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clwainwright / CosmoTransitions

A package for analyzing finite or zero-temperature cosmological phase transitions driven by single or multiple scalar fields.
MIT License
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Euclidean action as a function of temperature (and derivative) #28

Closed runburg closed 3 years ago

runburg commented 3 years ago

I may be missing something here, but I see that finding dS/dT is still listed as a todo. As far as I can tell, the action returned by transitionFinder.tunnelFromPhase is the action at the nucleation temperature. But it doesn't seem like the action as a function of temperature is stored.

Is there an easy way to do this? I saw that returning the derivative dS/dT was a todo so I imagine my request is not straightforward.

If there isn't, I would be interested in making these changes myself if that's useful. Thanks!

clwainwright commented 3 years ago

The easiest way to calculate it is to just run the pathDeformation.fullTunneling() function by feeding in your potential at a temperature that's slightly higher than the nucleation temperature and to take a finite difference in the action to calculate the derivative. See transitionFinder_tunnelFromPhaseAtT() to see how this is called. You could also calculate the derivative by modifying the tunnelFromPhase() function to return the full outdict object (which contains tunneling information as a function of temperature), and then take finite differences from that, but that's a little more prone to error because you won't be in control of the finite step size in temperature.