English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

To get the total cross section of one interaction from its amplitude ${\calM}$, one needs to integrate $|{\cal M}|^2$ over phase spaces of all out-goingparticles. Starting from this paper, we will propose a new method to performsuch integrations, which is inspired by the reduced phase space integration ofone-loop unitarity cut developed in the last few years. The new method reducesone constrained three-dimension momentum space integration to anone-dimensional integration, plus one possible Feynman parameter integration.There is no need to specify a reference framework in our calculation, sinceevery step is manifestly Lorentz invariant by the new method. The current paperis the first paper of a series for the new method. Here we have exclusivelyfocused on massless particles in 4D. There is no need to carve out acomplicated integration region in the phase space for this particular simplecase because the integration region is always simply $[0,1]$.

Cross Section Evaluation by Spinor Integration I: The massless case in 4D