标题： 关于胶子树幅的恒等式评述 显示英文标题

标题： Comment on the Identities of the Gluon Tree Amplitudes

摘要： 近日，Bjerrum-Bohr、Damgaard、Feng和Sondergaard推导出了一组新的有趣的Yang-Mills树散射振幅的二次恒等式。 这里我们指出，这些YM振幅的二次恒等式实际上可以直接从重引力子-标量-轴子散射振幅的KLT关系（四维时空）中得出。 这澄清了它们的物理起源，并且提供了一个更简单的恒等式版本。 我们还指出，最近发现的Bern-Carrasco-Johansson的YM旋手性振幅恒等式可以通过多次使用Schouten恒等式来验证。 我们还指出了可以从KLT关系中写出的其他二次恒等式。 显示英文摘要

摘要： Recently, Bjerrum-Bohr, Damgaard, Feng and Sondergaard derived a set of new interesting quadratic identities of the Yang-Mills tree scattering amplitudes. Here we comment that these quadratic identities of YM amplitudes actually follow directly from the KLT relation for graviton-dilaton-axion scattering amplitudes (in 4 dimensional spacetime). This clarifies their physical origin and also provides a simpler version of the new identities. We also comment that the recently discovered Bern-Carrasco-Johansson identities of YM helicity amplitudes can be verified by using (repeatedly) the Schouten identity. We also point out additional quadratic identities that can be written down from the KLT relations.