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arXiv 2501.19293hep-ph
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强子光致光散射的纵向短程约束及张量介子对缪子$g-2$的贡献

Longitudinal short-distance constraints on hadronic light-by-light scattering and tensor meson contributions to the muon $g-2$

Jonas Mager, Luigi Cappiello, Josef Leutgeb, Anton Rebhan

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REVTEX, 8 pages, 2 figures, 1 table; v4: reference to appendix A of accompanying longer paper arXiv:2501.09699 added, version to appear in PRL
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AI总结：

针对传统强子模型无法满足强子光致光散射短程约束、全息QCD仅部分满足对称约束的问题，本文发现张量介子（此前贡献被低估）可填补空白，其在低能区的正贡献能解释色散与格点结果的剩余差距。

摘要：

量子色动力学（QCD）中算符乘积展开的短程约束在评估强子光致光散射对缪子反常磁矩的贡献时起着重要作用。虽然包含有限数量共振态的传统强子模型无法重现这些约束所隐含的正确幂律，但全息QCD已被证明能自然纳入Melnikov-Vainshtein约束——该约束来自非对称极限下的三角反常，其中一个光子的虚质量与其他光子相比保持较小——对纵向振幅的限制。这一约束由无穷多的轴矢量介子塔饱和，且在AdS/QCD模型中它们对缪子$g-2$的数值贡献与最近的色散分析及其他方法相当吻合。然而，所有虚质量都很大的纵向短程约束仅被满足81%。在本文中，我们表明张量介子（其对缪子$g-2$的贡献最近被发现被低估）可以填补这一空白，因为在全息QCD中，它们的无穷多激发介子塔仅对对称纵向短程约束有贡献。数值上，它们在1.5 GeV以下的低能区产生显著的正贡献，在混合区产生较小贡献，在高能区产生可忽略的贡献，这可以解释最近色散结果与格点结果在完整强子光致光贡献上的剩余差距。

英文摘要：

Short-distance constraints from the operator product expansion in QCD play an important role in the evaluation of the hadronic light-by-light scattering contribution to the anomalous magnetic moment of the muon. While conventional hadronic models involving a finite number of resonances fail to reproduce the correct power laws implied by them, holographic QCD has been shown to naturally incorporate the Melnikov-Vainshtein constraint on the longitudinal amplitude following from the triangle anomaly in the asymmetric limit, where one photon virtuality remains small compared to the others. This is saturated by an infinite tower of axial vector mesons, and their numerical contribution to the muon $g-2$ in AdS/QCD models agrees rather well with a recent dispersive analysis and alternative approaches. However, the longitudinal short-distance constraint where all virtualities are large turns out to be matched only at the level of 81\%. In this Letter we show that tensor mesons, whose contribution to the muon $g-2$ has recently been found to be underestimated, can fill this gap, because in holographic QCD their infinite tower of excited mesons only contributes to the symmetric longitudinal short-distance constraint. Numerically, they give rise to a sizeable positive contribution from the low-energy region below 1.5 GeV, a small one from the mixed region, and a negligible one from the high-energy region, which could explain the remaining gap between the most recent dispersive and lattice results for the complete hadronic light-by-light contribution.

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