Question on Boundaries_MSSM.f90

[MailQuestion]

Dear Florian,

I would like to ask your comments on the internal behaviour of SARAH/SPheno which is not perfectly clear to me concerning the renormalisation procedure with high energy boundary conditions.
I will take as an example the MSSM generated by SARAH 4.9.3.

If I have understood correctly, the function “Sugra” in the “Boundaries_MSSM.f90” file takes care of the running from high to low scales using an iterative procedure which terminates after a given precision in the computation of the masses is reached. (Please, correct me if I am wrong).
If this procedure is successful “FoundResult= .True.” at line 1646.

I realised that the masses and couplings computed at this point of the algorithm do not correspond to the ones printed in the SPheno output file (at the SUSY scale).
Which is the definition of these parameters (in particular mHu, mHd, Mu, vevs and couplings)? Are they computed in the DRbar scheme at the MZ scale?
Indeed, using the vevs and the gauge couplings provided here one can exactly reproduce the MZ mass.

Moreover I noticed that the corresponding Mu parameter is extracted by SolveTadpoleEquations which is invoked at tree-level with zero loop-corrected tadpoles (line 1593).
If the parameters are defined in the DRbar scheme I would naively expect to see loop corrections to the tadpoles (Am I wrong?) which are, instead, exactly zero in a physical scheme as the on-shell.

Thanks for your time.

[FStaub]

Hi,

as you say correctly, the iterative procedure checks the convergence of masses. To save running time, these checks are only done for tree-level masses.
The loop masses and parameters are calculated afterwards because of these lines

Code: Select all

If (CalculateOneLoopMassesSave) Then 
CalculateOneLoopMasses =  CalculateOneLoopMassesSave 
Write(*,*) "Calculate loop corrected masses " 
Call OneLoopMasses(MAh,MAh2,MCha,MCha2,MChi,MChi2,MFd,MFd2,MFe,MFe2,MFu,              & 
& MFu2,MGlu,MGlu2,Mhh,Mhh2,MHpm,MHpm2,MSd,MSd2,MSe,MSe2,MSu,MSu2,MSv,MSv2,               & 
& MVWm,MVWm2,MVZ,MVZ2,pG,TW,UM,UP,v,ZA,ZD,ZDL,ZDR,ZE,ZEL,ZER,ZH,ZN,ZP,ZU,ZUL,            & 
& ZUR,ZV,ZW,ZZ,alphaH,betaH,vd,vu,g1,g2,g3,Yd,Ye,Yu,Mu,Td,Te,Tu,Bmu,mq2,ml2,             & 
& mHd2,mHu2,md2,mu2,me2,M1,M2,M3,kont)
...

If you want to check convergence with loop masses, you can simply adjust

Code: Select all

Write(*,*) "Calculating mass spectrum" 
CalculateOneLoopMassesSave = CalculateOneLoopMasses 
CalculateOneLoopMasses = .false. 

and remove the second line.

Note, the tadpoles in these routines are then still tree-level. The loop corrections are added in the routine "OneLoopMasses".

Cheers
Florian

[luigi]

Thanks for your comments. Best, Luigi