Covariant model for the Dalitz decay of the $N(1535)$ resonance

Abstract

We develop a covariant model for the ${\gamma }^{\ast }N\to N(1535)$ transition in the timelike kinematical region, the region where the square momentum transfer $q^2$ is positive. Our starting point is the covariant spectator quark model constrained by data in the spacelike kinematical region ($Q^2=-q^2>0$). The model is used to estimate the contributions of valence quarks to the transition form factors, and one obtains a fair description of the Dirac form factor at intermediate and large $Q^2$. For the Pauli form factor there is evidence that beyond the quark-core contributions there are also significant contributions of meson cloud effects. Combining the quark-core model with an effective description of the meson cloud effects, we derive a parametrization of the spacelike data that can be extended covariantly to the timelike region. This extension enabled us to estimate the Dalitz decay widths of the $N(1535)$ resonance, among other observables. Our calculations can help in the interpretation of the present experiments at HADES ($pp$ collisions and others).

23 pages, 17 figures

References in corpus (25)

• Unitary Isobar Model - MAID2007
• Dressed-quark anomalous magnetic moments
• A pure S-wave covariant model for the nucleon
• Dilepton production in proton-induced reactions at SIS energies with the GiBUU transport model
• D-state effects in the electromagnetic N-Delta transition
• A Covariant model for the nucleon and the $\Delta$
• A relativistic quark model for the Omega- electromagnetic form factors
• Dynamical coupled-channels analysis of 1H(e,e'pi)N reactions
• Octet baryon electromagnetic form factors in nuclear medium
• Transition form factors of the N*(1535) as a dynamically generated resonance
• First measurement of low momentum dielectrons radiated off cold nuclear matter
• Timelike gamma* N -> Delta form factors and Delta Dalitz decay
• Electroproduction of the N*(1535) resonance at large momentum transfer
• Valence quark and meson cloud contributions for the gamma* Lambda -> Lambda* and gamma* Sigma0 -> Lambda* reactions
• Electromagnetic form factors of the Delta in a S-wave approach
• ${\gamma }^{\ast }N\to N^{\ast }(1520)$ form factors in the timelike regime
• Covariant spectator quark model description of the ${\gamma }^{\ast }\Lambda \to {\Sigma }^0$ transition
• Using the Single Quark Transition Model to predict nucleon resonance amplitudes
• Analysis of pion production data measured by HADES in proton-proton collisions at 1.25 GeV
• Semirelativistic approximation to the ${\gamma }^{\ast }N\to N(1520)$ and ${\gamma }^{\ast }N\to N(1535)$ transition form factors
• ${\gamma }^{\ast }N\to N(1710)$ transition at high momentum transfer
• Transition form factors and helicity amplitudes for electroexcitation of negative- and positive parity nucleon resonances in a light-front quark model
• $\gamma N\to N^{\ast }(1535)$ transition in soft-wall AdS/QCD
• Low-$Q^2$ empirical parametrizations of the $N^{\ast }$ helicity amplitudes
• Production of negative parity baryons in the holographic Sakai-Sugimoto model

Cited by in corpus (9)

• Jülich-Bonn-Washington Model for Pion Electroproduction Multipoles
• Coupled-channel analysis of pion- and eta-electroproduction with the Jülich-Bonn-Washington model
• Electromagnetic form factors of the ${\Omega }^{-}$ baryon in the spacelike and timelike regions
• A covariant model for the decuplet to octet Dalitz decays
• Role of baryon resonances in the ${\pi }^{-}p\to n{e}^{+}{e}^{-}$ reaction within an effective-Lagrangian 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
• Quark model calculations of transition form factors at high photon virtualities