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Open charm production and asymmetry in $p$Ne collisions at $\sqrt{s_{\scriptscriptstyle\rm NN}} =$ 68.5 GeV

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Abstract

A measurement of $D^0$ meson production by the LHCb experiment in its fixed-target configuration is presented. The production of $D^0$ mesons is studied with a beam of 2.5 TeV protons colliding on a gaseous neon target at rest, corresponding to a nucleon-nucleon centre-of-mass energy of $\sqrt{s_{\rm NN}}$ = 68.5 GeV. The sum of the $D^0$ and ${\overline D^0}$ production cross-section in $p$Ne collisions in the centre-of-mass rapidity range $y^{\star}\in [-2.29, 0]$ is found to be $\sigma_{D^{0}}^{y^\star \in [-2.29, 0]} = 48.2 \pm 0.3 \pm 4.5 \mu\textrm{b/nucleon}$ where the first uncertainty is statistical and the second is systematic. The $D^0-{\overline D^0}$ production asymmetry is also evaluated and suggests a trend towards negative values at large negative $y^{\star}$. The considered models do not account precisely for all the features observed in the LHCb data, but theoretical predictions including 1$\%$ intrinsic charm and 10$\%$ recombination contributions better describe the data than the other models considered.

Figures and captions

Invariant mass distributions of (left) $ K ^-$ $\pi ^+$ and (right) $ K ^+$ $\pi ^-$ candidates. The data are overlaid with the result of the fit.

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Measured $ D ^0$ cross-section in $\sqrt{s_{\scriptscriptstyle\text{NN}}} = 68.5\text{ Ge V} $ $ p\text{Ne}$ collisions as function of (left) $y^\star$ and (right) $ p_{\mathrm{T}} $. The quadratic sums of statistical and uncorrelated systematic uncertainties are given by the bars, while the grey boxes represent the correlated systematic uncertainties. The data are overlaid with theoretical predictions as described in the text.

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The $ D ^0 -\overline{ D } {}^0 $ production asymmetry in $\sqrt{s_{\scriptscriptstyle\text{NN}}} = 68.5\text{ Ge V} $ $ p\text{Ne}$ collisions as function of (left) centre-of-mass rapidity $y^\star$, and as function of (right) transverse momentum $ p_{\mathrm{T}} $. Quadratic sums of statistical and uncorrelated uncertainties are given by the error bars, while the grey boxes represent the correlated systematic uncertainties. The data are overlaid with theoretical predictions as described in the text.

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Tables and captions

Systematic and statistical uncertainties on the signal yields. Systematic uncertainties correlated between $y^\star$ or $ p_{\mathrm{T}}$ bins affect all measurements by the same relative amount. Ranges denote the minimum and the maximum values among the $y^\star$ or $ p_{\mathrm{T}}$ bins.

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Created on 20 April 2024.