CMS-PAS-BPH-15-003

CMS-PAS-BPH-15-003
Measurements of correlations between J/ $\psi$ mesons and jets produced in $\sqrt{s}=$ 8 TeV pp collisions
CMS Collaboration
May 2019

Abstract: A study of the production of J/ $\psi$ mesons in conjunction with jets in pp collisions at $\sqrt{s} =$ 8 TeV is presented. The analysis is based on data corresponding to an integrated luminosity of 19.1 fb $^{-1}$ collected with the CMS detector at the LHC. For events with at least one observed jet, the angular separation between the J/ $\psi$ meson and the jet is used to test whether the J/ $\psi$ meson is a jet fragment. The differential distributions of jet fragmentation probability as a function of jet energy for a fixed J/ $\psi$ energy fraction $z$ are presented. The experimental results are compared to a theoretical model using the fragmenting jet function (FJF) approach. The J/ $\psi$ jet fragmentation data agree with the predictions of the FJF calculations that use specific long-distance matrix element parameters. This agreement shows that the combination of data on jet fragmentation to J/ $\psi$ mesons and FJF analysis is a new way to test predictions for charmonium production from nonrelativistic quantum chromodynamics and to evaluate long-distance matrix element parameter sets. The analysis also shows that most J/ $\psi$ mesons with energy above 15 GeV and rapidity $\|y\| <$ 1.0 are fragments of jets with pseudorapidity $\|\eta_{\mathrm{jet}}\| <$ 1.
Links: CDS record (PDF) ; CADI line (restricted) ; These preliminary results are superseded in this paper, PLB 804 (2020) 135409. The superseded preliminary plots can be found here.

Figures & Tables	Summary	References	CMS Publications

Figures
png pdf	Figure 1: Left: The $\Delta$ R for J/ $\psi$ events with one observed jet. Right: The $\Delta R_1$ vs. $\Delta R_2$ for two-jet events, where $\Delta R_1$ is associated with the higher-energy jet and $\Delta R_2$ with the lower-energy jet.
png pdf	Figure 1-a: The $\Delta$ R for J/ $\psi$ events with one observed jet.
png pdf	Figure 1-b: The $\Delta R_1$ vs. $\Delta R_2$ for two-jet events, where $\Delta R_1$ is associated with the higher-energy jet and $\Delta R_2$ with the lower-energy jet.
png pdf	Figure 2: Comparison of data (closed circles with vertical bars representing the statistical uncertainty (inner bars) and total uncertainty (outer bars)) with the four LDME terms for $z_1$ = 0.425, using: (left) the BCKL LDME set [18]; and (right) the BK LDME set [17]. The curves show the jet energy dependence of the FJF model predictions, from which the averages were calculated.
png pdf	Figure 2-a: Comparison of data (closed circles with vertical bars representing the statistical uncertainty (inner bars) and total uncertainty (outer bars)) with the four LDME terms for $z_1$ = 0.425, using the BCKL LDME set [18]. The curves show the jet energy dependence of the FJF model predictions, from which the averages were calculated.
png pdf	Figure 2-b: Comparison of data (closed circles with vertical bars representing the statistical uncertainty (inner bars) and total uncertainty (outer bars)) with the four LDME terms for $z_1$ = 0.425, using the BK LDME set [17]. The curves show the jet energy dependence of the FJF model predictions, from which the averages were calculated.
png pdf	Figure 3: Comparison of data (closed circles with vertical bars representing the statistical uncertainty (inner bars) and total uncertainty (outer bars)) with the four LDME terms for $z_1=$ 0.525, using: (left) the BCKL LDME set [18]; and (right) the BK LDME set [17]. The curves show the jet energy dependence of the FJF model predictions, from which the averages were calculated.
png pdf	Figure 3-a: Comparison of data (closed circles with vertical bars representing the statistical uncertainty (inner bars) and total uncertainty (outer bars)) with the four LDME terms for $z_1=$ 0.525, using the BCKL LDME set [18]. The curves show the jet energy dependence of the FJF model predictions, from which the averages were calculated.
png pdf	Figure 3-b: Comparison of data (closed circles with vertical bars representing the statistical uncertainty (inner bars) and total uncertainty (outer bars)) with the four LDME terms for $z_1=$ 0.525, using the BK LDME set [17]. The curves show the jet energy dependence of the FJF model predictions, from which the averages were calculated.
png pdf	Figure 4: Comparison of data (closed circles with vertical bars representing the statistical uncertainty (inner bars) and total uncertainty (outer bars)) with the four LDME terms for $z_1 =$ 0.625, using: (left) the BCKL LDME set [18]; and (right) the BK LDME set [17]. The curves show the jet energy dependence of the FJF model predictions, from which the averages were calculated.
png pdf	Figure 4-a: Comparison of data (closed circles with vertical bars representing the statistical uncertainty (inner bars) and total uncertainty (outer bars)) with the four LDME terms for $z_1 =$ 0.625, using the BCKL LDME set [18]. The curves show the jet energy dependence of the FJF model predictions, from which the averages were calculated.
png pdf	Figure 4-b: Comparison of data (closed circles with vertical bars representing the statistical uncertainty (inner bars) and total uncertainty (outer bars)) with the four LDME terms for $z_1 =$ 0.625, using the BK LDME set [17]. The curves show the jet energy dependence of the FJF model predictions, from which the averages were calculated.

Tables
png pdf	Table 1: The values of the $\chi ^2$ and the $\chi ^2$ probability (in parentheses) for 7 degrees of freedom in the comparison of the data and the FJF prediction for each LDME term with $z_1$ = 0.425.
png pdf	Table 2: The values of the $\chi ^2$ and the $\chi ^2$ probability (in parentheses) for 7 degrees of freedom in the comparison of the data and the FJF prediction for each LDME term with $z_1$ = 0.525.
png pdf	Table 3: The values of the $\chi ^2$ and the $\chi ^2$ probability (in parentheses) for 7 degrees of freedom in the comparison of the data and the FJF prediction for each LDME term with $z_1 =$ 0.625.

Summary

The first analysis comparing data for J/

$\psi$ mesons produced as fragmentation products of a central gluonic jet with a theoretical analysis based on Fragmenting Jet Function (FJF) approach has been presented. The data were collected by the CMS Collaboration from

$\mathrm{pp}$ collisions at

$\sqrt{s}=$ 8 TeV, corresponding to an integrated luminosity of 19.1 fb

$^{-1}$ . The agreement between the data and the FJF predictions over a wide range of

$z$ , where

$z$ is the J/

$\psi$ fraction of the jet energy, validates the FJF approach for gluon fragmentation. For the three

$z$ values, 0.425, 0.525, and 0.625, the nonrelativistic quantum chromodynamic long-distance matrix element (LDME) terms for the

$^{3}S_{1}^{(8)}$ and

$^3P_{J}^{(8)}$ configurations are not dominant for either the Bodwin, Chung, Kim and Lee (BCKL) [18] or Butenschoen and Kniehl (BK) [17] parameter sets, ie, these terms are not the main contributors to J/

$\psi$ production by jet fragmentation. For the BCKL LDME parameters, the

$^{1}S_{0}^{(8)}$ term dominates jet fragmentation to J/

$\psi$ for all three

$z$ values studied. This could explain the small J/

$\psi$ polarization at large

${p_{\mathrm{T}}}$ observed in high energy hadronic collisions at the Tevatron and LHC. However, the possible role of the

$^{3}S_{1}^{(1)}$ term using the BK parameters, with its implied large J/

$\psi$ polarization, has to be addressed theoretically. It has almost the same jet energy dependence as the BCKL

$^{1}S_{0}^{(8)}$ term for

$z >$ 0.5, but not for lower

$z$ .

For events with one observed jet, 84% of J/

$\psi$ mesons with

$E >$ 15 GeV and

$|y| <$ 1 are fragments of a jet produced in the angular region

$|\eta| <$ 1.0. We have also demonstrated that some J/

$\psi$ mesons are fragments of jets that fail the requirement

${p_{\mathrm{T}}}|_{\mathrm{jet}} >$ 25 GeV. Using a simple model to estimate the fraction of J/

$\psi$ mesons that are fragments of unobserved jets, we find that jet fragmentation can be the source of

$>$ 80% of the J/

$\psi$ mesons produced in this kinematic region.

References
1	E598 Collaboration	Experimental observation of a heavy particle $J$	PRL 33 (1974) 1404
2	J.-E. Augustin et al.	Discovery of a narrow resonance in e $^{+}$ e $^{-}$ annihilation	PRL 33 (1974) 1406
3	C.-H. Chang	Hadronic production of $J/\psi$ associated with a gluon	NPB 172 (1980) 425
4	R. Baier and R. Ruckl	Hadronic production of J/ $\psi$ and ${\Upsilon}$ : transverse momentum distributions	PLB 102 (1981) 364
5	CDF Collaboration	$J/\psi$ , $\psi^\prime \to \mu^{+} \mu^{-}$ and $B \to J/\psi$ , $\psi^\prime$ cross-sections	in 27th International Conference on High-energy Physics (ICHEP 94) Glasgow, Scotland, July 20-27, 1994 1994	hep-ex/9412013
6	CDF Collaboration	$J/\psi$ and $\psi(2S)$ production in $\mathrm{p}\bar{\mathrm{p}}$ collisions at $\sqrt{s} =$ 1.8 TeV	PRL 79 (1997) 572
7	P. Cho and A. K. Leibovich	Color-octet quarkonia production	PRD 53 (1996) 150
8	P. Cho and A. K. Leibovich	Color-octet quarkonia production. II	PRD 53 (1996) 6203
9	P. Artoisenet et al.	${\Upsilon}$ Production at Fermilab Tevatron and LHC energies	PRL 101 (2008) 152001
10	P. Faccioli et al.	Quarkonium production in the LHC era: a polarized perspective	PLB 736 (2014) 98	1403.3970
11	M. Procura and I. W. Stewart	Quark fragmentation within an identified jet	PRD 81 (2010) 074009	0911.4980
12	A. Jain, M. Procura, and W. J. Waalewijn	Parton fragmentation within an identified jet at NNLL	JHEP 05 (2011) 035	1101.4953
13	M. Procura and W. J. Waalewijn	Fragmentation in jets: cone and threshold effects	PRD 85 (2012) 114041	1111.6605
14	M. Baumgart, A. K. Leibovich, T. Mehen, and I. Z. Rothstein	Probing quarkonium production mechanisms with jet substructure	JHEP 1411 (2014) 003	1406.2295
15	G. Altarelli and G. Parisi	Asymptotic freedom in parton language	NPB126 (1977) 298--318
16	L. Dai and P. Shrivastava	Quarkonium polarization and the long distance matrix elements hierarchies using jet substructure		1707.08629
17	M. Butenschoen and B. A. Kniehl	Next-to-leading-order tests of NRQCD factorization with J/ $\psi$ yield and polarization	MPLA 28 (2013) 1350027	1212.2037
18	G. T. Bodwin, H. S. Chung, U.-R. Kim, and J. Lee	Fragmentation contributions to $J/\psi$ production at the Tevatron and the LHC	PRL 113 (2014) 022001	1403.3612
19	K.-T. Chao et al.	J/ ${\psi}$ polarization at hadron colliders in nonrelativistic QCD	PRL 108 (Jun, 2012) 242004	1201.2675
20	LHCb Collaboration	Study of J/ $\psi$ production in jets	PRL 118 (2017) 192001	1701.05116
21	CMS Collaboration	The CMS experiment at the CERN LHC	JINST 3 (2008) S08004	CMS-00-001
22	CMS Collaboration	$J/\psi$ and $\psi$ (2S) production in $\mathrm{pp}$ collisions at $\sqrt{s}=$ 7 TeV	JHEP 02 (2012) 011	CMS-BPH-10-014 1111.1557
23	CMS Collaboration	Measurement of J/ $\psi$ and $\psi$ (2S) prompt double-differential cross sections in $\mathrm{pp}$ collisions at $\sqrt{s}=$ 7 TeV	PRL 114 (2015) 191802	CMS-BPH-14-001 1502.04155
24	CMS Collaboration	Measurements of the $\Upsilon$ (1S), $\Upsilon$ (2S), and $\Upsilon$ (3S) differential cross sections in $\mathrm{pp}$ collisions at $\sqrt{s}=$ 7 TeV	PLB 749 (2015) 14	CMS-BPH-12-006 1501.07750
25	CMS Collaboration	Performance of CMS muon reconstruction in $\mathrm{pp}$ collision events at $\sqrt{s}=$ 7 TeV	JINST 7 (2012) P10002	CMS-MUO-10-004 1206.4071
26	CMS Collaboration	Particle-flow reconstruction and global event description with the cms detector	JINST 12 (2017) P10003	CMS-PRF-14-001 1706.04965
27	CMS Collaboration	Determination of jet energy calibration and transverse momentum resolution in CMS	JINST 6 (2011) P11002	CMS-JME-10-011 1107.4277
28	D. Lange	The EvtGen particle decay simulation package	NIMA 462 (2001) 152
29	E. Barberio, B. van Eijk, and Z. W\cas	$PHOTOS:$ A universal Monte Carlo for QED radiative corrections in decays	CPC 66 (1991) 115
30	S. Agostinelli et al.	GEANT4 -- a simulation toolkit	Nucl. Instr. Meth. A 506 (2003) 250
31	CMS Collaboration	Muon ID Performance: low- $\rm{p_T}$ muon efficiencies	CMS DP-2014/020
32	T. Adye	Unfolding algorithms and tests using RooUnfold	in Proceedings, PHYSTAT 2011 Workshop on Statistical Issues Related to Discovery Claims in Search Experiments and Unfolding, CERN,Geneva, Switzerland 17-20 January 2011, pp. 313--318, CERN CERN, Geneva	1105.1160
33	CDF Collaboration	Polarizations of $J/ {\psi}$ and ${\psi}(2S)$ mesons produced in $\mathrm{p}\overline{\mathrm{p}}$ Collisions at $\sqrt{s}=1.96\text{}\text{}\mathrm{TeV}$	PRL 99 (2007) 132001
34	CMS Collaboration	Measurement of the prompt J/ $\psi$ and $\psi$ (2S) polarizations in $\mathrm{pp}$ collisions at $\sqrt{s} =$ 7 TeV	PLB 727 (2013) 381	CMS-BPH-13-003 1307.6070