arXiv subjects

L. Ya. Glozman

Publications and source records attributed to L. Ya. Glozman.

139 records · Page 8Linked to original sources

arXiv1996

Baryon Magnetic Moments and Axial Coupling Constants with Relativistic and Exchange Current Effects

The large relativistic corrections to the constituent quark current operators improve the predictions for the axial couplings of the baryons, but worsen those for their magnetic moments. The exchange current corrections that are associated with flavor and spin dependent hyperfine interactions between the quarks with a form suggested by pseudoscalar meson exchange can compensate the relativistic corrections to the baryon magnetic moments. This is demonstrated by a calculation of the magnetic moments of the non-strange and strange baryons using wave functions and exchange current operators, which correspond to a recent phenomenological spin- and flavor dependent interquark interaction model with a linear confining interaction, which yields a spectrum close to the empirical one. The possibility that part of the flavor and spin dependent interaction could be due to vector and axial-vector exchange is explored.

hep-ph↗

arXiv1996

Binding of Quarks and the pi-N sigma-Term

It is shown that the binding effect that is associated with the short range part of the Goldstone boson exchange interaction between constituent quarks provides a good description of the $πN$ $σ$-term.

hep-ph↗

arXiv1996

Baryon Structure and the Chiral Symmetry of QCD

Beyond the spontaneous chiral symmetry breaking scale light and strange baryons should be considered as systems of three constituent quarks with an effective confining interaction and a chiral interaction that is mediated by the octet of Goldstone bosons (pseudoscalar mesons) between the constituent quarks.

hep-ph↗

arXiv1996

Light Baryons in a Constituent Quark Model with Chiral Dynamics

It is shown from rigorous three-body Faddeev calculations that the masses of all 14 lowest states in the $N$ and $Δ$ spectra can be described within a constituent quark model with a Goldstone-boson-exchange interaction plus linear confinement between the constituent quarks.

hep-ph↗

arXiv1995

Baryon Spectrum and Chiral Dynamics

New results on baryon structure and spectrum developed in collaboration with Dan Riska [1-4] are reported. The main idea is that beyond the chiral symmetry spontaneous breaking scale light and strange baryons should be considered as systems of three constituent quarks with an effective confining interaction and a chiral interaction that is mediated by the octet of Goldstone bosons (pseudoscalar mesons) between the constituent quarks.

hep-ph↗

arXiv1995

Chiral Symmetry and the Constituent Quark Model

hep-ph↗

arXiv1995

Quark Model Explanation of the $N^*\to Nη$ Branching Ratios

The constituent quark model can explain the strong selectivity of the $Nη$ decay branching ratios of the nucleon resonances if the fine structure interaction between the constituent quarks is described in terms of Goldstone boson exchange. This chiral quark model predicts that the resonances $N(1535)$, $N(1710)$, $Λ(1670)$, $Σ(1750)$, which have mixed flavor and spin symmetry $[21]_{FS} [21]_F [21]_S$ wavefunctions in lowest order, should have large $Nη$ branching ratios, while $Nη$ decay of the other resonances that have different flavor-spin symmetry should be strongly suppressed in agreement with the experimental branching ratios.

hep-ph↗

arXiv1995

The d'-Dibaryon in the Nonrelativistic Quark Model

The narrow peak recently found in various pionic double charge exchange (DCX) cross sections can be explained by the assumption of a universal resonance at 2065 MeV, called d'. We calculate the mass of a six-quark system with J^P=0^-, T=0 quantum numbers employing a cluster model and a shell model basis to diagonalize the nonrelativistic quark model Hamiltonian.

nucl-th↗

arXiv1995

The Spectrum of the Nucleons and the Strange Hyperons and Chiral Dynamics

The spectra of the nucleons, $Δ$ resonances and the strange hyperons are well described by the constituent quark model if in addition to the harmonic confinement potential the quarks are assumed to interact by exchange of the $SU(3)_F$ octet of pseudoscalar mesons, which are the Goldstone bosons associated with the hidden approximate chiral symmetry of QCD. In its $SU(3)_F$ invariant approximation the pseudoscalar exchange interaction splits the multiplets of $SU(6)_{FS}\times U(6)_{conf}$ in the spectrum to multiplets of $SU(3)_F\times SU(2)_S\times U(6)_{conf}$. The position of these multiplets differ in the baryon sectors with different strangeness because of the mass splitting of the pseudoscalar octet and the different constituent masses of the u,d and s quarks that breaks $SU(3)_F$ flavor symmetry. A description of the whole spectrum, to an accuracy of $\simeq$ 4\% or better, is achieved if one matrix element of the boson interaction for each oscillator shell is extracted from the empirical mass splittings. The ordering of the positive and negative parity states moreover agrees with the empirical one in all sectors of the spectrum. A discussion of the conceptual basis of the model and its various phenomenological ramifications is presented.

hep-ph↗

arXiv1995

Quark-exchange Effects in a Deuteron Breakup at Intermediate Energy

Microscopical approach to a deuteron breakup at high and intermediate energies is proposed. We show that the quark exchange effects, resulting from the full asymmetry of the $6q$-deuteron wave function with respect to the pair permutations of quark variables, strongly affect the proton momentum distribution in the deuteron, as well as the polarization observables of inclusive deuteron breakup, when the ``internal momentum'' in the deuteron is of order of a few hundreds MeV/c.

hep-ph↗

arXiv1995

Systematics of the Light and Strange Baryons and the Symmetries of QCD

The spectra of the nucleons and the strange hyperons are well described by a harmonic confinement potential for the constituent quarks and an SU(3) flavor-symmetric interaction mediated by the pseudoscalar octet that is associated with the hidden approximate chiral symmetry of QCD. The spectrum is formed of multiplets of $SU(6)_{FS}\times U(6)_{conf}$, which are mixed by the octet interaction. With 4 matrix elements of the octet mediated interaction determined by the lowest mass splittings in the nucleon spectrum the resulting mass formula predicts the whole spectrum with an accuracy of $\sim$ 5\%.

hep-ph↗

arXiv1995

Constituent Quark Model Calculation for a possible J^P=0^-,T=0 Dibaryon

There exists experimental evidence that a dibaryon resonance d' with quantum numbers J^P=0^-,T=0 and mass 2065 MeV could be the origin of the narrow peak in the (π^+ ,π^- ) double charge exchange cross--sections on nuclei. We investigate the six--quark system with these quantum--numbers within the constituent quark model, with linear confinement, effective one--gluon exchange at short range and chiral interactions between quarks (πand σexchange). We classify all possible six quark states with J^P=0^-,T=0, and with N=1 and N=3 harmonic oscillator excitations, using different reduction chains. The six--quark Hamiltonian is diagonalized in the basis including the unique N=1 state and the 10 most important states from the N=3 shell. We find, that with most of the possible sets of parameters, the mass of such a "dibaryon" lies above the N(939)+N^\ast(1535) threshold. The only possibility to describe the supposed d'(2065) in the present context is to reduce the confinement strength to very small values, however at the expense of describing the negative parity resonances N^\ast. We also analyze the J^P=0^-,T=2,N=1 six--quark state.

nucl-th↗

arXiv1994

The Baryon Spectrum and Chiral Dynamics

The fine structure of the low energy part of the nucleon and strange hyperon spectra, which are formed of single states without parity doublets, may be understood in terms of an $SU(3)$ flavor-symmetric quark-quark interaction that describes chiral pseudoscalar boson exchange. The model predicts the fine structure splittings within 10-30\% of their empirical values and provides an explanation of the reversed ordering of the lowest positive and negative parity resonances in the nucleon and the $Λ$ hyperon spectra.

hep-ph↗