Decay Constants of Charged Pseudoscalar Mesons

Understand

We review here the physics of purely leptonic decays of pi-, K-, D+, Ds+, and B- pseudoscalar mesons.

• The measured decay rates are related to the product of the relevant weak interaction based CKM matrix element of the constituent quarks and a strong interaction parameter related to the overlap of the quark and anti-quark wave-functions in the meson, called the decay constant fP.
• The interplay between theory and experiment is different for each particle.
• Theoretical predictions that are necessary in the B sector can be tested, for example, in the charm sector.