Dynamical spin effects in the pion

Abstract

Abstract. We take into account dynamical spin effects in the holographic light-front pion wavefunction in order to predict the pion radius, decay constant, the pion electromagnetic and photon-to-pion transition form factors. We report a striking improvement in the description of all data.

Light-front holographic distribution amplitudes of pseudoscalar mesons and their application to B -meson decays

“…Our result is more general in comparison with that of Ref. [19]. 2 In some references, the parameter κ = √ λ is used.…”

“…Besides √ λ, 1 Very recently, in Ref. [19], the twist-2 holographic LFDA of π meson is also evaluated with a S P h,h similar to S1. Our result is more general in comparison with that of Ref.…”

“…(3) has been successfully used to describe diffractive ρ meson electroproduction at HERA [16] as well as the spectroscopy and distribution amplitudes of light and heavy mesons [17][18][19]. After introducing the LF spinor structure of the wavefunctions for light vector mesons in analogy with that of the photon, the authors of Refs [20,21] have predicted the light-front distribution amplitudes (LFDAs) of the ρ and K * vector mesons and have used them to evaluate the branching fractions of B → ργ and B → K * γ decays.…”

“…Very recently, this spin structure has been used to evaluate the holographic DA of π meson in Ref. [19]. The helicity-dependent wavefunction is written explicitly as…”

“…An additional multiplying factor "M P ", which is added in Ref. [19], has been absorbed into the normalization constant. It should be noted, however, that this spin structure corresponds to light quark and antiquark of the pseudoscalar meson, such as the pion, to have parallel spin projections, and thus L z = ±1.…”