Abstract

We analyze the radiative pion decay π+→e+νeγ within nonlocal chiral quark models that include wave function renormalization. In this framework we calculate the vector and axial-vector form factors FV and FA at q2=0 — where q2 is the e+νe squared invariant mass — and the slope a of FV(q2) at q2→0. The calculations are carried out considering different nonlocal form factors, in particular those taken from lattice QCD evaluations, showing a reasonable agreement with the corresponding experimental data. The comparison of our results with those obtained in the (local) NJL model and the relation of FV and a with the form factor in π0→γ⁎γ decays are discussed.

Highlights

  • We analyze the radiative pion decay π + → e+νeγ within nonlocal chiral quark models that include wave function renormalization

  • According to the standard description, the corresponding decay amplitude consists of the inner bremsstrahlung (IB) and structure-dependent (SD) terms

  • Since π + → e+νe is helicity suppressed, same happens to the IB terms that contribute to its radiative counterpart, and, π + → e+νeγ turns out to be an appropriate channel to uncover the nonperturbative SD amplitude

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Summary

Pion radiative weak decays in nonlocal chiral quark models

We analyze the radiative pion decay π + → e+νeγ within nonlocal chiral quark models that include wave function renormalization. In this framework we calculate the vector and axial-vector form factors F V and. Gómez Dumm et al / Physics Letters B 698 (2011) 236–242 nonlocality arises naturally in several well-established approaches to low energy quark dynamics This is e.g. the case of the instanton liquid model [13] and the Schwinger–Dyson resummation techniques [14], and lattice QCD calculations [15,16,17] indicate that quark interactions should act over a certain range in momentum space. Replacing in the bosonized effective action and expanding in powers of meson fluctuations we get

The quadratic terms can be written as
In the present case
Ab Ac Ad
Findings
Set C
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