# computefps: Computes the pseudoscalar decay constant for the twisted mass... In hadron: Analysis Framework for Monte Carlo Simulation Data in Physics

 computefps R Documentation

## Computes the pseudoscalar decay constant for the twisted mass case from the pseudoscalar amplitude and mass

### Description

From a mass and amplitude determination (using matrixfit or fit.effectivemass, bootstrap.gevp and gevp2amplitude the pseudoscalar decay constant is determined for the case of Wilson twisted mass fermions from the pseudoscalar amplitude and mass

### Usage

computefps(mfit, PP, mass, mu1, mu2, Kappa, normalisation = "cmi",
disprel = "continuum", boot.fit = TRUE)

### Arguments

 mfit An object of type matrixfit or gevp.amplitude generated with matrixfit or gevp2amplitude, respectively. PP If mfit is missing this must contain the value for the pseudoscalar amplitude. mass If mfit is missing this must contain the value for the pseudoscalar mass. mu1, mu2 The values for the twisted quark masses involved in the pseudoscalar meson. If mu2 is missing it will be assumed to be equal to mu1. Kappa The kappa-value of the run, needed only if normalisation="cmi". normalisation normalisation of the correlators. If set to "cmi" the kappa value must be specified. disprel One of "continuum" or "lattice". Indicates whether the formula for the decay constant should take into account the lattice dispersion relation for the meson. Theoretically this can reduce lattice artefacts for heavy mesons. boot.fit 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.

### Details

The pseudoscalar decay constant is computed from

kappa (mu1+mu2) PP/sqrt(2)/sqrt(mps)^3

for normalisation="cmi" or

PP/sqrt(2)/sqrt(mps)^3

expecting physical normalisation of the amplitudes.
When disprel="lattice",

% sqrt(mps^3)

is replaced with

% sqrt(mps)*sinh(mps))

which can reduce lattice artefacts for heavy meson masses.

### Value

If mfit ist missing the value of fps will printed to stdout and returned as a simple numerical value.

If mfit is available, this object will be returned but with additional objects added: fps, fps.tsboot, mu1,mu2, normalistaion and Kappa if applicable.

### Author(s)

Carsten Urbach, curbach@gmx.de

matrixfit, gevp2amplitude,

### Examples

cfnew <- extractSingleCor.cf(correlatormatrix, id=1)
cfnew <- bootstrap.cf(cfnew, boot.R=99, boot.l=1)
cfnew.fit <- matrixfit(cf=cfnew, t1=12, t2=20, parlist=array(c(1,1),
dim=c(2,1)), sym.vec=c("cosh"), neg.vec=c(1))
cfnew.fps <- computefps(mfit=cfnew.fit, mu1=0.004, normalisation="new")
summary(cfnew.fps)

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