Multiplicity dependence of $\sigma_{\psi(2S)}/\sigma_{J/\psi}$ in $pp$ collisions at $\sqrt{s}=13$ TeV

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LHCb-PAPER-2023-035
CERN-EP-2023-277
arXiv:2312.15201 [PDF]

(Submitted on 23 Dec 2023)
JHEP
Inspire 2740583

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Abstract

The ratio of production cross-sections of $\psi(2S)$ over $J/\psi$ mesons as a function of charged-particle multiplicity in proton-proton collisions at a centre-of-mass energy $\sqrt{s}=13$ TeV is measured with a data sample collected by the LHCb detector, corresponding to an integrated luminosity of 658 pb$^{-1}$. The ratio is measured for both prompt and non-prompt $\psi(2S)$ and $J/\psi$ mesons. When there is an overlap between the rapidity ranges over which multiplicity and charmonia production are measured, a multiplicity-dependent modification of the ratio is observed for prompt mesons. No significant multiplicity dependence is found when the ranges do not overlap. For non-prompt production, the $\psi(2S)-to-J/\psi$ production ratio is roughly independent of multiplicity irrespective of the rapidity range over which the multiplicity is measured. The results are compared to predictions of the co-mover model and agree well except in the low multiplicity region. The ratio of production cross-sections of $\psi(2S)$ over $J/\psi$ mesons are cross-checked with other measurements in di-lepton channels and found to be compatible.

Figures and captions

Distributions of the (left) pseudo decay time and (right) mass for (upper) $ { J \mskip -3mu/\mskip -2mu\psi }$ and (lower) $\psi {(2S)}$ are plotted in the region $4\leq N_{\rm tracks}^{\rm PV} < 20$, $2.8<y<3.5$, and $6< p_{\mathrm{T}} <8\text{ Ge V /}c $. The fit results are overlaid.	n1y2pt4.pdf [35 KiB] HiDef png [812 KiB] Thumbnail [343 KiB]
	n1y2pt4.pdf [27 KiB] HiDef png [533 KiB] Thumbnail [259 KiB]
Normalised production ratio as a function of $N_{\rm tracks}^{\rm PV}/\langle N_{\rm tracks}^{\rm PV}\rangle_{\rm{NB}}$, integrated over the full $ p_{\mathrm{T}}$ -$y$ range of $2.0<y<4.5$ and $0.3< p_{\mathrm{T}} <20$ $\text{ Ge V /}c$ with $-60 < z_{\rm PV} < 180$ mm. The error bars represent statistical uncertainties and heights of the boxes represent systematical uncertainties.	All.pdf [16 KiB] HiDef png [244 KiB] Thumbnail [194 KiB]
Normalised production ratio as a function of (left) $N_{\rm bwd}^{\rm PV}/\langle N_{\rm bwd}^{\rm PV}\rangle_{\rm{NB}}$ , with $-30<z_{\rm PV}<180$ mm, and (right) $N_{\rm fwd}^{\rm PV}/\langle N_{\rm fwd}^{\rm PV}\rangle_{\rm{NB}}$, with $-180<z_{\rm PV}<180$ mm, integrated over the full $ p_{\mathrm{T}}$ -$y$ range of $2.0<y<4.5$ and $0.3< p_{\mathrm{T}} <20$ $\text{ Ge V /}c$ .	AllB.pdf [15 KiB] HiDef png [185 KiB] Thumbnail [155 KiB]
	AllF.pdf [15 KiB] HiDef png [185 KiB] Thumbnail [154 KiB]
Normalised production ratio as a function of $N_{\rm fwd}^{\rm PV}/\langle N_{\rm fwd}^{\rm PV}\rangle_{\rm{NB}}$, compared to a translation of the ratio as a function of $N_{\rm bwd}^{\rm PV}/\langle N_{\rm bwd}^{\rm PV}\rangle_{\rm{NB}}$.	AllBtoF.pdf [16 KiB] HiDef png [207 KiB] Thumbnail [173 KiB]
Normalised production ratio for (left) prompt and(right) non-prompt charmonia as a function of $N_{\rm tracks}^{\rm PV}/\langle N_{\rm tracks}^{\rm PV}\rangle_{\rm{NB}}$ in different $ p_{\mathrm{T}}$ intervals.	prompt[..].pdf [17 KiB] HiDef png [232 KiB] Thumbnail [174 KiB]
	frombR[..].pdf [17 KiB] HiDef png [231 KiB] Thumbnail [172 KiB]
Normalised production ratio for (left) prompt and(right) non-prompt charmonia as a function of $N_{\rm fwd}^{\rm PV}/\langle N_{\rm fwd}^{\rm PV}\rangle_{\rm{NB}}$ in different $ p_{\mathrm{T}}$ intervals.	prompt[..].pdf [17 KiB] HiDef png [231 KiB] Thumbnail [174 KiB]
	frombR[..].pdf [17 KiB] HiDef png [225 KiB] Thumbnail [170 KiB]
Normalised production ratio for (left) prompt and(right) non-prompt charmonia as a function of $N_{\rm bwd}^{\rm PV}/\langle N_{\rm bwd}^{\rm PV}\rangle_{\rm{NB}}$ in different $ p_{\mathrm{T}}$ intervals.	prompt[..].pdf [17 KiB] HiDef png [226 KiB] Thumbnail [169 KiB]
	frombR[..].pdf [17 KiB] HiDef png [224 KiB] Thumbnail [169 KiB]
Normalised production ratio for (left) prompt and(right) non-prompt charmonia as a function of $N_{\rm tracks}^{\rm PV}/\langle N_{\rm tracks}^{\rm PV}\rangle_{\rm{NB}}$ in different $y$ intervals.	prompt[..].pdf [15 KiB] HiDef png [173 KiB] Thumbnail [137 KiB]
	frombR[..].pdf [16 KiB] HiDef png [178 KiB] Thumbnail [139 KiB]
Normalised production ratio for (left) prompt and(right) non-prompt charmonia as a function of $N_{\rm fwd}^{\rm PV}/\langle N_{\rm fwd}^{\rm PV}\rangle_{\rm{NB}}$ in different $y$ intervals.	prompt[..].pdf [16 KiB] HiDef png [170 KiB] Thumbnail [134 KiB]
	frombR[..].pdf [16 KiB] HiDef png [173 KiB] Thumbnail [137 KiB]
Normalised production ratio for (left) prompt and(right) non-prompt charmonia as a function of $N_{\rm bwd}^{\rm PV}/\langle N_{\rm bwd}^{\rm PV}\rangle_{\rm{NB}}$ in different $y$ intervals.	prompt[..].pdf [16 KiB] HiDef png [173 KiB] Thumbnail [136 KiB]
	frombR[..].pdf [16 KiB] HiDef png [174 KiB] Thumbnail [138 KiB]
Production ratios compared to existing measurements [54].	Variou[..].pdf [15 KiB] HiDef png [219 KiB] Thumbnail [218 KiB]
Production ratios as a function of $ p_{\mathrm{T}}$ compared to existing measurements [54] and model predictions [65].	Compar[..].pdf [21 KiB] HiDef png [266 KiB] Thumbnail [181 KiB]
Animated gif made out of all figures.	PAPER-2023-035.gif Thumbnail

Tables and captions

Requirements on $z_{\rm PV}$ for different multiplicity variables.	Table_1.pdf [47 KiB] HiDef png [80 KiB] Thumbnail [31 KiB] tex code
Mean values of the three multiplicity variables in no-bias data.	Table_2.pdf [46 KiB] HiDef png [88 KiB] Thumbnail [32 KiB] tex code
Summary of systematic uncertainty ranges for the double-differential $\psi {(2S)}$ -to- $ { J \mskip -3mu/\mskip -2mu\psi }$ cross-section ratio, in different kinematic bins within corresponding multiplicity intervals in $\%$. Sources marked with $\dagger$ are considered to be correlated beween bins.	Table_3.pdf [65 KiB] HiDef png [199 KiB] Thumbnail [99 KiB] tex code
Ratios (%) of double differential production cross-section for $\psi {(2S)}$ to $ { J \mskip -3mu/\mskip -2mu\psi }$ in bins of ( $ p_{\mathrm{T}}$ ,$y$) for 4 $\leq$ $N_{\rm tracks}^{\rm PV}$ $<$ 20 (at least 4 tracks required to form a high-quality vertex). The first uncertainties are statistical, the second are systematic.	Table_4.pdf [53 KiB] HiDef png [126 KiB] Thumbnail [64 KiB] tex code
Ratios (%) of double differential production cross-section for $\psi {(2S)}$ to $ { J \mskip -3mu/\mskip -2mu\psi }$ in bins of ( $ p_{\mathrm{T}}$ ,$y$) for 20 $\leq$ $N_{\rm tracks}^{\rm PV}$ $<$ 45. The first uncertainties are statistical, the second are systematic.	Table_5.pdf [53 KiB] HiDef png [123 KiB] Thumbnail [64 KiB] tex code
Ratios (%) of double differential production cross-section for $\psi {(2S)}$ to $ { J \mskip -3mu/\mskip -2mu\psi }$ in bins of ( $ p_{\mathrm{T}}$ ,$y$) for 45 $\leq$ $N_{\rm tracks}^{\rm PV}$ $<$ 70. The first uncertainties are statistical, the second are systematic.	Table_6.pdf [53 KiB] HiDef png [127 KiB] Thumbnail [64 KiB] tex code
Ratios (%) of double differential production cross-section for $\psi {(2S)}$ to $ { J \mskip -3mu/\mskip -2mu\psi }$ in bins of ( $ p_{\mathrm{T}}$ ,$y$) for 70 $\leq$ $N_{\rm tracks}^{\rm PV}$ $<$ 95. The first uncertainties are statistical, the second are systematic.	Table_7.pdf [53 KiB] HiDef png [126 KiB] Thumbnail [64 KiB] tex code
Ratios (%) of double differential production cross-section for $\psi {(2S)}$ to $ { J \mskip -3mu/\mskip -2mu\psi }$ in bins of ( $ p_{\mathrm{T}}$ ,$y$) for 95 $\leq$ $N_{\rm tracks}^{\rm PV}$ $<$ 200. The first uncertainties are statistical, the second are systematic.	Table_8.pdf [53 KiB] HiDef png [129 KiB] Thumbnail [64 KiB] tex code
Ratios (%) of double differential production cross-section for $\psi {(2S)}$ to $ { J \mskip -3mu/\mskip -2mu\psi }$ in bins of ( $ p_{\mathrm{T}}$ ,$y$) for 0 $\leq$ $N_{\rm bwd}^{\rm PV}$ $<$ 8. The first uncertainties are statistical, the second are systematic.	Table_9.pdf [53 KiB] HiDef png [124 KiB] Thumbnail [64 KiB] tex code
Ratios (%) of double differential production cross-section for $\psi {(2S)}$ to $ { J \mskip -3mu/\mskip -2mu\psi }$ in bins of ( $ p_{\mathrm{T}}$ ,$y$) for 8 $\leq$ $N_{\rm bwd}^{\rm PV}$ $<$ 15. The first uncertainties are statistical, the second are systematic.	Table_10.pdf [53 KiB] HiDef png [127 KiB] Thumbnail [64 KiB] tex code
Ratios (%) of double differential production cross-section for $\psi {(2S)}$ to $ { J \mskip -3mu/\mskip -2mu\psi }$ in bins of ( $ p_{\mathrm{T}}$ ,$y$) for 15 $\leq$ $N_{\rm bwd}^{\rm PV}$ $<$ 22. The first uncertainties are statistical, the second are systematic.	Table_11.pdf [53 KiB] HiDef png [126 KiB] Thumbnail [64 KiB] tex code
Ratios (%) of double differential production cross-section for $\psi {(2S)}$ to $ { J \mskip -3mu/\mskip -2mu\psi }$ in bins of ( $ p_{\mathrm{T}}$ ,$y$) for 22 $\leq$ $N_{\rm bwd}^{\rm PV}$ $<$ 30. The first uncertainties are statistical, the second are systematic.	Table_12.pdf [53 KiB] HiDef png [126 KiB] Thumbnail [64 KiB] tex code
Ratios (%) of double differential production cross-section for $\psi {(2S)}$ to $ { J \mskip -3mu/\mskip -2mu\psi }$ in bins of ( $ p_{\mathrm{T}}$ ,$y$) for 30 $\leq$ $N_{\rm bwd}^{\rm PV}$ $<$ 80. The first uncertainties are statistical, the second are systematic.	Table_13.pdf [53 KiB] HiDef png [127 KiB] Thumbnail [63 KiB] tex code
Ratios (%) of double differential production cross-section for $\psi {(2S)}$ to $ { J \mskip -3mu/\mskip -2mu\psi }$ in bins of ( $ p_{\mathrm{T}}$ ,$y$) for 0 $\leq$ $N_{\rm fwd}^{\rm PV}$ $<$ 12. The first uncertainties are statistical, the second are systematic.	Table_14.pdf [53 KiB] HiDef png [127 KiB] Thumbnail [64 KiB] tex code
Ratios (%) of double differential production cross-section for $\psi {(2S)}$ to $ { J \mskip -3mu/\mskip -2mu\psi }$ in bins of ( $ p_{\mathrm{T}}$ ,$y$) for 12 $\leq$ $N_{\rm fwd}^{\rm PV}$ $<$ 24. The first uncertainties are statistical, the second are systematic.	Table_15.pdf [53 KiB] HiDef png [124 KiB] Thumbnail [64 KiB] tex code
Ratios (%) of double differential production cross-section for $\psi {(2S)}$ to $ { J \mskip -3mu/\mskip -2mu\psi }$ in bins of ( $ p_{\mathrm{T}}$ ,$y$) for 24 $\leq$ $N_{\rm fwd}^{\rm PV}$ $<$ 36. The first uncertainties are statistical, the second are systematic.	Table_16.pdf [53 KiB] HiDef png [124 KiB] Thumbnail [64 KiB] tex code
Ratios (%) of double differential production cross-section for $\psi {(2S)}$ to $ { J \mskip -3mu/\mskip -2mu\psi }$ in bins of ( $ p_{\mathrm{T}}$ ,$y$) for 36 $\leq$ $N_{\rm fwd}^{\rm PV}$ $<$ 48. The first uncertainties are statistical, the second are systematic.	Table_17.pdf [53 KiB] HiDef png [127 KiB] Thumbnail [64 KiB] tex code
Ratios (%) of double differential production cross-section for $\psi {(2S)}$ to $ { J \mskip -3mu/\mskip -2mu\psi }$ in bins of ( $ p_{\mathrm{T}}$ ,$y$) for 48 $\leq$ $N_{\rm fwd}^{\rm PV}$ $<$ 130. The first uncertainties are statistical, the second are systematic.	Table_18.pdf [53 KiB] HiDef png [128 KiB] Thumbnail [64 KiB] tex code