排序方式: 共有19条查询结果,搜索用时 15 毫秒
1.
C. M. Arizmendi A. H. Rizzo L. N. Epele C. A. García Canal 《Zeitschrift für Physik B Condensed Matter》1991,83(2):273-276
The Hamiltonian limit of the ANNNI model in (1+1) dimensions is studied by using the Quantum Statistical Monte Carlo method. Even if recent results suggest that Monte Carlo calculations may prove unreliable in the study of this system, the phase diagram of the quantum version of the model was successfully obtained. In particular, the clusive transitions between the disordered, the floating incommensurate and the degenerate 2, 2 are determined by analysing the correlation length behaviour in finite lattices.Partially supported by CONICET Argentina 相似文献
2.
Epele L. N. Fanchiotti H. García Canal C. A. Leader E. Sassot R. 《Zeitschrift fur Physik C Particles and Fields》1994,61(2):285-291
The thermodynamic potential (TDP) of the boson sector of the Weinberg-Salam model in an external uniform magnetic field at finite temperature and nonzero chemical potential is calculated in one-loop approximation. In the high temperature limit with the use of Mellin summation technique explicit expressions for the thermodynamic potential are obtained to analyze its new minimum, different from the ordinary Higgs one. This new minimum is due to the root singularity in the oneloop expression for the TDP, originating as a consequence of the tachyonic mode in the spectrum of gauge boson in the magnetic field. It is demonstrated that in the high temperature limit the Higgs minimum possesses properties common with the ordinary superconductors and Abelian Higgs model. The influence of the magnetic field on the Higgs minimum is indirect and has a sufficiently complicated character. The presence of the non-zero chemical potential lowers the critical temperature leading to the disappearance of the Higgs minimum. 相似文献
3.
L. Epele H. Fanchiotti A.G. Grunfeld 《The European Physical Journal C - Particles and Fields》2003,30(1):97-101
In this work we study the departure from the ideal
-
mixing angle within the framework of the Nambu-Jona-Lasinio model. In this context we show that the flavor symmetry breaking is unable to produce the shifting of the ideal mixing. We found that a nonet symmetry breaking in the neutral vector sector is necessary to regulate the non-strange content of the
meson. The phenomenology is well described by our proposal.Received: 14 November 2002, Revised: 22 April 2003, Published online: 11 July 2003 相似文献
4.
L. Epele H. Fanchiotti D. Gómez Dumm A.G. Grunfeld 《The European Physical Journal C - Particles and Fields》2001,20(3):531-539
We revisit the theoretical predictions for anomalous radiative decays of pseudoscalar and vector mesons. Our analysis is
performed in the framework of the Nambu–Jona–Lasinio model, introducing adequate parameters to account for the breakdown of
chiral symmetry. The results are comparable with those obtained in previous approaches.
Received: 14 September 2000 / Revised version: 1 March 2001 / Published online: 8 June 2001 相似文献
5.
This paper is the first of a series of three where we reconsider the derivation of rigorous absolute bounds for strong interactions. It is devoted to the solution of a preliminary extremum problem. From the knowledge, at a given physical energy s and unphysical angle cos θ0 > 1, of the absorptive part A (s, cos θ0) of the elastic scattering amplitude for two spinless particles, we find, by exploiting the unitarity condition, the least upper bound of the modulus |F(s, cos θ1)| of the scattering amplitude for the same energy s and various angles θ1. Upper (but not least upper) bounds given by previous authors are numerically compared with ours. 相似文献
6.
Salmanca Oviedo LN Gomez-Herrero A Landa Canovas AR Otero-Diaz LC 《Micron (Oxford, England : 1993)》2000,31(5):597-603
Two new misfit layer structures have been synthesized within the Sb-Nb-Se system. Powder X-ray diffraction and electron microscopy techniques (electron diffraction, HREM, XEDS) have been used to determine the nature of their structure. According to TEM and XEDS data (for more than 15 crystals studied) both phases are monolayer type, i.e. (SbSe)1+delta (NbSe2). Electron microscopy reveals a composite modulated structure that consists of the periodical intergrowth of a pseudotetragonal SbSe layer, denominated as Q, and a pseudohexagonal layer NbSe2, denominated as H. Both layers fit along b, stack along c and do not fit along a (misfit) giving rise to an incommensurate modulation along this direction. The two phases differ in the symmetry of the Q layers being in one case orthorhombic (for delta = 0.17) and monoclinic in the other (for delta = 0.19). After the characterization of the sample by electron microscopy the unit cells of the basic layers could be refined for both phases by powder X-ray diffraction: aQ = 5.824(2) A, bQ = 5.962(5) A, cQ = 23.927(6) A, alpha = 90 degrees, beta = 90 degrees and gamma = 90 degrees and aH = 3.415(5) A, bH = 5.962(6) A,, cH = 11.962(1) A, alpha = 90 degrees, beta = 90 degrees and gamma = 90 degrees for the orthorhombic phase; aQ = 5.844(2) A, bQ = 5.981(1) A, cQ = 23.919(5) A, alpha = 90 degrees, beta = 90 degrees and gamma = 96.00(3)degrees and aH = 3.439(1) A, bH = 5.994(2) A, cH = 11.956(3) A, alpha = 90 degrees, beta = 90 degrees and gamma = 90 degrees for the monoclinic phase. The phase with the monoclinic Q-sublattice often appears as twinned crystals. The more abundant crystals are disordered intergrowths of both monolayer phases. 相似文献
7.
C. M. Arizmendi L. N. Epele H. Fanchiotti C. A. García Canal 《Zeitschrift für Physik B Condensed Matter》1986,64(2):231-235
A renormalization group realization, allowing the simultaneous and analytic study of both the ferromagnetic and antiferromagnetic phases of the Blume-Capel model, is applied in (1+1)_and (2+1) dimensions. The model is also analyzed by using a variational technique. Critical and tricritical parameters are determined and the phase diagram is exhibited.Partially supported by CONICET, CIC Pcia. de Buenos Aires and SUBCYT, Argentina 相似文献
8.
We study the solutions of the coupled S- and P-wave Roy equations for low-energy pion-pion scattering which are in the neighbourhood of a given solution. We give a general method for constructing these solutions for fixed inelasticities and driving terms and variable S-wave scattering lengths. In the case of the neighbourhood of the physical amplitudes, our procedure leads to a seven-dimensional manifold of solutions. If we omit variations affecting only the I = 0 S-wave around the threshold, the number of dimensions is reduced to five, in accordance with the results of the phenomenological analysis of low-energy pion-pion scattering. Our solutions allow a study of the correlations between S- and P-waves implied by the Roy equations. This work completes a previous one dealing with the single-channel problem of the I = 1 P-wave. 相似文献
9.
Luis N. Epele Huner Fanchiotti Carlos A. García Canal Vicente Vento 《The European Physical Journal C - Particles and Fields》2009,62(3):587-592
Magnetic monopoles have attracted the attention of physicists since the founding of the electromagnetic theory. Their search
has been a constant endeavor which was intensified when Dirac established the relation between the existence of monopoles
and charge quantization. However, these searches have been unsuccessful. We have recently proposed that monopolium, a monopole–antimonopole
bound state, so strongly bound that it has a relatively small mass, could be easier to find and become an indirect but clear
signature for the existence of magnetic monopoles. Here we extend our previous analysis for its production to two photon fusion
at LHC energies. 相似文献
10.
Horacio E. Camblong Luis N. Epele Huner Fanchiotti Carlos A. García Canal Carlos R. Ordóñez 《Annals of Physics》2014,340(1):267-292
A multichannel S-matrix framework for singular quantum mechanics (SQM) subsumes the renormalization and self-adjoint extension methods and resolves its boundary-condition ambiguities. In addition to the standard channel accessible to a distant (“asymptotic”) observer, one supplementary channel opens up at each coordinate singularity, where local outgoing and ingoing singularity waves coexist. The channels are linked by a fully unitary S-matrix, which governs all possible scenarios, including cases with an apparent nonunitary behavior as viewed from asymptotic distances. 相似文献