Fractional Soft Limits of Scattering Amplitudes
Fractional Soft Limits of Scattering Amplitudes
复制标题
散射幅度的分数软极限
DOI：
10.1103/physrevlett.128.231601
复制
发表时间：
2022
影响因子：
8.6
通讯作者：
Penco, Riccardo
中科院分区：
文献类型：
--
作者：
Brauner, Tomáš;Esposito, Angelo;Penco, Riccardo
一个普遍的说法是，涉及一个软南武-戈德斯通玻色子的散射过程的振幅应该像软动量的整数幂那样缩放。通过考虑固体中声子的散射，我们重新审视了这一期望。我们表明，依赖于在散射过程中所涉及的声子的螺旋度，散射振幅实际上可能会消失一样fractionalpower的软动量。这是4点振幅的一个特点，可以追溯到（1）洛伦兹不变性的（自发或显式）破坏，以及（2）当其中一个声子变软时产生的近似共线运动学。我们的结果扩展到一般类的非相对论位移不变的矢量场理论。
It is a common lore that the amplitude for a scattering process involving one soft Nambu-Goldstone boson should scale like an integer power of the soft momentum. We revisit this expectation by considering thescattering of phonons in solids. We show that, depending on the helicities of the phonons involved in the scattering process, the scattering amplitude may in fact vanish like afractionalpower of the soft momentum. This is a peculiarity of the 4-point amplitude, which can be traced back to (1) the (spontaneous or explicit) breaking of Lorentz invariance, and (2) the approximately collinear kinematics arising when one of the phonons becomes soft. Our results extend to the general class of nonrelativistic shift-invariant theories of a vector field.