Hi, I'm reading through a paper and have come across what my tutor described as a 'theta function', however it seems to bear no resemblance to the actual 'theta function' I can find online. In the paper it reads:(adsbygoogle = window.adsbygoogle || []).push({});

[itex]\int^1_0 dz~\theta (s-\frac{4m^2}{z}-\frac{m^2}{1-z}) [/itex]

And apparently this ensures that s > [itex]\frac{4m^2}{z}+\frac{m^2}{1-z}[/itex] when that expression is included in a longer integration over s and z, however I've never come across something like this before. That expression above is obtained integrating

[itex]\delta (q-p-p')[/itex]

over p and p' (4-momenta). Does anyone have any advice about what this is and how to include it in the integral? Thanks!

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# 'Theta function' setting conditions similar to delta function?

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