flav-io/flavio v0.22

The major new feature in the release is the addition of frequentist fits to complement the Bayesian fits that have existed ever since v0.5. This allows to do analyses with both Bayesian and frequentist statistics in a single framework.

To determine frequentist confidence levels in one or two dimensions, there is a new profile likelihood fitter. In two dimensions, the results can be visualized using the existing contour plot function, while for one-dimensional p-value distributions, there is a new plot function pvalue_plot (which was inspired by the pretty plots generated by the GammaCombo package).

On this occasion, the documentation of fits & fitters has been overhauled completely. See in particular the new introduction to inference in flavio, the extended discussion of Bayesian fits, and the new discussion of frequentist fits.

There is also a new notebook in the flavio examples repository demonstrating the use of the new fitter and plots.

• A major limitation of the sm_error_budget function and its visualization error_budget_pie to display error budgets of SM predictions has been removed: previously, the error budget contributions were obtained by individually varying each parameter one by one; this lead to misleading results in case some of the parameters are strongly correlated. This applies for instance to angular observables in B→Vll decays, where uncertainties partially drop out in ratios. The new version now groups together all correlated parameters into common slices of the pie.
• The top quark mass dependence in the matching condition of the Wilson coefficient C₁₀ is now approximately taken into account (previously, it was taken as a constant).

• missing conjugation in QCDF corrections (thanks Jacky Kumar @jackypheno)
• wrong warning when defining several fits (thanks Peter Stangl @peterstangl for reporting & fixing it)