Charmless two- and four-body b-hadron decays at LHCb

In this document, two of the latest results obtained by the LHCb Collaboration on the area of charmless b decays are summarised. The first observation of the very rare B 0 → K + K − decay mode is presented, together with the most precise measurements of B (B 0 → K + K − ) and B (B 0 s → π + π − ). The second result is related to CP violation in baryonic matter. A search for P and CP violation was performed by studying triple-product asymmetries in the Λ 0 b → p π − π + π − and Λ 0 b → p π − K + K − decay channels. This leads to the first evidence of matter-antimatter asymmetry in the baryonic sector.