Isospin breaking in $K \to 3 \pi$ decays III : Bremsstrahlung and fit to experiment

ChPT Progress on Non-Leptonic and Radiative Kaon Decays

“…The first full NLO in ChPT results were presented in [23] where one can also find the K % 3π decay rate CP-violating asymmetries. At NLO in ChPT in the isospin limit, one gets for the K 22,23]. More details and similar expressions for ∆g N and the decay rate asymmetries can be found in [23].…”

“…In [22], the authors performed a combined fit to both data on K ππ and K 3π which is also known fully at NLO in ChPT including isospin breaking [22,23] and obtained …”

Radiative corrections in K→π ℓ + ℓ − decays

“…[22][23][24] are performed in the framework of Chiral Perturbation Theory. Such a framework is not suited to an extraction of the ππ scattering lengths from experimental data, as these do not appear directly as parameters of the theory.…”

“…Our work is not the first one to consider radiative corrections to K → 3π decays -recent examples include Refs. [22][23][24][25][26][27]. Whereas Isidori's article [25] fits into the framework considered here, the calculations of Refs.…”

“…Whereas Isidori's article [25] fits into the framework considered here, the calculations of Refs. [22][23][24] are of a wider scope and not useful to extract ππ scattering lengths with high precision by use of the approach proposed in Ref. [3], a framework also adapted here.…”