Problem with loop functions in MSSM

[oscarvives]

Hi Florian,
We have been using SARAH with SPheno and SPheno alone to calculate some LFV processes. We observed some differences between them and when checking for a single point, it writes the output without complaints, but then in Messages.out we discovered a lot of problems like:

IIp called with small input: 4.2314055921878632E-006 1215873.081 8997489 1949486.7161741729 1197328.3775434766

MM somehow called with small inputs: 1949486.7161741729 4.2314055921878632E-006 1949486.7161741729 4.2314055921878632E-006 1215873.0818997489 1197328.3775434766

all this repeated several times and ending with:

Problem in Function B0, divergence for k->0, m1=m2=0
Problem in Function B0, divergence for k->0, m1=m2=0

So, I guess the obtained results are not correct. This results were obtained in the SARAH MSSM model, with: SPheno-4.0.3, SARAH-4.12.3 (by the way, correcting the small bug in TadpoleEquations_MSSM.f90), and this very universal Input file.

Do you know what is happening?? is this a bug or a problem of my installation?

Best,
Oscar

Block MODSEL # Select model
1 1 # 1/0: High/low scale input
2 1 # Boundary Condition
5 2 # general CP phases
6 1 # Generation Mixing
Block SMINPUTS # Standard Model inputs
1 1.27918000e+02 # alpha_em^(-1)(MZ) SM MSbar
2 1.16639000e-05 # G_Fermi
3 1.18900000e-01 # alpha_s(MZ)MSbar
4 9.11876000e+01 # MZ(pole)
5 4.20000000e+00 # mb(mb)
6 1.70900000e+02 # Mtop(pole)
7 1.77700000e+00 # Mtau(pole)
21 4.75000000e-03 # Mdown(2 GeV) MSbar
22 2.40000000e-03 # Mup(2 GeV) MSbar
23 1.04000000e-01 # Mstrange(2 GeV) MSbar
24 1.27000000e+00 # Mcharm(Mcharm) MSbar
11 5.10998902e-04 # M2e(pole)
13 1.05658357e-01 # Mmu(pole)
Block MINPAR # minimal model parameters
1 +1.00000000E+03 # m0
2 +5.00000000E+02 # m12
3 +4.00000000E+01 # tanb at m_Z
4 1.00000000E+00 # Sign(mu)
5 +1.00000000E+02 # A0
Block SPhenoInput # SPheno specific input
1 -1 # error level
2 0 # SPA conventions
7 0 # Skip 2-loop Higgs corrections
8 3 # Method used for two-loop calculation
9 1 # Gaugeless limit used at two-loop
10 0 # safe-mode used at two-loop
11 0 # calculate branching ratios
13 1 # 3-Body decays: none (0), fermion (1), scalar (2), both (3)
14 0 # Run couplings to scale of decaying particle
12 1.000E-04 # write only branching ratios larger than this value
15 1.000E-30 # write only decay if width larger than this value
31 -1 # fixed GUT scale (-1: dynamical GUT scale)
32 0 # Strict unification
34 1.000E-04 # Precision of mass calculation
35 40 # Maximal number of iterations
36 5 # Minimal number of iterations before discarding points
37 1 # Set Yukawa scheme
38 2 # 1- or 2-Loop RGEs
50 1 # Majorana phases: use only positive masses (put 0 to use file with CalcHep/Micromegas!)
51 0 # Write Output in CKM basis
52 0 # Write spectrum in case of tachyonic states
55 1 # Calculate loop corrected masses
57 1 # Calculate low energy constraints
65 1 # Solution tadpole equation
66 1 # Two-Scale Matching
67 1 # effective Higgs mass calculation
75 0 # Write WHIZARD files
76 0 # Write HiggsBounds file
77 0 # Output for MicrOmegas (running masses for light quarks; real mixing matrices)
78 0 # Output for MadGraph (writes also vanishing blocks)
86 0. # Maximal width to be counted as invisible in Higgs decays; -1: only LSP
510 0. # Write tree level values for tadpole solutions
515 1 # Write parameter values at GUT scale
520 1. # Write effective Higgs couplings (HiggsBounds blocks): put 0 to use file with MadGraph!
521 1. # Diphoton/Digluon widths including higher order
525 0. # Write loop contributions to diphoton decay of Higgs
530 0. # Write Blocks for Vevacious
550 0. # Calculate Fine-Tuning

[FStaub]

Hi Oscar,

I don't think that this caused the problems with LFV processes. Both warnings can (at most) influence the numerical values of the Higgs masses. The one

Code: Select all

Problem in Function B0, divergence for k->0, m1=m2=0

is caused by Goldstone contributions which drop out at the end. These messages were always there (maybe I should think of a way to suppress them).

I need to check the origin of the other two messages, but IIp and MM are two-loop functions which only enter the Higgs mass. Since LFV processes hardly depend on the (light) Higgs mass, I don't see that this could lead to misleading effects.

How big are the differences between SPheno and SPhenoMSSM and in which observables does this show up.

Cheers,
Florain

[oscarvives]

Hi Florian,

Well, I was using before version 4.12.0 and I was getting, for the same input:
Spheno:

26 9.78232041E-14 # Brmu->egamma

29 6.08765204E-16 # Brmu->3e

and SARAH:

701 1.45868469E-16 # muegamma

901 1.95784487E-18 # mu3e

But now, with version 4.12.3 and the same input, I am getting:

701 8.21292646E-14 # BR(mu->e gamma)

901 5.71525898E-16 # BR(mu->3e)

So, now everything looks OK, but I do not understand what are the changes between 4.12.0 and 4.12.3 that solve this...

Oscar