Modern Physics Letters A

From ϕ-mapping method we construct a fouth-order topological tensor current in general. It is shown that the inner structure of this topological tensor current is labelled by the δ-function δ(ϕ), which represents some four-dimensional singular manifolds. By investigating the total expansion of δ(ϕ), these singular manifolds carry the topological numbers β_iη_i naturally, which does not involve any concrete models. As the generalization of Nielsen's Lagrangian and Nambu's action for strings, we present a new coordinate condition in general relativity, which includes the Fock's coordinate condition as a special case.

We impose the condition that the eigenvalues of the mass matrix in the shifted Lagrangian density be positive at ϕ=ϕ₀, the vacuum expectation value of the scalar field. Using the one-loop effective potential of the standard model, this condition leads to an upper bound on the Higgs boson mass m_H:m_H<230 GeV, for a top quark mass of 175 GeV.

We present a composite model that is based on nonperturbative effects of N=1 supersymmetric SU(N_C) gauge theory with N_f=N_C+1 flavors. In this letter, we consider N_C=7, where all fields of one generation (quarks, leptons and Higgs) are bound states of preons and anti-preons. When SU(7)_H coupling becomes strong. Yukawa couplings of quarks and leptons are generated dynamically. We show the one-generation model first and then we try to extend it to the three-generation model.

Using the quark–meson coupling (QMC) model, we study the density dependence of the quark and gluon condensates in nuclear matter. We show that the change of the quark condensate is mainly driven by the scalar field in the medium and that the reduction of the quark condensate is suppressed at high density, even in the mean-field approximation. The gluon condensate decreases by 4–6% at nuclear saturation density. We also give a simple relationship between the change of the quark condensate and that of a hadron mass in the medium.

A class of transformations of R_q-matrices is introduced such that the q→1 limit gives explicit nonstandard R_h-matrices. The transformation matrix is singular as q→1. For the transformed matrix, the singularities, however, cancel yielding a well-defined construction. Our method can be implemented systematically on R_q-matrices of all dimensions and not only for q-deformed sl(2) algebra but also for algebras of higher dimensions. Explicit constructions are presented starting with and , while choosing R_q for (fund. rep.) ⊗ (arbitrary irresp.). The treatment for the general case of algebras is indicated. Our method yields nonstandard deformations along with a nonlinear map of the h-Borel subalgebra on the corresponding classical Borel subalgebra. For this map is extended to the whole algebra and compared with the other proposed by us previously. The usual classical coproduct on and the non-cocommutative coproduct structure on are related via Drinfeld twist operators, determined up to O(h²) for both of these nonlinear maps.

U_A(1) dynamics have the potential to induce a polarised condensate inside a nucleon. The formation of this condensate is related to the realisation of U_A(1) symmetry breaking by tunneling processes such as instantons. If it is present, the polarised condensate induces a term in g₁ which has support only at x=0. Tunneling processes then induce a net transfer of "spin" from finite x to x=0. The polarised condensate may be measured by comparing the flavour-singlet axial charges which are extracted from polarised deep inelastic and νp elastic scattering experiments.

Using an energy–momentum complex, we give a physical interpretation to the constants in the well-known static spherically symmetric asymptotically flat vacuum solution to the Brans–Dicke equations. The positivity of the tensor mass puts a bound on parameters in the solution.

We consider possible modifications of the Calogero–Vasiliev quantum condition and address the problem of construction of coherent states.

A mechanism is proposed for the emission of radiation by charged particles in the gravitational field of a quasar whereby the gravitational field is coupled directly to the radiation field of the charge via the principle of equivalence. A generalized Larmor formula for the radiation emitted by a charge at rest in a gravitational field can account for the total radiant energy and spectral distribution emitted by quasars. This gravitational mechanism for the emission of electromagnetic radiation becomes more important than any other mechanism when the radius of the quasar is near its Schwarzschild radius.

The pole positions of various baryon resonances have been found to reveal a well-pronounced clustering, the so-called Höhler cluster. In a previous work, the Höhler clusters have been shown to be identical to Lorentz multiplets of the type with l′ integer. Here we show that the cluster positions are well-described by means of a Balmer series like recursive mass formula.