Speaker
Description
We present a model for the J/ψ Λ spectrum in B− → J/ψ Λ p ̄ decays, including the $P^\Lambda_{\psi s}(4338)$
baryon recently observed by the LHCb collaboration. We assume production via triangle diagrams
which couple to the final state via non-perturbative interactions which are constrained by heavy-
quark and SU3-flavor symmetry. The bulk of the distribution is described by a triangle diagram
with a color-favored electroweak vertex, while the sharp $P^\Lambda_{\psi s}(4338)$ enhancement is due to the ψs
triangle singularity in another diagram featuring a 1/2− baryon consistent with Σc(2800). We predict a comparable $P^\Lambda_{\psi s}(4338)$ signal in $\eta_c \Lambda$, and anticipate possible large isospin mixing effects
through decays to $J/\psi \Sigma^0$ and $η_c \Sigma^0$.
