Dear Florian,

I am trying to run SPheno with a complex neutrino Yukawa coupling.
As a reference, I am using the SARAH model B-L-SM, successfully producing and compiling the SPheno code.
I have modified the SPheno input file LesHouches.in.BLSM_low by switching to 1 the flag 5 of MODSEL and by adding the block IMYVIN.
I would naively expect different results for the mixing matrix UV with respect to the real case but I cannot see any effect.
Could you please clarify how to correctly implement the imaginary part of Yv?

Thanks,
Luigi

Hi Luigi,

that sounds correct. Is the imaginary part of YV printed in the spc file or is it missing as well?

Cheers,
Florian

Dear Florian,

exactly: IMYv is absent, despite UVMIX and IMUVMIX are always present (independently of the CPV flag (MODSEL 5)) but unchanged.

Best,
Luigi

Hi,

I just tested it myself and it looks actually fine. I attach my in- and output.

If I remember correctly, there was in earlier version the problem that the input name for the imaginary part was somehow changed. What version do you use? You should find in InputOutput_BLSM.f90



Best,
Florian

Hi Florian,

thanks for the examples you attached. I just realised from your SPheno input file that the flag 5 of MODSEL should be set to 2, not to 1, as I was incorrectly doing.
I was using your paper 1503.04200 as a reference and I thought the only two available options were 0 and 1.

Anyway, the SPheno version I am using is 3.3.8 while SARAH version is 4.9.3

Thanks for your help,
Luigi

Ah yes. I was switching some time ago to the official SLHA conventions, see 0801.0045:

0 : CP is conserved. No information even on the CKM phase is
used. This corresponds to the SLHA1.
1 : CP is violated, but only by the standard CKM phase. All
other phases are assumed zero.
2 : CP is violated. Completely general CP phases allowed.

Cheers,
Florian

Hi Florian,

thanks for your clarification. I have another question. I was playing with the neutrino mass matrix, extending it with more fermions and filling it with random numbers. I came across a matrix for which SPheno complains with "NaN appearing in CalculateMFv".
I looked into the code and I think that the problem is related to the function Call EigensystemQP(mat2, Eig, UV, ierr, test) which gives the following result:

NaN NaN 9.3799391496140626E-004 250745.27315567495 250746.26627344353 255846.30664839596 255847.24200795338 307984.25276381057 307985.10927670845

where the first two entries are NaN.

I did the same exercise with Mathematica and the eigenvalues should be:

{3.149324788354803*^-11, 5.603363258721244*^-10, 3.276124805568065*^-8, 250745.273155675, 250746.26627344365, 255846.30664839593, 255847.24200795332, 307984.25276381057, 307985.10927670845}

I attached the mathematica file with the specific matrix.

Thanks,
Luigi

Hi,

I think you missed the attachment.

The most common problem in this direction: you missed to edit src/Makefile:
in order to calculate the neutrino masses with QP precision, you need to remove -DONLYDOUBLE here (if you really missed that,make sure to recompile everything via a "make cleanall")

Cheers,
Florian

Hi Florian,
I am working in Type-I SeeSaw model with complex neutrino yukawa (Yv). I have done the necessary change that you have mentioned i.e. to edit src/Makefile: PreDef = -DGENERATIONMIXING
After that I had made all the necessary things (switching to 2 the flag 5 of MODSEL and by adding the block IMYVIN) but getting the error "NaN appearing in CalculateMFv" for a set of yukawa couplings which gives me reliable values of neutrino masses.
My SARAH version is 4.8.6 and SPheno version is 3.3.7
It will be really helpful if you please clarify this issue.

Thanks,
Avirup

It might be that your combination results in a negative mass squared. Did you try if it works in the real limit?