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  • Open Access

Heavy quarkonium spectrum and decay constants from a neural-network-based holographic model

Yu Zhang1,2, Xun Chen1,2,3,*, and Miguel Angel Martin Contreras1,2,†

  • *Contact author: chenxun@usc.edu.cn
  • †Contact author: miguelangel.martin@usc.edu.cn

Phys. Rev. D 113, 126029 – Published 30 June, 2026

DOI: https://doi.org/10.1103/qfqd-6jt2

Abstract

We present a data-driven inverse construction of the dilaton field in a bottom-up AdS/QCD description of heavy vector quarkonia. Instead of adopting an ad hoc analytic ansatz, we use a multilayer perceptron to learn Φ′(z) as a smooth function of the holographic coordinate, with Φ(0)=0 imposed to ensure ultraviolet consistency. The dilaton and its derivatives obtained by automatic differentiation generate the holographic potential U(z), and the associated Schrödinger-like equation is discretized and diagonalized to extract the low-lying eigenmodes. Masses and decay constants are then evaluated from the eigenvalues and the near-boundary behavior of the bulk-to-boundary modes. Training on PDG data for charmonium and bottomonium yields a nonquadratic dilaton profile that resolves the long-standing difficulty of simultaneously reproducing both the heavy quarkonium spectrum and the monotonic suppression of leptonic decay constants with radial excitation. The combined fit achieves rms deviations of 1.26% (charmonium) and 3.32% (bottomonium). This work establishes neural-network reconstruction as a flexible tool for holographic modeling and provides a basis for future extensions incorporating additional channels, lattice constraints, or finite-temperature backgrounds.

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