Gravitational effective field theory islands, low-spin dominance, and the four-graviton amplitude
Gravitational effective field theory islands, low-spin dominance, and the four-graviton amplitude
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引力有效场理论岛、低自旋优势和四引力子振幅
DOI：
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发表时间：
2021
期刊：
影响因子：
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通讯作者：
A. Zhiboedov
中科院分区：
文献类型：
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作者：
Z. Bern;Dimitrios I. Kosmopoulos;A. Zhiboedov
我们分析了从微扰么正性和交叉的高维算子的领先贡献的四个引力子振幅在四个时空维度的约束，包括从不同的螺旋配置遵循的约束。我们专注于领先的顺序效果，由于大量的自由度交换，使感兴趣的红外有限的振幅。特别是，我们把一个约束的系数的R3算子，纠正引力子三点振幅的R4系数。为了测试的约束，我们获得非平凡的有效场论数据的计算和采取的大质量扩展的一个循环的最小耦合四引力子振幅与大质量粒子自旋2循环中的循环。值得注意的是，我们观察到，领先的EFT系数从弦和单圈场理论振幅位于小岛。岛的形状和位置可以从威尔逊系数的色散表示中使用交叉并假设最低自旋谱密度是最大的。我们的分析表明，弱耦合引力物理理论的威尔逊系数比2 → 2散射的色散考虑所产生的界限所指示的约束要大得多。利用现代振幅方法，包括广义么正性、超对称分解和双拷贝，计算了用于获得EFT数据的单圈四引力子振幅。
We analyze constraints from perturbative unitarity and crossing on the leading contributions of higher-dimension operators to the four-graviton amplitude in four spacetime dimensions, including constraints that follow from distinct helicity configurations. We focus on the leading-order effect due to exchange by massive degrees of freedom which makes the amplitudes of interest infrared finite. In particular, we place a bound on the coefficient of the R 3 operator that corrects the graviton three-point amplitude in terms of the R 4 coefficient. To test the constraints we obtain nontrivial effective field-theory data by computing and taking the large-mass expansion of the one-loop minimally-coupled four-graviton amplitude with massive particles up to spin 2 circulating in the loop. Remarkably, we observe that the leading EFT coefficients obtained from both string and one-loop field-theory amplitudes lie in small islands. The shape and location of the islands can be derived from the dispersive representation for the Wilson coefficients using crossing and assuming that the lowest-spin spectral densities are the largest. Our analysis suggests that the Wilson coefficients of weakly-coupled gravitational physical theories are much more constrained than indicated by bounds arising from dispersive considerations of 2 → 2 scattering. The one-loop four-graviton amplitudes used to obtain the EFT data are computed using modern amplitude methods, including generalized unitarity, supersymmetric decompositions and the double copy.