Measurement of associated $J/\psi$-$\psi(2S)$ production cross-section in $pp$ collisions at $\sqrt{s}=13$ TeV

Information

LHCb-PAPER-2023-023
CERN-EP-2023-243
arXiv:2311.15921 [PDF]

(Submitted on 27 Nov 2023)
JHEP
Inspire 2726937

Tools

Abstract

The cross-section of associated $J/\psi$-$\psi(2S)$ production in proton-proton collisions at a centre-of-mass energy of $\sqrt{s}=13$ TeV is measured using a data sample corresponding to an integrated luminosity of 4.2 fb$^{-1}$, collected by the LHCb experiment. The measurement is performed for both $J/\psi$ and $\psi(2S)$ mesons having transverse momentum $p_{\text{T}}<14$ GeV/$c$ and rapidity $2.0<y<4.5$, assuming negligible polarisation of the $J/\psi$ and $\psi(2S)$ mesons. The production cross-section is measured to be $4.5\pm0.7\pm0.3$ nb, where the first uncertainty is statistical and the second systematic. The differential cross-sections are measured as functions of several kinematic variables of the $J/\psi$-$\psi(2S)$ candidates. The results are combined with a measurement of $J/\psi$-$J/\psi$ production, giving a cross-section ratio between $J/\psi$-$\psi(2S)$ and $J/\psi$-$J/\psi$ production of $0.274\pm0.044\pm0.008$, where the first uncertainty is statistical and the second systematic.

Figures and captions

Distributions of (a) $m_{\mu_1^+\mu_1^-}$ and (b) $m_{\mu_2^+\mu_2^-}$ for $ { J \mskip -3mu/\mskip -2mu\psi }$ - $\psi {(2S)}$ candidates together with the projections of the two-dimensional fit.	Fig1a.pdf [27 KiB] HiDef png [314 KiB] Thumbnail [266 KiB] *.C file
	Fig1b.pdf [25 KiB] HiDef png [262 KiB] Thumbnail [231 KiB] *.C file
Distributions of (a) $t_z^{ { J \mskip -3mu/\mskip -2mu\psi } }$ and (b) $t_z^{\psi {(2S)} }$ for $ { J \mskip -3mu/\mskip -2mu\psi }$ - $\psi {(2S)}$ candidates with backgrounds subtracted together with the projections of the two-dimensional fit.	Fig2a.pdf [18 KiB] HiDef png [252 KiB] Thumbnail [187 KiB] *.C file
	Fig2b.pdf [19 KiB] HiDef png [299 KiB] Thumbnail [239 KiB] *.C file
Differential cross-section of $ { J \mskip -3mu/\mskip -2mu\psi }$ - $\psi {(2S)}$ production as a function of (a) $\Delta y$, (b) $\Delta\phi$, (c) $ p_{\mathrm{T}} ^{ { J \mskip -3mu/\mskip -2mu\psi } \text{-}\psi {(2S)} }$, (d) $y_{ { J \mskip -3mu/\mskip -2mu\psi } \text{-}\psi {(2S)} }$ and (e) $m_{ { J \mskip -3mu/\mskip -2mu\psi } \text{-}\psi {(2S)} }$, compared with the NLO* CS predictions for SPS [54,55,56]. The $m_{ { J \mskip -3mu/\mskip -2mu\psi } \text{-}\psi {(2S)} }$ spectrum is also compared with the PRA+NRQCD predictions for SPS [57]. The data contain contributions from both SPS and DPS.	Fig3a.pdf [13 KiB] HiDef png [548 KiB] Thumbnail [314 KiB] *.C file
	Fig3b.pdf [11 KiB] HiDef png [644 KiB] Thumbnail [335 KiB] *.C file
	Fig3c.pdf [14 KiB] HiDef png [605 KiB] Thumbnail [348 KiB] *.C file
	Fig3d.pdf [13 KiB] HiDef png [574 KiB] Thumbnail [316 KiB] *.C file
	Fig3e.pdf [16 KiB] HiDef png [686 KiB] Thumbnail [356 KiB] *.C file
Cross-section ratios between $ { J \mskip -3mu/\mskip -2mu\psi }$ - $\psi {(2S)}$ and $ { J \mskip -3mu/\mskip -2mu\psi }$ - $ { J \mskip -3mu/\mskip -2mu\psi }$ production as a function of (a) $\Delta y$, (b) $\Delta\phi$, (c) $ p_{\mathrm{T}} ^{\text{di-}\psi}$ and (d) $y_{\text{di-}\psi}$. The error bars represent the statistical and systematic uncertainties added in quadrature. The symbol di-$\psi$ indicates $ { J \mskip -3mu/\mskip -2mu\psi }$ - $ { J \mskip -3mu/\mskip -2mu\psi }$ or $ { J \mskip -3mu/\mskip -2mu\psi }$ - $\psi {(2S)}$ .	Fig4a.pdf [10 KiB] HiDef png [73 KiB] Thumbnail [43 KiB] *.C file
	Fig4b.pdf [10 KiB] HiDef png [65 KiB] Thumbnail [39 KiB] *.C file
	Fig4c.pdf [11 KiB] HiDef png [77 KiB] Thumbnail [46 KiB] *.C file
	Fig4d.pdf [10 KiB] HiDef png [70 KiB] Thumbnail [43 KiB] *.C file
Animated gif made out of all figures.	PAPER-2023-023.gif Thumbnail

Tables and captions

Summary of relative systematic uncertainties on the measurement of $ { J \mskip -3mu/\mskip -2mu\psi }$ - $\psi {(2S)}$ production cross-section. The total systematic uncertainty is the quadratic sum of the individual contributions.	Table_1.pdf [35 KiB] HiDef png [130 KiB] Thumbnail [58 KiB] tex code
Differential cross-section $\mathrm{d}\sigma/\mathrm{d}\Delta y$ [nb] of $ { J \mskip -3mu/\mskip -2mu\psi }$ - $\psi {(2S)}$ production. The first uncertainty is statistical and the second systematic.	Table_2.pdf [44 KiB] HiDef png [142 KiB] Thumbnail [64 KiB] tex code
Differential cross-section $\mathrm{d}\sigma/\mathrm{d}\Delta\phi$ [nb] of $ { J \mskip -3mu/\mskip -2mu\psi }$ - $\psi {(2S)}$ production. The first uncertainty is statistical and the second systematic.	Table_3.pdf [44 KiB] HiDef png [122 KiB] Thumbnail [55 KiB] tex code
Differential cross-section $\mathrm{d}\sigma/\mathrm{d} p_{\mathrm{T}} ^{ { J \mskip -3mu/\mskip -2mu\psi } \text{-}\psi {(2S)} }$ [nb/( $\text{Ge V}/c$ )] of $ { J \mskip -3mu/\mskip -2mu\psi }$ - $\psi {(2S)}$ production. The first uncertainty is statistical and the second systematic.	Table_4.pdf [60 KiB] HiDef png [71 KiB] Thumbnail [28 KiB] tex code
Differential cross-section $\mathrm{d}\sigma/\mathrm{d} y_{ { J \mskip -3mu/\mskip -2mu\psi } \text{-}\psi {(2S)} }$ [nb] of $ { J \mskip -3mu/\mskip -2mu\psi }$ - $\psi {(2S)}$ production. The first uncertainty is statistical and the second systematic.	Table_5.pdf [59 KiB] HiDef png [111 KiB] Thumbnail [50 KiB] tex code
Differential cross-section $\mathrm{d}\sigma/\mathrm{d} m_{ { J \mskip -3mu/\mskip -2mu\psi } \text{-}\psi {(2S)} }$ [nb/( $\text{Ge V}/c^2$ )] of $ { J \mskip -3mu/\mskip -2mu\psi }$ - $\psi {(2S)}$ production. The first uncertainty is statistical and the second systematic.	Table_6.pdf [60 KiB] HiDef png [70 KiB] Thumbnail [33 KiB] tex code
Cross-section ratio between $ { J \mskip -3mu/\mskip -2mu\psi }$ - $\psi {(2S)}$ and di- $ { J \mskip -3mu/\mskip -2mu\psi }$ production $\sigma_{ { J \mskip -3mu/\mskip -2mu\psi } \text{-}\psi {(2S)} }/\sigma_{\text{di-} { J \mskip -3mu/\mskip -2mu\psi } }$ in intervals of $\Delta y$. The first uncertainty is statistical and the second systematic.	Table_7.pdf [59 KiB] HiDef png [139 KiB] Thumbnail [63 KiB] tex code
Cross-section ratio between $ { J \mskip -3mu/\mskip -2mu\psi }$ - $\psi {(2S)}$ and di- $ { J \mskip -3mu/\mskip -2mu\psi }$ production $\sigma_{ { J \mskip -3mu/\mskip -2mu\psi } \text{-}\psi {(2S)} }/\sigma_{\text{di-} { J \mskip -3mu/\mskip -2mu\psi } }$ in intervals of $\Delta\phi$. The first uncertainty is statistical and the second systematic.	Table_8.pdf [57 KiB] HiDef png [125 KiB] Thumbnail [53 KiB] tex code
Cross-section ratio between $ { J \mskip -3mu/\mskip -2mu\psi }$ - $\psi {(2S)}$ and di- $ { J \mskip -3mu/\mskip -2mu\psi }$ $\sigma_{ { J \mskip -3mu/\mskip -2mu\psi } \text{-}\psi {(2S)} }/\sigma_{\text{di-} { J \mskip -3mu/\mskip -2mu\psi } }$ in intervals of $ p_{\mathrm{T}} ^{\text{di-}\psi}$ [ $\text{Ge V}/c$ ]. The first uncertainty is statistical and the second systematic.	Table_9.pdf [59 KiB] HiDef png [104 KiB] Thumbnail [45 KiB] tex code
Cross-section ratio between $ { J \mskip -3mu/\mskip -2mu\psi }$ - $\psi {(2S)}$ and di- $ { J \mskip -3mu/\mskip -2mu\psi }$ $\sigma_{ { J \mskip -3mu/\mskip -2mu\psi } \text{-}\psi {(2S)} }/\sigma_{\text{di-} { J \mskip -3mu/\mskip -2mu\psi } }$ in intervals of $y_{\text{di-}\psi}$. The first uncertainty is statistical and the second systematic.	Table_10.pdf [58 KiB] HiDef png [124 KiB] Thumbnail [55 KiB] tex code