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

Abstract

The charged-particle production ratios $\bar{p}/p$, $K^-/K^+$, $π^-/π^+$, $(p + \bar{p})/(π^+ + π^-)$, $(K^+ + K^-)/(π^+ + π^-)$ and $(p + \bar{p})/(K^+ + K^-)$ are measured with the LHCb detector using $0.3 {\rm nb^{-1}}$ of $pp$ collisions delivered by the LHC at $\sqrt{s} = 0.9$ TeV and $1.8 {\rm nb^{-1}}$ at $\sqrt{s} = 7$ TeV. The measurements are performed as a function of transverse momentum $p_{\rm T}$ 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 $\bar{p}/p$ is also considered as a function of rapidity loss, $Δy \equiv y_{\rm beam} - y$, and is used to constrain models of baryon transport.

Incorrect entries in Table 2 corrected. No consequences for rest of paper