v0.18

This first release in 2017 brings lots of new features and some bug fixes.

Several improvements have been made to probability distributions, which are required to quantify both theoretical and experimental uncertainties needed to compute prediction uncertainties and to construct likelihoods for fits:

• A new class GammaUpperLimit appropriate for low-statistics measurements resulting in an upper limit (e.g. on a rare decay branching ratio),
• A new class MultivariateNumericalDistribution that allows to specify any probability distribution in an arbitrary number of dimensions. This works with all the functions implemented, like computing uncertainties and Bayesian fits.
• Constraints in the form of a fixed range (uniform likelihood within and zero outside) can now be specified in YAML files in the intuitive form [0.1, 3.5].
• A new way of specifying arbitrary probability distributions in YAML files.

There is also a new page in the documentation about details on the treatment of probability distributions and how to define them in YAML. The API docs have been updated as well.

On the physics side, the following processes have been added:

• The forward-backward asymmetry in inclusive B→X_ql⁺l^- decays. Like The branching ratio added in v0.15, this is based on arXiv:1503.04849 and profited a lot from help by Tobias Huber.
• The branching ratio of B_c→lν.
• Lepton flavour ratios in B→Mlν decays, including experimental measurements of the μ/τ ratios in B→D^(*)lν.

Finally, the following bugs have been fixed:

• In the presence of new physics, the decay B_d→l⁺l^- erroneously used b→s Wilson coefficients. Thanks to @jackypheno (Jacky Kumar) for spotting and fixing this.
• Measurements with a Gaussian upper limit constraint returned the wrong likelihood if the confidence level specified was different from 68%.
• A glitch in the log-enhanced QED corrections to B→X_ql⁺l^- was fixed (the change is numerically irrelevant).

v0.17

The main new feature in this release is the addition of the branching ratio of the inclusive semi-leptonic B decay B→X_clν, with l=e or μ (or their average). Many thanks to Paolo Gambino for useful discussions and for sharing numerical results necessary for implementing and validating this! See arXiv:1411.6560 and references therein for details on the theory.

An additional, minor improvement since v0.16.1 concerns the treatment of correlated ucertainties in Bayesian fits; see commit a32c80d for details.

Finally, the default values of masses and widths have been updated from PDG 2015 to PDG 2016 values. There has not been any numerically relevant change for the currently implemented observables.

v0.16.1

This bug fix release fixes

• a regression introduced by the recent internal change in the Constraints class in v0.16 that broke the fit functions,
• an inconsistency in the combination of experimental likelihoods in the presence of multiple experiments measuring the same observable when using the FastFit class.

Additional unit tests have been added to improve the stability of these fitting functions.

v0.16

This release focuses on stability improvements with only few new features.

Improvements on the physics side:

• Added lepton flavour ratios for B->Plnu decays, e.g. <Rtaumu>(B0->Dlnu)
• Added lepton flavour ratios for B->Xll decays, e.g. <Remu>(B->Xsll)
• Added measurements of B->K*mumu "optimised" angular observables (P') by LHCb

Other improvements:

• More consistent behaviour of flavio.plots.band_plot when using the pre_calculated_z and interpolation_factor options (see API docs)
• flavio.plots.q2_plot_exp now properly handles asymmetric experimental uncertainties

In addition there have been a few under-the-hood changes in preparation for future features.

v0.15.1

This minor release fixes the following bugs:

• An erroneous factor of 1/2 in the angular observables A_FB, F_H, as well as the direct CP asymmetry in B->Pll decays was removed. Note that these quantities are compatible with zero in the SM, so this is relevant in the presence of new physics. Thanks to Christoph Niehoff for pointing this out.
• The plot function q2_plot_th_bin now also works for non-SM Wilson coefficients (#24, thanks @f-thiele)

As a new feature, a function np_uncertainty was added that works just like sm_uncertainty but allows to specify non-SM Wilson coefficients. This allows to compute the uncertainties in the presence of new physics (see API docs).

v0.15

The major new physics feature in this release is the addition of the branching ratio of the rare inclusive B→X_ql⁺l^- (l=e or μ) decay. Many thanks to Tobias Huber for providing analytical expressions and making numerical cross-checks that made the implementation of (most of) the corrections in arXiv:1503.04849 possible. Thanks also to the Munich Institute for Astro- and Particle Physics (MIAPP) for hospitality during this effort.

Another new feature is more cosmetic: metadata have been added to all observables, making it possible to split the list of observables into categories rather than one huge list.

Finally, thanks to Christoph Niehoff for improvements and cross-checks in B_q→l⁺l^-.

v0.14.1

This release does not bring any new features but various speed optimisations, most significantly:

• Observables in B→Vll at very low q², that used to be slow to compute, are now a factor of 50 (fifty) faster! (318944e)
• Generating random parameter sets is now 4 times faster, which also speeds up the generation of pseudo measurements for FastFit (0758c67)

v0.14

News in this release:

• New observable: effective lifetime in B_s→ll added. Thanks to @ChristophNiehoff for this addition!
• Improvements in the plotting function flavio.plots.band_plot
  • It is now possible to save the data corresponding to any individual likelihood plot, which allows to easily change or rearrange plots later without having to recompute the likelihood. Thanks to Albert Puig for this addition!
  • It is now possible to interpolate the likelihood in between computed points to obtain smoother contours without computing on a finer grid. For the time being, this feature must be activated manually by setting interpolation_factor to an integer greater than 1.
• Typos in measurements fixed and measurements of Λ_b→Λμμ added

v0.13.1

This point release features a few minor improvements:

• Two typos in measurements fixed (thanks to S. Reichert for spotting one of them)
• Improvement in plot functions: band_plot now plots multiple confidence levels and supports legends out of the box
• Stability improvements for FastFit

v0.13

The focus in this release is on experimental measurements and treatment of likelihoods:

• A large number of measurements by LHCb have been added - thanks to Stefanie Reichert for that!
• While by default only the most recent measurements of an observable by a given experiment are included in the code, data files for older measurements can be found in a separate repository now.
• A new function to read measurements from a URL can be useful for this purpose: for instance

flavio.measurements.read_url(
    'https://github.com/flav-io/measurements/blob/master/2011-lhcb-bksmumu.yaml')

All existing mesurements can be cleared with the new method flavio.Measurement.clear_all().

• The combination of univariate likelihoods has been completely rewritten. For parameters or measurements with several uncertainties, these are now combined by computing the convolution of the PDFs. Here is an example for a symmetric and an asymmetric uncertainty. Thanks to Jens Jasche for discussions.
• For measurements, instead of central values and uncertainties, now also upper limits can be specified. In the YAML data file, they are written simply as a string of the form < 1.5e-8 @95% CL - this works for arbitrary confidence levels.

Finally, there are two new observables: the direct CP asymmetries in B→K*ll and B→Kll.