Measurement of $V^0$ production ratios in $pp$ collisions at $\sqrt{s}=0.9$ and 7\,TeV

Abstract

The $\bar{\hat{I}}›/\hat{I}›$ and $\bar{\hat{I}}›/K_{\mathrm{S}}^0$ production ratios are measured by the LHCb detector from $0.3{\mathrm{nb}}^{-1}$ of $pp$ collisions delivered by the LHC at $\sqrt{s}=0.9$\,TeV and $1.8{\mathrm{nb}}^{-1}$ at $\sqrt{s}=7$\,TeV. Both ratios are presented as a function of transverse momentum, $p_{\mathrm{T}}$, and rapidity, $y$, in the ranges {$0.15<p_{\mathrm{T}}<2.50\mathrm{GeV}/c$} and {$2.0<y<4.5$}. Results at the two energies are in good agreement as a function of rapidity loss, $\hat{I}”y=y_{\mathrm{beam}}-y$, and are consistent with previous measurements. The ratio $\bar{\hat{I}}›/\hat{I}›$, measuring the transport of baryon number from the collision into the detector, is smaller in data than predicted in simulation, particularly at high rapidity. The ratio $\bar{\hat{I}}›/K_{\mathrm{S}}^0$, measuring the baryon-to-meson suppression in strange quark hadronisation, is significantly larger than expected.