AI 中文总结
该研究提出类CSW递归框架计算电磁EFT的树级螺旋度振幅，利用Hafnians构造接触振幅，给出N≤14光子的接触拉格朗日量，计算多光子树振幅并证明电磁对偶与螺旋度守恒的等价性。
AI 中文摘要
我们提出了一种用于计算电磁学一般有效场论（EFT）中任意树级螺旋度振幅的递归框架。我们证明光子振幅可通过类CSW递归构造，其构建块由纯局域子振幅组成。对于固定数量的外腿，仅需计算有限个此类接触振幅，且这些接触振幅可通过 Hafnians 表示为紧凑形式。我们进一步表明，这些接触振幅编码于有效接触拉格朗日量中，该拉格朗日量可通过合适的生成泛函从一般 EFT 拉格朗日量系统计算得出。我们提供了适用于光子数 N≤14 的该接触拉格朗日量。我们论证该接触拉格朗日量揭示了螺旋度守恒振幅的隐藏简洁性，为离壳电磁对偶性与螺旋度守恒之间的等价性提供了简洁证明。我们还展示了如何对螺旋度守恒理论的接触拉格朗日量进行全 N 求和，并以玻恩-因费尔德（BI）电磁学为例说明该过程。基于这些方法和结果，我们计算了由一般 EFT 算符产生的完整6点和8点树级螺旋度振幅，以及 BI 电磁学中高达10点的树振幅。
英文摘要
We present a recursive framework for computing arbitrary tree-level helicity amplitudes in the general effective field theory (EFT) of electromagnetism. We show that photon amplitudes can be constructed using a CSW-like recursion, whose building blocks consist of purely local subamplitudes. For a fixed number of external legs, only a finite number of these contact amplitudes need to be computed, and these admit compact expressions in terms of Hafnians. We further show that the contact amplitudes are encoded in an effective contact Lagrangian, that can be computed systematically from the general EFT Lagrangian using a suitable generating functional. We provide this contact Lagrangian up to $N=14$ photons. We argue that the contact Lagrangian reveals the hidden simplicity of helicity-conserving amplitudes, providing a simple proof of the equivalence between off-shell electromagnetic duality and helicity conservation. We further show how to resum the contact Lagrangian of a helicity-conserving theory to all $N$, and illustrate the procedure for Born-Infeld (BI) electromagnetism. Building on these methods and results, we compute the complete 6-point and 8-point tree-level helicity amplitudes generated by generic EFT operators, and the tree amplitudes up to 10-point in BI electromagnetism.
Comments60 pages, 3 figures
