Extracting color octet NRQCD matrix elements from 
J/ψ
 production at the EIC

Abstract The prompt $$J/\psi $$J/ψ photoproduction within the non-relativistic QCD (NRQCD) framework at the future Circular Electron Positron Collider (CEPC) is studied, including the contributions from both direct and resolved photons. Employing different sets of long distance matrix elements, the total cross section is dominated by the color-octet channel. We present different kinematic distributions of $$J/\psi $$J/ψ production and the results show there will be about 50 $$J/\psi $$J/ψ events when the transverse momentum of $$J/\psi $$J/ψ is up to 20 GeV. It renders that the $$J/\psi $$J/ψ photoprodution at the CEPC is a well laboratory to test the NRQCD and further clarify the universality problem in NRQCD between electron positron collider and hadron collider.

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Spin correlations and velocity scaling in color-octet nonrelativistic QCD matrix elements

Physical Review D ◽

10.1103/physrevd.72.014009 ◽

2005 ◽

Vol 72 (1) ◽

Cited By ~ 24

Author(s):

Geoffrey T. Bodwin ◽

Jungil Lee ◽

D. K. Sinclair

Keyword(s):

Matrix Elements ◽

Spin Correlations ◽

Color Octet ◽

Nonrelativistic Qcd

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$$\chi _{c1}$$ and $$\chi _{c2}$$ polarization as a probe of color octet channel

The European Physical Journal C ◽

10.1140/epjc/s10052-020-08617-0 ◽

2020 ◽

Vol 80 (11) ◽

Author(s):

S. P. Baranov ◽

A. V. Lipatov

Keyword(s):

Bound States ◽

Distance Matrix ◽

Wave Functions ◽

Color Singlet ◽

Matrix Elements ◽

Polarization Data ◽

Long Distance ◽

Factorization Approach ◽

Color Octet ◽

Polar Anisotropy

AbstractWe analyze joint LHC data on the production of $$\chi _{c1}$$ χ c 1 and $$\chi _{c2}$$ χ c 2 mesons together with the polarization data obtained very recently by the CMS Collaboration at $$\sqrt{s} = 8$$ s = 8 TeV. Our consideration is based on the $$k_T$$ k T -factorization approach and nonrelativistic QCD formalism for the formation of bound states. The observed polar anisotropy of $$\chi _{c1}$$ χ c 1 and $$\chi _{c2}$$ χ c 2 decays can be described as a combined effect of the color-singlet and color-octet contributions. We extract the corresponding long-distance matrix elements from the fits. Our fits point to unequal color singlet wave functions for $$\chi _{c1}$$ χ c 1 and $$\chi _{c2}$$ χ c 2 states.

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Determining Color-Octet ψ-Production Matrix Elements from γp and ep Processes

International Journal of Modern Physics A ◽

10.1142/s0217751x97002140 ◽

1997 ◽

Vol 12 (22) ◽

pp. 3995-4004 ◽

Cited By ~ 2

Author(s):

Sean Fleming

Keyword(s):

Experimental Data ◽

Phase Space ◽

Momentum Transfer ◽

Large Momentum Transfer ◽

Large Momentum ◽

Matrix Elements ◽

Forward Region ◽

Color Octet ◽

Factorization Formalism

We calculate, within the NRQCD factorization formalism, the leading color-octet contributions to ψ production in photon-nucleon and electron-nucleon collisions. The expressions we obtaine depend on the NRQCD matrix elements [Formula: see text] and [Formula: see text]. These matrix elements can be determined by fitting to experimental data. The color-octet contribution to ψ photoproduction is in the forward region of phase space, where there may be large corrections to the NRQCD result from higher twist terms. As to ψ leptoproduction we point out that the theoretical uncertainties plaguing the photoproduction calculation vanish in the large momentum transfer limit. In this region of phase space the NRQCD formalism should be valid, making ψ leptoproduction an ideal laboratory for testing the theory.

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