New release (lambdab-polarised)

While working on their publication EOS-2017-02, Tom Blake and Michal Kreps derived the full set of angular observables for the decay Λ_b → Λ ℓ⁺ ℓ^- in the case of a polarised Λ_b baryon. They find a total of 34 angular observables compared to the 10 observables in the unpolarised case (compare the theory paper EOS-2014-01 and the fit to LHCb data in EOS-2016-02). The additional 24 observables can be classified as:

1. A set of 2 observables that are copies of 2 of the unpolarised ones, diluted by the overall polarisation.
2. A set of 22 observables that are sensitive to the same combinations of Wilson coefficients as the unpolarised ones, but with a different dependence on the hadronic matrix elements.

They modified the existing EOS code such that now all angular observables can be predicted. Their modifications have already been pushed to the master branch, and a corresponding tag has been pushed as well. A big thank you to Tom and Michal from my side for their contributions to EOS!

DFG Emmy-Noether Junior Research Group

Since August 1st 2017, the continued development and maintenance of EOS is funded by the Deutsche Forschungsgemeinschaft (DFG) as part of a DFG Emmy-Noether Junior Research Group.

Specifying options in constraint and observable names

A new class QualifiedName was added to EOS, in order

• to centralize parsing of Constraint and Observable names, and
• to ensure that these names follow the correct syntax everywhere they are used.

Beside centralizing and reducing the code, in the process the syntax of these qualified names was changed in a backward-incompatible way. As of commit 348db60, a qualified name’s list of options is separated from the rest of the name by a ; character, e.g.: B->pipilnu::BR;model=CKMScan. The rationale for this change is that it makes the parsing a lot easier, and also allows for the usage of , characters in observable names. The latter is quite handy in order to distinguish between observables of the same basic name but varying dependence on kinematic variables. For example, we can now distinguish between three- and two-differential branching ratios ℬ(B → π π ℓ ν) through the names B->pipilnu::BR(q2,k2,cos(theta_pi)) and B->pipilnu::BR(q2,k2); see commit c897932. Also, the manual was updated and can be found in the usual place.

A big thank you to Rafael Silva Coutinho for help and discussions.

New release (btopipilnu-qcdf)

I have tagged the btopipilnu-qcdf release of EOS, which was used to produce the numerical results in EOS-2016-04. Noteworthy on the physics side are

• Adding one-to-two-body form factors, with the B → π π form factors being their first implementation.
• Adding the four-body decay B → π π ℓ ν to the list of available decays, both for new observables (e.g. B->pipilnu::BR) and one new signal PDF (B->pipilnu::d^3Gamma@QCDF).

On the usability side, the new Python interface allows to produce publication-quality plots. One such plot has been published in EOS-2016-04, and shows contours of the pionic forward-backward asymmetry in B → π π ℓ ν decays. The Python script that was used to produce this plot has been made available as an example.

New homepage

We moved from a six year-old hand written HTML file to Jekyll. Let’s see how that works out.