  Angular distribution of individual $\gamma$-rays, emitted from a
neutron-induced compound nuclear state via radiative capture reaction of
${}^{139}$La(n,$\gamma$) has been studied as a function of incident neutron
energy in the epithermal region by using germanium detectors.
  An asymmetry $A_{\mathrm{LH}}$ was defined as $(N_{\mathrm L}-N_{\mathrm
H})/(N_{\mathrm L}+N_{\mathrm H})$, where $N_{\mathrm L}$ and $N_{\mathrm H}$
are integrals of low and high energy region of a neutron resonance
respectively, and we found that $A_{\mathrm{LH}}$ has the angular dependence of
$(A\cos\theta_\gamma+B)$, where $\theta_\gamma$ is emitted angle of
$\gamma$-rays, with $A= -0.3881\pm0.0236$ and $B=-0.0747\pm0.0105$ in 0.74 eV
p-wave resonance.
  This angular distribution was analyzed within the framework of interference
between s- and p-wave amplitudes in the entrance channel to the compound
nuclear state, and it is interpreted as the value of the partial p-wave neutron
width corresponding to the total angular momentum of the incident neutron
combined with the weak matrix element, in the context of the mechanism of
enhanced parity-violating effects. Additionally we used the result to quantify
the possible enhancement of the breaking of the time-reversal invariance in the
vicinity of the p-wave resonance.
