Thermofield-Bosonization on Compact Space

We develop the construction of fermionic fields in terms of bosonic ones to describe free and interaction models in the circle, using thermofielddynamics. The description in the case of finite temperature is developed for both normal modes and zero modes. The treatment extends the thermofield-bosonization for periodic space

Spiral Patterns and Shocks in Low-compressibility Accretion Disks around Collapsed Objects: Two-dimensional SPH Modeling

In recent years contrasting results have been found regarding the onset of spiral structures and shock fronts in accretion disks around compact objects. Indeed, according to some authors, spiral structures and shock fronts do not develop if an adiabatic index γ > 1.16 is adopted. On the contrary, other authors obtain well-developed spiral patterns and shocks adopting γ = 1.2. In this paper, by using a smoothed particle hydrodynamics (SPH) code, we show that clear spiral patterns and strong radial shocks come out even in very low compressibility (γ = 1.3 > 1.16) accretion disk models in close binaries if the primary is a massive black hole (MBH) with a mass 30-60 times larger than the secondary, whatever the geometrical and dynamical conditions at the inner Lagrangian point, L1, may be, independent of sonic or subsonic injection flow boundary conditions. Indeed, the rationale of this work is that in close binary systems in which the primary is a MBH and the secondary is a low-mass star, we have enough initial energy and angular momentum at the inner Lagrangian point, L1, and a wide and deep enough primary potential well to favor the development of well-defined spiral structures, and eventually spiral shocks, independent of the gas compressibility. According to our results the presence of a MBH triggers the development of spiral structures and spiral shock fronts in the accretion disk both at its outer edge and in the disk bulk, because of the high particle concentration and the strong collisions induced by the strongly accelerated stream particles with the high initial angular momentum at L1

Higher-Derivative Two-Dimensional Massive Fermion Theories

We consider the canonical quantization of a generalized two-dimensional massive fermion theory containing higher odd-order derivatives. The requirements of Lorentz invariance, hermiticity of the Hamiltonian and absence of tachyon excitations suffice to fix the mass term, which contains a derivative coupling. We show that the basic quantum excitations of a higher-derivative theory of order 2N+1 consist of a physical usual massive fermion, quantized with positive metric, plus 2N unphysical massless fermions, quantized with opposite metrics. The positive metric Hilbert subspace, which is isomorphic to the space of states of a massive free fermion theory, is selected by a subsidiary-like condition. Employing the standard bosonization scheme, the equivalent boson theory is derived. The results obtained are used as a guideline to discuss the solution of a theory including a current-current interaction.Comment: 23 pages, Late

Origin of long-period Alfv{\'e}n waves in the solar wind

We suggest that the observed long-period Alfv{\'e}n waves in the solar wind may be generated in the solar interior due to the pulsation of the Sun in the fundamental radial mode. The period of this pulsation is about 1 hour. The pulsation causes a periodical variation of density and large-scale magnetic field, this affecting the Alfv{\'e}n speed in the solar interior. Consequently the Alfv{\'e}n waves with the half frequency of pulsation (i.e. with the double period) can be parametrically amplified in the interior below the convection zone due to the recently suggested swing wave-wave interaction. Therefore the amplified Alfv{\'e}n waves have periods of several hours. The waves can propagate upwards through the convection zone to the solar atmosphere and cause the observed long-period Alfv{\'e}n oscillations in the solar wind.Comment: 5 pages, 2 figures, accepted in MNRAS Letter

Evidences for butterfly diagrams for spots on active late-type stars

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Parity properties of an advection-dominated solar \alpha^2\Om-dynamo

We have developed a high-precision code which solves the kinematic dynamo problem both for given rotation law and meridional flow in the case of a low eddy diffusivity of the order of $10^{11}$ cm$^2$/s known from the sunspot decay. All our models work with an \alf-effect which is positive (negative) in the northern (southern) hemisphere. It is concentrated in radial layers located either at the top or at the bottom of the convection zone. We have also considered an \alf-effect uniformly distributed in all the convection zone. In the present paper the main attention is focused on i) the parity of the solution, ii) the form of the butterfly diagram and iii) the phase relation of the resulting field components. If the helioseismologically derived internal solar rotation law is considered, a model without meridional flow of high magnetic Reynolds number (corresponding to low eddy diffusivity) fails in all the three issues in comparison with the observations. However, a meridional flow with equatorial drift at the bottom of the convection zone of few meters by second can indeed enforce the equatorward migration of the toroidal magnetic field belts similar to the observed butterfly diagram but, the solution has only a dipolar parity if the (positive) \alf-effect is located at the base of the convection zone rather than at the top. We can, therefore, confirm the main results of a similar study by Dikpati & Gilman (2001).Comment: 9 pages, 16 figures, to appear on Astronomy and Astrophysic