A study of six quark cluster states in chiral SU(3) quark model

The energies of the (0S)⁶ six quark cluster states are calculated in the chiral SU(3) quark model. The results show that some states with high strangeness have more attraction from the chiral SU(3) coupling, and this feature is interesting in discussing if there exists some new narrow width six quark states. Further, we did a RGM calculation to study some multi-strangeness dibaryon states. We found that ΩΩ dibaryon is a deeply bound state and ΞΩ dibaryon is slightly bound.     

The SU(3) dibaryons in the chiral quark soliton model

In this Letter we investigate an SU(3) extension of the axially symmetric B=2 chiral quark soliton model. The classical soliton is extended to the SU(3) by trivial embedding. We expand the quark determinant in terms of the collective angular velocity up to the second order and the quark mass difference of the first order. The mass spectrum and the binding energy of the baryon–baryon channels down to strangeness S=−6 are then obtained.     

SU(6) × SL(3, R) color quark model

A nonrelativistic color quark model based on the spectrum generating group SU(6)×SL(3, R) is presented. The model unifies SU(6) and the Regge classification with linear L vs m² mass spectrum. Baryons are predicted to belong to the ($\text{56}\text{, L}{}^{\mathrm{P}}\text{= (}\text{even}{}^{\mathrm{+}}\text{)}\text{and}\text{(}\text{70}\text{, L}{}^{\mathrm{P}}\text{= (}\text{odd}{}^{\mathrm{?}}\text{)}$ multiplets of the SU (6) × O(3) group.     

The light-baryon spectrum in a relativistic quark model with instanton-induced quark forces

This is the second of a series of three papers treating light-baryon resonances up to 3 GeV within a relativistically covariant quark model based on the three-fermion Bethe-Salpeter equation with instantaneous two- and three-body forces. In this paper we apply the covariant Salpeter framework (which we developed in the first paper, U. L?ring, K. Kretzschmar, B.Ch. Metsch, H.R. Petry, Eur. Phys. J. A 10, 309 (2001)) to specific quark model calculations. Quark confinement is realized by a linearly rising three-body string potential with appropriate spinorial structures in Dirac space. To describe the hyperfine structure of the baryon spectrum we adopt 't Hooft's residual interaction based on QCD-instanton effects and demonstrate that the alternative one-gluon exchange is disfavored on phenomenological grounds. Our fully relativistic framework allows to investigate the effects of the full Dirac structures of residual and confinement forces on the structure of the mass spectrum. In the present paper we present a detailed analysis of the complete non-strange-baryon spectrum and show that several prominent features of the nucleon spectrum such as, e.g., the Roper resonance and approximate “parity doublets” can be uniformly explained due to a specific interplay of relativistic effects, the confinement potential and 't Hooft's force. The results for the spectrum of strange baryons will be discussed in a subsequent paper, see U. L?ring, B.Ch. Metsch, H.R. Petry, this issue, p. 447. Received: 27 March 2001 / Accepted: 17 April 2001     

Quark matter and meson properties in a Nonlocal SU(3) chiral quark model at finite temperature

We study the finite temperature behavior of light scalar and pseudoscalar meson properties in the context of a three-flavor nonlocal chiral quark model. The model includes mixing with active strangeness degrees of freedom, and takes care of the effect of gauge interactions by coupling the quarks with a background color field. We analyze the chiral restoration and deconfinement transitions, as well as the temperature dependence of meson masses, mixing angles, and decay constants.     

A decomposition theorem for SU(n) and its application to CP-violation through quark mass diagonalisation

It is proved that the groupG=SU(n) has a decompositionG=FCF whereF is a maximal abelian subgroup andC is an (n − 1)² parameter subset of matrices. The result is applied to the problem of absorbing the maximum possible number of phases in the mass-diagonalising matrix of the charged weak current into the quark fields; i.e., of determining the exact number of CP-violating phases for arbitrary number of generations. The inadequacies of the usual way of solving this problem are discussed. Then=3 case is worked out in detail as an example of the constructive procedure furnished by the proof of the decomposition theorem.     

SU(3) × SU(3) symmetry breaking in a simple model

A field-theoretical model, due to Lévy, is studied. It contains a triplet of quarks and a pseudoscalar and a scalar meson nonet. The original SU(3) × SU(3) symmetry is broken by terms linear in the scalar meson fields. A renormalization and regularization procedure is defined in order to remove the ultra-violet divergences. The possibility of a spontaneous breakdown of the symmetry is described and the Goldstone theorem is verified in the one-loop approximation.     

Slowly rotating neutron stars and hadronic stars in the chiral SU(3) quark mean-field model

The equations of state for neutron matter, strange and non-strange hadronic matter in the chiral SU(3) quark mean-field model are applied in the study of slowly rotating neutron stars and hadronic stars. The radius, mass, moment of inertia, and other physical quantities are carefully examined. The effect of the nucleon crust for the strange hadronic star is exhibited. Our results show that the rotation can increase the maximum mass of compact stars significantly. For a big enough mass of pulsars which cannot be explained as strange hadronic stars, theoretical approaches to increase the maximum mass are addressed.     

X(2900) in a chiral quark model

Recently,the LHCb Collaboration reported their observation of the first two fully open-flavor tetraquark states named Xo(2900) and X_1(2900) with unknown parity.Inspired by the report,we consider all the possible fourquark candidates for X(2900),which include the molecular structure,diquark structure,and their coupling in a chiral quark model via the Gaussian expansion method.To identify the genuine resonances,the real-scaling method(stabilization method) was employed.Our results show that five possible resonances,R_0(2914) with Γ=42 MeV,R1(2906) with Γ=29 MeV,R_1(2912) with Γ=10 McV,Rj(2920) with Γ=9 MeV,and R_J(2842) with Γ=24 MeV,originate in the cs■ system.Compared with experimental data,R_0(2914) with Γ=42 MeV may be an optimal X_0(2900) candidate.However,none of the resonances have a similar width for X_1(2900).Hence,further study is required.     

SU(n) MULTIPLETS AND YOUNG DIAGRAMS

<正>Written by C.G.Wohl(LBNL).This note tells(1)how SU(n)particle multiplets are identified or labeled,(2)how to find the number of particles in a multiplet from its label,(3)how to draw the Young diagram for a multiplet,and(4)how to use Young diagrams to determine the overall multiplet structure of a composite system,such as a 3-quark or a meson-baryon system.In much of the literature,the wordrepresentationis used where we usemultiplet,andtableauis used where we usediagram.     

The baryonic spectrum in a constituent quark model including a three-body force

We analyze, within a non-relativistic quark model, the low energy part of the baryonic spectrum in the octet and decuplet flavour representations. The relevance of a strong Coulomb potential is emphasized in order to explain its general features. The addition of a three-body force allows to solve the Roper puzzle, giving a consistent explanation to its relative position in the spectrum.This work has been supported by the grants CICYT: AEN-90-0040 and DGICYT: PB88-0064 and Acción Integrada HF-101. We are also grateful to V. Vento for illuminating discussions.     

Exact SU(n) instantons with cylindrical symmetry

We construct SO(3) symmetric, irreducible instantons in an SU(n) gauge theory. The solutions are symmetric with respect to J = ?ir × ? + T, where T spans the maximal SO(3) subalgebra of SU(n). Our ansatz as well as the resulting self dual equations are closely related to those for monopoles.     

Five-dimensional SU(2)-monopole: Continuous spectrum

Hyperspherical and parabolic wave functions are calculated for the five-dimensional “charge-SU(2) monopole” system in the continuous spectrum. It is shown that the coefficients of parabolic-hyperspherical and hyperspherical-parabolic transformations are proportional to the generalized hyperge-ometric function ₃ F ₂{...|1}.