Measurement of prompt hadron production ratios in $pp$ collisions at $\sqrt{s}=$ 0.9 and 7 TeV

The charged-particle production ratios $\bar{p}\mathrm{/}p$, $K^{-}\mathrm{/}{K}^{+}$, ${\pi }^{-}\mathrm{/}{\pi }^{+}$, $(p+\bar{p})\mathrm{/}({\pi }^{+}+{\pi }^{-})$, $(K^{+}+K^{-})\mathrm{/}({\pi }^{+}+{\pi }^{-})$ and $(p + \bar{p})/(K^+ + K^-)$aremeasuredwiththeLHCbdetectorusing$0.3 {\rm nb^{-1}}$of$pp$collisionsdeliveredbytheLHCat$\sqrt{s} = 0.9$TeVand$1.8 {\rm nb^{-1}}$at$\sqrt{s} = 7$ TeV. The measurements are performed as a function of transverse momentum $p_{\mathrm{T}}$ 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 $\bar{p}\mathrm{/}p$ is also considered as a function of rapidity loss, $\mathrm{\Delta }y\equiv y_{\mathrm{b}\mathrm{e}\mathrm{a}\mathrm{m}}-y$, and is used to constrain models of baryon transport.