We investigate the $bar KN$ and coupled channels system in a finite volume and study the properties of the $Lambda(1405)$ resonance. We calculate the energy levels in a finite volume and solve the inverse problem of determining the resonance position
in the infinite volume. We devise the best strategy of analysis to obtain the two poles of the $Lambda(1405)$ in the infinite volume case, with sufficient precision to distinguish them.
We report on a recent calculation of the properties of the $DNN$ system, a charmed meson with two nucleons. The system is analogous to the $bar K NN$ system substituting a strange quark by a charm quark. Two different methods are used to evaluate the
binding and width, the Fixed Center approximation to the Faddeev equations and a variational calculation. In both methods we find that the system is bound by about 200 MeV and the width is smaller than 40 MeV, a situation opposite to the one of the $bar K NN$ system and which makes this state well suited for experimental observation.
The loop level flavor changing neutral currents transitions of the $Sigma_{b}to n l^+l^-$ and $Sigma_{c}to p l^+l^-$ are investigated in full QCD and heavy quark effective theory in the light cone QCD sum rules approach. Using the most general form o
f the interpolating current for $Sigma_{Q}$, $Q=b$ or $c$, as members of the recently discovered sextet heavy baryons with spin 1/2 and containing one heavy quark, the transition form factors are calculated using two sets of input parameters entering the nucleon distribution amplitudes, namely, QCD sum rules and lattice QCD inputs. The obtained results are used to estimate the decay rates of the corresponding transitions. Since such type transitions occurred at loop level in the standard model, they can be considered as good candidates to search for the new physics effects beyond the SM.
