International Journal of Modern Physics A

In this paper we review the experimental and observational searches for stable, massive, elementary particles other than the electron and proton. The particles may be neutral, may have unit charge or may have fractional charge. They may interact through the strong, electromagnetic, weak or gravitational forces or through some unknown force. The purpose of this review is to provide a guide for future searches — what is known, what is not known, and what appear to be the most fruitful areas for new searches. A variety of experimental and observational methods such as accelerator experiments, cosmic ray studies, searches for exotic particles in bulk matter and searches using astrophysical observations is included in this review.

A general two-dimensional fractional supersymmetric conformal field theory is investigated. The structure of the symmetries of the theory is studied. Then, applying the generators of the closed subalgebra generated by (L_-1,L₀,G_-1/3) and , the two-point functions of the component fields of supermultiplets are calculated.

We present in a simple terms the theory of the factorizing operator introduced recently by Maillet and Sanches de Santos for the spin-1/2 chains. We obtain the explicit expressions for the matrix elements of the factorizing operator in terms of the elements of the monodromy matrix. We use this results to derive the expression for the general scalar product for the quantum spin chain. We comment on the previous determination of the scalar product of Bethe eigenstate with an arbitrary dual state. We also establish the direct correspondence between the calculations of scalar products in the F-basis and the usual basis.

The semirelativistic wave equation which appears in the theory of relativistic quark–antiquark bound states, is cast into a constituent second order Schrödinger-like equation with the inclusion of relativistic corrections up to order (v/c)² in the quarks speeds. The resulting equation is solved via the Shifted-l expansion technique (SLET), which has been recently developed to get eigenvalues and wave functions of relativistic and nonrelativistic wave equations. The Coulomb, Oscillator, and the Coulomb-plus-linear potentials used in phenomenology are tested. It is observed that, the energy eigenvalues can be explained well upon the more commonly used nonrelativistic models, when such a dynamical relativistic corrections are introduced. In particular, it provides a remarkable accurate and simple analytic expression for the Coulomb ground-state energy problem, a result which is in the right direction at least to serve as a test of this approach.

A possibility is considered of explaining the low experimental value of the ratio of the lifetimes τ(Λ_b)/τ (B_d) by a new "centiweak" four-quark interaction, i.e. with a strength on the order of 10^-2G_F. It is noted that the considered interaction can also improve agreement with the data on low semileptonic branching ratio B_sl(B) in B meson decays with a simultaneous slight decrease in the prediction for the average charm yield in those decays. The proposed new interaction modifies within the present experimental limits the predictions for differences of lifetimes among B mesons, and can thus be probed by more precise data on these differences. A sample model is briefly discussed, where the new interaction arises through a weak SU(2) singlet scalar field with quantum numbers of a diquark.

We study hadron properties near the deconfining transition in the quenched lattice QCD simulation. This paper focuses on the heavy quarkonium states, such as J/ψ meson. In order to treat heavy quarks at T<0, we adopt the O(a) improved Wilson action on anisotropic lattice. We discuss bound state observing the wave function and compare the meson correlators at above and below T_c. Although we find a large change of correlator near the T_c, the strong spatial correlation which is almost the same as confinement phase survives even T~1.5T_c.

We describe the spontaneous creation of the brane world in AdS₅ with external field. The resulting brane world consists of a flat 4d spatially finite expanding universe and curved expanding "regulator" branes. No negative tension branes are involved.

In this paper, we use Parisi and Sourlas dimensional reduction to show that QED has two phases, the strong coupling phase and weak coupling phase. Because chiral symmetry is spontaneously broken, particles with fractional charges are confined in the strong coupling phase by the condensation of topological configurations, and particles with integer charges are screened by fermion pairs.

The finite temperature spatial correlation modes in the π and ρ channels are studied with the rainbow-ladder truncated quark Dyson–Schwinger equation and Bethe–Salpeter equation in the Matsubara formalism. To retain the finite range of the effective interaction while facilitating summation over fermion Matsubara modes necessary to ensure continuity at T=0, a separable kernel is used. The model is fixed by T=0 properties and it implements dynamical chiral symmetry breaking and quark confinement. Transition temperatures for deconfinement (T_d) and chiral restoration (T_c) are identified. Above and below these transitions we study M_π(T), f_π(T) and the three-space transverse and longitudinal masses and . We also study the intrinsic T-dependence of the electromagnetic coupling constant g_ρ(T) and the strong coupling constant g_ρππ(T). For both this model and a related semi-analyticinfrared dominant model, we analyze the high T behavior of the obtained masses in comparison to the M(T)→2πT behavior found in lattice QCD simulations.