantity, the
orbital magnetic moment, which can be defined uniformly over the entire
Brillouin zone. This description removes the arbitrariness in the choice of
arbitrary cut-off for the valley-restricted integrals in the valley Hall
conductivity, as the conductivity in the orbital Hall effect is now defined as
the Brillouin zone integral of a new quantity, called the orbital Berry
curvature. This reformulation in terms of OHE provides the direct explanation
to the accumulated opposite orbital moments at the edges of the sample,
observed in previous Kerr rotation measurements.
