• Fermion masses from Yukawa matrices

Hello SARAH/Spheno users,

I'm implementing a 3HDM model with SARAH and then using the LesHouches file as input for SPheno.

In the LesHouches file I specify a total of 6 complex Yukawa matrices Yu1,Yu2,Yu3, Yd1,Yd2,Yd3 (i have the flag allowing CP violation, namely:

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     5  2   #  switching on CP violation

I want to have SPheno to calculate the fermion masses Fd_1,2,3 and Fu_1,2,3 using the Yukawa matrices that I have specified in the LesHouches file but I get the default values for the masses, namely

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         1     5.00000000E-03  # Fd_1
         3     9.50000000E-02  # Fd_2
         5     4.18000000E+00  # Fd_3
         2     2.50000000E-03  # Fu_1
         4     1.27000000E+00  # Fu_2
         6     1.73500000E+02  # Fu_3
        11     5.10998930E-04  # Fe_1
        13     1.05658372E-01  # Fe_2
        15     1.77669000E+00  # Fe_3

I always get these masses even if all Yukawa matrices are set to zero and I'd like to know why this happens. I have defined the Yukawa matrices in the parameter.m file as follows

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{Yu1,       { Description -> "Up-Yukawa1-Coupling",
	        LaTeX -> "Y_1^u",
               LesHouches -> Yu1,
               OutputName-> Yu1            }},

I specify the values later after running SARAH in the LesHouches file.

And the fermions I define in SARAH as

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      {Fu,    {   Description -> "Up-Quarks",
                 PDG -> {2,4,6},
                 PDG.IX->{110100401,110100402,110100403},
                 Mass -> {LesHouches, LesHouches, LesHouches},
                 Width -> {External, External, External},
                 FeynArtsNr -> 3,
                 LaTeX -> "u",
                 ElectricCharge -> 2/3,
                 OutputName -> "u" }},

Which should not take any default number for the masses but rather calculate them given the Yukawa matrices. What am I doing wrong?

thanks for the help!
Ian

As far as I know, SPheno always takes fixed (measured) values for the SM fermion masses. Your input Yukawa values are hence irrelevant.

Avelino wrote:As far as I know, SPheno always takes fixed (measured) values for the SM fermion masses. Your input Yukawa values are hence irrelevant.

Hi avelino,

thanks for your answer. Do you have documentation supporting that fact? I'm a bit confused since I find the following code in the
TreeLevelMasses_3HDM.f90 file,

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NameOfUnit(Iname) = 'CalculateMFd'

MFd = 0._dp
ZDL = 0._dp
ZDR = 0._dp
mat(1,1) = 0._dp
mat(1,1) = mat(1,1)+(v1*Yd1(1,1))/sqrt(2._dp)
mat(1,1) = mat(1,1)+(v2*Yd2(1,1))/sqrt(2._dp)
mat(1,1) = mat(1,1)+(v3*Yd3(1,1))/sqrt(2._dp)

,

which is apparently reading my Yukawa matrices.

Thanks,
Ian

Yes, but look at the InputOutput file. You will see that it finally prints out the fixed values I mentioned before.

Avelino wrote:Yes, but look at the InputOutput file. You will see that it finally prints out the fixed values I mentioned before.

It's not obvious to me, in the InputOutput.F90 one can find the line

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 Write(io_L,102) INT(Abs(PDGFd(1))),MFd(1),"# "//Trim(NameParticleFd(1))// ""

where supposedly MFd got calculated in TreeLevelMasses.F90 when calling the function

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Subroutine CalculateMFd(Yd1,Yd2,Yd3,v1,v2,v3,ZDL,ZDR,MFd,kont)

Real(dp),Intent(in) :: v1,v2,v3

Complex(dp),Intent(in) :: Yd1(3,3),Yd2(3,3),Yd3(3,3)

Integer, Intent(inout) :: kont
Integer :: i1,i2,i3,i4, ierr
Integer :: j1,j2,j3,j4
Real(dp), Intent(out) :: MFd(3)
 Complex(dp), Intent(out) :: ZDL(3,3), ZDR(3,3)

 Complex(dp) :: mat(3,3)=0._dp, mat2(3,3)=0._dp, phaseM

Complex(dp) :: ZDL2(3,3), ZDR2(3,3)

 Real(dp) :: ZDL1(3,3), ZDR1(3,3), test(2), MFd2(3)

 Iname = Iname + 1
NameOfUnit(Iname) = 'CalculateMFd'

It seems that you're probably right but I find strange that it actually calculates them and should print them as well but it doesn't.

best,
Ian

I think you are right, sorry for the confusion. Anyway, somewhere in the SPheno code the computed values are replaced by the fixed ones. I will try to have a deeper look tomorrow and find where this happens.

Avelino wrote:I think you are right, sorry for the confusion. Anyway, somewhere in the SPheno code the computed values are replaced by the fixed ones. I will try to have a deeper look tomorrow and find where this happens.

Thank you, I appreciate your help a lot. I've been trying hard to solve this since, in my opinion, the facts that I'm using very specific Yukawa matrices and that the masses are not getting computed by Spheno, are contradictory to each other, in the sense that the couplings of my lightest Higgs to the fermions can't be trusted since the masses are always the "correct ones".

Let's talk soon, thanks

best,
Ian

Avelino wrote:I think you are right, sorry for the confusion. Anyway, somewhere in the SPheno code the computed values are replaced by the fixed ones. I will try to have a deeper look tomorrow and find where this happens.

Hello Avelino,

sorry for bothering so much with this, but have you had the chance to look in to the problem of how to compute the fermion masses given a set of input Yukawa matrices?

best,
Ian

Hi, sorry, I did not have time yesterday. Fortunately, Werner Porod (SPheno's father) is currently visiting Valencia and I had the chance to ask him. It turns out that SPheno deletes the input values for the SM Yukawa couplings and replaces them by those required to get the correct masses and mixing angles. You should be able to see this by comparing the output Yukawa parameters with your input values. They should be different. Is that the case?

Avelino wrote:Hi, sorry, I did not have time yesterday. Fortunately, Werner Porod (SPheno's father) is currently visiting Valencia and I had the chance to ask him. It turns out that SPheno deletes the input values for the SM Yukawa couplings and replaces them by those required to get the correct masses and mixing angles. You should be able to see this by comparing the output Yukawa parameters with your input values. They should be different. Is that the case?

Hi Avelino,

I'm attaching my input and output files. As you can see the input Yukawas are not replaced as they remain the same in the output file.

To be precise, the problem I'm having is that my lightest higgs hh_1 has (according to Spheno) SM-like coupings, which is not surprising since I'm woking in the alignment limit, these means that hh1 = 1/vSM*(v1*phi1 + v2*phi2 + v3*phi3) and do not mix with the others hh2, hh3.

I would then expect a decay width for hh1 very close to the SM value 4.3 x 10^-3 GeV since no new channels should be there due to the alignment limit. Surprisingly this is not the case since I'm getting a value of roughly 2 x 10^-3 Gev for the decay width of hh1, which is contradictory to the previous statements of alignment and SM-like couplings of hh1. My guess was that something weird was happening when I specified a set of Yukawas in the input file. One check I did was replacing my Yukawa lagrangian

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LagHC =  - ( Yd1 conj[H1].d.q + Yd2 conj[H2].d.q + Yd3 conj[H3].d.q - Yu1 H1.u.q - Yu2 H2.u.q - Yu3 H3.u.q + Ye conj[H1].e.l );

with

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LagHC =  -(Yd conj[H1].d.q + Ye conj[H1].e.l - Yu H1.u.q);

and I do get values very close to the ones predicted by the SM. This makes me think that there's some fishy when specifying Yukawas but I cannot exactly pinpoint the problem. I hope you can help me out finding this out.

best,
Ian

Fermion masses from Yukawa matrices

Fermion masses from Yukawa matrices

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