Axial form factors of the octet baryons in a covariant quark model

Abstract

We study the weak interaction axial form factors of the octet baryons, within the covariant spectator quark model, focusing on the dependence of four-momentum transfer squared, Q^2. In our model the axial form factors G_A(Q^2) (axial-vector form factor) and G_P(Q^2) (induced pseudoscalar form factor), are calculated based on the constituent quark axial form factors and the octet baryon wave functions. The quark axial current is parametrized by the two constituent quark form factors, the axial-vector form factor g_A^q(Q^2), and the induced pseudoscalar form factor g_P^q(Q^2). The baryon wave functions are composed of a dominant S-state and a P-state mixture for the relative angular momentum of the quarks. First, we study in detail the nucleon case. We assume that the quark axial-vector form factor g_A^q(Q^2) has the same function form as that of the quark electromagnetic isovector form factor. The remaining parameters of the model, the P-state mixture and the Q^2-dependence of g_P^q(Q^2), are determined by a fit to the nucleon axial form factor data obtained by lattice QCD simulations with large pion masses. In this lattice QCD regime the meson cloud effects are small, and the physics associated with the valence quarks can be better calibrated. Once the valence quark model is calibrated, we extend the model to the physical regime, and use the low Q^2 experimental data to estimate the meson cloud contributions for G_A(Q^2) and G_P(Q^2). Using the calibrated quark axial form factors, and the generalization of the nucleon wave function for the other octet baryon members, we make predictions for all the possible weak interaction axial form factors G_A(Q^2) and G_P(Q^2) of the octet baryons. The results are compared with the corresponding experimental data for G_A(0), and with the estimates of baryon-meson models based on SU(6) symmetry.

To appear in PRD. 32 pages, 13 figures and 11 tables

References in corpus (41)

• Chiral Perturbation Theory and Baryon Properties
• Nucleon isovector couplings from $N_f=2$ lattice QCD
• Nucleon and pion structure with lattice QCD simulations at physical value of the pion mass
• Axial, induced pseudoscalar, and pion-nucleon form factors in manifestly Lorentz-invariant chiral perturbation theory
• Dynamical coupled-channels model for neutrino-induced meson productions in resonance region
• Measurement of the Rate of Muon Capture in Hydrogen Gas and Determination of the Proton's Pseudoscalar Coupling $g_P$
• A pure S-wave covariant model for the nucleon
• Octet-baryon axial-vector charges and SU(3)-breaking effects in the semileptonic hyperon decays
• Resolution of the Proton Spin Problem
• First Calculation of Hyperon Axial Couplings from Lattice QCD
• D-state effects in the electromagnetic N-Delta transition
• A relativistic quark model for the Omega- electromagnetic form factors
• A Covariant model for the nucleon and the $\Delta$
• Octet baryon electromagnetic form factors in nuclear medium
• Lattice study of flavor SU(3) breaking in hyperon beta decay
• Electroweak structure of the nucleon, meson cloud and light-cone wavefunctions
• Timelike gamma* N -> Delta form factors and Delta Dalitz decay
• Chiral extrapolation of g_A with explicit Delta(1232) degrees of freedom
• Hyperon Semileptonic decay constants with flavor SU(3) symmetry breaking
• Rôle of the pion electromagnetic form factor in the $\Delta (1232)\to {\gamma }^{\ast }N$ timelike transition
• Nucleon Form Factors of the Isovector Axial-Vector Current: Situation of Experiments and Theory
• Nucleon form factors from quenched lattice QCD with domain wall fermions
• Axial charges of octet and decuplet baryons
• Weak charged and neutral current induced one pion production off the nucleon
• Extracting the Omega- electric quadrupole moment from lattice QCD data
• Valence quark and meson cloud contributions for the gamma* Lambda -> Lambda* and gamma* Sigma0 -> Lambda* reactions
• Fixed-axis polarization states: covariance and comparisons
• Axial-vector dominance predictions in quasielastic neutrino-nucleus scattering
• Two-component model for the axial form factor of the nucleon
• Model-independent determination of the axial mass parameter in quasielastic antineutrino-nucleon scattering
• Chiral Corrections to Nucleon Two- and Three-Point Correlation Functions
• Covariant spectator quark model description of the ${\gamma }^{\ast }\Lambda \to {\Sigma }^0$ transition
• SU(3)-flavour breaking in octet baryon masses and axial couplings
• Baryon vector and axial content up to the 7Q component
• Using the Single Quark Transition Model to predict nucleon resonance amplitudes
• The shape of the $\Delta$ baryon in a covariant spectator quark model
• Axial-vector form factors for the low lying octet baryons in the chiral quark constituent model
• ${\gamma }^{\ast }N\to N(1710)$ transition at high momentum transfer
• Isovector axial-vector form factors of octet baryons in QCD
• Axial exchange currents and nucleon spin
• Meson cloud contributions to baryon axial form factors

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• Electromagnetic Transition Form Factors of Baryon Resonances
• Axial form factor of the nucleon at large momentum transfers
• ${\gamma }^{\ast }N\to N^{\ast }(1520)$ form factors in the timelike regime
• Semirelativistic approximation to the ${\gamma }^{\ast }N\to N(1520)$ and ${\gamma }^{\ast }N\to N(1535)$ transition form factors
• $N^{\ast }$ Form Factors based on a Covariant Quark Model
• Contact interaction analysis of octet baryon axialvector and pseudoscalar form factors
• Electromagnetic form factors of the ${\Omega }^{-}$ baryon in the spacelike and timelike regions
• Covariant model for the Dalitz decay of the $N(1535)$ resonance
• Pion constituent quarks couplings strong form factors: a dynamical approach
• Gravitational form factors of hyperons in light-cone QCD
• A covariant model for the decuplet to octet Dalitz decays
• Octet baryon electromagnetic form factor double ratios $(G_E^{\ast }/G_M^{\ast })/(G_E/G_M)$ in a nuclear medium
• Form factors for pions couplings to constituent quarks under weak magnetic field
• Holographic estimate of the meson cloud contribution to nucleon axial form factor
• Axial transition form factors of octet baryons in the perturbative chiral quark model
• Weak interaction axial form factors of the octet baryons in nuclear medium
• Meson cloud contributions to the Dalitz decays of decuplet to octet baryons
• Electroweak form factors of baryons in dense nuclear matter
• A Relativistic Model for the Electromagnetic Structure of Baryons from the 3rd Resonance Region
• Comparisons of electric charge and axial charge meson cloud distributions in the PCQM