Measurement of prompt hadron production ratios in pp collisions at √s = 0.9 and 7 TeV

The charged−particle production ratios p/p, K ⁻/K ⁺, π ⁻/π ⁺, (p + p)/(π ⁺+π ⁻), (K ⁺+K ⁻)/(π ⁺ + π ⁻) and (p+ p)/(K ⁺ + K ⁻) are measured with the LHCb detector using 0.3 nb⁻¹ of pp collisions delivered by the LHC at √s = 0.9 TeV and 1.8 nb⁻¹ at √s = 7 TeV. 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 p/p is also considered as a function of rapidity loss, Δy ≡ y_beam − y, and is used to constrain models of baryon transport.