Aharonov-Anandan phase in Lipkin-Meskov-Glick model

In the system of several interacting spins, geometric phases have been researched intensively.However, the studies are mainly focused on the adiabatic case (Berry phase), so it is necessary for us to study the non-adiabatic counterpart (Aharonov and Anandan phase). In this paper, we analyze both the non-degenerate and degenerate geometric phase of Lipkin-Meskov-Glick type model, which has many application in Bose-Einstein condensates and entanglement theory. Furthermore, in order to calculate degenerate geometric phases, the Floquet theorem and decomposition of operator are generalized. And the general formula is achieved

Rhigonema trichopeplum sp. n. (Nematoda : Rhigonematidae), parasite of a millipede (Diplopoda : Spirobolida) from Myanmar

Une nouvelle espèce de parasite appartenant aux #Rhigonematidae, #Rhigonema trichopeplum sp. n., est décrite provenant de l'intestin d'un Spirobolide (#Diplopoda : #Spirobolida) indéterminé récolté au Myanmar. Cette nouvelle espèce est caractérisée par la combinaison de caractères suivante : corps de la femelle long d'environ 6,6 cm; pilosité cuticulaire limitée à la partie antérieure du corps; tractus génital femelle comportant un long vagin divisé en une région distale musculaire à paroi épaisse suivie par une chambre vaginale à paroi mince; volets advulvaires présents; diverticulum vaginal absent; queue de la femelle pourvue d'une lèvre anale postérieure nettement saillante; trois paires de papilles post-cloacales situées subdorsalement ou latéralement, mais non subventralement. Des photographies au microscope électronique à balayage de la région cervicale et de la queue de la femelle complètent la description. (Résumé d'auteur

Rhigonematida from New Britain diplopods : 1. The genus Carnoya Gilson, 1898 (Ransomnematoidea : Carnoyidae) with descriptions of three new species

Le genre #Carnoya Gilson, 1898 est défini et une liste des ses espèces nominales établie. Trois nouvelles espèces extraites de Diplopodes Spirobolides provenant de l'île de Nouvelle-Bretagne sont décrites et illustrées, y compris au MEB. #C. caputbulla sp. n. est caractérisé par la région céphalique femelle présentant un anneau en bouton, la forme nombre (onze) de papilles réduites supplémentaires et leur répartition, l'annélation de la région cervicale du mâle laquelle n'est pas renforcée, la queue extrêmement longue et les larges anneaux chez les deux sexes. #C. posterovulva sp. n. est caractérisé par l'anneau cervical en bouton de la femelle, la position postérieure unique de la vulve, la présence d'épines cervicales chez la femelle, la position des onze papilles copulatrices réduites, l'annélation de la région cervicale du mâle, la présence d'un seul collier céphalique de seize épines bien séparées chez le mâle, la queue extrêmement longue et les larges anneaux chez les deux sexes. #C. janiceae sp. n. est caractérisé par la région céphalique femelle sans anneau en ailes latérales au niveau du cloaque chez le mâle, la disposition des treize papilles mâles, l'annélation de la région cervicale du mâle, laquelle n'est pas renforcée, la longue queue et les larges anneaux chez les deux sexes. La taxonomie du genre et la valeur de certains caractères morphologiques sont discutées et les espèces des Amériques et de la région Australasie/Pacifique sont comparées et différenciées. (Résumé d'auteur

Statistical and Dynamical Study of Disease Propagation in a Small World Network

We study numerically statistical properties and dynamical disease propagation using a percolation model on a one dimensional small world network. The parameters chosen correspond to a realistic network of school age children. We found that percolation threshold decreases as a power law as the short cut fluctuations increase. We found also the number of infected sites grows exponentially with time and its rate depends logarithmically on the density of susceptibles. This behavior provides an interesting way to estimate the serology for a given population from the measurement of the disease growing rate during an epidemic phase. We have also examined the case in which the infection probability of nearest neighbors is different from that of short cuts. We found a double diffusion behavior with a slower diffusion between the characteristic times.Comment: 12 pages LaTex, 10 eps figures, Phys.Rev.E Vol. 64, 056115 (2001

Open String Star as a Continuous Moyal Product

We establish that the open string star product in the zero momentum sector can be described as a continuous tensor product of mutually commuting two dimensional Moyal star products. Let the continuous variable $\kappa \in [~0,\infty)$ parametrize the eigenvalues of the Neumann matrices; then the noncommutativity parameter is given by $\theta(\kappa) =2\tanh(\pi\kappa/4)$. For each $\kappa$, the Moyal coordinates are a linear combination of even position modes, and the Fourier transform of a linear combination of odd position modes. The commuting coordinate at $\kappa=0$ is identified as the momentum carried by half the string. We discuss the relation to Bars' work, and attempt to write the string field action as a noncommutative field theory.Comment: 30 pages, LaTeX. One reference adde

Star Algebra Spectroscopy

The spectrum of the infinite dimensional Neumann matrices M^{11}, M^{12} and M^{21} in the oscillator construction of the three-string vertex determines key properties of the star product and of wedge and sliver states. We study the spectrum of eigenvalues and eigenvectors of these matrices using the derivation K_1 = L_1 + L_{-1} of the star algebra, which defines a simple infinite matrix commuting with the Neumann matrices. By an exact calculation of the spectrum of K_1, and by consideration of an operator generating wedge states, we are able to find analytic expressions for the eigenvalues and eigenvectors of the Neumann matrices and for the spectral density. The spectrum of M^{11} is continuous in the range [-1/3, 0) with degenerate twist even and twist odd eigenvectors for every eigenvalue except for -1/3.Comment: LaTeX, 30 pages, 2 figure

Siegel Gauge in Vacuum String Field Theory

We study the star algebra of ghost sector in vacuum string field theory (VSFT). We show that the star product of two states in the Siegel gauge is BRST exact if we take the BRST charge to be the one found in hep-th/0108150, and the BRST exact states are nil factors in the star algebra. By introducing a new star product defined on the states in the Siegel gauge, the equation of motion of VSFT is characterized as the projection condition with respect to this new product. We also comment on the comma form of string vertex in the ghost sector.Comment: 13 pages, lanlmac; v3: comment adde

Ghost Kinetic Operator of Vacuum String Field Theory

Using the data of eigenvalues and eigenvectors of Neumann matrices in the 3-string vertex, we prove analytically that the ghost kinetic operator of vacuum string field theory obtained by Hata and Kawano is equal to the ghost operator inserted at the open string midpoint. We also comment on the values of determinants appearing in the norm of sliver state.Comment: 19 pages, 1 figure, lanlmac; v2: typos correcte

The Spectrum of the Neumann Matrix with Zero Modes

We calculate the spectrum of the matrix M' of Neumann coefficients of the Witten vertex, expressed in the oscillator basis including the zero-mode a_0. We find that in addition to the known continuous spectrum inside [-1/3,0) of the matrix M without the zero-modes, there is also an additional eigenvalue inside (0,1). For every eigenvalue, there is a pair of eigenvectors, a twist-even and a twist-odd. We give analytically these eigenvectors as well as the generating function for their components. Also, we have found an interesting critical parameter b_0 = 8 ln 2 on which the forms of the eigenvectors depend.Comment: 25+1 pages, 3 Figures; typos corrected and some comments adde

S matrix of collective field theory

By applying the Lehmann-Symanzik-Zimmermann (LSZ) reduction formalism, we study the S matrix of collective field theory in which fermi energy is larger than the height of potential. We consider the spatially symmetric and antisymmetric boundary conditions. The difference is that S matrices are proportional to momenta of external particles in antisymmetric boundary condition, while they are proportional to energies in symmetric boundary condition. To the order of $g_{st}^2$, we find simple formulas for the S matrix of general potential. As an application, we calculate the S matrix of a case which has been conjectured to describe a "naked singularity".Comment: 19 page, LaTe