  We present a renormalization group analysis of the disorder effects on the
low-energy behaviors of twodimensional tilted Dirac-fermion systems, in which
the fermions have two distinct orbitals unrelated by any symmetry. Four types
of disordered potential, two interorbital and two intraorbital, are considered.
If there is only one type of interorbital disorder, the fermion-disorder
scattering induces logarithmic or power-law corrections to the fermion density
of states and specific heat. In contrast, the intraorbital disorder can turn
the system into a strongly disordered phase. In this disordered phase,
calculations based on self-consistent Born approximation reveal that the Dirac
point is destroyed and replaced by a bulk Fermi arc. We also study the
interplay of four types of disorder, and find that the Dirac point can either
remain intact or give place to a Fermi arc. We obtain the condition for the
emergence of a Fermi arc in this case. Our results indicate that disorders can
result in rich low-energy properties of tilted Dirac fermions.
