The first measurement of the branching fraction of the Ξc0 baryon in its decay to π− and Λ+c hadrons, B(Ξc0 → π−Λ+c ), is presented. This measurement was conducted with the LHCb detector, located on the Large Hadron Collider, using 13 TeV proton-proton collisions. There have been a number of theoretical predictions for the size of this branching fraction, spanning more than an order of magnitude; this large difference is primarily due to differing assumptions about the internal interactions contributing to the decay. The branching fraction measured here provides the first experimental evidence for the nature of these interactions; it is consistent with the larger predictions and inconsistent with the smaller ones, indicating a constructive interference effect. In addition, the second measurement of the branching fraction of the Ξc+ baryon in its decay to p, K−, and π+ hadrons, B(Ξc+ → pK−π+), is presented and found to be consistent with the Belle collaboration\u27s previous measurement while carrying a lower relative uncertainty
