hadron (version 3.1.2)

gevp2amplitude: Extracts physical amplitudes from a GEVP

Description

Given a GEVP generated with bootstrap.gevp and masses determined from the principle correlator with given id, the physical amplitudes are extracted and bootstraped. The man amplitude is determined from a constant fit to the data in the specified time range.

Usage

gevp2amplitude(gevp, mass, id = 1, op.id = 1, type = "cosh", t1, t2,
  useCov = TRUE, fit = TRUE)

Arguments

gevp

An object of class gevp as generated with a call to bootstrap.gevp.

mass

Optimally, this is an object either of class effectivemassfit generated using fit.effectivemass or of class matrixfit generated with matrixfit to the principal correlator extracted using gevp2cf applied to gevp using the same value of id.

It can also be given as a numerical vector with the bootstrap samples as entries. The mean will then be computed as the bootstrap mean over this vector. The number of samples must agree with the number of bootstrap samples in gevp.

id

The index of the principal correlator to extract, i.e. the physical state to extract.

op.id

The index of the operator for which to extract the amplitude.

type

The symmetry of the pricipal correlator in time, can be either "cosh" or "sinh".

t1, t2

The time range in which to fit the amplitude starting with 0. If not given it will be tried to infer these from the mass object.

useCov

Use the covariance matrix for fitting the constant to the amplitude data.

fit

perform a fit to the data.

Value

Returns an object of S3 class gevp.amplitude, generated as a list with named elements amplitude the numeric vector of amplitudes, amplitude.tsboot the corresponding bootstrap samples, damplitude the estimates for the standard errors, fit the object returned by the fit routine, meanAmplitude and meanAmplitude.tsboot mean amplitude and its bootstrap samples, chisqr the residual sum of squares, dof the numberi of degrees of freedom, t1 and t2 the fit range, and then all the input objects.

See Also

matrixfit, fit.effectivemass, gevp, gevp2cf, computefps

Examples

# NOT RUN {
data(correlatormatrix)
## bootstrap the correlator matrix
correlatormatrix <- bootstrap.cf(correlatormatrix, boot.R=99, boot.l=1, seed=132435)
## solve the GEVP
t0 <- 4
correlatormatrix.gevp <- bootstrap.gevp(cf=correlatormatrix, t0=t0, element.order=c(1,2,3,4))
## extract the ground state and plot
pion.pc1 <- gevp2cf(gevp=correlatormatrix.gevp, id=1)
pion.pc1.effectivemass <- bootstrap.effectivemass(cf=pion.pc1, type="solve")
pion.pc1.effectivemass <- fit.effectivemass(pion.pc1.effectivemass, t1=8, t2=23,
                                            useCov=FALSE)
## now determine the amplitude
pion.pc1.amplitude <- gevp2amplitude(correlatormatrix.gevp, pion.pc1.effectivemass,
                                     useCov=FALSE, t1=8, t2=14)
plot(pion.pc1.amplitude)
summary(pion.pc1.amplitude)

# }