International Journal of Modern Physics A

We have examined the physics and the experimental feasibility of studying various kaon decay processes in which the polarization of a muon in the final state is measured. Valuable information on CP violation, the quark mixing (CKM) matrix, and new physics can be obtained from such measurements. We have considered muon polarization in K_L→μ⁺μ^- and K→πμ⁺μ^- decays. Although the effects are small, or difficult to measure because of the small branching ratios involved, these studies could provide clean measurements of the CKM parameters. The experimental difficulty appears comparable to the observation of . New sources of physics, involving nonstandard CP violation, could produce effects observable in these measurements. Limits from new results on the neutron and electron electric dipole moment, and in neutral kaon decays, do not eliminate certain models that could contribute to the signal. A detailed examination of muon polarization out of the decay plane in K⁺→μ⁺π⁰ν and K⁺→μ⁺νγ decays also appears to be of interest. With current kaon beams and detector techniques, it is possible to measure the T-violating polarization for K⁺→μ⁺π⁰ν and with uncertainties approaching ~10^-4. This level of sensitivity would provide an interesting probe of new physics.

In this paper, I study the effect of a strong magnetic field on the quark/gluon plasma, whose properties are investigated by using a quasiparticle model with effective thermal masses for both the quarks and the gluons. This analysis is performed looking at the perspectives opened by the study of the interior of neutron stars, where large magnetic fields, as high as 10¹⁸ G, might exist; the high densities present in their core might also favor the matter deconfinement. I show that the presence of a large magnetic field has an important influence on the equation of state of the deconfined plasma; the astrophysical relevance of this effect is also discussed, together with the present possibilities to detect a quark matter star.

A new recursion procedure for deriving renormalized perturbation expansions for the one-dimensional anharmonic oscillator is offered. Based upon the ℏ-expansions and suitable quantization conditions, the recursion formulae obtained have the same simple form both for ground and excited states and can be easily applied to any renormalization scheme. As an example, the renormalized expansions for the sextic anharmonic oscillator are considered.

Exclusive semileptonic B decays into excited charmed mesons are studied up to the order of 1/m_Q in the framework of the heavy quark effective field theory (HQEFT), which contains the contributions of both particles and antiparticles. Two wave functions and , which characterize the contributions from the kinematic operator at the order of 1/m_Q, are calculated by using QCD sum rule approach in HQEFT. Zero recoil values of other two wave functions and are extracted from the excited charmed-meson masses. Possible effects from the transition wave functions arising from the chromomagnetic operators at the order of 1/m_Q are analyzed. It is shown that the experimental measurements for the branching ratios of B→D₁lν and can be understood in the framework of HQEFT.

We study the deformation quantization of scalar and Abelian gauge classical free fields. Stratonovich–Weyl quantizer, star products and Wigner functionals are obtained in field and oscillator variables. The Abelian gauge theory is particularly intriguing since the Wigner functional is factorized into a physical part and the other one containing the constraints only. Some effects of nontrivial topology within the deformation quantization formalism are also considered.

We discuss several closely related concepts in the NSR formulation of superstring theory. We demonstrated that recently proposed NSR model for superstrings on AdS₅× S⁵ is described by the world sheet logarithmic conformal field theory (LCFT). The origin of LCFT on a world sheet is closely connected to the matter-ghost mixing in the structure of a brane-like vortex operators. We suggest a dynamical origin of M theory as a string theory with an extra dimension given by bosonized superconformal ghosts.

Previously matrix model actions for "fuzzy" fields have been proposed using noncommutative geometry. They retained "topological" properties extremely well, being capable of describing instantons, θ-states, the chiral anomaly, and even chiral fermions with no "doubling." Here, we demonstrate that the standard scalar and spinor actions on a d-dimensional manifold are recovered from such actions in the limit of large matrices if their normalizations are correctly scaled as the limit is taken.

The theoretical existence of oscillating boson stars consisting of a real scalar field, stable to radial perturbations, has been proven by Seidel and Suen. For the QCD axion of the heterotic superstring theory, this implies a mini-star of mass , where λ≡ f_a′/f_a is the ratio of the decay constants of the second and model-independent axions, which, for a suitable value in the range 1≲λ≲10, can explain the astronomical microlensing observations towards the Galactic centre and the Large and Small Magellanic Clouds. Here, we apply the non-linear relaxation theory developed by Tkachev to show that the condition τ_f<τ_r<τ₀ for the formation of such an object, where τ_f, τ_r and τ₀ are the free-fall and relaxation times and the age of the Universe, respectively, leads to the condition , where is the strong-interaction coupling parameter and C is a dimensionless constant defined below. From this, we argue, considering the approximations involved, that the star does condense.