Properties of "35" Spin-(5/2) Baryon Resonances in a Model with Broken SU(3)

We investigate the properties of a set of J =(5/2)^+ resonances appearing in a 35-dimensional representation of SU(3), as proposed by Abers, Balázs, and Hara. A simple dynamical calculation gives an estimate for the mass differences within the supermultiplet. The matrix elements for the SU(3) allowed decays into meson plus resonance are given in terms of one parameter and the SU(3)-violating matrix elements for decay into meson plus baryon are given by two parameters

General S-Matrix Methods for Calculation of Perturbations on the Strong Interactions

Recently, the authors proposed an on-the-mass-shell, S-matrix method for computing the effects of small perturbations on the masses and coupling constants of strongly interacting particles. In the present paper, the method is generalized to the multichannel case. The use of group-theoretical techniques in reducing the complexity of the method is described in detail

Some general features of the bootstrap theory of octet enhancement

Some general features of the boostrap theory of octet enhancement, which can be understood without detailed calculations, are discussed. These features include: (i) the connection of this theory to the vector-mixing theory of symmetry breaking advocated by Sakurai, and to the tadpole theory of Coleman and Glashow; (ii) an understanding of why it is representations of low multiplicity that are dynamically emphasized in symmetry breaking; (iii) a demonstration that the theory remains valid when a number of assumptions made in previous applications are dropped

Baryon-Pion Couplings from Large-N QCD

We derive a set of consistency conditions for the pion-baryon coupling constants in the large-N limit of QCD. The consistency conditions have a unique solution which are precisely the values for the pion-baryon coupling constants in the Skyrme model. We also prove that non-relativistic $SU(2N_f)$ spin-flavor symmetry (where $N_f$ is the number of light flavors) is a symmetry of the baryon-pion couplings in the large-N limit of QCD. The symmetry breaking corrections to the pion-baryon couplings vanish to first order in $1/N$. Consistency conditions for other couplings, such as the magnetic moments are also derived.Comment: (12 pages, 2 figs, uses harvmac and uufiles), UCSD/PTH 93-1

Spin-Flavor Structure of Large N Baryons

The spin-flavor structure of large N baryons is described in the 1/N expansion of QCD using quark operators. The complete set of quark operator identities is obtained, and used to derive an operator reduction rule which simplifies the 1/N expansion. The operator reduction rule is applied to the axial currents, masses, magnetic moments and hyperon non-leptonic decay amplitudes in the $SU(3)$ limit, to first order in $SU(3)$ breaking, and without assuming $SU(3)$ symmetry. The connection between the Skyrme and quark representations is discussed. An explicit formula is given for the quark model operators in terms of the Skyrme model operators to all orders in $1/\N$ for the two flavor case.Comment: 36 pages, 2 eps figures, uses revte

Calculation of the proton-neutron mass difference by S-matrix methods

The proton-neutron mass difference is calculated using S-matrix methods developed in the previous paper. Neutrons and protons are treated as bound-state poles in the π-N scattering amplitude, and the mass difference is obtained by finding the electromagnetic corrections to their binding energies. The results are in good agreement with experiment. No cutoffs or other purely theoretical parameters are involved. All the long-range electromagnetic corrections to the π-N interaction are investigated. Photon exchange turns out to be the most important. Form factors appear as short-range modifications of the photon exchange force. The results of the calculation are not sensitive to the detailed behavior of the form factors at large momentum transfer

Chew-Low model for Regge-pole couplings

The couplings of a meson trajectory α(t) to the baryon octet B and the decimet Δ are studied in the Chew-Low model. The model predicts ratios, though not absolute magnitudes, for SU(3)-symmetric couplings of the 0- octet Π, 1- octet V, and 2+ octet T trajectories at the small t of either sign for which static kinematics is applicable. For non-spin-flip, the V and T trajectories are predicted to couple to B̅ B like F+1 / 4D, independent of t. For magnetic dipole terms, the Π, V, and T trajectories are all predicted to couple to B̅ B like D+2 / 3F, and to Δ̅ B with the same relative strength as the 0- octet, independent of t. The electric quadrupole couplings of the Π, V, and T trajectories are predicted to be small, independent of t. These results generally agree with existing data, improve Sawyer's explanation of the Johnson-Treiman relations, provide a partial justification of the recent suggestion that V and T couplings are similar, predict that T exchange produces large spin flips, and predict certain ratios such as dσ / dt(π-p→π0n) / (dσ / dt)(π+p→π0N*++)