WHIZARD

Is it possible to switch the weinberg angle?

Asked by Nico Rehberg

Hi,
I am trying to compare analytical Higgsstrahlung scaling factors with whizard data. I recognized that whizard uses the weinberg angle from CODATA (sin^2(theta)=0.2223) but I have to use the one from particle data group (sin^2(theta)=0.23122) to get the same results. Is there a way to define the electroweak mixing angle directly (I couldn't find one in the manual, but maybe I'm just blind) ? And if not, do you have any suggestions how I can change the angle indirectly? I tried just to define the W and Z masses, but that did not have the desired effect.

Thank you!
Nico

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Language:
English Edit question
Status:
Solved
For:
WHIZARD Edit question
Assignee:
Juergen Reuter Edit question
Solved by:
Nico Rehberg
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Juergen Reuter (j.r.reuter) said : 		#1

Hi Nico,
indeed, Whizard uses for the Standard Model either the GF-MZ-MW scheme or the complex-mass scheme. For both, sin(theta_w) is not an independent, but a derived parameter. For the GF-MZ-MW scheme, Whizard uses the on-shell definition , sin^2 theta_w = 1 - mw^2/mz^2.
If you take e.g. the following SINDARIN, you will see a sin2(theta_w) of 0.231156 which is close to your value:
model = SM
mW = 79.95
mZ = 91.18
real sw2 = sw^2

with the following output:
| Switching to model 'SM', scheme 'default'
 SM.mW => 7.995000000000E+01
SM.mZ => 9.118000000000E+01
[user variable] sw2 = 2.311568304255E-01
| WHIZARD run finished.

Cheers,
    JRR

Revision history for this message
Nico Rehberg (nicore) said : 		#2

Thank you for your quick answer!

I implemented the SINDARIN in my file, and it works perfectly.

Thank you!
Nico