论文标题
振幅的积极性与司血力：SMEFT中的尺寸6和8 Gluonic操作员的因果关系和单位性约束
Amplitude's positivity vs. subluminality: Causality and Unitarity Constraints on dimension 6 & 8 Gluonic operators in the SMEFT
论文作者
论文摘要
我们在标准模型有效场理论（SMEFT）中得出了维度6和维度8 Gluon场强的尺寸的因果关系约束。在本文的第一部分中，我们使用“振幅分析”，即以$ 2 \ rightarrow2 $散射的分散关系，以将界限放在Wilson系数上。我们表明，只有在某些Dimension 8运算符的存在下，尺寸6运算符才能存在。有趣的是，即使在树级别，尺寸6威尔逊系数的平方也可以受到约束。在这项工作的第二部分中，我们使用经典的因果关系论证成功地重新逐渐重新逐渐重新逐渐重新逐步化，即任何非平凡背景的波动速度都不应超过光速。我们还指出了关于较低频率速度是否可以用作因果关系违规的相关数量的高频率分析中的一些微妙之处：例如，我们表明，由于这些细微的速度，如果在手势lagrangian中添加了一个小的pion质量，那么在手势lagrangian中添加了一个小的pion质量。最后，我们提到了一个有趣的非宗教示例，在该例子中，崇高性要求比“振幅分析”产生更强的结合。
We derive the causality and unitarity constraints on dimension 6 and dimension 8 Gluon field strength operators in the Standard Model Effective Field Theory (SMEFT). In the first part of the paper, we use the 'amplitude analysis' i.e. dispersion relation for $2\rightarrow2$ scattering in the forward limit, to put bounds on the Wilson coefficients. We show that the dimension 6 operators can exist only in the presence of certain dimension 8 operators. It is interesting that the square of the dimension 6 Wilson coefficients can be constrained in this case even at the tree level. In the second part of this work, we successfully rederive all these bounds using the classical causality argument that demands that the speed of fluctuations about any non-trivial background should not exceed the speed of light. We also point out some subtleties in the superluminality analysis regarding whether the low-frequency phase velocity can always be used as the relevant quantity for Causality violation: as an example, we show that, due to these subtleties, if a small pion mass is added in the chiral Lagrangian, it is unclear if any strict positivity bound can be derived on the dimension 8 Wilson coefficient. Finally, we mention an interesting non-relativistic example where the subluminality requirement produces a stronger bound than the 'amplitude analysis'.
