Dear Guy, I am Keping Xie. I am focus on the 1-loop rho parameter calcualtions within SPheno. This is 1-loop is very simple, only need calculate Pi1LoopVZ and Pi1LoopVWm. But when SPheno invoke these two functions in the section of calculating the low energy contraints, the input mass of will updated, possibly because of the 1-loop correction of self energy. Here I print it out the tree level mass of charginos, as follows.
MCha
1 21.181547107144951 msq 448.65793785220063
2 231.98454027338730 msq 53816.826925854853
3 657.39422192379925 msq 432167.16301879741
4 1006.2208495777107 msq 1012480.3981248899
Calculating low energy constraints
MCha
1 36.376413704600829 msq 1323.2434740082711
2 231.98454027338690 msq 53816.826925854664
3 716.96472441886874 msq 514038.41606102441
4 1008.2333912610417 msq 1016534.5712537407
MCha
1 38.561823744214074 msq 1487.0142504798323
2 231.98454027338730 msq 53816.826925854853
3 719.31737600290796 msq 517417.48741970886
4 1008.4006328054703 msq 1016871.8362424730
MCha
1 231.98454027339014 msq 53816.826925856170
2 918.12675751814982 msq 842956.74287079147
3 4082.9979116753680 msq 16670871.946745416
4 4673.4795886467437 msq 21841411.465497736

What is the mechanism that SPheno invokes here for this update? I saw it updates 3 times after it do the really calculation of Pi1LoopVZ and Pi1LoopVWm in the Delta_rho calculation. What is the criterion that SPheno use to exit this update?

Best regards,
Keping

Hi,

SPheno calculcates three times the tree-level masses used in the different low-energy observables:

- Quark flavour violating observables: running parameters at Q=160 GeV are used
- Lepton flavour violating observables: running parameters at Q=M_Z are used
- ew precission observables (delta rho, S,T,U): 'on-shell' values of the ew VEV and Weinberg angle are used

I must say that I'm confused by the huge jump of the masses you show. It seems that something goes wrong. Please note: I uploaded yesterday SARAH 4.12.2 where the calculation of the S,T,U parameters (one-loop corrections only) has been added, and the input parameters are calculated slightly differently (the Z-pole mass is used, no longer G_Fermi).

Cheers,
Florian

Dear Florian,

Thank you for your reply.

The big jump of mass seems to result from the 1-loop corrections. When I switch the option 55 (Calculate loop corrected masses) on, I got a warning
Problem in OneLoophh 7.4228703961003235E-016 5.1321914971975651E-016 5.5606867633741281E-016 5.7852942888222340E-013 6.2378975855181335E-006 470499.88325848238 680500.65098215942 1674833.7287216098 3523874.5240209587 5505308.6401427072
Problem in OneLoopHpm 0.0000000000000000 1.8773550077333509E-015 3.4074002566099048E-016 0.0000000000000000 3.4066680239950320E-013 6.3412206418798734E-006 11505.565576762659 682113.15112020099 1366617.5155220404 3184071.7569668950 3518429.5771940388 5516108.4988230430

In the previous version of SPheno, the code will stop because of the tachyonic state (negative mass square of scalars). But this new version 4.0.0 or 4.0.3 will pass this problem and continue other calculations.

Best regards,
Keping