Flavor physics: Precision as an avenue to discovery.

This paper describes the work pursued in the years 2008–2013 on improving the Standard Model prediction of selected flavor-physics observables. The latter includes: (1) 𝜖 K , that quantifies indirect CP violation in the K 0 − K ̄ 0 system and (2) the very rare decay B s → μ μ , recently measured at the LHC. Concerning point (1), the paper describes our reappraisal of the long-distance contributions to 𝜖 K , 1 – 3 that have permitted to unveil a potential tension between CP violation in the K 0 - and B d -system. Concerning point (2), the paper gives a detailed account of various systematic effects pointed out in Ref. 4 and affecting the Standard Model B s → μ μ decay rate at the level of 10% — hence large enough to be potentially misinterpreted as nonstandard physics, if not properly included. The paper further describes the multifaceted importance of the B d , s → μ μ decays as new physics probes, for instance how they compare with Z -peak observables at LEP, following the effective-theory approach of Ref. 5. Both cases (1) and (2) offer clear examples in which the pursuit of precision in Standard Model predictions offered potential avenues to discovery. Finally, this paper describes the impact of the above results on the literature, and what is the further progress to be expected on these and related observables. [ABSTRACT FROM AUTHOR]