Pseudoscalar mesons with symmetric bound state vertex functions on the light front

Abstract

We study the electromagnetic form factors, decay constants and charge radii of the pion and kaon within the framework of light-front field theory formalism where we use an ansatz for the quark-meson interaction bound-state function which is symmetric under exchange of quark and antiquark momentum. The above mentioned observables are evaluated for the + component of the electromagnetic current, J + , in the Breit frame. We also check the invariance of these observables in other frames, whereby both the valance and the non-valence contributions have to be taken into account, and study the sensitivity of the electromagnetic form factors and charge radius to the model's parameters; namely, the quark masses, mu = m d , ms, and the regulator mass, mR. It is found that after a fine tuning of the regulator mass, i.e. mR = 0.6 GeV, the model is suitable to fit the available experimental data within the theoretical uncertainties of both the pion and kaon.fined by the coordinate x + = x 0 + x 3 = 0, and due to the stability of the Fock-state decomposition these wave functions are covariant under kinematic boosts [4,6].

Parton distribution in pseudoscalar mesons with a light-front constituent quark model

“…where g = m 0 − / f 0 − is the coupling constant, m 0 − and f 0 − denote the mass and decay constant of a pseudoscalar meson, respectively, and φ the pseudoscalar field, namely the pion or the kaon [1,3]. Here, the symmetric vertex function for theqq-meson vertex which describes the bound state, is used as in Refs.…”

“…The model used in the present study is the light-front constituent quark model (LFCQM) with a symmetric vertex function, which has already been used in the previous work for the pion [1,11], and recently for the pion and kaon [3] to calculate the observables associated with them. The effective interaction Lagrangian density for the quark and pseudoscalar meson is given by,…”

“…Here, the symmetric vertex function for theqq-meson vertex which describes the bound state, is used as in Refs. [1,3]:…”

“…The pseudoscalar meson wave function either for the pion or kaon in the present light-front constituent quark model, is given by [1,3] …”

“…

Abstract.We compute the distribution amplitudes of the pion and kaon in the light-front constituent quark model with the symmetric quark-bound state vertex function [1,2,3]. In the calculation we explicitly include the flavor-SU(3) symmetry breaking effect in terms of the constituent quark masses of the up (down) and strange quarks.

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