Measurement of $\Upsilon$ production in $pp$ collisions at $\sqrt{s}=5 \ \rm{TeV}$

Information

LHCb-PAPER-2022-036
CERN-EP-2022-269
arXiv:2212.12664 [PDF]

(Submitted on 24 Dec 2022)
JHEP 07 (2023) 069
Inspire 2618202

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Abstract

The production cross-sections of $\Upsilon$ mesons, namely $\Upsilon(1S)$, $\Upsilon(2S)$ and $\Upsilon(3S)$, in $pp$ collisions at $\sqrt{s}=5 \ \rm{TeV}$ are measured with a data sample corresponding to an integrated luminosity of $9.13\pm{0.18} \ \rm{pb}^{-1}$ collected by the LHCb detector. The $\Upsilon$ mesons are reconstructed in the decay mode $\Upsilon \to {\mu}^+ {\mu}^-$. Double differential cross-sections times branching fractions, as functions of the transverse momentum $p_{\rm{T}}$ and the rapidity $y$ of the $\Upsilon$ mesons, are measured in the range $p_{\rm{T}} < 20 \ \rm{GeV}/c$ and $2.0<y<4.5$. The results integrated over these $p_{\rm{T}}$ and $y$ ranges are $\sigma(\Upsilon(1S)) \times\mathcal{B}(\Upsilon(1S)\to {\mu}^+ {\mu}^-) = 2101\pm33\pm83 \ \rm{pb},$ $\sigma(\Upsilon(2S)) \times\mathcal{B}(\Upsilon(2S)\to {\mu}^+ {\mu}^-) = 526\pm20\pm21 \ \rm{pb},$ $\sigma(\Upsilon(3S)) \times\mathcal{B}(\Upsilon(3S)\to {\mu}^+ {\mu}^-) = 242\pm16\pm10 \ \rm{pb},$ where the first uncertainties are statistical and the second are systematic. The ratios of cross-sections between measurements of two different $\Upsilon$ states and between measurements at different center-of-mass energies are determined. The nuclear modification factor of $\Upsilon(1S)$ at $\sqrt{s}=5 \ \rm{TeV}$ is updated as well using the directly measured cross-section results from this analysis.

Figures and captions

Invariant mass distribution of $\Upsilon $ candidates in the kinematic range $ p_{\mathrm{T}} \in[0,20]\text{ Ge V /}c $ and $y\in[2.0,4.5]$. The result of the fit with three Crystal Ball functions for the signal plus an exponential function for the background is also shown.	Fig1.pdf [36 KiB] HiDef png [717 KiB] Thumbnail [308 KiB] *.C file
Double-differential cross-section times $\Upsilon \rightarrow \mu ^+\mu ^- $ branching fraction as a function of $ p_{\mathrm{T}} $ in bins of $y$ for (upper left) ${\Y1S} $, (upper right) ${\Y2S} $ and (bottom) ${\Y3S} $ mesons. Statistical and systematic uncertainties are added in quadrature.	Fig2a.pdf [17 KiB] HiDef png [166 KiB] Thumbnail [164 KiB] *.C file
	Fig2b.pdf [17 KiB] HiDef png [180 KiB] Thumbnail [176 KiB] *.C file
	Fig2c.pdf [17 KiB] HiDef png [183 KiB] Thumbnail [173 KiB] *.C file
Differential cross-section times $\Upsilon \rightarrow \mu ^+\mu ^- $ branching fraction (left) as a function of $ p_{\mathrm{T}} $ for $y$ integrated from 2.0 to 4.5 and (right) as a function of $y$ for $ p_{\mathrm{T}} $ integrated from 0 to 20 $\text{ Ge V /}c$ , for the ${\Y1S} $, ${\Y2S} $ and ${\Y3S} $ states. Statistical and systematic uncertainties are added in quadrature.	Fig3a.pdf [15 KiB] HiDef png [129 KiB] Thumbnail [128 KiB] *.C file
	Fig3b.pdf [14 KiB] HiDef png [128 KiB] Thumbnail [134 KiB] *.C file
Differential cross-section of ${\Y1S} $ mesons as a function of $ p_{\mathrm{T}} $, compared with the NRQCD prediction of Ref. \cite{Feng:2015wka}.	Fig4.pdf [15 KiB] HiDef png [193 KiB] Thumbnail [158 KiB] *.C file
Production cross-sections in the range $ p_{\mathrm{T}} < 15 \text{ Ge V /}c $ and $2.0 < y < 4.5$ multiplied by $\Upsilon \rightarrow \mu ^+\mu ^- $ branching fractions as a function of the centre-of-mass energy of $pp$ collisions for (black boxes) ${\Y1S} $, (red upward triangles) ${\Y2S} $ and (blue downward triangles) ${\Y3S} $ states. Statistical and systematic uncertainties are added in quadrature.	Fig5.pdf [13 KiB] HiDef png [88 KiB] Thumbnail [79 KiB] *.C file
Ratios of the ${\Y2S} $ or ${\Y3S} $ production cross-section over that of the ${\Y1S} $ state, (left) as a function of $ p_{\mathrm{T}} $ for $2.0<y<4.5$ and (right) as a function of $y$ for $ p_{\mathrm{T}} <20\text{ Ge V /}c $. Statistical and systematic uncertainties are added in quadrature.	Fig6a.pdf [15 KiB] HiDef png [124 KiB] Thumbnail [130 KiB] *.C file
	Fig6b.pdf [14 KiB] HiDef png [110 KiB] Thumbnail [118 KiB] *.C file
Ratios of $\Upsilon $ production cross-sections measured at $\sqrt{s} =13\text{ Te V} $ over those measured at $ \sqrt{s} =5\text{ Te V} $ (left) as a function of $ p_{\mathrm{T}} $ for $2.0<y<4.5$ and (right) as a function of $y$ for $ p_{\mathrm{T}} <20\text{ Ge V /}c $. The statistical and systematic uncertainties are added in quadrature.	Fig7a.pdf [16 KiB] HiDef png [126 KiB] Thumbnail [125 KiB] *.C file
	Fig7b.pdf [15 KiB] HiDef png [110 KiB] Thumbnail [116 KiB] *.C file
Nuclear modification factor $R_{p{\rm Pb}}$ as a function of $y$ for the ${\Y1S} $ state, together with the theoretical predictions mentioned in the text. The inner error bars show the statistical uncertainties, while the outer ones show the statistical and systematic uncertainties added in quadrature.	Fig8.pdf [17 KiB] HiDef png [276 KiB] Thumbnail [203 KiB] *.C file
Animated gif made out of all figures.	PAPER-2022-036.gif Thumbnail

Tables and captions

Relative systematic uncertainty ($\%$) from various sources. The ranges correspond to results measured in each $( p_{\mathrm{T}} ,y)$ bin of $\Upsilon $ mesons. For some systematic uncertainties, the results are correlated among different $( p_{\mathrm{T}} ,y)$ bins as noted in the last column.	Table_1.pdf [42 KiB] HiDef png [75 KiB] Thumbnail [33 KiB] tex code
Differential cross-section times the $\Upsilon \rightarrow \mu ^+\mu ^- $ branching fraction (in unit of pb$/( \text{ Ge V /}c )$) in bins of ( $ p_{\mathrm{T}}$ , $y$) for the ${\Y1S} $ meson. The first uncertainties are statistical and the second are systematic.	Table_2.pdf [52 KiB] HiDef png [105 KiB] Thumbnail [49 KiB] tex code
Differential cross-section times the $\Upsilon \rightarrow \mu ^+\mu ^- $ branching fraction (in unit of pb$/( \text{ Ge V /}c )$) in bins of ( $ p_{\mathrm{T}}$ , $y$) for the ${\Y2S} $ meson. The first uncertainties are statistical and the second are systematic.	Table_3.pdf [51 KiB] HiDef png [101 KiB] Thumbnail [47 KiB] tex code
Differential cross-section times the $\Upsilon \rightarrow \mu ^+\mu ^- $ branching fraction (in unit of pb$/( \text{ Ge V /}c )$) in bins of ( $ p_{\mathrm{T}}$ , $y$) for the ${\Y3S} $ meson. The first uncertainties are statistical and the second are systematic.	Table_4.pdf [51 KiB] HiDef png [112 KiB] Thumbnail [51 KiB] tex code
Differential cross-section times the $\Upsilon \rightarrow \mu ^+\mu ^- $ branching fraction (in unit of pb$/( \text{ Ge V /}c )$) of the ${\Y1S} $, ${\Y2S} $ and ${\Y3S} $ mesons as a function of $ p_{\mathrm{T}} $ for $y$ integrated from 2.0 to 4.5.	Table_5.pdf [51 KiB] HiDef png [91 KiB] Thumbnail [48 KiB] tex code
Differential cross-section times the $\Upsilon \rightarrow \mu ^+\mu ^- $ branching fraction (in unit of pb) of ${\Y1S} $, ${\Y2S} $ and ${\Y3S} $ mesons as a function $y$ for $ p_{\mathrm{T}} $ integrated from 0 to 20 $\text{ Ge V /}c $.	Table_6.pdf [42 KiB] HiDef png [56 KiB] Thumbnail [29 KiB] tex code
Cross-section ratios between $\sqrt{s}=13\text{ Te V} $ and $5\text{ Te V} $ of ${\Y1S} $, ${\Y2S} $ and ${\Y3S} $ mesons as a function of $ p_{\mathrm{T}} $ for $y$ integrated from 2.0 to 4.5.	Table_7.pdf [51 KiB] HiDef png [110 KiB] Thumbnail [54 KiB] tex code
Cross-section ratios between $\sqrt{s}=13\text{ Te V} $ and $5\text{ Te V} $ of ${\Y1S} $, ${\Y2S} $ and ${\Y3S} $ mesons as a function of $y$ for $ p_{\mathrm{T}} $ integrated from 0 to 20 $\text{ Ge V /}c $.	Table_8.pdf [42 KiB] HiDef png [59 KiB] Thumbnail [32 KiB] tex code
Relative changes of double-differential cross-sections of $\Upsilon (1S)$ (in %), for a polarisation of $\lambda_{\theta}=0.1$ rather than zero, in ( $ p_{\mathrm{T}}$ ,$y$) intervals.	Table_9.pdf [51 KiB] HiDef png [116 KiB] Thumbnail [58 KiB] tex code
Relative changes of cross-sections of $\Upsilon (2S)$ (in %), for a polarisation of $\lambda_{\theta}=0.1$ rather than zero, in ( $ p_{\mathrm{T}}$ ,$y$) intervals.	Table_10.pdf [51 KiB] HiDef png [117 KiB] Thumbnail [58 KiB] tex code
Relative changes of cross-sections of $\Upsilon (3S)$ (in %), for a polarisation of $\lambda_{\theta}=0.1$ rather than zero, in ( $ p_{\mathrm{T}}$ ,$y$) intervals	Table_11.pdf [51 KiB] HiDef png [115 KiB] Thumbnail [58 KiB] tex code
Relative changes of cross-sections of $\Upsilon (1S)$ (in %), for a polarisation of $\lambda_{\theta}=1$ rather than zero, in ( $ p_{\mathrm{T}}$ ,$y$) intervals	Table_12.pdf [51 KiB] HiDef png [103 KiB] Thumbnail [54 KiB] tex code
Relative changes of cross-sections of $\Upsilon (2S)$ (in %), for a polarisation of $\lambda_{\theta}=1$ rather than zero, in ( $ p_{\mathrm{T}}$ ,$y$) intervals.	Table_13.pdf [51 KiB] HiDef png [103 KiB] Thumbnail [54 KiB] tex code
Relative changes of cross-sections of $\Upsilon (3S)$ (in %), for a polarisation of $\lambda_{\theta}=1$ rather than zero, in ( $ p_{\mathrm{T}}$ ,$y$) intervals.	Table_14.pdf [51 KiB] HiDef png [104 KiB] Thumbnail [54 KiB] tex code
Relative changes of cross-sections of $\Upsilon (1S)$ (in %), for a polarisation of $\lambda_{\theta}=-1$ rather than zero, in ( $ p_{\mathrm{T}}$ ,$y$) intervals.	Table_15.pdf [51 KiB] HiDef png [94 KiB] Thumbnail [48 KiB] tex code
Relative changes of cross-sections of $\Upsilon (2S)$ (in %), for a polarisation of $\lambda_{\theta}=-1$ rather than zero, in ( $ p_{\mathrm{T}}$ ,$y$) intervals.	Table_16.pdf [51 KiB] HiDef png [95 KiB] Thumbnail [49 KiB] tex code
Relative changes of cross-sections of $\Upsilon (3S)$ (in %), for a polarisation of $\lambda_{\theta}=-1$ rather than zero, in ( $ p_{\mathrm{T}}$ ,$y$) intervals.	Table_17.pdf [51 KiB] HiDef png [95 KiB] Thumbnail [48 KiB] tex code