January 2004 arXiv papers — page 22

C. Vogt, K. Dolag, T. A. Ensslin

We proposed a new method -- "Pacman" -- to calculate Faraday rotation measure (RM) maps from multi-frequency polarisation angle data (Dolag et al.) in order to avoid the so-called n-pi ambiguity. Here, we apply our "Pacman" algorithm to two polarisation data sets of extended radio sources in the Abell 2255 and the Hydra A cluster, and compare

Graham G. Ross, Liliana Velasco-Sevilla, Oscar Vives

We analyse the properties of generic models based on an SU(3) family symmetry providing a full description of quark charged lepton and neutrino masses and mixing angles. We show that a precise fit of the resulting fermion textures is consistent with CP being spontaneously broken in the flavour sector. The CP violating phases are determined by the scalar pote

K. Dolag, C. Vogt, T. A. Ensslin

We propose a new method to calculate Faraday rotation measure maps from multi-frequency polarisation angle data. In order to solve the so called n-pi ambiguity problem which arises from the observationally ambiguity of the polarisation angle which is only determined up to additions of +-n*pi, where n is an integer, we suggest using a global scheme. Instead o

Nathan Broaddus

Hempel has shown that the fundamental groups of knot complements are residually finite. This implies that every nontrivial knot must have a finite-sheeted, noncyclic cover. We give an explicit bound, $Φ(c)$, such that if $K$ is a nontrivial knot in the three-sphere with a diagram with $c$ crossings and a particularly simple JSJ decomposition then the complem

Olalla Castro-Alvaredo, Andreas Fring

We compute for various perturbed conformal field theories the vacuum energies by means of the thermodynamic Bethe ansatz. Depending on the infrared and ultraviolet divergencies of the models, governed by the scaling dimensions of the underlying perturbed conformal field theory in the ultraviolet, the vacuum energies exhibit different types of characteristics

Yungui Gong

The recent observations support that our universe is flat and expanding with acceleration. A quintessence model with a general relation between the quintessence potential and the quintessence kinetic energy was proposed to explain the phenomenon. The dark energy potential includes both the hyperbolic and the double exponential potentials. We analyze this mod

Andrew R. Liddle

Constraints on cosmological parameters depend on the set of parameters chosen to define the model which is compared with observational data. I use the Akaike and Bayesian information criteria to carry out cosmological model selection, in order to determine the parameter set providing the preferred fit to the data. Applying the information criteria to the cur

N. Brouzakis, N. Tetradis

We study the universal properties of the phase diagram of QCD near the critical point using the exact renormalization group. For two-flavour QCD and zero quark masses we derive the universal equation of state in the vicinity of the tricritical point. For non-zero quark masses we explain how the universal equation of state of the Ising universality class can

Yu. A. Genenko, S. V. Yampolskii, A. V. Pan

On the basis of exact solutions to the London equation the magnetic moment of a type II superconductor filament surrounded by a soft-magnet environment is calculated and the procedure of extracting the superconductor contribution from magnetic measurements is suggested. Comparison of theoretical results with experiments on MgB_2/Fe wires allows estimation of

Iver Brevik, Shin'ichi Nojiri, Sergei D. Odintsov, Luciano Vanzo

We study the entropy of a FRW universe filled with dark energy (cosmological constant, quintessence or phantom). For general or time-dependent equation of state $p=wρ$ the entropy is expressed in terms of energy, Casimir energy, and $w$. The correspondent expression reminds one about 2d CFT entropy only for conformal matter. At the same time, the cosmologica

Thomas H. Loftus, Tetsuya Ido, Andrew D. Ludlow, Martin M. Boyd

We present an extensive study of the unique thermal and mechanical dynamics for narrow-line cooling on the 1S0 - 3P1 88Sr transition. For negative detuning, trap dynamics reveal a transition from the semiclassical regime to the photon-recoil-dominated quantum regime, yielding an absolute minima in the equilibrium temperature below the single-photon recoil li

P. Keranen, J. Maalampi, M. Myyrylainen, J. Riittinen

We consider the possibility that there exist sterile neutrinos which are closely degenerate in mass with the active neutrinos and mixed with them. We investigate the effects of this kind of active-sterile neutrino mixing on the composition of supernova neutrino flux at the Earth. If an adiabatic MSW-transition between active and sterile neutrinos takes place

Jean-Michel Delhotel

Is quantum mechanics about 'states'? Or is it basically another kind of probability theory? It is argued that the elementary formalism of quantum mechanics operates as a well-justified alternative to 'classical' instantiations of a probability calculus. Its providing a general framework for prediction accounts for its distinctive traits, whic

M. Negrello, M. Magliocchetti, L. Moscardini, G. De Zotti

We present detailed predictions for the confusion noise due to extragalactic sources in the far-IR/(sub)-millimeter channels of ESA/ISO, NASA/Spitzer, ESA/Herschel and ESA/Planck satellites, including the contribution from clustering of unresolved SCUBA galaxies. Clustering is found to increase the confusion noise, compared to the case of purely Poisson fluc

Silvio M. Duarte Queiros, Constantino Tsallis

Engle's ARCH algorithm is a generator of stochastic time series for financial returns (and similar quantities) characterized by a time-dependent variance. It involves a memory parameter $b$ ($b=0$ corresponds to {\it no memory}), and the noise is currently chosen to be Gaussian. We assume here a generalized noise, namely $q_n$-Gaussian, characterized by

Giovanni Landi, Fedele Lizzi, Richard J. Szabo

We construct an approximation to field theories on the noncommutative torus based on soliton projections and partial isometries which together form a matrix algebra of functions on the sum of two circles. The matrix quantum mechanics is applied to the perturbative dynamics of scalar field theory, to tachyon dynamics in string field theory, and to the Hamilto

Agnieszka Bieniek

The pi omega rho coupling constant is calculated in a relativistic hadronic framework incorporating nucleons and Delta(1232) isobars. Medium modifications are included. The vertex is analyzed in context of the omega to pi e+e- and rho to pi e+e- Dalitz decays in nuclear matter. A sizeable increase of the widths for these decays is found for invariant mass of

M. Gmitra, D. Horvath

We present iterative Monte Carlo algorithm for which the temperature variable is attracted by a critical point. The algorithm combines techniques of single histogram reweighting and linear filtering. The 2d Ising model of ferromagnet is studied numerically as an illustration. In that case, the iterations uncovered stationary regime with invariant probability

Roberto Percacci, Daniele Perini

We clarify a point concerning the ultraviolet behaviour of the Quantum Field Theory of gravity, under the assumption of the existence of an ultraviolet Fixed Point. We explain why Newton's constant should to scale like the inverse of the square of the cutoff, even though it is technically inessential. As a consequence of this behaviour, the existence of

S. Cortiglioni, G. Bernardi, E. Carretti, L. Casarini

SPOrt is an ASI-funded experiment specifically designed to measure the sky polarization at 22, 32 and 90 GHz, which was selected in 1997 by ESA to be flown on the International Space Station. Starting in 2006 and for at least 18 months, it will be taking direct and simultaneous measurements of the Stokes parameters Q and U at 660 sky pixels, with FWHM=7 degr

ZEUS Collaboration

A search for physics beyond the Standard Model has been performed with high-Q^2 neutral current deep inelastic scattering events recorded with the ZEUS detector at HERA. Two data sets, e^+ p \to e^+ X and e^- p \to e^- X, with respective integrated luminosities of 112 pb^-1 and 16 pb^-1, were analyzed. The data reach Q^2 values as high as 40000 GeV^2. No sig

Hui Zhai, Qi Zhou, Rong Lv, Lee Chang

In this paper we systematically study the double layer vortex lattice model, which is proposed to illustrate the interplay between the physics of a fast rotating Bose-Einstein condensate and the macroscopic quantum tunnelling. The phase diagram of the system is obtained. We find that under certain conditions the system will exhibit one novel phase transition

Matthias Jamin, Jose Antonio Oller, Antonio Pich

Employing results from a recent determination of the scalar KPi form factor F_0^KPi within a coupled channel dispersion relation analysis \cite{JOP01}, in this work we calculate the slope and curvature of F_0^KPi(t) at zero momentum transfer. Knowledge of the slope and curvature of the scalar KPi form factor, together with a recently calculated expression fo

Gino Isidori

We present a concise theoretical overview of radiative and rare B decays mediated by flavour-changing neutral-current transitions of the type b->s(d)gamma and b->s(d)l+l-.

J. Farihi

The discovery of a low luminosity common proper motion companion to the white dwarf GD392 at a wide separation of $46''$ is reported. $BVRI$ photometry suggests a low temperature ($T_{\rm eff}\sim4000$ K) while $JHK$ data strongly indicate suppressed flux at all near infrared wavelengths. Thus, GD392B is one of the few white dwarfs to show significan

Charles Favre, Mattias Jonsson

We show that valuations on the ring R of holomorphic germs in dimension 2 may be naturally evaluated on plurisubharmonic functions, giving rise to generalized Lelong numbers in the sense of Demailly. Any plurisubharmonic function thus defines a real-valued function on the set V of valuations on R and--by way of a natural Laplace operator defined in terms of

V. Sunil Kumar, Biswanath Layek, Soma Sanyal, Ajit M. Srivastava

Formation of topological objects during phase transitions has been discussed extensively in literature. In all these discussions defects and anti-defects form with equal probabilities. In contrast, many physical situations, such as formation of baryons in relativistic heavy-ion collisions at present energies, flux tube formation in superconductors in the pre

O. Kiriyama

The stability of color-flavor locked (CFL) strangelets is studied in the three-flavor Nambu--Jona-Lasinio model. We consider all quark flavors to be massless, for simplicity. By making use of the multiple reflection expansion, we explicitly take into account finite size effects and formulate the thermodynamic potential for CFL strangelets. We find that the C

S. I. Nam, A. Hosaka, H. -Ch. Kim

We compute cross sections of $Θ^+$ production near threshold for a polarized proton reaction, $\vec p \vec p \to Σ^+ Θ^+$ which was recently proposed to determine unambiguously the parity of $Θ^+$. Within theoretical uncertainties cross sections for the allowed spin configuration are estimated; it is of order of one microbarn for the positive parity $Θ^+$ an

Fumihiko Sugino

We construct super Yang-Mills theories with ${\cal N}=2, 4$ supersymmetries on the two-dimensional square lattice keeping one or two supercharges exactly. Along the same line as the previous paper \cite{sugino}, the construction is based on topological field theory formulation. In order to resolve the problem of degenerate classical vacua encountered in the

Y. Tsue, H. Akaike

With the aim of the extension of the TDHF theory in the canonical form in the Lipkin model, the trial state for the variation is constructed, which is an extension of the Slater determinant. The canonicity condition is imposed to formulate the variational approach in the canonical form. A possible solution of the canonicity condition is given and the zero-po

Masatoshi Kokubu, Wayne Rossman, Kentaro Saji, Masaaki Umehara

It is well-known that the unit cotangent bundle of any Riemannian manifold has a canonical contact structure. A surface in a Riemannian 3-manifold is called a (wave) front if it is the projection of a Legendrian immersion into the unit cotangent bundle. We shall give easily-computable criteria for a singular point on a front to be a cuspidal edge or a swallo

Christopher M. Dawson, Michael A. Nielsen

Entanglement in the ground state of a many-body quantum system may arise when the local terms in the system Hamiltonian fail to commute with the interaction terms in the Hamiltonian. We quantify this phenomenon, demonstrating an analogy between ground-state entanglement and the phenomenon of frustration in spin systems. In particular, we prove that the amoun

G. Kofinas, E. Papantonopoulos

We study the collapse of a homogeneous braneworld dust cloud in the context of the various curvature correction scenarios, namely, the induced-gravity, the Gauss-Bonnet, and the combined induced-gravity and Gauss-Bonnet. In accordance to the Randall-Sundrum model, and contrary to four-dimensional general relativity, we show in all cases that the exterior spa

Yin-Zhong Wu, Wei-Min Zhang, Ming-Rong Shen, Zhen-Ya Li

Using effective-field theory with correlations, we investigate the effects of interfacial pseudo-spin coupling fluctuations on the susceptibility and polarization of ferroelectric superlattices within the framework of transverse Ising model. It is found that the interfacial coupling fluctuations increase the susceptibility in the low temperature region. For

Kristian. L. McDonald, B. H. J. McKellar

The singular see-saw mechanism is a variation of the see-saw mechanism whereby the right-chiral neutrino Majorana mass matrix is singular. Previous works employing the singular see-saw mechanism have assumed a vanishing left-chiral Majorana mass matrix. We study the neutrino spectrum obtained under a singular see-saw mechanism when the left-chiral neutrinos

S. C. Benjamin, S. Bose

It has recently been shown that one can perform quantum computation in a Heisenberg chain in which the interactions are 'always on', provided that one can abruptly tune the Zeeman energies of the individual (pseudo-)spins. Here we provide a more complete analysis of this scheme, including several generalizations. We generalize the interaction to an a

Krunoslav Ljolje, Srecko Botric

Effects of the quadratic interaction term in the real Dirac field theory are considered.

Krunoslav Ljolje, Srecko Botric

Reduction of the self-interaction in the theory of real Dirac field is considered.

Krunoslav Ljolje

The Dirac field is analysed in real domain. A connection with the classical field theory is shown and corresponding relation to the quantum physics.

C. W. J. Beenakker, D. P. DiVincenzo, C. Emary, M. Kindermann

It is known that a quantum computer operating on electron-spin qubits with single-electron Hamiltonians and assisted by single-spin measurements can be simulated efficiently on a classical computer. We show that the exponential speed-up of quantum algorithms is restored if single-charge measurements are added. These enable the construction of a CNOT (control

Anjana Sinha, Geza Levai, Pinaki Roy

A conditionally exactly solvable potential, the supersymmetric partner of the harmonic oscillator is investigated in the PT-symmetric setting. It is shown that a number of properties characterizing shape-invariant and Natanzon-class potentials generated by an imaginary coordinate shift $x-{\rm i}ε$ also hold for this potential outside the Natanzon class.

F. Verstraete, M. A. Martin-Delgado, J. I. Cirac

We prove the existence of gapped quantum Hamiltonians whose ground states exhibit an infinite entanglement length, as opposed to their finite correlation length. Using the concept of entanglement swapping, the localizable entanglement is calculated exactly for valence bond and finitely correlated states, and the existence of the so--called string-order param

F. Popescu

We analyze the formation of polarization-squeezed light in a medium with electronic Kerr nonlinearity. Quantum Stokes parameters are considered and the spectra of their quantum fluctuations are investigated. It is established that the frequency at which the suppression of quantum fluctuations is the greatest can be controlled by adjusting the linear phase di

I. A. Shkrob, M. C. Sauer,, D. Gosztola

Time-resolved transient absorption spectroscopy has been used to study nanosecond and sub-microsecond electron dynamics in aqueous anatase nanoparticles in the presence of hole scavengers: chemisorbed polyols and carbohydrates. These polyhydroxylated compounds are rapidly oxidized by the holes; 50-60% of these holes are scavenged within the duration of 355 n

Ilya A. Shkrob, Myran C. Sauer,

While ionization of some polyatomic molecular liquids (such as water and aliphatic alcohols) yields so-called "solvated electrons" in which the excess electron density is localized in the interstices between the solvent molecules, most organic and inorganic liquids yield radical anions and cations in which the electron and spin densities reside on th

Rui Lian, Robert A. Crowell, Ilya A. Shkrob, David M. Bartels

Picosecond dynamics of hydrated electrons and hydroxyl radicals generated in 200 nm photodissociation of aqueous hydroxide and 400 nm (3-photon) ionization of water in concentrated alkaline solutions were obtained. No deprotonation of hydroxyl radicals was observed on sub-nanosecond time scale, even in 1-10 M KOH solutions. This result is completely at odds

Z. Yin

Numerical and analytical studies of "final states" of two-dimensional (2D) decaying turbulence are reported. The first part of this work is trying to give a definition for final states of 2D decaying turbulence. Although the functional relation of $ω-ψ$ is frequently used as the characterization of those "final states," it is just a sufficien

Cyriaque Genet, Martin P. van Exter, J. P. Woerdman

We present a unifying point of view which allows to understand spectral features reported in recent experiments with two-dimensional arrays of subwavelength holes in metal films. We develop a Fano analysis of the related scattering problem by distinguishing two interfering contributions to the transmission process, namely a non-resonant contribution (direct

Ake Ingerman, Cedric Linder, Delia Marshall

This is a report on a qualitative study of students' learning where a physics computer simulation session is used to supplement lectures on the topic. Drawing on phenomenography as the analytical framework, the students' learning-focuses were analysed. The result is a description of four distinctly different learning-focuses that emerged when the stu

Ake Ingerman, Shirley Booth

With an investigation into how students in a physics Master of science program make sense of their whole first year study experience in one of the years following a programme reform, we try to offer insights and advice to consider when involved in similar changes. We conclude and argue that by trying to support the students' in making sense of their stud

V. A. Kuz'menko

The concept of coherent states in explanation of a nature of nonlinear phenomena in optics will be inevitably replaced by the concept of inequality of forward and reversed transitions.

F. Montani, C. May, H. Müther

Properties of the matter in the inner crust of a neutron star are investigated in a Hartree-Fock plus BCS approximation employing schematic effective forces of the type of the Skyrme forces. Special attention is paid to differences between a homogenous and inhomogeneous description of the matter distribution. For that purpose self-consistent Hartree Fock cal

M. S. Mehta, T. K. Jha, S. K. Patra, Raj K. Gupta

We have investigated the ground-state structures of even-even neutron-deficient isotopes of Hg and Pb nuclei within the framework of a deformed relativistic mean field formalism for a number of commonly used parameter sets, namely NL1, NL3, NL-SH, NL-RA1 and TM1. The ground states of a bunch of Hg and Pb-isotopes towards the proton-dripline are found to be d

P. Arumugam, G. Shanmugam, S . K. Patra

The shape fluctuations due to thermal effects in the giant dipole resonance (GDR) observables are calculated using the exact free energies evaluated at fixed spin and temperature. The results obtained are compared with Landau theory calculations done by parameterizing the free energy. The Landau theory is found to be insufficient when the shell effects are d

H. Akaike, Y. Tsue, S. Nishiyama

It is shown that a variational approach with fermionic squeezed states to many-fermion systems such as pairing model is one of useful methods beyond the usual Hartree-Fock-Bogoliubov approximation. A pairing-type quasi-spin squeezed state is constructed and adopted as a trial state in the variational method. By using this state, quantum fluctuations are take

Roman Lietava, Jan Pisut, Neva Pisutova, Boris Tomasik

We describe a model of jet quenching in nuclear collisions at RHIC energies. In the model, jet quenching is to be caused by the interruption of jet formation by nucleons arriving at the position of jet formation in a time shorter than the jet formation time. Our mechanism predicts suppression of high-pt spectra also in d+Au reactions.

D. V. Shetty, A. S. Botvina, S. J. Yennello, A. Keksis

The isospin properties of primary and secondary fragments produced in multifragmentation of Fe + Ni and Fe + Fe systems with respect to Ni + Ni system are analyzed within the statistical multifragmentation model framework. The reduced neutron and proton densities show an asymmetry in the primary fragments, that is lessened after secondary decay. with increas

Jai Sukhatme

Employing the formalism introduced by Sinai and Yakhot [PRL, 63(18), p. 1962, 1989], we study the probability density functions (pdf's) of decaying passive scalars in periodic domains under the influence of smooth large scale velocity fields. The particular regime we focus on is one where the normalized scalar pdf's attain a self-similar profile in f

Joerg Schumacher

Upper bounds of the Hausdorff volume of scalar gradient field graphs are derived by means of geometric measure theory. The approach reproduces that scalar gradient fields along a mean imposed scalar gradient become space filling for sufficiently high values of Schmidt numbers Sc. The bounds are consistent with findings from recent high-resolution numerical e

M. Marvan

Direct and inverse recursion operator is derived for the vacuum Einstein equations for metrics with two commuting Killing vectors that are orthogonal to a foliation by 2-dimensional leaves.

José R. Salgueiro, Yuri S. Kivshar

We study the properties of linear and nonlinear waveguides induced by optical vortex solitons in both self-defocusing and self-focusing nonlinear media, for the case of a saturable nonlinear response. We demonstrate that the vortex-induced waveguides can guide both fundamental and first-order guided modes which together with the vortex may form, for larger a

Fabian Brau

We obtain, using the Birman-Schwinger method, a series of necessary conditions for the existence of at least one bound state applicable to arbitrary central potentials in the context of nonrelativistic quantum mechanics. These conditions yield a monotonic series of lower limits on the "critical" value of the strength of the potential (for which a fir

Fabian Brau

We obtain, using the Birman-Schwinger method, upper limits on the total number of bound states and on the number of $\ell$-wave bound states of the semirelativistic spinless Salpeter equation. We also obtain a simple condition, in the ultrarelativistic case ($m=0$), for the existence of at least one $\ell$-wave bound states: $C(\ell,p/(p-1))$ $\int_0^{\infty

Fabian Brau, Francesco Calogero

We introduce and investigate the class of central potentials $$V_{\text{CIC}}(g^{2},μ^{2},\ell,R;r)=-\frac{g^{2}}{R^{2}} (\frac{r}{R})^{4\ell} {[ 1+(\frac{1}{2\ell+1}) (\frac{r}{R})^{2\ell+1}]^{2}-1+μ^{2}}^{-2}$$, which possess, in the context of nonrelativistic quantum mechanics, a number of $\ell$-wave bound states given by the ($\ell$-independent !) formu

Fabian Brau, Francesco Calogero

In a recent paper new upper and lower limits were given, in the context of the Schrödinger or Klein-Gordon equations, for the number $N_{0}$ of S-wave bound states possessed by a monotonically nondecreasing central potential vanishing at infinity. In this paper these results are extended to the number $N_{\ell}$ of bound states for the $\ell$-th partial wave

Michel Bauer, Denis Bernard

The aim of these notes is threefold. First, we discuss geometrical aspects of conformal covariance in stochastic Schramm-Loewner evolutions (SLEs). This leads us to introduce new ``dipolar'' SLEs, besides the known chordal, radial or annular SLEs. Second, we review the main features of our approach connecting SLEs to conformal field theories (CFTs).

Benoit Bellet

The main issue of this work consists in extracting one or several finite values for the sum of series involved in perturbation theories. It is supposed to work for all cases in which two physical parameters are involved, and makes thorough use of dimensional arguments concerning these physical quantities. Weak and strong coupling expansions are considered as

Narutaka Ozawa

This is an expository note on non-amenabilty of the Banach algebra B(\ell_p) for p=1,2. These were proved respectively by Connes (p=2) and Read (p=1) via very different methods. We give a single proof which reproves both.

Alexander Kirillov

In this paper, we study $G$-equivariant tensor categories for a finite group $G$. These categories were introduced by Turaev under the name of $G$-crossed categories; the motivating example of such a category is the category of twisted modules over a vertex operator algebra $V$ with a finite group of automorphisms $G$. We discuss the notion of "orbifold

Michael Huber

A Steiner quadruple system of order v is a 3-(v,4,1) design, and will be denoted SQS(v). Using the classification of finite 2-transitive permutation groups all SQS(v) with a flag-transitive automorphism group are completely classified, thus solving the "still open and longstanding problem of classifying all flag-transitive 3-(v,k,1) designs" for the

Amparo Gil, Wolfram Koepf, Javier Segura

Algorithms for the computation of the real zeros of hypergeometric functions which are solutions of second order ODEs are described. The algorithms are based on global fixed point iterations which apply to families of functions satisfying first order linear difference differential equations with continuous coefficients. In order to compute the zeros of arbit

David J. Aldous, Gregory Miermont, Jim Pitman

We study the asymptotics of the $p$-mapping model of random mappings on $[n]$ as $n$ gets large, under a large class of asymptotic regimes for the underlying distribution $p$. We encode these random mappings in random walks which are shown to converge to a functional of the exploration process of inhomogeneous random trees, this exploration process being der

Ibrahim Assem, Manuel Saorin

In the category of finitely generated modules over an artinian ring, we classify all the abelian exact subcategories closed under predecessors or, equivalently, all the split torsion pairs with torsion-free class closed under quotients.

Paul-Emile Paradan

This is my Habilitation a Diriger des Recherches (French thing). In this paper I summarize the work I have done to realize the program of Witten called -non abelian localization-. This work deals first with problems of localization in equivariant cohomology. The second part of this paper concerns the Guillemin-Sternberg problem -Quantization commutes with re

Ron M. Adin, Yuval Roichman

Let $T_n$ be the set of 321-avoiding permutations of order $n$. Two properties of $T_n$ are proved: (1) The {\em last descent} and {\em last index minus one} statistics are equidistributed over $T_n$, and also over subsets of permutations whose inverse has an (almost) prescribed descent set. An analogous result holds for Dyck paths. (2) The sign-and-last-des

Meng Chen

Let $X$ be a Gorenstein minimal projective 3-fold with at worst locally factorial terminal singularities. Suppose the canonical map is of fiber type. Denote by $F$ a smooth model of a generic irreducible component in fibers of the canonical map of $X$ and so $F$ is a smooth curve or a smooth surface. The main result of the paper is that there is a computable

G. A. Alekseev, M. V. Yurova

The generalized Einstein - Maxwell field equations which arise from a truncated bosonic part of the low - energy string gravity effective action in four dimensions (the so called Einstein-Maxwell - axion - dilaton theory) are considered. The integrable structure of these field equations for D=4 space-times with two commuting isometries is elucidated. We expr

Laurent Freidel, David Louapre

We show how to properly gauge fix all the symmetries of the Ponzano-Regge model for 3D quantum gravity. This amounts to do explicit finite computations for transition amplitudes. We give the construction of the transition amplitudes in the presence of interacting quantum spinning particles. We introduce a notion of operators whose expectation value gives ris

A. E. Milovidov, G. S. Sharov

For the closed relativistic string carrying a pointlike mass the exact solutions of the dynamical equations are obtained and studied. These solutions describe states of the mentioned system moving in Minkowski space and also in the space that is the direct product of Minkowski space and a compact manifold (torus).

Oscar J. C. Dias

We analyze the quantum process in which a cosmic string breaks in an anti-de Sitter (AdS) background, and a pair of charged or neutral black holes is produced at the ends of the strings. The energy to materialize and accelerate the pair comes from the strings tension. In an AdS background this is the only study done in the process of production of a pair of

Junya Kato

The recent investigations of pure Landau gauge SU(3) Yang-Mills theories which are based on the truncated Schwinger-Dyson equations (SDE) indicate an infrared power law behavior of the gluon and the ghost propagators. It has been shown that the gluon propagator vanishes (or finite) in the infrared limit, while the ghost propagator is more singular than a mas

Sumit R. Das

In the matrix model formulation of two dimensional noncritical string theory, a D0 brane is identified with a single eigenvalue excitation. In terms of open string quantities (i.e fermionic eigenvalues) the classical limit of a macroscopically large number of D0 branes has a smooth classical limit : they are described by a filled region of phase space whose

Rui F. L. Matos

The fibre bundle formalism inherent to the construction of non-abelian Kaluza-Klein theories is presented and its associated dimensional reduction process analysed: is performed the dimensional reduction of G-invariant matter and gauge fields over a multidimensional universe; the harmonic decomposition of non-symmetric fields over its internal space establis

Alexander Burinskii

We show that the frame of the Kerr spinning particle consists of two topologically coupled strings. One of them is the Kerr singular ring representing a string with an orientifold world-sheet. It has electromagnetic excitations (traveling waves), which corresponds to the old model of the Kerr's microgeon. The excitations induce the appearance of the extr

John Son

We consider the RNS superstrings in $AdS_3 \times S^3 \times {\cal M}$, where $\cal M$ may be $K3$ or $T^4$, based on $SL(2,R)$ and SU(2) WZW models. We construct the physical states and calculate the spectrum. A subsector of this theory describes strings propagating in the six dimensional plane wave obtained by the Penrose limit of $AdS_3 \times S^3 \times

A. E. Shabad

It is pointed, that effects of refraction of electromagnetic radiation in the medium, formed by the magnetized vacuum, become essential already for relatively soft photons, not hard enough to create an electron-positron pair, including those belonging to soft gamma-, X-ray, optic and radio- range, if the magnetic field B exceeds the critical value of Bcr=m^2

Martijn Wijnholt

In this paper we consider a somewhat unconventional approach for deriving worldvolume theories for D3 branes probing Calabi-Yau singularities. The strategy consists of extrapolating the calculation of F-terms to the large volume limit. This method circumvents the inherent limitations of more traditional approaches used for orbifold and toric singularities. W

A. M. Gavrilik

Treating the issue of hadron masses and mass relations by the use of quantum groups U_q(su_n) taken as hadron flavor symmetries suggests, at least in the case of baryons, a direct connection of the deformation parameter q with the Cabibbo angle. We discuss possible manifestations of the Cabibbo mixing implied by such connection, including unusual ones.

Gianni Fiorentini, Marcello Lissia, Fabio Mantovani, Riccardo Vannucci

In preparation to the experimental results which will be available in the future, we consider geo-neutrino production in greater detail than in [F. Mantovani et al., arXiv:hep-ph/0309013], putting the basis for a more refined model. We study geo-neutrino production for different models of matter circulation and composition in the mantle. By using global mass

Ralf Lehnert

The modified Dirac equation in the Lorentz-violating Standard-Model Extension (SME) is considered. Within this framework, the construction of a hermitian Hamiltonian to all orders in the Lorentz-breaking parameters is investigated, discrete symmetries and the first-order roots of the dispersion relation are determined, and various properties of the eigenspin

F. Buccella, P. Sorba

A general study of pentaquarks built with four quarks in a L=1 state and an antiquark in S-wave shows that several of such states are forbidden by a selection rule, which holds in the limit of flavour symmetry, to decay into a baryon and a meson final state. We identify the most promising \bar{10} multiplet for the classification of the Theta^+ and Xi^{--} p

S. Dubnicka, A. -Z. Dubnickova

It is demonstrated that new JLAB proton polarization data, which are in a rather strong disagreement with the proton electric form factor data in the space-like region obtained by Rosenbluth technique, are consistent with all known form factor properties, including also the QCD asymptotics, but they require an existence of a zero (i.e. a diffraction minimum)

V. A. Khoze, A. D. Martin, M. G. Ryskin

We study the central diffractive production of the (three neutral) Higgs bosons, with a rapidity gap on either side, in an MSSM scenario with CP-violation. We consider the bb-bar and tautau-bar decay for the light H_1 boson and the four b-jet final state for the heavy H_2 and H_3 bosons, and discuss the corresponding backgrounds. A direct indication of the e

Sonny Mantry, Dan Pirjol, Iain W. Stewart

We discuss the soft-collinear effective theory (SCET) and kinematic expansions in B-decays, focusing on recent results for color suppressed B -> D^(*) X decays. In particular we discuss model independent predictions for B^0 -> D^0 pi^0 and B^0 -> D^*0 pi^0, and update the comparison using new experimental data. We show why HQET alone is insufficient to give

S. V. Goloskokov

We discuss the problem of gauge invariance of the vector meson photoproduction at small $x$ within the two-gluon exchange model. It is found that the gauge invariance is fulfilled if one includes the graphs with higher Fock states in the meson wave function. Obtained results are used to estimate the amplitudes with longitudinal and transverse photon and vect

Kamal K. Seth

The latest data for J/psi and psi' leptonic decays, and the latest measurement of the R-parameter are used to show that the present summary values of the branching ratios of the virtual photon mediated hadronic decays of both J/psi and psi' are overestimated. The current best results are B(J/psi -> gamma^{*} -> h) = (13.3 +- 0.3)%, and B(psi' ->

H. G. Fischer, S. Wenig

Recent evidence for pentaquark baryons in the channels $Ξ^-π^-$, $Ξ^-π^+$ and their anti-particles claimed by the NA49 collaboration is critically confronted with the vast amount of existing data on $Ξ$ spectroscopy which was accumulated over the past decades. It is shown that the claim is at least partially inconsistent with these data. In addition two furt

P. Azzurri

Four-fermion productions measured in the LEP2 data are reviewed. The total and differential cross-section yields represent the first clear evidence for the existence of gauge boson self couplings, in support of the non-abelian SU(2)xU(1) structure of the electroweak model, at the percent level.

P. Azzurri

The negative outcome of gaugino searches at LEP has been one of the most disappointing results for fans of supersymmetric models. In the framework of minimal supersymmetric models with GUT unification assumptions, the combined absence of supersymmetry and Higgs signals in the LEP data, sets stringent constraints on the models parameter space, and lower limit