Measurement of prompt hadron production ratios in pp collisions at

The charged-particle production ratios , K − /K + , π − /π + , , (K + +K − )/(π + +π − ) and are measured with the LHCb detector using 0.3 nb−1 of pp collisions delivered by the LHC at and 1.8 nb−1 at . The measurements are performed as a function of transverse momentum p T and pseudorapidity η . The production ratios are compared to the predictions of several Monte Carlo generator settings, none of which are able to describe adequately all observables. The ratio is also considered as a function of rapidity loss, Δy ≡y beam −y , and is used to constrain models of baryon transport.