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[, extended, ...])

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.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.TruncatedGauss(mu, sigma, low, ...)

Gaussian distribution that is 0 outside of low, high.

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

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