Calculation of Wilson Coefficients in SPheno

Questions about the interface between SARAH and SPheno as well as the FlavorKit functionality
SoundSonic1
Posts: 3
Joined: 10. Jan 2018, 14:53

Calculation of Wilson Coefficients in SPheno

Postby SoundSonic1 » 10. Jan 2018, 15:16

Hello,

i tried to verify the coeffC8sm = 0.16443888E-10 (real part) at Q = 160 GeV taken from the SPheno output with the formula given in hep-ph/9805303v2 Eq. 10 on page 5,
but what i got was C8 = -0.0964357.
Then i normalized my C8 with n_cq^-1 = 8.87289*10^-9 as stated in arxiv:1405.1434 and got C8norm = -8.55663*10^-10.

Could you tell me what kind of normalization i should use to get the appropriate value?

FStaub
Site Admin
Posts: 546
Joined: 13. Apr 2016, 14:05

Re: Calculation of Wilson Coefficients in SPheno

Postby FStaub » 12. Jan 2018, 14:11

Hi,

the normalisation was chosen to be in agreement with the conventions of flav-io. I would need to check what the exact factor is, but I'm still on parental leave. I hope that checking the flav-io documentation is of some help for you.

Best,
Florian

Avelino
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Joined: 13. Apr 2016, 14:57
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Re: Calculation of Wilson Coefficients in SPheno

Postby Avelino » 12. Jan 2018, 14:41

If this is not solved earlier, I will have a look next week.

In the meantime, perhaps it would be useful to point out that the most recent version of SARAH/SPheno produces output for the Wilson coefficients in WCxf format (see 1712.05298 and https://wcxf.github.io/). This format was recently defined to avoid confusions regarding normalization (and other conventions) and to allow for an easier exchange of I/O files between different flavor codes). In this case the normalization of the operator you are interested about was unambiguously fixed when defining the FlavorKit basis (https://wcxf.github.io/assets/pdf/WET.FlavorKit.pdf).

SoundSonic1
Posts: 3
Joined: 10. Jan 2018, 14:53

Re: Calculation of Wilson Coefficients in SPheno

Postby SoundSonic1 » 12. Jan 2018, 15:32

Hi,

@Staub
it seems like flav-io and the paper i referred to use the same basis. Is it possible to output the Wilson Coefficients of flav-io?
On a different note: i was able to confirm coeffC7sm using the steps i mentioned in the first post.

@Avelino
The json files from SPheno/FlavorKit contain only the chirality flipped coeffC7p and coeffC8p as Q1R_32 and Q2R_32?
This was testet with SARAH-4.12.3 and SPheno-4.0.3 and the THDM-II.

Best regards,
SoundSonic1

Avelino
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Re: Calculation of Wilson Coefficients in SPheno

Postby Avelino » 12. Jan 2018, 15:43

SoundSonic1 wrote:Hi,

The json files from SPheno/FlavorKit contain only the chirality flipped coeffC7p and coeffC8p as Q1R_32 and Q2R_32?


You also have the operators obtained by exchanging the flavor indices: Q1R_23 and Q2R_23. With those you should be able to get the coefficients you are interested in.

SoundSonic1
Posts: 3
Joined: 10. Jan 2018, 14:53

Re: Calculation of Wilson Coefficients in SPheno

Postby SoundSonic1 » 12. Jan 2018, 15:54

Hi Avelino,

they are zero :/
You can have a look at my files:

https://pastebin.com/PTZk2ATv SPheno.spc.THDMII
https://pastebin.com/DFurKQeH WC.THDMII_1.json


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