computefpsOS: Computes the pseudoscalar decay constant for the Osterwalder...

computefpsOSR Documentation

Computes the pseudoscalar decay constant for the Osterwalder Seiler case from the pseudoscalar amplitude and mass


From a mass and amplitude determination (using matrixfit) the pseudoscalar decay constant is determined for the case of Osterwalder Seiler (OS) fermions from the AS and SS amplitude (in the twisted basis), ZA and the OS pion mass.


computefpsOS(mfit, Kappa = sqrt(0.5), normalisation = "cmi", = TRUE, ZA = 1, ZAboot, dZA)



An object of type matrixfit generated with matrixfit. The correlation matrix (SS, SA, AS, AA) must have been analysed, where the correlators are in the twisted basis.


The kappa-value of the run, needed only if normalisation="cmi".


normalisation of the correlators. If set to "cmi" the kappa value must be specified.

If set to FALSE, the computation is not bootstrapped, even if the matrixfit or gevp.amplitude contain bootstrap samples. This is a useful time-saver if error information is not strictly necessary. Of course, this affects the return values related to the bootstrap, which are set to NA.


The value of the renormalisation constant ZA.


Bootstrap samples for ZA. If they are provided, they are used for computing fps, if not, bootstrap samples are generated from dZA. If both are missing, the error of ZA is not taken into account.


The value of the (normally distributed) error of the renormalisation constant ZA.


The pseudoscalar decay constant is computed from

% fpsOS = sqrt(2) kappa ZA <0|A|pi>/mps

for normalisation="cmi" or

% fpsOS = ZA <0|A|pi>/mps

expecting physical normalisation of the amplitudes.


If mfit is available, this object will be returned but with additional objects added: fpsOS, fpsOS.tsboot, normalistaion, ZA, ZAboot and kappa if applicable.


Carsten Urbach,

See Also


hadron documentation built on Sept. 9, 2022, 5:06 p.m.