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

The charged-particle production ratios (p) over bar /p, K-/K+, pi(-)/pi(+), (p+(p) over bar)/(pi(+)/pi(-)), (K++K-)/(pi(+)/pi(-)) and (p+(p) over bar)/(K++K-) are measured with the LHCb detector using 0.3 nb(-1) of pp collisions delivered by the LHC at root s = 0.9 TeV and 1.8 nb(-1) at root s = 7 TeV. The measurements are performed as a function of transverse momentum p(T) and pseudorapidity eta. 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) over bar /p is also considered as a function of rapidity loss, Delta y equivalent to y(beam) - y, and is used to constrain models of baryon transport.