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

The $bar{Lambda} / Lambda$ and $bar{Lambda} / K^0_mathrm{S}$ 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, $Delta y = y_mathrm{beam} - y$, and are consistent with previous measurements. The ratio $bar{Lambda} / Lambda$, 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 $bar{Lambda} / K^0_mathrm{S}$, measuring the baryon-to-meson suppression in strange quark hadronisation, is significantly larger than expected.