  We investigate two-pion emission decays of singly charmed and bottom baryons,
focusing on $\Lambda_Q^*(1P)$ and $\Xi_Q^*(1P)$ with $Q=c$ (charm) or $b$
(bottom) quarks and $J^P=1/2^-,3/2^-$, belonging to antisymmetric flavor
triplet $\bar{\boldsymbol{3}}_F$. Our analysis encompasses both sequential
processes, involving intermediate states belonging to symmetric flavor sextet
$\boldsymbol{6}_F$ such as $\Sigma_Q(1S)$ and $\Xi_Q^\prime(1S)$ respectively
with $J^P=1/2^+,3/2^+$, derived from the chiral quark model, and direct process
crucial for comparison with experimental data, whose coupling constants
estimated using the chiral-partner scheme. We also incorporate the convolution
of the parent particle's mass for the Dalitz plot, enabling a more realistic
comparison with experimental data. We scrutinize the Dalitz plots of these
negative parity states in light of recent Belle measurements for
$\Lambda_c(2625)^+$. Our findings support the assignment of $\Lambda_c(2625)^+$
as the $\lambda$-mode excitation with $J^P=3/2^-$ in the quark model, deduced
from the the ${\Lambda_c\pi}$ invariant mass distribution, and we then give
predictions for other cases, including the $\Xi_Q^*$ decays. The observed
asymmetry in the ${\pi\pi}$ invariant mass distribution underscores the
important role of the direct process, reflecting the chiral-partner structure
in the heavy baryon sector. It is evident that the presence of the direct
process is not significant in the three-body decays unless the $S$-wave
resonance contribution is suppressed. We suggest further experimental
verification to test our predictions and get more insights into the structure
of heavy baryons.
