Fermion masses from Yukawa matrices

[Avelino]

You mention that your hh_1 state has SM-like couplings. However, I see that you get a BR(h -> b bbar) much below the SM prediction. Could it be that one of your Yukawa inputs is too low?

[ianpaga]

You mention that your hh_1 state has SM-like couplings. However, I see that you get a BR(h -> b bbar) much below the SM prediction. Could it be that one of your Yukawa inputs is too low?

Hi Avelino,

you're right, this is exactly my problem since the hh_1 branching ratios are not very SM-like but its couplings are according to the following block

Code: Select all

Block HiggsBoundsInputHiggsCouplingsFermions # 
   [b] 1.00000000E+00    6.45743075E-17        3             25         5         5 # h_1 b b coupling 
    1.00000000E+00    6.55177166E-17        3             25         3         3 # h_1 s s coupling 
    1.00000000E+00    0.00000000E+00        3             25         6         6 # h_1 t t coupling  
    1.00000000E+00    0.00000000E+00        3             25         4         4 # h_1 c c coupling 
    1.00000000E+00    0.00000000E+00        3             25        15        15 # h_1 tau tau coupling 
    1.00000000E+00    0.00000000E+00        3             25        13        13 # h_1 mu mu coupling  [/b]
    4.39491100E-02    1.80418531E-25        3             35         5         5 # h_2 b b coupling 
    1.52782680E+01    1.30258615E-16        3             35         3         3 # h_2 s s coupling 
    4.39490641E-02    0.00000000E+00        3             35         6         6 # h_2 t t coupling  
    1.52782681E+01    0.00000000E+00        3             35         4         4 # h_2 c c coupling 
    3.73256199E-01    0.00000000E+00        3             35        15        15 # h_2 tau tau coupling 
    3.73256199E-01    0.00000000E+00        3             35        13        13 # h_2 mu mu coupling  
    5.91266046E-01    6.45743075E-17        3             35         5         5 # h_3 b b coupling 
    2.82692582E+00    2.03529086E-17        3             35         3         3 # h_3 s s coupling 
    5.91266155E-01    0.00000000E+00        3             35         6         6 # h_3 t t coupling  
    2.82692586E+00    1.68159292E-16        3             35         4         4 # h_3 c c coupling 
    1.66354142E+00    0.00000000E+00        3             35        15        15 # h_3 tau tau coupling 
    1.66354142E+00    0.00000000E+00        3             35        13        13 # h_3 mu mu coupling

or am I interpreting this HiggsBoundsInputHiggsCouplingsFermions block incorrectly?

best,
Ian

[ianpaga]

You mention that your hh_1 state has SM-like couplings. However, I see that you get a BR(h -> b bbar) much below the SM prediction. Could it be that one of your Yukawa inputs is too low?

Hi Avelino,

you're right, this is exactly my problem since the hh_1 branching ratios are not very SM-like but its couplings are according to the following block

Code: Select all

Block HiggsBoundsInputHiggsCouplingsFermions # 
    1.00000000E+00    6.45743075E-17        3             25         5         5 # h_1 b b coupling 
    1.00000000E+00    6.55177166E-17        3             25         3         3 # h_1 s s coupling 
    1.00000000E+00    0.00000000E+00        3             25         6         6 # h_1 t t coupling  
    1.00000000E+00    0.00000000E+00        3             25         4         4 # h_1 c c coupling 
    1.00000000E+00    0.00000000E+00        3             25        15        15 # h_1 tau tau coupling 
    1.00000000E+00    0.00000000E+00        3             25        13        13 # h_1 mu mu coupling 
    4.39491100E-02    1.80418531E-25        3             35         5         5 # h_2 b b coupling 
    1.52782680E+01    1.30258615E-16        3             35         3         3 # h_2 s s coupling 
    4.39490641E-02    0.00000000E+00        3             35         6         6 # h_2 t t coupling  
    1.52782681E+01    0.00000000E+00        3             35         4         4 # h_2 c c coupling 
    3.73256199E-01    0.00000000E+00        3             35        15        15 # h_2 tau tau coupling 
    3.73256199E-01    0.00000000E+00        3             35        13        13 # h_2 mu mu coupling  
    5.91266046E-01    6.45743075E-17        3             35         5         5 # h_3 b b coupling 
    2.82692582E+00    2.03529086E-17        3             35         3         3 # h_3 s s coupling 
    5.91266155E-01    0.00000000E+00        3             35         6         6 # h_3 t t coupling  
    2.82692586E+00    1.68159292E-16        3             35         4         4 # h_3 c c coupling 
    1.66354142E+00    0.00000000E+00        3             35        15        15 # h_3 tau tau coupling 
    1.66354142E+00    0.00000000E+00        3             35        13        13 # h_3 mu mu coupling

or am I interpreting this HiggsBoundsInputHiggsCouplingsFermions block incorrectly?

best,
Ian

[BjHerrmann]

Hi Ian, hi Avelino,

we are picking up this thread, since we are working on almost the same question.

We have high-scale model predicting a certain pattern of the Yukawa matrices at the high scale. It is basically the Seesaw1 model (with minor modifications, which are not relevant to this question) and we have generated the SPheno version using SARAH.
Starting from the high scale, we would like to obtain the corresponding Yukawas at the low scale together with the CKM and PMNS matrices.

However, as you guys mentioned above, SPheno seems to enforce the matching at the low scale to the known SM masses as well as the gauge couplings.

We have tried the following: in SPheno.m, we have edited the low-scale matching conditions, defined by "DEFINITION[MatchingConditions]". To be more specific, we have first replaced the line

DEFINITION[MatchingConditions] = Default[THDMII]

by the full list (copied from SARAH/Package/SPheno/SPheno.m):

DEFINITION[MatchingConditions]={
{hyperchargeCoupling,g1SM},
{leftCoupling,g2SM},
{strongCoupling,g3SM},
{VEVSM1,vSM/Sqrt[1+TanBeta^2]},
{VEVSM2,VEVSM1*TanBeta},
{UpYukawa,YuSM vSM/VEVSM2},
{DownYukawa,YdSM vSM/VEVSM1},
{ElectronYukawa,YeSM vSM/VEVSM1}
};,

We have checked that this gives the same result as the Default[THDMII] for a given parameter point.

Then, we have removed the Yukawa part of the above list:

DEFINITION[MatchingConditions]={
{hyperchargeCoupling,g1SM},
{leftCoupling,g2SM},
{strongCoupling,g3SM},
{VEVSM1,vSM/Sqrt[1+TanBeta^2]},
{VEVSM2,VEVSM1*TanBeta}
};,

SARAH then issues a warning in the style of "SM matching conditions too short, this may cause some problem...", when creating SPheno source code.
Running SPheno, we observe the following error:

Calculating mass spectrum
1 .-iteration
Loop corrections to Yukawa couplings at renormalisation scale too large!
Note: The following floating-point exceptions are signalling: IEEE_DIVIDE_BY_ZERO IEEE_UNDERFLOW_FLAG IEEE_DENORMAL
STOP Subroutine TerminateProgram

In the ideal case, we would like to run SPheno starting from the high scale, evolve the parameters (especially the Yukawas) to the low scale, but ignoring SM matching conditions for the Yukawas (but keeping the matching of the gauge couplings), such that we would have the evolved Yukawas as output at the low scale.

Is this somehow achievable using SARAH+SPheno?
Otherwise, can SPheno just do one run from high to low scale, where input is given at the high scale?

Greetings from Annecy,
Sam, Jordan, Björn

[FStaub]

Hi,

That no possibility I have ever thaught off. Maybe, it helps to rename the Yukawas and remove the description in parameters.m in order to treat them as any other parameter. However, I really expect that this will break many things like the flavour observables.
I guess there is no way around modifying the code by hand.

Cheers
Florian