  We theoretically investigated the magnetoresistance (MR) and planar Hall
effect (PHE) in Weyl semimetals based on the semiclassical Boltzmann theory,
focusing on the fine structure of the band dispersion. We identified that the
negative longitudinal MR and sign change in the PHE occur because of the
negative off-diagonal effective-mass with no topological effects or chiral
anomaly physics. Our results highlight the crucial role of the off-diagonal
effective-mass, which can cause anomalous galvanomagnetic effects. We propose
that the PHE creates a dip in their temperature dependence, which enables the
experimental detection of the Weyl point.
