论文标题
转弯大 - $ n_c $ QCD具有积极范围
Cornering Large-$N_c$ QCD with Positivity Bounds
论文作者
论文摘要
在大$ n_c $限制中，介子散射幅度的简单分析结构，结合光谱密度的阳性，为低能观测值提供了精确的预测。在先前的研究基础上，我们探索了手性拉格朗日参数和介子耦合的允许区域。我们在手性膨胀中揭示了扭结的结构，并开发了分析工具，以表明扭结始终与单极的振幅相对应。我们构建了Lovelace-Shapiro和Coon uv-Complete振幅的（无标量和无矢量）变形，并表明它们靠近边界。此外，交叉对称的约束表明，随着旋转的增加，介子耦合到培来变得越来越小，这为矢量中介子优势和全息QCD的成功提供了解释。我们研究这些结论如何取决于对振幅高能行为的假设。最后，我们强调了我们的结果与晶格计算之间的互补性，以探索大$ N_C $ QCD。
The simple analytic structure of meson scattering amplitudes in the large-$N_c$ limit, combined with positivity of the spectral density, provides precise predictions on low-energy observables. Building upon previous studies, we explore the allowed regions of chiral Lagrangian parameters and meson couplings to pions. We reveal a structure of kinks at all orders in the chiral expansion and develop analytical tools to show that kinks always correspond to amplitudes with a single light pole. We build (scalar- and vector-less) deformations of the Lovelace-Shapiro and Coon UV-complete amplitudes, and show that they lie close to the boundaries. Moreover, constraints from crossing-symmetry imply that meson couplings to pions become smaller as their spin increases, providing an explanation for the success of Vector Meson Dominance and holographic QCD. We study how these conclusions depend on assumptions about the high-energy behavior of amplitudes. Finally, we emphasize the complementarity between our results and Lattice computations in the exploration of large-$N_c$ QCD.
