Related papers: Roper resonance in a quark-diquark model
The standard description of the nucleon in the non-relativistic quark model is an $1S,L=0$ state without orbital motion. Yet, there are several indications from phenomenology that an admixture of states with nonzero orbital motion maybe…
Analyses of the three valence-quark bound-state problem in relativistic quantum field theory predict that the nucleon may be understood primarily as a Borromean bound-state, in which binding arises mainly from two separate effects. One…
In a relativistic quark model we study the structure of the $N(1710)$ resonance, and the $\gamma^\ast N \to N(1710)$ reaction focusing on the high momentum transfer region, where the valence quark degrees of freedom are expected to be…
The $\rho(770)$ vector resonance, its radial recurrences, and the corresponding P-wave $\pi\pi$ phase shifts are investigated in an unquenched quark model with all classes of relevant decay channels included, viz. pseudoscalar-pseudoscalar,…
We develop a formally covariant quark-diquark model of the nucleon. The nucleon is treated as a bound state of a constituent quark and a diquark interacting via a quark exchange. We include both scalar and axial-vector diquarks. The…
Treating the quark and diquark as elementary particles, the Bethe-Salpeter equation for the nucleon is solved numerically. The dependence of the mass on the diquark mass and on the coupling constants is investigated. The resulting…
In this paper we develop a theoretical framework which allows us to study excitations of the nucleon. Assuming an effective two-body interaction as a model for low-energy QCD, we derive a relativistic TDHF equation for a many-body system of…
In this work, the spectrum of ground state and excited baryons (N, {\Delta}, , , and {\Omega} particles) has been investigated by using a non-relativistic quantum mechanics under the Killingbeck plus isotonic oscillator potentials. Using…
Vibrations of the Jeffcott rotor are modelled by a three degree of freedom system including coupling between lateral and torsional modes. The crack in a rotating shaft of the rotor is introduced via time dependent stiffness with off…
A new mechanism for the pp --> pp pi0 reaction close to threshold is suggested coming from the isoscalar excitation of the Roper and its decay into N(pi pi)S-wave, with one of the pi0 emitted and the other one reabsorbed on the second…
We introduce diquarks as separable correlations in the two-quark Green's function to facilitate the description of baryons as relativistic three-quark bound states. These states then emerge as solutions of Bethe-Salpeter equations for…
We propose a four-quark structure for some of the excited states of heavy mesons containing a single charm or bottom quark. The four-quark wave functions are constructed based on a diquark-antidiquark form under the constraint that they…
Masses of the ground and excited (1P, 2S, 1D, 2P, 3S) states of the fully-heavy tetraquarks, composed of charm ($c$) and bottom ($b$) quarks and antiquarks, are calculated in the diquark-antidiquark picture within the relativistic quark…
We study positive and negative parity nucleons on the lattice using the chirally improved lattice Dirac operator. Our analysis is based on a set of three operators chi_i with the nucleon quantum numbers but in different representations of…
The chromomagnetic interaction, with proper account for flavour-symmetry breaking, is shown to explain the mass and coupling properties of the X(3872) resonance as a $J^{PC}$ = 1$^{++}$ state consisting of a heavy quark-antiquark pair and a…
The firm understanding of standard quark-antiquark states (including excited states) is necessary to search for non-conventional mesons with the same quantum numbers. In this work, we study the phenomenology of two nonets of excited vector…
Assuming four-quark structure for the $X$ resonances in low-lying region, we calculate their masses using the color-spin interaction. In specific, the hyperfine masses of the color-spin interaction are calculated for the possible states in…
We look for $\Delta\Delta$ and $N\Delta$ resonances by calculating $NN$ scattering phase shifts of two interacting baryon clusters of quarks with explicit coupling to these dibaryon channels. Two phenomenological nonrelativistic chiral…
We investigate the $P$-wave states $T^-_{bb}$ in the isospin singlet and three excited modes [excitation occurring in the diquark $[bb]^{s_1}_{c_1}$ ($\rho $-mode), antidiquark $[\bar{u}\bar{d}]^{s_2}_{c_2}$ ($r$-mode) or between them…
A chiral Lagrangian containing, besides the usual meson fields, their first radial excitations is constructed. The Lagrangian is derived by bosonization of a Nambu--Jona-Lasinio (NJL) type quark model with separable nonlocal interactions.…