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1.
M. C. Bergère C. de Calan A. P. C. Malbouisson 《Communications in Mathematical Physics》1978,62(2):137-158
For any Feynman amplitude, where any subset of invariants and/or squared masses is scaled by a real parameter going to zero or infinity, the existence of an expansion in powers of and ln is proved, and a method is given for determining such an expansion. This is shown quite generally in euclidean metric, whatever the external momenta (exceptional or not) and the internal masses (vanishing or not) may be, and for some simple cases in minkowskian metric, assuming only finiteness of the — eventually renormalized — amplitude before scaling. The method uses what is called Multiple Mellin representation, the validity of which is related to a generalized power-counting theorem.On leave of absence from University of Bahia (Brazil). Fellow of CAPES, Brazil 相似文献
2.
G. Magela e Silva L. A. C. Malbouisson J. D. M. Vianna 《Journal of mathematical chemistry》1995,17(3):347-355
The continuation of the previous work is presented. Here the instability matrices for the eight classes of HF solutions, considering time reversal and spin symmetries, are derived and explicitly shown. These matrices are expressed in terms of LCAO coefficients. Hence they are of immediate application to the verification of instabilities in HF calculations. 相似文献
3.
H. Queiroz F.C. Khanna J.M.C. Malbouisson M. Revzen A.E. Santana 《Annals of Physics》2005,317(1):220-237
A generalization of the Bogoliubov transformation is developed to describe a space compactified fermionic field. The method is the fermionic counterpart of the formalism introduced earlier for bosons [Phys. Rev. A 66 (2002) 052101], and is based on the thermofield dynamics approach. We analyze the energy-momentum tensor for the Casimir effect of a free massless fermion field in a d-dimensional box at finite temperature. As a particular case the Casimir energy and pressure for the field confined in a three-dimensional parallelepiped box are calculated. It is found that the attractive or repulsive nature of the Casimir pressure on opposite faces changes depending on the relative magnitude of the edges. We also determine the temperature at which the Casimir pressure in a cubic box changes sign and estimate its value when the edge of the cube is of the order of the confining lengths for baryons. 相似文献
4.
D. Bazeia L. Losano J. M. C. Malbouisson J. R. L. Santos 《The European Physical Journal C - Particles and Fields》2011,71(10):1767
This work deals with the presence of defect structures in generalized sine-Gordon models. The models are described by periodic
potentials, with substructure having one, two, three, or more distinct topological sectors, with multiplicity one, two, three
or more, respectively. The investigation takes advantage of the deformation procedure introduced in previous work, which is
used to introduce the new models, and to study all the defect structures they may comprise. 相似文献
5.
J. C. Anjos J. Sá Borges A. P. C. Malbouisson F. R. A. Simão 《Zeitschrift fur Physik C Particles and Fields》1984,23(3):243-245
Critical temperatures forSU(N)-singlet bags are determined and a deconfinement phase transition is exhibited. 相似文献
6.
A. P. C. Malbouisson F. R. A. Simão J. Sá Borges 《Zeitschrift fur Physik C Particles and Fields》1985,29(1):75-77
We give a naïve perturbative proof of the existence of infrared renormalons for large distance asymptotically free theories. We argue that the extension of the result for small distance asymptotically free theories is not obvious. Indeed we do not find infrared renormalons for QCD. 相似文献
7.
We perform a study about effects of an applied magnetic field and a finite chemical potential on the size-dependent phase structure of a first-order transition. These effects are introduced by using methods of quantum fields defined on toroidal spaces, and we study in particular the case of two compactified dimensions, imaginary time and a spatial one (a heated film). It is found that for any value of the applied field, there is a minimal size of the system, independent of the chemical potential, below which the transition disappears. 相似文献
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9.
G. Magela e Silva L. A. C. Malbouisson A. Naves de Brito J. D. M. Vianna 《Journal of mathematical chemistry》1993,13(1):317-330
Concepts of functional analysis, namely, regular points, tangent subspaces, constraint surfaces, Lagrangian matrix restricted to the tangent subspace of a constraint surface, are presented in connection with the Hartree-Fock (HF) problem. The energy functional in LCAO approximation is considered to be a polynomial function of several variables subject to subsidiary conditions. General HF equations and instability conditions for the unrestricted Hartree-Fock (UHF) solutions are derived from this standpoint. 相似文献
10.