Hi,

Is it possible to Run RG from EW scale to planck scale in SPheno ? I noticed that for high scale SPheno, one can give input at GUT scale and run down to EW scale. But like in SM we know the value for \[Lambda] at EW scale only and we run down to planck scale to check the value there. I was using High scale SPheno for SM, I fixed the GUT scale Flag 31 to 1.00E+02 such that it become EW scale and I gave the input value for \[Lambda] as 0.27 and vary the Renormalization scale by flag 12 in MODSEL. I was able to vary the renormalization scale upto 1.00E+16 only, and for value 1.00E+17 or beyond I am getting the following error,

Problem with boundary conditions at EW scale
Note: The following floating-point exceptions are signalling: IEEE_INVALID_FLAG IEEE_DIVIDE_BY_ZERO IEEE_UNDERFLOW_FLAG IEEE_DENORMAL
STOP Subroutine TerminateProgram

I am also attaching the SPheno.m file that I used. Looking forward for your answer.

Hi,

you need to do it the other way and move MGUT to higher values. Setting the renormalization scale to value much higher than the ew scale will screw up all loop corrections.

Cheers
Florian

Hi,

I tried as you ask to do. I fixed the GUT scale to 1.00E+19, and varied the renormalization scale from 1.00E+02 to 1.00E+19. But I can only go to scale 1.00E+16, beyond that scale I am getting the following error,

Problem with boundary conditions at EW scale
Note: The following floating-point exceptions are signalling: IEEE_INVALID_FLAG IEEE_DIVIDE_BY_ZERO IEEE_UNDERFLOW_FLAG IEEE_DENORMAL
STOP Subroutine TerminateProgram

I think as the value of GUT scale is 1.00E+16, so we can only run the RG upto that scale only, am I right ?

Hi,

that's not what I meant. The renormalization of 10^19 makes no sense. You need to change SPheno.m to and vary _only_ the GUT scale in the Les Houches file. I can go up without any problems to 10^19.

Cheers,
Florian

Hi,

Thank you so much. That solved my problem.

Cheers,
Sanjoy