Measurement of forward $J/\psi$ production cross-sections in $pp$ collisions at $\sqrt{s}=13$ TeV

Information

LHCb-PAPER-2015-037
CERN-PH-EP-2015-222
arXiv:1509.00771 [PDF]

(Submitted on 02 Sep 2015)
JHEP 10 (2015) 172
Inspire 1391511

Tools

Abstract

The production of $J/\psi$ mesons in proton-proton collisions at a centre-of-mass energy of $\sqrt{s}=13$ TeV is studied with the \lhcb detector. Cross-section measurements are performed as a function of the transverse momentum $p_\mathrm{T}$ and the rapidity $y$ of the $J/\psi$ meson in the region $p_\mathrm{T}<14\mathrm{GeV}/c$ and $2.0<y<4.5$, for both prompt $J/\psi$ mesons and $J/\psi$ mesons from $b$-hadron decays. The production cross-sections integrated over the kinematic coverage are $15.03\pm 0.03\pm 0.94$ $\mu$b for prompt $J/\psi$ and $2.25\pm 0.01\pm 0.14$ $\mu$b for $J/\psi$ from $b$-hadron decays, assuming zero polarization of the $J/\psi$ meson. The first uncertainties are statistical and the second systematic. The cross-section reported for $J/\psi$ mesons from $b$-hadron decays is used to extrapolate to a total $b\bar{b}$ cross-section. The ratios of the cross-sections with respect to $\sqrt{s}=8$ TeV are also determined.

Figures and captions

Invariant mass (left) and pseudo decay time (right) distributions for the kinematic bin $2< p_{\rm T} <3 {\mathrm{ Ge V /}c} $, $3.0<y<3.5$, with fit results superimposed. The solid (red) line is the total fit function, the shaded (green) area corresponds to the background component. The prompt $ { J \mskip -3mu/\mskip -2mu\psi \mskip 2mu}$ contribution is shown in cross-hatched area (blue), $ { J \mskip -3mu/\mskip -2mu\psi \mskip 2mu}$ -from-$b$ in a solid (black) line and the tail contribution due to the association of $ { J \mskip -3mu/\mskip -2mu\psi \mskip 2mu}$ with the wrong PV is shown in full filled (magenta) area. The tail contribution is not visible in the invariant mass plot.	Fig1a.pdf [23 KiB] HiDef png [413 KiB] Thumbnail [224 KiB] *.C file
	Fig1b.pdf [36 KiB] HiDef png [676 KiB] Thumbnail [299 KiB] *.C file
Double differential cross-section for prompt $ { J \mskip -3mu/\mskip -2mu\psi \mskip 2mu}$ mesons as a function of $p_{\rm T}$ in bins of $y$. Statistical and systematic uncertainties are added in quadrature.	Fig2.pdf [17 KiB] HiDef png [166 KiB] Thumbnail [166 KiB] *.C file
Double differential cross-section for $ { J \mskip -3mu/\mskip -2mu\psi \mskip 2mu}$ -from-$b$ mesons as a function of $p_{\rm T}$ in bins of $y$. Statistical and systematic uncertainties are added in quadrature.	Fig3.pdf [17 KiB] HiDef png [171 KiB] Thumbnail [172 KiB] *.C file
Fractions of $ { J \mskip -3mu/\mskip -2mu\psi \mskip 2mu} $-from-$b$ mesons in bins of $ { J \mskip -3mu/\mskip -2mu\psi \mskip 2mu}$ $p_{\rm T}$ and $y$. Statistical and systematic uncertainties are added in quadrature.	Fig4.pdf [17 KiB] HiDef png [155 KiB] Thumbnail [149 KiB] *.C file
Differential cross-sections as a function of $ p_{\rm T} $ integrated over $y$ for (left) prompt $ { J \mskip -3mu/\mskip -2mu\psi \mskip 2mu}$ and (right) $ { J \mskip -3mu/\mskip -2mu\psi \mskip 2mu}$ -from-$b$ mesons.	Fig5a.pdf [15 KiB] HiDef png [149 KiB] Thumbnail [150 KiB] *.C file
	Fig5b.pdf [15 KiB] HiDef png [147 KiB] Thumbnail [145 KiB] *.C file
Differential cross-sections as a function of $y$ integrated over $p_{\rm T}$ for (left) prompt $ { J \mskip -3mu/\mskip -2mu\psi \mskip 2mu}$ and (right) $ { J \mskip -3mu/\mskip -2mu\psi \mskip 2mu}$ -from-$b$ mesons.	Fig6a.pdf [14 KiB] HiDef png [118 KiB] Thumbnail [119 KiB] *.C file
	Fig6b.pdf [14 KiB] HiDef png [114 KiB] Thumbnail [116 KiB] *.C file
Ratios of differential cross-sections between measurements at $\sqrt{s}=13\mathrm{ Te V} $ and $\sqrt{s}=8\mathrm{ Te V} $ as a function of $p_{\rm T}$ in bins of $y$ for (left) prompt $ { J \mskip -3mu/\mskip -2mu\psi \mskip 2mu}$ mesons and (right) $ { J \mskip -3mu/\mskip -2mu\psi \mskip 2mu}$ -from-$b$ mesons.	Fig7a.pdf [19 KiB] HiDef png [194 KiB] Thumbnail [179 KiB] *.C file
	Fig7b.pdf [20 KiB] HiDef png [214 KiB] Thumbnail [204 KiB] *.C file
Ratios of differential cross-sections between measurements at $\sqrt{s}=13\mathrm{ Te V} $ and $\sqrt{s}=8\mathrm{ Te V} $ as a function of $y$ integrated over $p_{\rm T}$ for (left) prompt $ { J \mskip -3mu/\mskip -2mu\psi \mskip 2mu}$ and (right) $ { J \mskip -3mu/\mskip -2mu\psi \mskip 2mu}$ -from-$b$ mesons. The FONLL calculation [64] is compared to the measured $ { J \mskip -3mu/\mskip -2mu\psi \mskip 2mu}$ -from-$b$ production ratio.	Fig8a.pdf [13 KiB] HiDef png [100 KiB] Thumbnail [99 KiB] *.C file
	Fig8b.pdf [16 KiB] HiDef png [247 KiB] Thumbnail [160 KiB] *.C file
Ratios of differential cross-sections between measurements at $\sqrt{s}=13\mathrm{ Te V} $ and $\sqrt{s}=8\mathrm{ Te V} $ as a function of $ p_{\rm T} $ integrated over $y$ for (left) prompt $ { J \mskip -3mu/\mskip -2mu\psi \mskip 2mu}$ mesons and (right) $ { J \mskip -3mu/\mskip -2mu\psi \mskip 2mu}$ -from-$b$ mesons. Calculations of NRQCD [65] and FONLL [64] are compared to prompt $ { J \mskip -3mu/\mskip -2mu\psi \mskip 2mu}$ mesons and $ { J \mskip -3mu/\mskip -2mu\psi \mskip 2mu}$ -from-$b$ mesons, respectively.	Fig9a.pdf [15 KiB] HiDef png [142 KiB] Thumbnail [130 KiB] *.C file
	Fig9b.pdf [17 KiB] HiDef png [230 KiB] Thumbnail [168 KiB] *.C file
The $ { J \mskip -3mu/\mskip -2mu\psi \mskip 2mu}$ production cross-section for (left) prompt $ { J \mskip -3mu/\mskip -2mu\psi \mskip 2mu}$ and (right) $ { J \mskip -3mu/\mskip -2mu\psi \mskip 2mu}$ -from-$b$ mesons as a function of $pp$ collision energy in the LHCb fiducial region compared to the FONLL calculation [27]. In general, the correlated and uncorrelated systematic uncertainties among different measurements are of comparable magnitude.	Fig10a.pdf [13 KiB] HiDef png [52 KiB] Thumbnail [30 KiB] *.C file
	Fig10b.pdf [13 KiB] HiDef png [143 KiB] Thumbnail [115 KiB] *.C file
Differential cross-sections as a function of $p_{\rm T}$ integrated over $y$ in the range $2.0<y<4.5$, (left) compared with the NRQCD calculation [65] for prompt $ { J \mskip -3mu/\mskip -2mu\psi \mskip 2mu}$ and (right) compared with the FONLL calculation [27] for $ { J \mskip -3mu/\mskip -2mu\psi \mskip 2mu}$ -from-$b$ mesons.	Fig11a.pdf [16 KiB] HiDef png [228 KiB] Thumbnail [174 KiB] *.C file
	Fig11b.pdf [17 KiB] HiDef png [352 KiB] Thumbnail [214 KiB] *.C file
Animated gif made out of all figures.	PAPER-2015-037.gif Thumbnail

Tables and captions

Relative systematic uncertainties (in %) on the $ { J \mskip -3mu/\mskip -2mu\psi \mskip 2mu}$ cross-section measurements. The uncertainty from the $t_z$ fit only affects $ { J \mskip -3mu/\mskip -2mu\psi \mskip 2mu} $-from-$b$ mesons. Most of the uncertainties are fully correlated between bins, with the exception of the $p_{\rm T}$ , $y$ spectrum dependence and the simulation statistics, which are considered uncorrelated.	Table_1.pdf [57 KiB] HiDef png [99 KiB] Thumbnail [47 KiB] tex code
Double differential production cross-section in $\mathrm{nb}/( {\mathrm{ Ge V /}c} )$ for prompt $ { J \mskip -3mu/\mskip -2mu\psi \mskip 2mu}$ mesons in bins of ($ p_{\rm T} ,y$). The first uncertainties are statistical, the second are the correlated systematic uncertainties shared between bins and the last are the uncorrelated systematic uncertainties.	Table_2.pdf [35 KiB] HiDef png [119 KiB] Thumbnail [50 KiB] tex code
Double differential production cross-section in $\mathrm{nb}/( {\mathrm{ Ge V /}c} )$ for $ { J \mskip -3mu/\mskip -2mu\psi \mskip 2mu} $-from-$b$ mesons in bins of ($ p_{\rm T} ,y$). The first uncertainties are statistical, the second are the correlated systematic uncertainties shared between bins and the last are the uncorrelated systematic uncertainties.	Table_3.pdf [36 KiB] HiDef png [123 KiB] Thumbnail [51 KiB] tex code
Relative systematic uncertainty (in %) on the ratio of the cross-section in $pp$ collisions at $\sqrt{s}=13 \mathrm{ Te V} $ relative to that at $\sqrt{s}=8\mathrm{ Te V} $. The systematic uncertainty from $t_z$ fits only affects $ { J \mskip -3mu/\mskip -2mu\psi \mskip 2mu} \text{-from-}b$ .	Table_4.pdf [46 KiB] HiDef png [37 KiB] Thumbnail [16 KiB] tex code
Production cross-sections of prompt $ { J \mskip -3mu/\mskip -2mu\psi \mskip 2mu}$ and $ { J \mskip -3mu/\mskip -2mu\psi \mskip 2mu}$ -from-$b$ mesons, integrated over the LHCb fiducial region, in $pp$ collisions at various centre-of-mass energies [12,18,30]. The first uncertainty is the uncorrelated component, and the second the correlated one.	Table_5.pdf [53 KiB] HiDef png [30 KiB] Thumbnail [14 KiB] tex code
The fraction of $ { J \mskip -3mu/\mskip -2mu\psi \mskip 2mu}$ -from-$b$ mesons (in %) in bins of the $ { J \mskip -3mu/\mskip -2mu\psi \mskip 2mu}$ transverse momentum and rapidity. The uncertainties are statistical only. The systematic uncertainties are negligible.	Table_6.pdf [35 KiB] HiDef png [134 KiB] Thumbnail [68 KiB] tex code
Differential cross-sections $d\sigma/dp_\mathrm{T}$ (in $\mathrm{nb}/( {\mathrm{ Ge V /}c} )$) for prompt $ { J \mskip -3mu/\mskip -2mu\psi \mskip 2mu}$ and $ { J \mskip -3mu/\mskip -2mu\psi \mskip 2mu}$ -from-$b$ mesons, integrated over $y$. The first uncertainties are statistical and the second (third) are uncorrelated (correlated) systematic uncertainties amongst bins.	Table_7.pdf [36 KiB] HiDef png [140 KiB] Thumbnail [75 KiB] tex code
Differential cross-sections $d\sigma/dy$ (in $ {\rm \upmu b}$ ) for prompt $ { J \mskip -3mu/\mskip -2mu\psi \mskip 2mu}$ and $ { J \mskip -3mu/\mskip -2mu\psi \mskip 2mu}$ -from-$b$ mesons, integrated over $p_{\rm T}$ . The first uncertainties are statistical and the second (third) are the uncorrelated (correlated) systematic uncertainties.	Table_8.pdf [28 KiB] HiDef png [72 KiB] Thumbnail [34 KiB] tex code
The ratio of cross-sections between measurements at 13 TeV and 8 TeV in different bins of $p_{\rm T}$ and $y$ for prompt $ { J \mskip -3mu/\mskip -2mu\psi \mskip 2mu}$ mesons. The systematic errors are negligible.	Table_9.pdf [35 KiB] HiDef png [145 KiB] Thumbnail [73 KiB] tex code
The ratio of cross-sections between measurements at 13 TeV and 8 TeV in different bins of $p_{\rm T}$ and $y$ for $ { J \mskip -3mu/\mskip -2mu\psi \mskip 2mu}$ -from-$b$ mesons. The systematic uncertainties are negligible.	Table_10.pdf [35 KiB] HiDef png [148 KiB] Thumbnail [78 KiB] tex code
The relative increase of the total efficiency (in %), for a $-20\%$ polarisation rather than zero, in different bins of $p_{\rm T}$ and $y$.	Table_11.pdf [35 KiB] HiDef png [132 KiB] Thumbnail [64 KiB] tex code

Supplementary Material [file]

Supplementary material full pdf	supple[..].pdf [414 KiB]
This ZIP file contains supplemetary material for the publication LHCb-PAPER-2015-037. The files are: supplementary.pdf : An overview of the extra figures .C .pdf, .png, .eps : The figures in various formats	Fig1.pdf [18 KiB] HiDef png [212 KiB] Thumbnail [215 KiB] *C file
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