$D$-wave effects in diffractive electroproduction of heavy quarkonia from the photon-like $V\to Q\bar{Q}$ transition

Abstract

We analyze the validity of a commonly used identification between structures of the virtual photon ${\gamma }^{\ast }\to Q\bar{Q}$ and vector meson $V\to Q\bar{Q}$ transitions. In the existing studies of $S$-wave vector-meson photoproduction in the literature, such an identification is typically performed in the light-front (LF) frame while the radial component of the meson wave function is rather postulated than computed from the first principles. The massive photon-like $V\to Q\bar{Q}$ vertex, besides the $S$-wave component, also contains an extra $D$-wave admixture in the $Q\bar{Q}$ rest frame. However, the relative weight of these contributions cannot be justified by any reasonable nonrelativistic $Q\bar{Q}$ potential model. In this work, we investigate the relative role of the $D$-wave contribution starting from the photon-like quarkonium $V\to Q\bar{Q}$ transition in both frames: in the $Q\bar{Q}$ rest frame (with subsequent Melosh spin transform to the LF frame) and in the LF frame (without Melosh transform). We show that the photon-like transition imposed in the $Q\bar{Q}$ rest frame leads to significant discrepancies with the experimental data. In the second case we find that the corresponding total $J/\psi (1S)$ photoproduction cross sections are very close to those obtained with the "$S$-wave only" $V\to Q\bar{Q}$ transition, both leading to a good description of the data. However, we find that the "$S$-wave only" transition leads to a better description of photoproduction data for excited heavy quarkonium states, which represent a more effective tool for study of $D$-wave effects. Consequently, the predictions for production of excited states based on the photon-like structure of $V\to Q\bar{Q}$ transition should be treated with a great care due to a much stronger sensitivity of the $D$-wave contribution to the nodal structure of quarkonium wave functions.

arXiv comment18 pages of Latex including 6 figures. The modified version which has been accepted for publication by European Physical Journal C

References in corpus (25)

• Heavy quarkonium: progress, puzzles, and opportunities
• Diffractive Leptoproduction of Vector Mesons in QCD
• Exclusive photoproduction of J/psi mesons at HERA
• Elastic J/Psi Production at HERA
• Hard diffractive electroproduction of vector mesons in QCD
• Nonperturbative Effects in Gluon Radiation and Photoproduction of Quark Pairs
• Colour dipoles and rho, phi electroproduction
• Scanning the BFKL pomeron in elastic production of vector mesons at HERA
• Diffractive Vector Meson Production at HERA: from Soft to Hard QCD
• Novel Color Transparency Effect: Scanning the Wave Function of Vector Mesons
• Photoproduction of Charmonia and Total Charmonium-Proton Cross Sections
• Decisive test of color transparency in exclusive electroproduction of vector mesons
• Color Transparency versus Quantum Coherence in Electroproduction of Vector Mesons off Nuclei
• Nuclear effects in the Drell-Yan process at very high energies
• Charmonium Production in Deep Inelastic Scattering at HERA
• Theoretical uncertainties in exclusive electroproduction S-wave heavy quarkonia
• The diffraction cone for exclusive vector meson production in deep inelastic scattering
• Spin rotation effects in diffractive electroproduction of heavy quarkonia
• Anomalous A-dependence of diffractive leptoproduction of radial excitation ${\rho }^{\prime }(2S)$
• Small Gluonic Spots in the Nucleon: Searching for Signatures in Data
• Glue drops inside hadrons
• The ${\gamma }^{\ast }{\gamma }^{\ast }\to {\eta }_c(1S,2S)$ transition form factors for spacelike photons
• The Wave Function of 2S Radially Excited Vector Mesons from Data for Diffraction Slope
• Production of Polarized Vector Mesons off Nuclei
• Anomalous t-dependence in diffractive electroproduction of 2S radially excited light vector mesons at HERA

Cited by in corpus (8)

• Relativistic corrections to the vector meson light front wave function
• Nuclear suppression from coherent $J/\psi$ photoproduction at the Large Hadron Collider
• Selected topics in diffraction with protons and nuclei: past, present, and future
• Light-front wavefunctions of mesons by design
• Electroproduction of heavy quarkonia: significance of dipole orientation
• Exclusive photoproduction of excited quarkonia in ultraperipheral collisions
• D-wave effects in heavy quarkonium production in ultraperipheral nuclear collisions
• Coherent photo- and electroproduction of charmonia on nuclear targets revisited: Green function formalism