July 1997 arXiv papers — page 15

P. Di Vecchia, M. Frau, I. Pesando, S. Sciuto

We show that the boundary state description of a Dp-brane is strictly related to the corresponding classical solution of the low-energy string effective action. By projecting the boundary state on the massless states of the closed string we obtain the tension, the R-R charge and the large distance behavior of the classical solution. We discuss both the case

V. B. Kopeliovich

Semiclassical quantization of the SU(3)-skyrmions is performed by means of the collective coordinate method. The quantization condition known for the SU(2)-solitons quantized with SU(3) collective coordinates is generalized for the SU(3) skyrmions with strangeness content different from zero. Quantization of the dipole-type configuration with large strangene

R. R. Metsaev

Free massless fermionic fields of arbitrary spins $s>0$ corresponding to totally (anti)symmetric tensor-spinor representations of the $SO(d-1)$ compact subgroup and in $d$-dimensional anti-de Sitter space are investigated. We propose the free equations of motion, subsidiary conditions and corresponding gauge transformations for such fields. The equations obt

Maxim Zabzine

We discuss the possibility of generalizing some aspects of the C-theorem within two different approaches, the conventional RG and the Wilson RG flows. We show that the original Zamolodchikov's theorem is related to the existence of the phase transitions in finite temperature QFT. We present some arguments related to the holomorphic property of the low en

Friedemann Brandt, Joaquim Gomis, Joan Simon

We analyse the classical symmetries of bosonic D-string actions and generalizations thereof. Among others, we show that the simplest actions of this type have infinitely many nontrivial rigid symmetries which act nontrivially and nonlinearly both on the target space coordinates and on the U(1) gauge field, and form a Kac-Moody version of the Weyl algebra (=

N. G. Deshpande, B. Dutta

We examine the consequences of leptoquark explanation of HERA anomaly in the context of R parity conserving supersymmetric gauge unified theory with the gauge unification scale at $\sim 10^{16}$ GeV. We pointed out the difficulty of constructing a grandunified theory. However gauge unification is still possible at $\sim 10^{16}$ GeV when additional multiplet

D. H. Lyth, A. Riotto

An inflationary stage dominated by a D-term avoids the slow-roll problem of inflation in supergravity and can naturally emerge in theories with a non-anomalous or anomalous U(1) gauge symmetry. In the latter case, however, the scale of inflation as imposed by the COBE normalization is in contrast with the value fixed by the Green-Schwarz mechanism of anomaly

R. C. Hwa

The scaling behavior of factorial moments of the differences in multiplicities between well separated bins in heavy-ion collisions is proposed as a probe of quark-hadron phase transition. The method takes into account some of the physical features of nuclear collisions that cause some difficulty in the application of the usual method. It is shown in the Ginz

Damir Becirevic

We analyzed two form factors $T_1(q^2)$ and $T_2(q^2)$ which enter the $B\to K^* \ell^+ \ell^-$ decay rate and are accessible in the lattice calculations for $B \to K^* γ$. The extrapolation to $q^2=0$, necessary for $B\to K^* γ$ is examined. The flat behavior of $T_2(q^2)$ is shown to be disfavored. From the double constrained unitarity bounds by the lattic

Janko Binnewies

We present new sets of fragmentation functions in next-to-leading order QCD that are determined from e+e- annihilation data of inclusive particle production. In addition to the O(alpha_s) unpolarized cross section the longitudinal cross section is also used to extract the gluon fragmentation function from e+e- annihilation data. As the O(alpha_s) vanishes fo

Y. N. Srivastava, A. Widom

Recent theoretical claims not withstanding, muons can and do oscillate. Muons produced in association with neutrinos (if masses and mixing angles are nonzero) exhibit a joint oscillating spatial distribution. The possible use of muon oscillations as a probe of neutrino mass and mixing parameters is discussed using very simple physical arguments. Space-time o

Agustin Nieto

Effective field theory methods provide a convenient approach to study static observables in field theory at finite temperature. In this talk, I will outline the construction of the effective field theory that describes effective observables in QCD at high temperature. An analysis of the convergence of the perturbative series for the free energy of QCD will a

G. Piller, G. Niesler, W. Weise

Shadowing effects in deep-inelastic lepton-nucleus scattering probe the mass spectrum of diffractive leptoproduction from individual nucleons. We explore this relationship using current experimental information on both processes. In recent data from the NMC and E665 collaboration, taken at small x << 0.1 and Q^2 < 1 GeV^2, shadowing is dominated by the diffr

H. G. Dosch, T. Gousset, H. J. Pirner

One of the challenging aspects of electroproduction at high-energy is the understanding of the transition from real photons to virtual photons in the GeV^2 region. We study inclusive electroproduction on the proton at small x_B using a nonperturbative dipole-proton cross section calculated from the gauge invariant gluon field correlators as input. By quark-h

M. Buza, Y. Matiounine, J. Smith, W. L. van Neerven

We examine the charm component F_{2,c}(x,Q^2,m^2) of the proton structure function F_2(x,Q^2) in three different schemes and compare the results with the data in the x and Q^2 region explored by the HERA experiments. Studied are (1) the three flavour number scheme (TFNS) where the production mechanisms are given by the photon-gluon fusion process and the hig

L. P. A. Haakman, O. K. Kancheli, J. H. Koch

We discuss the BFKL equation with a running gauge coupling and identify in its solutions the contributions originating from different transverse momentum scales. We show that for a running coupling constant the distribution of the gluons making up the BFKL Pomeron shifts to smaller transverse momenta so that the dominant part of Pomeron can have a nonperturb

F. M. Renard

We discuss the sensitivity of the processes $e^+e^-\to t\bar t$ and $e^+e^-\to b\bar b$ to special sets of operators describing residual New Physics effects. Experimental data in this sector together with those expected in the bosonic sector should allow to constrain possible New Physics schemes with effective scales in the 10 TeV range.

J. Fujimoto, T. Ishikawa, Y. Kurihara, Y. Shimizu

Using the automatic system GRACE-LOOP, the full $O(α)$ electroweak corrections has been calculated for the process $e^+e^- \to W^+μ\barν_μ$. The total correction to the cross section is found to be typically -6.4% at $\sqrt{s}=190$ GeV with $10^\circ$ cut on the muon angle from the beam, including the correction from the hard photon emission. It is observed

Wolfgang Franzki, John B. Kogut, Maria-Paola Lombardo

We study the interplay between topological observables and chiral and Higgs transitions in lattice scalar QED with quenched fermions. Emphasis is put on the chiral transition line and magnetic monopole percolation at strong gauge coupling. We confirm that at infinite gauge coupling the chiral transition is described by mean field exponents. We find a rich an

Brad Abbott

We have measured the dijet angular distribution in $\sqrt{s}$=1.8 TeV $p\bar{p}$ collisions using the D0 detector. Order $α^{3}_{s}$ QCD predictions are in good agreement with the data. At 95% confidence the data exclude models of quark compositeness in which the contact interaction scale is below 2 TeV.

Mark Hayes

Dijet cross sections from the original 1994 ZEUS data analysis are shown compared to NLO calculations. New 1995 cross sections are shown compared to Monte Carlo predictions. The fraction of dijet events with a rapidity gap inbetween the jets is also presented for the new 1995 data.

Sujan Sengupta

Trajectories of charged particle in combined poloidal, toroidal magnetic field and rotation-induced unipolar electric field superposed in Schwarzschild background geometry have been investigated extensively in the context of accreting black holes. The main purpose of the paper is to obtain a reasonably well insight on the effect of spacetime curvature to the

Chuu-Lian Terng, Karen Uhlenbeck

Conservation laws, heirarchies, scattering theory and Bäcklund transformations are known to be the building blocks of integrable partial differential equations. We identify these as facets of a theory of Poisson group actions, and apply the theory to the ZS-AKNS nxn heirarchy (which includes the non-linear Schrödinger equation, modified KdV, and the n-wave e

Akhil Ranjan

In this paper we give a generalisation of the Radius Rigidity theorem of F.Wilhelm. This is done by showing that if a Riemannian submersion of $S^{15}$ with 7-dimensional fibres has at least one fibre which is a great sphere then all the fibres are so. Some weaker than known conditions which force the existence of such a fibre are also discussed.

P. Simon

In this paper we consider the $J_1-J_2-J_3$ classical and quantum 2D XY model. Spin wave calculations show that a spin liquid phase still exists in the quantum case as for Heisenberg models. We formulate a semiclassical approach of these models based on spin wave action and use a variational method to study the role played by vortices. Liquid and crystal pha

Nelson A. Alves, J. R. Drugowich de Felicio, Ulrich H. E. Hansmann

A general numerical method is presented to locate the partition function zeros in the complex beta plane for large lattice sizes. We apply this method to the 2D Ising model and results are reported for square lattice sizes up tp L=64. We also propose an alternative method to evaluate corrections to scaling which relies only on the leading zeros. This method

I. T. Drummond, R. R. Horgan, C. A. da Silva Santos

We study the long-range effective drift and diffusivity of a particle in a random medium moving subject to a given molecular diffusivity and a local drift. The local drift models the effect of a random electrostatic field on a neutral but polarizable molecule. Although the electrostatic field is assumed to obey Gaussian statistics the induced statistics of t

Diptiman Sen, B. Sriram Shastry

We study a rotation invariant Majorana fermion model in one dimension using diagrammatic perturbation theory and numerical diagonalization of small systems. The model is inspired by a Majorana representation of the antiferromagnetic spin-1/2 chain, and it is similar in form to the t-J model of electrons, except that the Majorana fermions carry spin-1 and Z_2

R. Berkovits, Y. Avishai

The concept of localization in Fock space is extended to the study of the many particle excitation statistics of interacting electrons in a two dimensional quantum dot. In addition, a finite size scaling hypothesis for Fock space localization, in which the excitation energy replaces the system size, is developed and tested by analyzing the spectral propertie

Kicheon Kang, Min-Chul Cha, S. -R. Eric Yang

A linearly coupled chain of spin-polarized quantum dots is investigated under the condition that the number of electrons is equal to or less than the number of the dots. The chemical potential of the system, $μ_{N}=E(N)-E(N-1)$, satisfies, $(μ_{N}+μ_{N_{\ell}+2-N)}/2 \approx V+2t (N, N_{\ell}, V, E(N)$ and $t$ are the number of electrons, the number of dots,

Alban L. Fauchere, Gianni Blatter

We study the magnetic response of a clean normal-metal slab of finite thickness in proximity with a bulk superconductor. We determine its free energy and identify two (meta-)stable states, a diamagnetic one where the applied field is effectively screened, and a second state, where the field penetrates the normal-metal layer. We present a complete characteriz

Martin van Hecke

We obtain a family of uniformly propagating hole-solutions to the complex Ginzburg-Landau equation which differ from the well-known Nozaki-Bekki holes. They describe the spatial organization and velocity of the dominant local structures in the spatiotemporal intermittent regime. We discuss the phenomenology of these intermittent states in terms of the proper

E. J. Bakker

In this paper we discuss the relevance of, and possible scientific gains which can be acquired from studying circumstellar molecular spectra toward evolved stars. Where can we expect circumstellar molecular spectra, why would we want to study these spectra, which molecules might be present, and what can we learn from these studies? We present an overview of

Melinda L. Weil, Jonathan Bland-Hawthorn, David F. Malin

In a new survey of nearby galaxies from stacked photographic images, M87 shows a diffuse fan of stellar material which extends along the projected SE (major) axis out to about 100 kpc at a limiting (B) surface brightness of $28 \hbox{mag arcsec}^{-2}$. We suggest that disruption of a small spheroidal galaxy within a larger potential is the most likely explan

F. M. Walter, F. J. Vrba, S. J. Wolk, R. D. Mathieu

We report on optical identifications of X-ray sources in the vicinity of the R~CrA association. We identify 11 low-mass pre-main-sequence stars as counterparts of 9 X-ray sources. We also find X-ray emission from coordinates consistent with the position of 3 bright late-B stars, although the emission may come from lower mass companions. The X-ray-selected st

C. S. Reynolds, A. C. Fabian

The broad iron K$α$ emission line, commonly seen in the X-ray spectrum of Seyfert nuclei, is thought to originate when the inner accretion disk is illuminated by an active disk-corona. We show that relative motion between the disk and the X-ray emitting material can have an important influence on the observed equivalent width (EW) of this line via special re

A. Franceschini, H. Aussel, A. Bressan, C. J. Cesarsky

Our present understanding of the extragalactic source counts and background radiation at infrared and sub-mm wavelengths is reviewed. Available count data are used to constrain evolutionary models of galaxies and Active Nuclei. The CIRB, on the other hand, provides crucial information on the integrated past IR emissivity, including sources so faint to be nev

Paola Grandi, R. M. Sambruna, L. Maraschi, G. Matt

We present simultaneous observations of the superluminal radio galaxy 3C120 performed with the ASCA and GRO (OSSE) satellites on February-March 1994, as well as an analysis of all the ROSAT archival data. The ASCA spectrum of this object can be described by an absorbed (N_H=1.6e^21 cm^-2) power law with photon index Gamma_ASCA=2 and a very broad sigma>0.8 ke

Gian Luigi Granato, Laura Silva, Lugi Danese, Alessandro Bressan

We present the first results of a detailed modeling of chemical and photometric evolution of galaxies including the effects of a dusty interstellar medium. A chemical evolution code follows the SF rate, the gas fraction and the metallicity, basic ingredients for the stellar population synthesis. The latter is performed with a grid of integrated spectra for S

G. Marconi, D. Hamilton, M. Tosi, A. Bragaglia

UBGVRI photometry for the open cluster NGC 2506 is presented. From comparison of the observed colour-magnitude diagrams with simulations based on stellar evolutionary models we derive in a self consistent way reddening, distance, and age of the cluster: E(B-V)=0-0.07, (m-M)o = 12.6, age = 1.5-2.2 Gyr. The cluster shows a well definite secondary sequence, sug

L. Pietronero, F. Sylos Labini, M. Montuori

In the last years there has been a growing interest in the understanding a vast variety of scale invariant and critical phenomena occurring in nature. Experiments and observations indeed suggest that many physical systems develop spontaneously correlations with power law behaviour both in space and time. Pattern formation, aggregation phenomena, biological s

R. de Grijs, R. F. Peletier, P. C. van der Kruit

We present a detailed study of a statistically complete sample of highly inclined disk galaxies in the near-infrared K&#39; band. Since the K&#39;-band light is relatively insensitive to contamination by galactic dust, we have been able to follow the vertical light distributions all the way down to the galaxy planes. The mean levels for the sharpness of the

P. Grandi, M. Guainazzi, T. Mineo, A. N. Parmar

We report the results of a 3C273 observation performed during the Science Verification Phase (SVP) of the BeppoSax satellite. The broad-band spectrum is well represented by a power-law between 1 keV and 200 keV. The spectral slope is flat (Γ~1.6) with a weak emission line at ~ 6.4 keV (rest frame) of EW ~ 30 eV. Below 1 keV, a deviation from a power-law due

P. O. Petrucci, G. Henri, J. Malzac, E. Jourdain

We develop a self-consistent model of Seyfert galaxies continuum emission. High energy emission is produced by Inverse Compton process on soft photons emitted as thermal radiation by the accretion disk. Thermal emission is, at turn, entirely due to reprocessing of the impinging high energy photons. The high energy source is assumed to be an optically thin pl

Stefanie Komossa, Henner Fink

An analysis of survey and pointed ROSAT PSPC observations of the Seyfert 1.8 galaxy NGC 3786 has revealed interesting spectral and temporal behaviour. The spectrum is found to show clear signs of excess absorption, and there is evidence that part (or all) of it is caused by the presence of a warm absorber. The soft X-ray spectral properties are discussed in

Fabrizio Brighenti, William G. Mathews

We compare optical and high quality x-ray data for three bright ellipticals in the Virgo cluster, NGC 4472, 4649, and 4636. The distribution of total mass in NGC 4472 and 4649 determined from x-ray data is sensitive to the stellar mass over a considerable range in galactic radius extending to r = r_e, the effective radius. The agreement of x-ray and opticall

Henry C. Ferguson, Thomas M. Brown

The far-ultraviolet is the most rapidly evolving portion of the spectrum in both very young galaxies and very old galaxies. The ``UV upturn'' in the spectra of elliptical galaxies shortward of 2000 Angstroms offers a promising probe of the ages and chemical evolution of very old galaxies. In early-type non-active galaxies with the bluest 1550-V colors, the b

A. P. Young

We study numerically the paramagnetic phase of the spin-1/2 random transverse-field Ising chain, using a mapping to non-interacting fermions. We extend our earlier work, Phys. Rev. 53, 8486 (1996), to finite temperatures and to dynamical properties. Our results are consistent with the idea that there are ``Griffiths-McCoy&#39;&#39; singularities in the param

V. M. Shabaev, M. B. Shabaeva, I. I. Tupitsyn, V. A. Yerokhin

The ground state hyperfine splitting values and the transition probabilities between the hyperfine structure components of high Z lithiumlike ions are calculated in the range $Z=49-83$. The relativistic, nuclear, QED and interelectronic interaction corrections are taken into account. It is found that the Bohr-Weisskopf effect can be eliminated in a combinati

M K Samal

After reviewing the general framework to study EPR-like neutrino oscillations, we derive expressions for the oscillation probabilities and a direct measure of CP violation. We compare the possibility of studying CP violation in this case with that of baseline accelerator experiments and conclude that it is possible to study CP violation in experiments with l

C. P. Burgess, A. de la Macorra, I. Maksymyk, F. Quevedo

We propose a general mechanism for stabilizing the dilaton against runaway to weak coupling. The method is based on features of the effective superpotential which arise for supersymmetric gauge theories which are not asymptotically free. Consideration of the 2PI effective action for bilinear operators of matter and gauge superfields allows one to overcome th

Shardha Jogee, Jeffrey D. P. Kenney, Beverly J. Smith

We show that the starburst-driven outflow in the peculiar galaxy NGC 2782 forms a well-defined collimated bubble which has an extent of $\sim$ 1 kpc and a closed shell at its edge, as seen in H$α$, [O III], and 5 GHz radio continuum. The shell coincides with the maximum in intensity and linewidths of [O III] lines in a blueshifted emission nebula which was p

A. N. Artemyev, V. M. Shabaev, V. A. Yerokhin

Vacuum polarization screening corrections to the ground state energy of two-electron ions are calculated in the range $Z=20-100$. The calculations are carried out for a finite nucleus charge distribution.

J. Barrette

Results are presented of an analysis of proton and charged pion azimuthal distributions measured with respect to the reaction plane in Au + Au collisions at a beam momentum of about 11 AGeV/c. The azimuthal anisotropy is studied as a function of particle rapidity and transverse momentum for different centralities of the collisions. The triple differential (i

P. Desgrolard, J. Kontros, A. I Lengyel, E. S. Martynov

The local nuclear slope $B(s,t) = {d \over d t} (\ln {dσ_n (s,t)\over dt})$ is reconstructed from the experimental angular distributions with a procedure that uses overlapping $t$-bins, for an energy that ranges from the ISR to the $S\bar ppS$ and the Tevatron. Predictions of several models of ($p,p$) and ($\bar p,p$) elastic scattering at high energy are te

C. Ewerz

In this talk I describe recent progress in investigating the high energy limit of perturbative QCD. I review some of the steps that have been done in the direction of constructing an effective field theory for this limit. I describe some of its building blocks and explain why we expect the effective theory to be a 2+1-dimensional conformal field theory.

Charanjit S. Aulakh, Alejandra Melfo, Goran Senjanovic

We construct the truly minimal left-right symmetric model by utilizing only the fields dictated by supersymmetry and automatic R-parity conservation. Allowing for non-renormalizable operators in the superpotential, we show that parity can be spontaneously broken while preserving electromagnetic gauge invariance. The scale of parity breakdown is predicted in

Jorge Vinals, W. W. Mullins

We examine the validity of the hypothesis of self-similarity in systems coarsening under the driving force of interface energy reduction in which three dimensional particles are intersected by a one or two dimensional diffusion matrix. In both cases, solute fluxes onto the surface of the particles, assumed spherical, depend on both particle radius and inter-

S. Conti, R. Nifosi&#39;, M P Tosi

The dynamical, long-wavelength longitudinal and transverse exchange-correlation potentials for a homogeneous electron gas are evaluated in a microscopic model based on an approximate decoupling of the equation of motion for the current-current response function. The transverse spectrum turns out to be very similar to the longitudinal one. We obtain evidence

K. Ismail, J. O. Chu, Dragana Popovic, A. B. Fowler

In a recent Letter, Kravchenko et al. [cond-mat/9608101] have provided evidence for a metal-insulator transition (MIT) in a two-dimensional electron system (2DES) in Si metal-oxide-semiconductor field-effect transistors (MOSFETs). The transition observed in these samples occurs at relatively low electron densities $n_{s}\sim (1-2)\times 10^{11}cm^{-2}$ and h

Takayuki Shirakura, Fumitaka Matsubara

We investigate low temperature properties of a random Ising model with $+J$ and $-aJ (a \neq 1)$ bonds in two dimensions using a cluster heat bath method. It is found that the Binder parameters $g_L$ for different sizes of the lattice come together at almost the same temperature implying the occurrence of the spin glass(SG) phase transition. From results of

J. G. Bartlett, A. Blanchard, D. Barbosa, J. Oukbir

We discuss the implications of two possible, recent Sunyaev-Zel&#39;dovich (SZ) detections for which no optical or X--ray counterparts have been found. This suggests that the objects reside at high redshift, which is difficult to reconcile with a critical cosmology. We develop this argument and find that an open model with $\Omo=0.2$ remains consistent with

Jonathan Bagger, Alexander Galperin

We show that the tensor gauge multiplet of N=1 supersymmetry can serve as the Goldstone multiplet for partially broken rigid N=2 supersymmetry. We exploit a remarkable analogy with the Goldstone-Maxwell multiplet of hep-th/9608177 to find its nonlinear transformation law and its invariant Goldstone action. We demonstrate that the tensor multiplet has two dua

M. R. Rahimi Tabar, S. Rouhani

We consider perturbation of a conformal field theory by a pair of relevant logarithmic operators and calculate the beta function up to two loops. We observe that the beta function can not be derived from a potential. Thus the renormalization group trajectories are not always along decreasing values of the central charge. However there exists a domain of stru

A. Ali, C. Greub

We report a theoretical analysis of the exclusive non-leptonic decays of B mesons into two light mesons,some of which have been measured recently by the CLEO collaboration. Our analysis is carried out in the context of an effective Hamiltonian based on the Standard Model using next-to-leading order perturbative QCD calculations. Using a factorization ansatz

F. Zhou, P. Charlat, B. Spivak, B. Pannetier

We consider the chi_0 dependence of the density of states inside the normal metal of a superconductor - normal metal - superconductor (SNS) junction.Here chi_0 is the phase difference of two superconductors of the junction. It is shown that in the absence of electron-electron interaction the energy dependence of the density of states has a gap which decrease

Bao-An Li, C. M. Ko

Using a relativistic transport (ART) model, we study the stopping power, the formation of superdense hadronic matter as well as the strength of transverse and radial flow in central Au+Au collisions at beam momentum from 2 to 12 GeV/c per nucleon. We find that complete stopping is achieved in the whole beam momentum range. In particular, the proton rapidity

Mathieu Meyer, Elisabeth Werner

Motivated by the Blaschke-Santaló inequality, we define for a convex body K in ${\bf R}^n$ and for $t \in {\bf R}$ the Santaló-regions S(K,t) of K. We investigate properties of these sets and relate them to a concept of Affine Differential Geometry, the affine surface area of K.

Xiangdong Ji, Jonathan Osborne

We show that the one-loop QCD correction to deeply-virtual Compton scattering can be factorized into the finite perturbative contributions and the collinearly-divergent terms, which correspond to the matrix elements of the off-forward parton distributions. As a by-product, we obtain the next-to-leading order coefficient functions in the generalized operator

A. G. Williams, H. B. O&#39;Connell, A. W. Thomas

In this paper we improve and extend a recent analysis which showed that the rho-omega mixing amplitude cannot be unambiguously extracted from the pion electromagnetic form-factor in a model independent way. In particular, we focus on the argument that the extraction is sensitive to the presence of any intrinsic omega_I -> pi pi coupling. Our extended analysi

O. Benhar, S. Fantoni. G. I. Lykasov, N. V. Slavin

We analize semi-inclusive electron-nucleus processes e+A->e&#39;+h+X at moderate Q**2 and energy transfer nu. Our results show that nucleons bound in the nuclear medium are distributed according to a function f_A that reduces to the standard light-cone distribution in the Bjorken limit and exhibits a sizeable Q**2-dependence at lower Q**2, particular Q**2 is

A. Griffin, E. Zaremba

We have recently derived two-fluid hydrodynamic equations for a trapped weakly-interacting Bose gas. In this paper, we use these equations to discuss first and second sound in a uniform Bose gas. These results are shown to agree with the predictions of the usual two-fluid equations of Landau when the thermodynamic functions are evaluated for a weakly-interac

Yasuhiro Hieida, Kouichi Okunishi, Yasuhiro Akutsu

The product-wavefunction renormalization group method, which is a novel numerical renormalization group scheme proposed recently,is applied to one-dimensional quantum spin chains in a magnetic field. We draw the zero-temperature magnetization curve of the spin chains, which excellently agrees with the exact solution in the whole range of the field.

Juan Garcia-Bellido

We propose a new model of inflation based on the soft-breaking of N=2 supersymmetric SU(2) Yang-Mills theory. The advantage of such a model is the fact that we can write an exact expression for the effective scalar potential, including non-perturbative effects, which preserves the analyticity and duality properties of the Seiberg-Witten solution. We find tha

Alain Comtet, Christophe Texier

We consider the scattering by a one-dimensional random potential and derive the probability distribution of the corresponding Wigner time delay. It is shown that the limiting distribution is the same for two different models and coincides with the one predicted by random matrix theory. It is also shown that the corresponding stochastic process is given by an

Yoshinori Gotoh, Tsuneo Uematsu

We investigate the nonlinear realization of spontaneously broken N=2 superconformal symmetry in 4 dimensions. We particularly study Nambu-Goldstone degrees of freedom for the partial breaking of N=2 superconformal symmetry down to N=1 super-Poincar{é} symmetry, where we get the chiral NG multiplet of dilaton and the vector NG multiplet of NG fermion of broke

T. Portengen, J. R. Chapman, V. Nikos Nicopoulos, N. F. Johnson

We investigate the properties of a Skyrmionic exciton consisting of a negatively charged Skyrmion bound to a mobile valence hole. A variational wave function is constructed which has the generalized total momentum P as a good quantum number. It is shown that the Skyrmionic exciton can have a larger binding energy than an ordinary magnetoexciton and should th

Marek Czachor, Marcin Marciniak

The spectrum of a density matrix $ρ(t)$ is conserved by a Lie-Nambu dynamics if $ρ(t)$ is a self-adjoint and Hilbert-Schmidt solution of a nonlinear triple-bracket equation. This generalizes to arbitrary separable (positive- and indefinite-metric) Hilbert spaces the previous result which was valid for finite-dimensional Hilbert spaces.

Lapo Casetti, Raoul Gatto, Michele Modugno

We investigate the dynamics of classical and quantum N-component phi^4 oscillators in the presence of an external field. In the large N limit the effective dynamics is described by two-degree-of-freedom classical Hamiltonian systems. In the classical model we observe chaotic orbits for any value of the external field, while in the quantum case chaos is stron

M. Hernanz, J. Gomez-Gomar, J. Jose, J. Isern

An implicit hydrodynamic code following the explosion of classical novae, from the accretion phase up to the final ejection of the envelope, has been coupled to a MonteCarlo code able to simulate their gamma-ray emission. Carbon-oxygen (CO) and oxygen-neon (ONe) novae have been studied and their gamma-ray spectra have been obtained, as well as the gamma-ray

Yoshiyuki Y. Yamaguchi, Tetsuro Konishi

We introduce a model of Poincaré mappings which represents hierarchical structure of phase spaces for systems with many degrees of freedom. The model yields residence time distribution of power type, hence temporal correlation remains long. The power law behavior is enhanced as the system size increases.

S. Alam, C. Bentley

We treat the interaction of a trapped ion with a standing-wave light field relaxing the previous condition of the trapping ion being on the node of the standing wave. In addition we work to second order in the Lamb-Dicke parameter $η$, the extension to higher orders in $η$ is also indicated. Only a simple transformation to the ``dressed basis&#39;&#39; [subj

A. Barbieri

A new link between tetrahedra and the group SU(2) is pointed out: by associating to each face of a tetrahedron an irreducible unitary SU(2) representation and by imposing that the faces close, the concept of quantum tetrahedron is seen to emerge. The Hilbert space of the quantum tetrahedron is introduced and it is shown that, due to an uncertainty relation,

Dong Pyo Chi, Jinsoo Kim

In this paper, we give a quantum algorithm which solves collision problem in an expected polynomial time. Especially, when the function is two-to-one, we present a quantum algorithm which can find a collision with certainty in a worst-case polynomial time. We also give a quantum algorithm which solves claw problem with certainty in a worst-case polynomial ti

Tomonori Totani

Evolution of the rate density of cosmological gamma-ray bursts (GRBs) is calculated and compared to the BATSE brightness distribution in the context of binary neutron-star mergers as the source of GRBs, taking account of the realistic star formation history in the universe and evolution of compact binary systems. We tried two models of the evolution of cosmi

Mihoko M. Nojiri, Damien M. Pierce, Youichi Yamada

We investigate an important radiative correction to the slepton and chargino production processes. We consider a supersymmetric spectrum with a large splitting between the squark and slepton masses. In this case, in the effective theory below the squark mass threshold, the supersymmetric Slavnov-Taylor identities which enforce the equality of the gauge and g

J. C. Lopez, P. O. Hess, A. Turbiner

Using a single trial function we perform an accurate calculation of the ground state $1σ_g$ of the hydrogenic molecular ion $H^+_2$ in a constant uniform magnetic field ranging $0-10^{13}$ G. We show that this trial function also makes it possible to study the negative parity ground state $1σ_u$. We obtain that over the whole range of magnetic fields studied

Shigeki Matsutani

In this article, I have investigated statistical mechanics of a non-stretched elastica in two dimensional space using path integral method. In the calculation, the MKdV hierarchy naturally appeared as the equations including the temperature fluctuation.I have classified the moduli of the closed elastica in heat bath and summed the Boltzmann weight with the t

S. F Huelga, C. Macchiavello, T. Pellizzari, A. K. Ekert

The optimal precision of frequency measurements in the presence of decoherence is discussed. We analyze different preparations of n two level systems as well as different measurement procedures. We show that standard Ramsey spectroscopy on uncorrelated atoms and optimal measurements on maximally entangled states provide the same resolution. The best resoluti

Stefano Mancini, Paolo Tombesi

We propose the cyclotron state retrieval of an electron trapped in a Penning trap by using different measurement schemes based on suitable modifications of the applied electromagnetic fields and exploiting the axial degree of freedom as a probe. A test for matter-antimatter symmetry of the quantum state is proposed.

Chryssomalis Chryssomalakos

We give a detailed description of the adjoint representation of Drinfeld&#39;s twist element, as well as of its coproduct, for $su_{q}(2)$. We also discuss, as applications, the computation of the universal R-matrix in this representation and the problem of symmetrization of identical-particle states with quantum $su(2)$ symmetry.

Zora Thomova, Pavel Winternitz

The maximal Abelian subalgebras of the Euclidean e(p,0) and pseudoeuclidean e(p,1)Lie algebras are classified into conjugacy classes under the action of the corresponding Lie groups E(p,0) and E(p,1), and also under the conformal groups O(p+1,1) and O(p+1,2), respectively. The results are presented in terms of decomposition theorems. For e(p,0) orthogonally

S. A. Babin, E. V. Podivilov, D. A. Shapiro

The explicit solution is obtained for Raman four-wave mixing $ω_4=ω_1-ω_2+ω_3$ of two strong fields $E_1, E_3$ and two weak fields $E_2, E_4$ in a four-level system with the large Doppler broadening. The resonance of the mixing coefficient vs intensity is found near equal Rabi frequencies of strong fields and interpreted as an intersection of quasi-energy le

M. Effenberger, U. Mosel

We calculate the total photoabsorption cross section and cross sections for inclusive pion and eta photoproduction in nuclei in the energy range from 300 MeV to 1 GeV within the framework of a semi-classical BUU transport model. Besides medium modifications like Fermi motion and Pauli blocking we focus on the collision broadening of the involved resonances.

FOPI Collaboration

The production of charged pions, protons and deuterons has been studied in central collisions of 58Ni on 58Ni at incident beam energies of 1.06, 1.45 and 1.93 AGeV. The dependence of transverse-momentum and rapidity spectra on the beam energy and on the centrality of the collison is presented. It is shown that the scaling of the mean rapidity shift of proton

M. Gyory, Lajos Molnar

The aim of this paper is to solve a linear preserver problem on the function algebra $C(X)$. We show that in case $X$ is a first countable compact Hausdorff space, every linear bijection $ϕ:C(X)\to C(X)$ having the property that $diam(ϕ(f)(X))=diam(f(X))$ $(f\in C(X))$ is of the form \[ ϕ(f)=τ\cdot f\circ φ+t(f)1 \qquad (f\in C(X)) \] where $τ$ is a complex

Ricardo Amorim, Ashok Das

We have constructed the N=1/2 supersymmetric general Abelian model with asymmetric chiral couplings. This leads to a N=1/2 supersymmetrization of the Schwinger model. We show that the supersymmetric general model is plagued with problems of infrared divergence. Only the supersymmetric chiral Schwinger model is free from such problems and is dynamically equiv

Tomasz Maslowski, Marek Wieckowski

We study the similarity renormalization scheme for hamiltonians to the fourth order in perturbation theory using a model hamiltonian for fermions coupled to bosons. We demonstrate that the free finite parts of counterterms can be chosen in such a way that the T-matrix is covariant up to the fourth order and the eigenvalue equation for the physical fermion re

Dhurjati Prasad Datta

The nonadiabatic geometric phase in a time dependent quantum evolution is shown to provide an intrinsic concept of time having dual properties relative to the external time. A nontrivial extension of the ordinary quantum mechanics is thus obtained with interesting scaling laws. A fractal like structure in time is thus revealed.

A. Buonanno, M. Gasperini, C. Ungarelli

We present a class of static, spherically symmetric, non-singular solutions of the tree-level string effective action, truncated to first order in $α&#39;$. In the string frame the solutions approach asymptotically (at $r\to 0$ and $r\to \infty$) two different anti-de Sitter configurations, thus interpolating between two maximally symmetric states of differe