  Quantum materials having Dirac fermions in conjunction with superconductivity
is believed to be the candidate materials to realize exotic physics as well as
advanced technology. Angle resolved photoemission spectroscopy (ARPES), a
direct probe of the electronic structure, has been extensively used to study
these materials. However, experiments often exhibit conflicting results on
dimensionality and momentum of the Dirac Fermions (e.g. Dirac states in BiPd, a
novel non-centrosymmetric superconductor), which is crucial for the
determination of the symmetry, time-reversal invariant momenta and other
emerging properties. Employing high-resolution ARPES at varied conditions, we
demonstrated a methodology to identify the location of the Dirac node
accurately and discover that the deviation from two-dimensionality of the Dirac
states in BiPd proposed earlier is not a material property. These results
helped to reveal the topology of the anisotropy of the Dirac states accurately.
We have constructed a model Hamiltonian considering higher-order spin-orbit
terms and demonstrate that this model provides an excellent description of the
observed anisotropy. Intriguing features of the Dirac states in a
non-centrosymmetric superconductor revealed in this study expected to have
significant implication in the properties of topological superconductors.
