Mathematical equation involving integrals and delta functions

Prompt

\[ \mathcal{A} = \int \prod_{i=1}^4 \frac{d^{26}k_i}{(2\pi)^{26}} \, \delta^{(26)}\left(k_1 + k_2 - k_3 - k_4\right) \, \frac{1}{s \, t \, u} \prod_{i<j} \left( \alpha' (k_i - k_j)^2 \right). \] Let's break down each component of this formula. ### Components of the Scattering Amplitude 1. **Momentum Integration:** The integral \( \int \prod_{i=1}^4 \frac{d^{26}k_i}{(2\pi)^{26}} \) represents the integration over the momentum space of all four strings involved in the scattering. Each \( d^{26}k_i \) is an integration over the 26-dimensional momentum vector \( k_i \), and the normalization factor \( (2\pi)^{26} \) ensures the correct scaling for a field in a 26-dimensional space Redraw