SOME REMARKS ON EXOTIC RESONANCES

Using large Nc counting rule, it is argued that tetra-quark resonances do not exist. Also it is pointed out that there exists the violation of exchange degeneracy in the exotic KN scattering channel. It implies either the failure of resonance saturation assumption or it suggests the existence of exotic baryon resonances in such a channel.

The Regge Pole Model and Forward Elastic Data at High Energies ? An Analysis

Using O"to" Re/lm and relevant forward differential cross-section data up to the highest available energies we determine the P, f, p, OJ, A2 intercepts and forward residues in nN, NN and KN scattering. We find evidence for low-lying contributions in the nN and NN non-flip amplitudes including the 0" trajectory in the nN case. We also test various phenomenological notions like exchange degeneracy (EXD) , p universality, OJ universality etc. against our parameter values. Comparison is made with other works.

Proton-Proton Total Cross Sections and the Neglect of Masses in Data Fitting in the Regge Region

It is shown by taking the example of pp total cross .sections that the use of the approximation s ~ 2qs-t while fitting data in the Regge region can be misleading. Several standard fits to O"tot(pp) data are based on the assumption of weak p-f-w-A2 exchange degeneracy (EXD). However, these fits involve the use of the approximation mentioned. We find, quite surprisingly, that it is impossible to fit the O"tot(pp) data in the range 6 ~ Plab ~ 2092 GeVjc using the precise factor 2qs~ in conjunction with weak p-f-w-A2 EXD. OUf investigation shows that O"tot(pp) data alone seem to indicate either a breaking of weak p-f-w-A 2 EXD or the presence of low-lying contributions, or both, provided one does not ignore the masses of the interacting particles in data fitting in the Regge region (Plab ;:;: 5 GeVjc). Caution is therefore urged in the use of such approximations in phenomenological calculations.