Momentum spectrum of hadronic secondaries in the multiperipheral model

Journal ArticleMotivated by a simplified multiperipheral model, we formulate a general qualitative description of the momentum spectrum of secondaries, resulting from a collision of two hadrons at high energies. Arguing from two fundamental multiperipheral concepts, (a) that transverse momenta are limited and (b) that distant particles on the multiperipheral chain are uncorrelated, we predict that at sufficiently high incident energies, the momentum spectrum of particle X in the reaction a ± b → X + anything, when presented in the variables pi and y = sinh-1[pll(pi2±mx2)½], develops a central plateau in the y dependence, which elongates and flattens to a value that is normalized b y the total cross section as the incident energy increases. Moreover, it is shown that the resultant particle density distribution is consistent with the hypothesis of limiting fragmentation. We contrast this description with the predictions of the two-fireball model, the isobar-pionization model, and the statistical thermodynamical model

Quark-bag model with low-energy pion interactions. II. Application

Journal ArticleThe hybrid pion-quark-bag model discussed in I is applied to a calculation of masses, pion couplings, and other parameters of various light hadrons in an effort to determine the extent to which the bag parameters must be modified in the presence of pion interactions. Corrections for the finite spread of the cm. wave packet are also included in each case

Quark-bag model with low-energy pion interactions. I. Theory

Journal ArticleA standard method for restoring chiral symmetry in the bag model is to introduce an explicit external pion field. Questions of the consistency and compatibility of this method with the assumptions of the static-cavity approximation of the bag model are discussed. An approximate version of the model is justified. It is argued that consistency requires treating pion-induced quark-pair creation and annihilation at the bag surface as a zeroth-order process in pion-coupling perturbation theory. An approximation treating these pairs as an inward extension of the pion field is discussed. The resulting model gives an improved value of gA

Tensor component of the two-nucleon interaction in the quark-bag model

Journal ArticleA previously developed method for computing the interaction energy of the two-nucleon system at short distances in the static MIT bag model of confined quarks is extended to all isospin and spin channels available to the two-nucleon interaction. The present study is restricted to spherical geometries and short distances (separations less than about one F) to simplify the computation. The tensor component of the interaction in the isosinglet and isotriplet channels is found to agree in sign with the accepted phenomeriological two-body tensor potential

Conjecture concerning the modes of excitation of the quark-gluon plasma

Journal ArticleIt is a widely held belief that at temperatures much higher than the confinement scale of quantumchromodynamics (QCD), quarks and gluons become free, giving rise to a new form of matter, called the quark-gluon plasma. It is conjectured here that the characterization of the plasma as a free or weakly interacting gas of quarks and gluons is valid only for short distances and short time scales of the order l/T, but that at scales larger than l/g2T (where g2 is the running QCD coupling) the plasma exhibits confining features similar to that of the low-temperature hadronic phase. The confining features are manifest in the long-range, i.e., long-wavelength, low-frequency, modes of the plasma. To examine the long-range real-time response of the plasma goes beyond the capabilities of current lattice-gauge-theory techniques. However, some properties of these modes can be determined indirectly. An attempt is made to characterize the long-range modes of excitation by examining the static high-temperature limit, focusing upon the static screening lengths of colored and neutral local operators. Since g2 is not small at temperatures likely to be accessible in heavy-ion collisions, the nonperturbative effects associated with vestiges of confinement are likely to be important in the phenomenological analysis of measurements made at accelerators

Hadronic deformation energy. II. Two-nucleon interaction

Journal ArticleThe MIT bag model for hadrons is treated in the static cavity approximation. The adiabatic deformation of a six-quark hadron with quantum numbers of the deuteron is studied in a configuration which permits the separation of two triplets with quantum numbers of the neutron and proton. The energy of the system is computed to second order in the gluon coupling and presented as a function of two choices of a single collective variable: a separation parameter for the nucleons and the baryonic quadrupole moment. The present study considers only interactions at short and intermediate range in a state with nuclear spins aligned in parallel along the deformation axis. It does not treat effects depending on nucleon momenta. The energy, when expressed in terms of a nuclear separation parameter, exhibits a soft repulsive core at short range due to a color-magnetic gluon interaction, and strong attraction in intermediate range due to a color-electric interaction