论文标题
在保形场理论中对能量量张量的分析约束
Analytic constraints on the energy-momentum tensor in conformal field theories
论文作者
论文摘要
在这项工作中，我们研究了在四维单一，局部和庞加莱协变量量子场理论中无体外壳状态的能量量张量的矩阵元素。我们证明，这些矩阵元素可以通过Lorentz发电机的协变量来参数化，并且这会引起形式的分解，在这种构成因素分解中，在该分解中，状态的螺旋性依赖性是分解的。使用这种分解，我们继续探索对共形场理论的某些后果，得出由共形对称性施加的显式分析条件，并使用示例来说明它们独特地固定矩阵元素的形式。我们还提供了有关无质量颗粒所施加的约束的新见解，特别表明无质量的自由理论必然是顺式的。
In this work we investigate the matrix elements of the energy-momentum tensor for massless on-shell states in four-dimensional unitary, local, and Poincaré covariant quantum field theories. We demonstrate that these matrix elements can be parametrised in terms of covariant multipoles of the Lorentz generators, and that this gives rise to a form factor decomposition in which the helicity dependence of the states is factorised. Using this decomposition we go on to explore some of the consequences for conformal field theories, deriving the explicit analytic conditions imposed by conformal symmetry, and using examples to illustrate that they uniquely fix the form of the matrix elements. We also provide new insights into the constraints imposed by the existence of massless particles, showing in particular that massless free theories are necessarily conformal.
