Hi,

Starting with "BoundaryLowScaleInput", is it possible for SPheno to calculate the running couplings to high scale?
Does SPheno use only top-down approach?


Cheers,
Sam

Of course SPheno can run couplings in both directions. But if there is no input at the high energy scale what should it do at that point, and where should it run to?

I think what you want is to specify

BoundarySUSYScale

along with a ConditionGUTScale (so that it knows where to run to)

If you use the BoundaryLowScaleInput that's because you want to directly specify parameters at the "Low" scale without running, so it will not run the high-energy theory.