Helical Phase Inflation and Monodromy in Supergravity Theory
  We study helical phase inflation in supergravity theory in details. The
inflation is driven by the phase component of a complex field along helical
trajectory. The helicoid structure originates from the monodromy of
superpotential with an singularity at origin.
  We show that such monodromy can be formed by integrating out heavy fields in
supersymmetric field theory. The supergravity corrections to the potential
provide strong field stabilizations for the scalars except inflaton, therefore
the helical phase inflation accomplishes the "monodromy inflation" within
supersymmetric field theory.
  The phase monodromy can be easily generalized for natural inflation, in which
the super-Planckian phase decay constant is realized with consistent field
stabilization. The phase-axion alignment is fulfilled indirectly in the process
of integrating out the heavy fields.
  Besides, we show that the helical phase inflation can be naturally realized
in no-scale supergravity with $SU(2,1)/SU(2)\times U(1)$ symmetry since the
no-scale K\"ahler potential provides symmetry factors of phase monodromy
directly. We also demonstrate that the helical phase inflation can reduce to
the shift symmetry realization of supergravity inflation. The super-Planckian
field excursion is accomplished by the phase component, which admits no
dangerous polynomial higher order corrections. The helical phase inflation
process is free from the UV-sensitivity problem, and it suggests that inflation
can be effectively studied in supersymmetric field theory close to the
unification scale in Grand Unified Theory and a UV-completed frame is not
prerequisite.
