scholarly journals Relativistic correction toe+e−→J/ψ+ggatBfactories and constraint on color-octet matrix elements

2010 ◽  
Vol 81 (5) ◽  
Author(s):  
Zhi-Guo He ◽  
Ying Fan ◽  
Kuang-Ta Chao
Keyword(s):  
Relativistic Correction ◽  
Matrix Elements ◽  
Color Octet

Bc → J/ψ tensor form factors at large momentum recoil

2021 ◽  
pp. 2150135
Author(s):  
Dandan Shen ◽  
Huimin Ren ◽  
Fan Wu ◽  
Ruilin Zhu
Keyword(s):  
Form Factors ◽  
Distance Matrix ◽  
Relativistic Correction ◽  
Large Momentum ◽  
Matrix Elements ◽  
Leading Order ◽  
Lattice Data ◽  
Tensor Form ◽  
Long Distance ◽  
Current Form

We present a next-to-leading order (NLO) relativistic correction to [Formula: see text] tensor form factors within nonrelativistic QCD (NRQCD). We also consider complete Dirac bilinears [Formula: see text] with [Formula: see text] matrices [Formula: see text] in the [Formula: see text] transition. The relation among different current form factors is given and it shows that symmetries emerge in the heavy bottom quark limit. For a phenomenological extension, we propose to extract the long-distance matrix elements (LDMEs) for [Formula: see text] meson from the recent HPQCD lattice data and the NLO form factors at large momentum recoil.

scholarly journals Determination of color-octet matrix elements frome+e−processes at low energies

1997 ◽  
Vol 56 (3) ◽  
pp. 1663-1667 ◽  
Author(s):  
Feng Yuan ◽  
Cong-Feng Qiao ◽  
Kuang-Ta Chao
Keyword(s):  
Matrix Elements ◽  
Color Octet ◽  
Low Energies

scholarly journals Energy levels in muonic helium

2019 ◽  
Vol 222 ◽  
pp. 03009
Author(s):  
A.V. Eskin ◽  
V.I. Korobov ◽  
A.P. Martynenko ◽  
V.V. Sorokin
Keyword(s):  
Hyperfine Structure ◽  
Bound States ◽  
Energy Levels ◽  
Computer Code ◽  
Bound State ◽  
Relativistic Correction ◽  
Matrix Elements ◽  
Gaussian Form ◽  
Stochastic Variational Method ◽  
The Matrix

The energy spectrum of bound states and hyperfine structure of muonic helium is calculated on the basis of stochastic variational method. The basis wave functions of muonic helium are taken in the Gaussian form. The matrix elements of the Hamiltonian are calculated analytically. For numerical calculation a computer code is written in the MATLAB system. As a result, numerical values of bound state energies and hyperfine structure are obtained. We calculate also correction to the structure of the nucleus, vacuum polarization and relativistic correction.

scholarly journals Prompt $$J/\psi $$ photoproduction within the non-relativistic QCD framework at the CEPC

2020 ◽  
Vol 80 (8) ◽  
Author(s):  
Xi-Jie Zhan ◽  
Jian-Xiong Wang
Keyword(s):  
Transverse Momentum ◽  
Total Cross Section ◽  
Cross Section ◽  
Hadron Collider ◽  
Distance Matrix ◽  
Matrix Elements ◽  
Long Distance ◽  
Color Octet ◽  
Electron Positron ◽  
The Future

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.

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

2021 ◽  
Vol 103 (7) ◽  
Author(s):  
Daniël Boer ◽  
Cristian Pisano ◽  
Pieter Taels
Keyword(s):  
Matrix Elements ◽  
Color Octet

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

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.

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

1997 ◽  
Vol 12 (22) ◽  
pp. 3995-4004 ◽  
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.

scholarly journals Study of color-octet matrix elements through $$J/\psi $$ J / ψ production in $$e^{+}e^{-}$$ e + e - annihilation

2017 ◽  
Vol 77 (9) ◽  
Author(s):  
Yi-Jie Li ◽  
Guang-Zhi Xu ◽  
Pan-Pan Zhang ◽  
Yu-Jie Zhang ◽  
Kui-Yong Liu
Keyword(s):  
Matrix Elements ◽  
Color Octet
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