@ollerulf] $$\label{bs}
T = [1 - V G]^{-1}\, V \, ,$$ with $G$ the meson-baryon loop function. We choose to regularize it with the cutoff method to avoid potential pathologies of the dimensional regularization in the charm sector, where $G$ can become positive below threshold (and eventually produce bound states with a repulsive potential) [@zouwu]. There is another reason, because in order to respect rules of heavy quark symmetry in bound states, it was shown in Refs. [@lugeng; @xiaooz] that the same cutoff has to be used in all cases. Alternatively one can use a special $G$ function defined in Ref. [@altenbu].

The $G$ function for meson-baryon with the cutoff method is given by $$\begin{aligned}
 G_l &=& i \int \frac{d^4q}{(2\pi)^4} \frac{M_l}{E_l({\bf q})}\frac{1}{k^0+p^0 - q^0 - E_l({\bf q})+i\epsilon} \frac{1}{{\bf q}^2-m^2_l+i\epsilon}\nonumber\\
 &=& \int_{|{\bf q}|< q_{max}} \frac{d^3q}{(2\pi)^3}\frac{1}{2\omega_l({\bf q})}\frac{M_l}{E_l({\bf q})}\frac{1}{k^0+p^0-\omega_l({\bf q}) - E_l({\bf q})+i\epsilon}\, ,
 \end{aligned}$$ where $k^0+p^0=\sqrt{s}$ and $\omega_l$, $E_l$, are the energies of the meson and baryon respectively and $m_l,\,M_l$ the meson and baryon masses.

We evaluate Eq.  and look for poles in the second Riemann sheet, where we define $G^{II}_l$ for ${\rm Re}(\sqrt{s})$ bigger than the threshold of the $l$ channel as $$\begin{aligned}
G^{II}_l = G^I_l + i \frac{2M_l\,q}{4\pi\sqrt{s}}\, ,\end{aligned}$$ with 