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Study of prompt $D^0$ meson production in $p$Pb at $\sqrt{s_{\mathrm{NN}}}= 8.16$ TeV at LHCb

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Abstract

The production of prompt $ D ^0 $ mesons in proton-lead collisions in the forward and backward configurations is studied. The data are collected with the LHCb detector at a center-of-mass energy per nucleon pair of $\sqrt{s_{\scriptscriptstyle\text{NN}}} =8.16\text{ Te V} $ and correspond to an integrated luminosity of $12.2\pm0.3\text{ nb} ^{-1} $ ($18.6\pm0.5\text{ nb} ^{-1} $) in the forward (backward) configuration. The integrated $ D ^0$ and $\overline{ D } {}^0$ cross-sections are measured to be $288.3\pm0.2 (\mathrm{stat.})\pm17.4 (\mathrm{syst.})\text{ mb} $ for the forward rapidity range $1.5<y^*<4$ and $308.9\pm0.1 (\mathrm{stat.})\pm30.5 (\mathrm{syst.})\text{ mb} $ for the backward range,$-5<y^*<-2.5$, in the $ p_{\mathrm{T}} $ interval from 0 to 16 $\text{ Ge V /}c$ . A suppression of $ D ^0$ production in the forward rapidity region relative to the backward rapidity is observed.

Figures and captions

Fit to the $M( K \pi )$ distributions in the (left) forward and (right) backward collision configurations. The kinematic range is $2.0< p_{\mathrm{T}} <3.0\text{ Ge V /}c ,\ 3.0<y^*<3.5$ ($2.0< p_{\mathrm{T}} <3.0\text{ Ge V /}c ,\ -4.5<y^*<-4.0$) for the forward (backward) configuration.

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Fit to the $\log_{10}\chi^2_{\text{IP}}$ ( $ D ^0$ ) distributions in the (left) forward and (right) backward collision configurations. The kinematic range is $2.0< p_{\mathrm{T}} <3.0\text{ Ge V /}c ,\ 3.0<y^*<3.5$ ($2.0< p_{\mathrm{T}} <3.0\text{ Ge V /}c ,\ -4.5<y^*<-4.0$) for the forward (backward) configuration.

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Double-differential cross-sections of prompt $ D ^0$ and $\overline{ D } {}^0$ mesons in $p$Pb collisions in the (left) forward and (right) backward collision configurations. The error bars are the statistical uncertainties while the boxes are the systematic uncertainties.

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X_conf_bwd.pdf [17 KiB]
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Differential cross-sections of prompt $ D ^0$ and $\overline{ D } {}^0$ mesons in $p$Pb collisions as a function of (left) $ p_{\mathrm{T}}$ and (right) $y^{*}$ in the forward and backward configurations. The error bars are the statistical uncertainties while the boxes are the systematic uncertainties.

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Forward and backward production ratio $R_{\mathrm{FB}}$ (left) as a function of $ p_{\mathrm{T}}$ integrated over common rapidity range $2.5 < |y^*| < 4.0$ for $ p_{\mathrm{T}} <7\text{ Ge V /}c $, over $2.5 < |y^*| < 3.5$ for $7< p_{\mathrm{T}} <9\text{ Ge V /}c $ and over $2.5<|y^*|<3.0$ for $9< p_{\mathrm{T}} <10\text{ Ge V /}c $, and (right) as a function of $y^*$ integrated up to $ p_{\mathrm{T}}$ = 16 $\text{ Ge V /}c$ . For the measurement at 8.16 $\text{ Te V}$ , the error bars mark statistical uncertainties and the boxes mark systematic uncertainties. At 5.02 $\text{ Te V}$ , the error bars represent the combined statistical and systematic uncertainties. The coloured bands mark the theoretical calculations using the HELAC-Onia generator, incorporating nPDFs EPPS16 (grey) and nCTEQ15 (blue).

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Animated gif made out of all figures.

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Tables and captions

Summary of systematic uncertainties, in %. For the forward sample, the kinematic range is $1.5<y^*<4$ for $ p_{\mathrm{T}} <7\text{ Ge V /}c $, $1.5<y^*<3.5$ for $7< p_{\mathrm{T}} <9\text{ Ge V /}c $, $1.5<y^*<3$ for $9< p_{\mathrm{T}} <14\text{ Ge V /}c $ and $1.5<y^*<2.5$ for $14< p_{\mathrm{T}} <16\text{ Ge V /}c $. For the backward sample, the kinematic range is $-5<y^*<-2.5$ for $ p_{\mathrm{T}} <6\text{ Ge V /}c $, $-4.5<y^*<-2.5$ for $6< p_{\mathrm{T}} <9\text{ Ge V /}c $, $-4<y^*<-2.5$ for $9< p_{\mathrm{T}} <13\text{ Ge V /}c $ and $-3.5<y^*<-2.5$ for $13< p_{\mathrm{T}} <16\text{ Ge V /}c $.

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Double differential cross-section $\frac{\mathrm{d}^2 \sigma}{\mathrm{d} p_{\mathrm{T}} \mathrm{d} y^*} \left[\text{ mb} /(\text{ Ge V /}c )\right]$ for prompt $ D ^0$ and $\overline{ D } {}^0$ mesons as functions of $ p_{\mathrm{T}}$ and $|y^{*}|$ in $p$Pb forward and backward data, respectively. The first uncertainty is statistical, the second is the component of the systematic uncertainty that is uncorrelated between bins and the third is the correlated component.

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Differential cross-section $\frac{\mathrm{d}\sigma}{\mathrm{d} p_{\mathrm{T}} } [\text{ mb} /(\text{ Ge V /}c )]$ for prompt $ D ^0 $ and $\overline{ D } {}^0$ mesons as a function of $ p_{\mathrm{T}} $ in $p$Pb forward and backward data, respectively. The first uncertainty is statistical, the second is the component of the systematic uncertainty that is uncorrelated across bins and the third is the correlated component.

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Differential cross-section $\frac{\mathrm{d} \sigma}{\mathrm{d} y^*} [\text{ mb} ]$ for prompt $ D ^0 $ and $\overline{ D } {}^0$ mesons as a function of $y^{*}$ in $p$Pb forward and backward data, respectively. The first uncertainty is statistical, the second is the component of the systematic uncertainty that is uncorrelated between bins and the third is the correlated component.

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Forward and backward production ratio $R_{\mathrm{FB}}$ in different $ p_{\mathrm{T}}$ bins integrated over the common rapidity range $2.5 < |y^*| < 4.0$ for $ p_{\mathrm{T}} <7\text{ Ge V /}c $ and over $2.5 < |y^*| < 3.5$ for $7< p_{\mathrm{T}} <10\text{ Ge V /}c $, and in different $y^*$ bins integrated up to $ p_{\mathrm{T}}$ = 16 $\text{ Ge V /}c$ . The first uncertainty is the statistical and the second is the systematic component.

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Created on 06 March 2021.