Measurements of the absolute branching fraction of Λc+ → pK-π+ and the relative branching fraction of Bu+ → p π+ π+ Σc(2520)--.

The baryonic decay Bu+ → p π+ π+ Σc(2455)-- is exploited in this thesis for two different measurements and constitutes their common element. A measurement of the absolute Λc+ → pK-π+ branching fraction was performed, in a model independent way and for the first time in a hadronic environment, on data recorded by the LHCb experiment during the years 2011 and 2012, corresponding to an integrated luminosity of 3fb-1 . The branching fraction is measured to be B(Λc+ → pK-π+ ) = 0.079 ± 0.015(stat) ± 0.008(syst) In addition, the first observation of the decays Bu+ → p π+ π+ Σc(2520)-- and Bu+ → p π+ π- Σc(2520)0 are reported using the same data sample. The branching fraction of the decay Bu+ → p π+ π+ Σc(2520)-- is measured with respect to the Bu+ → p π+ π+ Σc(2455)-- mode to be B(Bu+ → p π+ π+ Σc(2520)--) = (2.4 ± 0.78(stat) ± 0.64(syst)) · 10-4