Production of prompt $\Lambda ^+_ c $ baryons is studied in protonlead and leadproton collisions collected with the LHCb detector at the LHC. The data sample corresponds to an integrated luminosity of $1.58\pm0.02\,nb^{1} $ recorded at a nucleonnucleon centreofmass energy of $\sqrt{ s_{ {NN}}}=5.02\mathrm{\,TeV} $. Measurements of the differential crosssection and the forwardbackward production ratio are reported using $\Lambda ^+_ c $ candidates with transverse momenta in the range $210 {\mathrm{\,GeV\!/}c} $ and rapidities in the ranges of $1.54.0$ and $4.5 2.5$ in the nucleonnucleon centreofmass system. The ratio of crosssections of $\Lambda ^+_ c $ baryons and $ D ^0$ mesons is also reported. The results are compared with nexttoleading order theoretical calculations using nuclear parton distribution functions.
Distributions of the invariant mass, $m( p K ^ \pi ^+ )$, for (a) the forward data sample with $2 < p_{\mathrm{ T}} < 10 {\mathrm{\,GeV\!/}c} $ and $1.5 < y^* < 4.0$ and (b) the backward data sample with $2 < p_{\mathrm{ T}} < 10 {\mathrm{\,GeV\!/}c} $ and $4.5 < y^* < 2.5$. The red dotted line is the inclusive $\Lambda ^+_ c $ candidates, the grey shaded area the combinatorial background while the blue solid line is the sum of the two. 
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Distributions of $\log_{10}\chi^2_{\text{IP}} (\Lambda ^+_ c ) $ distribution with the fit results overlaid for (a) the forward data sample with $2 < p_{\mathrm{ T}} < 10 {\mathrm{\,GeV\!/}c} $ and $1.5 < y^* < 4.0$, and (b) the backward data sample with $2 < p_{\mathrm{ T}} < 10 {\mathrm{\,GeV\!/}c} $ and $4.5 < y^* < 2.5$. The solid blue curve is the sum. The red dotted line is the prompt component, the green is the $\Lambda ^+_ c \mathrm{\text{}from\text{}}b $ component while the grey shaded area denotes the combinatorial background. 
ipchi2_pA.pdf [23 KiB] HiDef png [363 KiB] Thumbnail [100 KiB] *.C file 

ipchi2_Ap.pdf [23 KiB] HiDef png [454 KiB] Thumbnail [114 KiB] *.C file 

Doubledifferential crosssection of prompt $\Lambda ^+_ c $ baryons in $ p\mathrm{Pb} $ collisions in the (a) forward and (b) backward collision samples. The error bars represent the quadratic sum of the statistical and the systematic uncertainties. 
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Differential crosssection of prompt $\Lambda ^+_ c $ baryons in $ p\mathrm{Pb} $ collisions as a function of (a) $ p_{\mathrm{ T}} $ and (b) $y^{*}$ in the forward and backward sample. The error bars represent the quadratic sum of the statistical and the systematic uncertainties. 
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cy.pdf [14 KiB] HiDef png [127 KiB] Thumbnail [49 KiB] *.C file 

Forwardbackward production ratios $R_\mathrm{FB}$ as functions of (a) $ p_{\mathrm{ T}} $ integrated over $2.5<y^*<4$ and (b) $y^*$ integrated over $2< p_{\mathrm{ T}} <10 {\mathrm{\,GeV\!/}c} $. The error bars represent the quadratic sum of the statistical and the systematic uncertainties. 
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Production ratio $ R_{\Lambda ^+_ c / D ^0 }$ between $\Lambda ^+_ c $ baryons to $ D ^0$ mesons as a function of $ p_{\mathrm{ T}} $ integrated over four different rapidity regions. The error bars represent the quadratic sum of the statistical and the systematic uncertainties. 
lc2d0_pt.pdf [32 KiB] HiDef png [314 KiB] Thumbnail [97 KiB] *.C file 

Production ratio $ R_{\Lambda ^+_ c / D ^0 }$ between $\Lambda ^+_ c $ baryons and $ D ^0$ mesons as a function of $y^*$ integrated over $2 < p_{\mathrm{ T}} < 10 {\mathrm{\,GeV\!/}c} $. The error bars represent the quadratic sum of the statistical and the systematic uncertainties. 
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Animated gif made out of all figures. 
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Summary of systematic and statistic uncertainties for differential crosssections. The ranges indicate the variations between bins. 
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Measured differential crosssections (in units of $\mathrm{ \,mb} /( {\mathrm{\,GeV\!/}c} )$) of prompt $\Lambda ^+_ c $ baryons as functions of $ p_{\mathrm{ T}} $ in $ p\mathrm{Pb} $ forward and backward data in different rapidity regions. The right column shows the results for $ p_{\mathrm{ T}} > 7 {\mathrm{\,GeV\!/}c} $ and $2.5<y^*<3.5$, which are used to compute the $ R_\mathrm{FB} $ values at $ p_{\mathrm{ T}} > 7 {\mathrm{\,GeV\!/}c} $. The first uncertainties are statistical and the second are systematic. 
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Differential crosssections (in units of $\mathrm{ \,mb} $) for prompt $\Lambda ^+_ c $ baryons as functions of $y^{*}$ in $ p\mathrm{Pb} $ forward and backward data. The first uncertainties are statistical and the second are systematic. 
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Forwardbackward prompt $\Lambda ^+_ c $ production ratio $ R_\mathrm{FB} $ as a function of $ p_{\mathrm{ T}} $ in the common $y^*$ range between 2.5 and 4. The first uncertainty is statistical and the second is systematic. 
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$ R_\mathrm{FB} $ ratio as a function of $y^*$ in $2 < p_{\mathrm{ T}} < 10 {\mathrm{\,GeV\!/}c} $. The first uncertainty is statistical and the second is systematic. 
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Production ratio $ R_{\Lambda ^+_ c / D ^0 } $ as a function of $ p_{\mathrm{ T}} $ in the forward and backward rapidity regions. The first uncertainty is statistical and the second is systematic. 
Table_7.pdf [44 KiB] HiDef png [219 KiB] Thumbnail [34 KiB] tex code 

Production ratio $ R_{\Lambda ^+_ c / D ^0 } $ as a function of $y^*$ in $2 < p_{\mathrm{ T}} < 10 {\mathrm{\,GeV\!/}c} $. The first uncertainty is statistical and the second is systematic. 
Table_8.pdf [42 KiB] HiDef png [163 KiB] Thumbnail [26 KiB] tex code 

Measured differential crosssections (in units of $\mathrm{ \,mb} /( {\mathrm{\,GeV\!/}c} )$) of prompt $\Lambda ^+_ c $ baryons as functions of $ p_{\mathrm{ T}} $ in $ p\mathrm{Pb} $ forward and backward data in different rapidity regions. The right column shows the results for $ p_{\mathrm{ T}} > 7 {\mathrm{\,GeV\!/}c} $ and $2.5<y^*<3.5$, which are used to compute the $ R_\mathrm{FB} $ values at $ p_{\mathrm{ T}} > 7 {\mathrm{\,GeV\!/}c} $. The first uncertainties are statistical and the second are systematic. 
Table_3.pdf [45 KiB] HiDef png [128 KiB] Thumbnail [21 KiB] tex code 

Differential crosssections (in units of $\mathrm{ \,mb} $) for prompt $\Lambda ^+_ c $ baryons as functions of $y^{*}$ in $ p\mathrm{Pb} $ forward and backward data. The first uncertainties are statistical and the second are systematic. 
Table_4.pdf [45 KiB] HiDef png [147 KiB] Thumbnail [25 KiB] tex code 

Forwardbackward prompt $\Lambda ^+_ c $ production ratio $ R_\mathrm{FB} $ as a function of $ p_{\mathrm{ T}} $ in the common $y^*$ range between 2.5 and 4. The first uncertainty is statistical and the second is systematic. 
Table_5.pdf [35 KiB] HiDef png [137 KiB] Thumbnail [22 KiB] tex code 

$ R_\mathrm{FB} $ ratio as a function of $y^*$ in $2 < p_{\mathrm{ T}} < 10 {\mathrm{\,GeV\!/}c} $. The first uncertainty is statistical and the second is systematic. 
Table_6.pdf [41 KiB] HiDef png [67 KiB] Thumbnail [11 KiB] tex code 

Production ratio $ R_{\Lambda ^+_ c / D ^0 } $ as a function of $ p_{\mathrm{ T}} $ in the forward and backward rapidity regions. The first uncertainty is statistical and the second is systematic. 
Table_7.pdf [44 KiB] HiDef png [219 KiB] Thumbnail [34 KiB] tex code 

Production ratio $ R_{\Lambda ^+_ c / D ^0 } $ as a function of $y^*$ in $2 < p_{\mathrm{ T}} < 10 {\mathrm{\,GeV\!/}c} $. The first uncertainty is statistical and the second is systematic. 
Table_8.pdf [42 KiB] HiDef png [163 KiB] Thumbnail [26 KiB] tex code 
Created on 09 December 2018.Citation count from INSPIRE on 09 December 2018.