Modern Physics Letters A

The highlights and conflicts at the B factories are briefly reviewed. CP violation was established in 2001 in B⁰→J/ψK_S and related modes, which has now become a precision measurement of CP violation in mixing. However, the situation for the B⁰→π⁺π^- and charmless b→s modes, which also probe CP violation in the decay amplitude, are not quite settled yet. They could be hinting at the presence of both strong (CP conserving) and new physics (CP violating) phases. We critically assess the developments and discuss some related discrepancies and highlights, such as observation of direct CP violation, and make a projection towards the next few years.

We consider the Palatini formalism of gravity with cosmological constant Λ coupled to a scalar field ϕ in n dimensions. The n-dimensional Einstein equations with Λ can be derived by the variation of the coupled Palatini action provided n>2. The Hamiltonian analysis of the coupled action is carried out by a 1+(n-1) decomposition of the spacetime. It turns out that both Palatini action and Hilbert action lead to the same geometric dynamics in the presence of Λ and ϕ while the n-dimensional Palatini action could not give a dynamical formalism of connection directly.

We show that the vacuum polarization of quantum fields in an anti-de Sitter space can naturally give rise to a small but nonzero cosmological constant in a brane world living in it. To explain the extremely small ratio of mass density in the cosmological constant to the Planck mass density in our universe (≈10^-123) as suggested by cosmological observations, all we need is a four-dimensional brane world (our universe) living in a five-dimensional anti-de Sitter space with a curvature radius r₀~10^-3cm and a fundamental Planck energy M_P~10⁹GeV, and a scalar field with a mass . Probing gravity down to a scale ~10^-3 cm, which is attainable in the near future, will provide a test of the model.

We describe the Sato–Wilson type formulation of the KP hierarchy within the framework of closed string theory. A matrix generalization of this formalism is shown to allow natural interpretation of coincident D-branes as a sourse of non-Abelian gauge theory.

The rare t-quark decays , via the scalar leptoquark doublets are investigated in the minimal four-color symmetry model with the Higgs mechanism of the quark–lepton mass splitting. The partial widths of these decays are calculated and the total width of the charged lepton mode and the total width of the neutrino mode are found. The corresponding branching ratios are shown to be

We study the Hamiltonian structure and constraints of twistor-like super p-brane which preserves 3/4 of D = 4, N = 1 supersymmetry using the conversion method. Classical and quantum realizations of the BRST charge, the unified superalgebra of symmetries of the p-brane action, including generalized global superconformal OSp(1|8) symmetry together with Virasoro and Weyl symmetries, are presented. We prove nilpotency of the Hermitian quantum BRST charge of the p-brane and closure of the quantized superalgebra OSp(1|8) of its global symmetry.

We study a Newtonian cosmological model in the context of a noncommutative space. It is shown that the trajectories of a test particle undergo modifications such that it no longer satisfies the cosmological principle. For the case of a positive cosmological constant, spiral trajectories are obtained and corrections to the Hubble constant appear. It is also shown that, in the limit of a strong noncommutative parameter, the model is closely related to a particle in a Gödel-type metric.