Spin-dependent polarizabilities of heavy vector mesons

Hao Dang; Liang-Zhen Wen; Yan-Ke Chen; Shi-Lin Zhu

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arXiv · 2608.15263

Spin-dependent polarizabilities of heavy vector mesons

Hao Dang·Liang-Zhen Wen·Yan-Ke Chen·Shi-Lin Zhu

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Abstract

We investigate the spin-dependent electromagnetic polarizabilities of the heavy vector mesons $D^*$ and $B^*$ in heavy meson chiral perturbation theory up to $\mathcal O(p^3)$. Using a twelve-element tensor basis for the real-photon Compton scattering on a spin-1 target, we determine two scalar, four vector and six tensor polarizabilities. We take the charm- and bottom-sector axial couplings from the measured $D^*$ width and lattice-QCD calculations, respectively, and estimate the magnetic couplings in the nonrelativistic constituent-quark model. In the charm sector, the proximity of the charged $Dπ$ thresholds generates strongly nonanalytic $Pϕ$-loop contributions, producing large real contributions to several $\bar D^{*0}$ polarizabilities and sizable imaginary parts for $D^{*-}$, whose charged $Dπ$ channel is open. The $E1E1$-type polarizabilities are enhanced much more strongly than their $M1M1$-type counterparts, consistent with the velocity suppression of the pion-cloud magnetic coupling. No analogous enhancement occurs for $B^*$: the Born terms govern the magnetic polarizabilities, and the anomaly poles dominate the vector polarizabilities that receive no Born contribution. These results resolve the spin dependence of the $Dπ$ threshold effect and provide benchmarks for future lattice-QCD studies.

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Hao Dang, Liang-Zhen Wen, Yan-Ke Chen, Shi-Lin Zhu. 2026-08-15. Spin-dependent polarizabilities of heavy vector mesons. https://arxiv.org/abs/2608.15263

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