Basic shapes are fundamendal PDFs, with often well-known functional form. They are usually fully analytically implemented and often a thin wrapper around Distribution. Any missing shape can be easily wrapped using WrapDistribution.

zfit.pdf.Gauss(mu, sigma, obs, *[, ...])

Gaussian or Normal distribution with a mean (mu) and a standartdeviation (sigma).

zfit.pdf.Exponential([lam, obs, extended, ...])

Exponential function exp(lambda * x).

zfit.pdf.CrystalBall(mu, sigma, alpha, n, obs, *)

Crystal Ball shaped PDF.

zfit.pdf.DoubleCB(mu, sigma, alphal, nl, ...)

Double-sided Crystal Ball shaped PDF.

zfit.pdf.GeneralizedCB(mu, sigmal, alphal, ...)

Generalized asymmetric double-sided Crystal Ball shaped PDF.

zfit.pdf.GaussExpTail(mu, sigma, alpha, obs, *)

GaussExpTail shaped PDF.

zfit.pdf.GeneralizedGaussExpTail(mu, sigmal, ...)

GeneralizedGaussedExpTail shaped PDF which is Generalized assymetric double-sided GaussExpTail shaped PDF.

zfit.pdf.Uniform(low, high, obs, *[, ...])

Uniform distribution which is constant between low, high and zero outside.

zfit.pdf.Cauchy(m, gamma, obs, *[, ...])

Non-relativistic Breit-Wigner (Cauchy) PDF representing the energy distribution of a decaying particle.

zfit.pdf.Voigt(m, sigma, gamma[, obs, ...])

Voigt profile.

zfit.pdf.TruncatedGauss(mu, sigma, low, ...)

Gaussian distribution that is 0 outside of low, high.

zfit.pdf.BifurGauss(mu, sigmal, sigmar, obs, *)

Bifurcated Gaussian distribution different standard deviations for the left and right side of the mean.

zfit.pdf.Poisson([lam, obs, extended, norm, ...])

Poisson distribution, parametrized with an event rate parameter (lamb).

zfit.pdf.LogNormal(mu, sigma, obs, *[, ...])

Log-normal distribution, the exponential of a normal distribution.

zfit.pdf.QGauss(q, mu, sigma, obs, *[, ...])

Q-Gaussian distribution with parameter q.

zfit.pdf.ChiSquared(ndof, obs, *[, ...])

ChiSquared distribution for ndof degrees of freedom.

zfit.pdf.StudentT(ndof, mu, sigma, obs[, ...])

StudentT distribution for ndof degrees of freedom.

zfit.pdf.Gamma(gamma, beta, mu, obs, *[, ...])

Gamma distribution.

zfit.pdf.JohnsonSU(mu, lambd, gamma, delta, ...)

Johnson's SU distribution.