March 1996 arXiv papers

Martin Gremm, Anton Kapustin

We compute the order 1/m_b^3 nonperturbative contributions to the inclusive differential B\to X_c\ell\barνdecay rate. They are parametrized by the expectation values of two local and four nonlocal dimension-six operators. We use our results to estimate part of the theoretical uncertainties in the extraction of matrix elements \barΛand λ_1 from the lepton spe

Girish S. Setlur, Y. C. Chang

We investigate the role played by nonequilibrium dynamical screening in the thermalization of carriers in a simplified two-component two-band model of a semiconductor. The main feature of our approach is the theoretically sound treatment of collisions. We abandon Fermi's Golden rule in favor of a nonequilibrium field theoretic formalism as the former is

S. Majid

We clarify some aspects of quantum group gauge theory and its recent generalisations (by T. Brzezinski and the author) to braided group gauge theory and coalgebra gauge theory. We outline the diagrammatic version of the braided case. We study the bosonisation of any braided group provides as a trivial principal bundle in three ways.

O. K. Vorov, N. Auerbach, V. V. Flambaum

The structure of the collective low-energy $J^π=0^{-}$ (T=0 and T=1) modes is studied for a doubly magic nucleus in a schematic analytic model of RPA. The $0^{-}$ phonon states ($T= 0,1$) lie at energies $E_{T=0}(0^{-}) \alt ω$ and $E_{T=1}(0^{-}) > ω$, where $ω$ is the oscillator frequency. The matrix elements of P-odd and P- and T-odd weak one-body potenti

Richard F. Lebed

The spectrum of baryons containing heavy quarks of one flavor is described in terms of representations of the group SU(2) X SU(6), where the two factor groups refer to spin rotations of the heavy quarks and spin-flavor rotations of the light quarks, respectively. This symmetry has a natural interpretation in the heavy quark limit. We exhibit the decompositio

Hong-Yi Zhou, Chong-Sheng Li, Yu-Ping Kuang

The O(alpha m_t^2/m_W^2) corrections to top quark pair production by gluon-gluon fusion at the LHC are calculated in two-Higgs-doublet models. We find that the correction to the cross-section can exceed about -10% for certain parameter values.

A. M. Tsvelik

The density-density correlation function of the Calogero-Sutherland model is represented as a Fourier transformation of the correlation function of bosonic exponents in the Gaussian model on a curved manifold.

T. Portengen, Th. Ostreich, L. J. Sham

We calculate the linear and nonlinear optical properties of the Falicov-Kimball model for a mixed-valent system within the self-consistent mean-field approximation. Second-harmonic generation can only occur if the mixed-valent state has a built-in coherence between the itinerant d-electrons and the localized f-holes. By contrast, second-harmonic generation c

Harald Totland, Yuri Galperin

A theory of d.c. electric current induced in a quantum channel by a propagating surface acoustic wave (acoustoelectric current) is worked out. The first observation of the acoustoelectric current in such a situation was reported by J. M. Shilton et al., Journ. Phys. C (to be published). The authors observed a very specific behavior of the acoustoelectric cur

Diego Alvarez, Silvio Franz, Felix Ritort

In this paper we propose a short range generalization of the $p$-spin interaction spin-glass model. The model is well suited to test the idea that an entropy collapse is at the bottom-line of the dynamical singularity encountered in structural glasses. The model is studied in three dimensions through Monte Carlo simulations, which put in evidence fragile gla

Michael C. Martin, Laszlo Mihaly

Molecular dynamics calculations and optical spectroscopy measurements of weakly active infrared modes are reported. The results are qualitatively understood in terms of the "motional diminishing" of IR lines, a process analogous to the motional narrowing of a nuclear magnetic resonance (NMR) signal. In molecular solids or liquids where the appropriat

E. Balkovsky, G. Falkovich, I. Kolokolov, V. Lebedev

We consider the tails of probability density functions (PDF) for different characteristics of velocity that satisfies Burgers equation driven by a large-scale force. The saddle-point approximation is employed in the path integral so that the calculation of the PDF tails boils down to finding the special field-force configuration (instanton) that realizes the

A. Anselm, A. Johansen, E. Leader, L. L ukaszuk

The $π^0 γγ$ vertex for virtual photons of squared masses $q_1^2$ and $q_2^2$ plays a vital rôle in several physical processes; for example for $q_1^2<0$, $q_2^2<0$, in the two-photon physics reaction $e^+ e^-\to e^+ e^- π^0$, and for $q_1^2>0$, $q_2^2>0$, in the annihilation process $e^+ e^-\to π^0 l^+ l^-$. It is also of interest because of its link to the

E. Kh. Akhmedov, A. Lanza, S. T. Petcov, D. W. Sciama

A new mechanism of supernova shock revival is proposed, which involves resonant spin--flavor precession of neutrinos with a transition magnetic moment in the magnetic field of the supernova. The mechanism can be operative in supernovae for transition magnetic moments as small as $10^{-14}μ_B$ provided the neutrino mass squared difference is in the range $Δm^

Eric D&#39;Hoker, Yukihiro Mimura, Norisuke Sakai

We analyze the effects of soft supersymmetry breaking terms on N=1 supersymmetric QCD with $N_f$ flavors and color gauge group $SU(N_c)$. The mass squared of some squarks may be negative, as long as vacuum stability is ensured by a simple mass inequality. For $N_f<N_c$, we include the dynamics of the non-perturbative superpotential and use the original (s)qu

J. E. Paschalis, P. I. Porfyriadis

The four dimensional SU(3) WZW model coupled to electromagnetism is treated as a constrained system in the context of Batalin-Fradkin- Vilkovisky formalism. It is shown that this treatment is equivalent to the Faddeev-Jackiw (FJ) approach. It is also shown that the field redefinitions that transform the fields of the model into BRST and $σ$ closed are actual

A. G. Akeroyd

We study the phenomenology of the neutral Higgs sector of a non-SUSY non-minimal Standard Model. Models with more than one Higgs doublet are possible, and may contain neutral Higgs scalars with branching ratios significantly different to those of the Minimal Standard Model Higgs boson. We show how these differences may be exploited at LEP2 in order to distin

Jin Min Yang, Chong Sheng Li

Taking into account the mixing effects between left- and right-handed top-squarks, we calculate the genuine supersymmetric eletroweak correction to top quark production at the Tevatron in the minimal supersymmetric model. The analytic expressions of the corrections to both the parton level cross section and the total hadronic cross section are presented. Som

D. Schütte, Zheng Weihong, C. J. Hamer

The coupled cluster or exp S form of the eigenvalue problem for lattice Hamiltonian QCD (without quarks) is investigated. A new construction prescription is given for the calculation of the relevant coupled cluster matrix elements with respect to an orthogonal and independent loop space basis. The method avoids the explicit introduction of gauge group coupli

Carlo Rovelli

We argue that the statistical entropy relevant for the thermal interactions of a black hole with its surroundings is (the logarithm of) the number of quantum microstates of the hole which are distinguishable from the hole&#39;s exterior, and which correspond to a given hole&#39;s macroscopic configuration. We compute this number explicitly from first princip

I. J. R. Aitchison, N. E. Mavromatos

We provide evidence that the gauge-fermion interaction in multiflavour quantum electrodynamics in $(2 + 1)$-dimensions is responsible for non-fermi liquid behaviour in the infrared, in the sense of leading to the existence of a non-trivial (quasi) fixed point (cross-over) that lies between the trivial fixed point (at infinite momenta) and the region where dy

G. E. Volovik

We discuss the nondissipative Magnus-type force acting on linear defects in Fermi systems, such as Abrikosov vortices in superconductors, singular and continuous vortices in superfluid phases of $^3$He, magnetic vortices and skyrmions in ferromagnets. Spectral flow of fermion zero modes in the vortex core gives an essential contribution to the nondissipative

D. J. Thouless, P. Ao, Q. Niu

We have derived an exact expression for the total nondissipative transverse force acting on a quantized vortex moving in a uniform background. The derivation is valid for neutral boson or fermion superfluids, provided the order parameter is a complex scalar quantity. This force is determined by the one-particle density matrix far away from the vortex core, a

Rajiv R. P. Singh, Joan Adler

We study the two and four dimensional Nishimori multicritical point via high temperature expansions for the $\pm J$ distribution, random-bond, Ising model. In $2d$ we estimate the the critical exponents along the Nishimori line to be $γ=2.37\pm 0.05$, $ν=1.32\pm 0.08$. These, and earlier $3d$ estimates $γ=1.80\pm 0.15$, $ν=0.85\pm 0.08$ are remarkably close

David P. Bennett, Sun Hong Rhie

We show that Earth mass planets orbiting stars in the Galactic disk and bulge can be detected by monitoring microlensed stars in the Galactic bulge. The star and its planet act as a binary lens which generates a lightcurve which can differ substantially from the lightcurve due only to the star itself. We show that the planetary signal remains detectable for

David G. Robertson

This is an overview of the problem of the vacuum in light-cone field theory, stressing its close connection to other puzzles regarding light-cone quantization. I explain the sense in which the light-cone vacuum is ``trivial,&#39;&#39; and describe a way of setting up a quantum field theory on null planes so that it is equivalent to the usual equal-time formu

Daniel Zwanziger

The lattice Coulomb-gauge hamiltonian is derived from the transfer matrix of Wilson&#39;s Euclidean lattice gauge theory, wherein the lattice form of Gauss&#39;s law is satisfied identically. The restriction to a fundamental modular region (no Gribov copies) is implemented in an effective hamiltonian by the addition of a &#34;horizon function&#34; $G$ to the

M. A. Clayton

The massive nonsymmetric gravitational theory is shown to posses a linearisation instability at purely GR field configurations, disallowing the use of the linear approximation in these situations. It is also shown that arbitrarily small antisymmetric sector Cauchy data leads to singular evolution unless an ad hoc condition is imposed on the initial data hype

David Merritt

The standard method of modelling axisymmetric stellar systems begins from the assumption that mass follows light. The gravitational potential is then derived from the luminosity distribution, and a unique two-integral distribution function f(E,Lz) that generates the stellar density in this potential is found. We show that the gravitational potential can inst

Jaume Guasch, Joan Sola

We survey all possible supersymmetric three-body decays of the top quark in the framework of the MSSM and present detailed numerical analyses of the most relevant cases. Although the two-body channels are generally dominant, it is not inconceivable that some or all of our most favourite two-body SUSY candidates could be suppressed. In this event there is sti

Christian Okonek, Andrei Teleman

In this paper we describe the Seiberg-Witten invariants, which have been introduced by Witten, for manifolds with $b_+=1$. In this case the invariants depend on a chamber structure, and there exists a universal wall crossing formula. We take into account the contribution of the 1-homology of the base-manifold. For every Kähler surface with $p_g=0$ and $q$=0,

Masaki Kashiwara, Tetsuji Miwa, Jens-Ulrik H. Petersen, Chong Ming Yung

A general scheme for the wedge construction of q-deformed Fock spaces using the theory of perfect crystals is presented. Let $U_q(\g)$ be a quantum affine algebra. Let $V$ be a finite-dimensional $U&#39;_q(\g)$-module with a perfect crystal base of level~$l$. Let $V_\aff\simeq V\otimes\C[z,z^{-1}]$ be the affinization of $V$, with crystal base $(L_\aff,B_\af

H. C. Rosu, J. Socorro

Using as an illustrative example the p=1 operator-ordered Wheeler-DeWitt equation for a closed, radiation-filled Friedmann-Robertson-Walker universe, we introduce and discuss the supersymmetric double Darboux method in quantum cosmology. A one-parameter family of ``quantum&#39;&#39; universes and the corresponding ``wavefunctions of the universe&#34; for thi

Katrina D. Barron

Huang&#39;s geometric interpretation of vertex operator algebras is extended to a supergeometric interpretation of vertex operator superalgebras. In particular, the geometry of spheres with punctures and local analytic coordinates in terms of exponentials of derivations is extended to the geometry of superspheres with punctures, a given spin structure, and l

Chongying Dong, Haisheng Li, Geoffrey Mason

We give a new, construction-free proof of the associativity of tensor product for modules for rational vertex operator algebras under certain convergence conditions.

Friedrich Knop

We define a family of symmetric and a family of non-symmetric polynomials in terms of vanishing conditions. These families depend on two paramters, q and t. Their main feature is that they consist of non-homogeneous polynomials. The symmetric polynomials form the quantized version of polynomials occuring in the context of generalized Capelli identities. We s

Friedrich Knop

The two variable Kostka functions are the scalar products of the Macdonald polynomials with the Schur polynomials with respect to the scalar product which makes the Hall-Littlewood polynomials pairwise orthogonal. A conjecture of Macdonald states that they are polynomials in q and t with non-negative integral coefficients. We prove that the Kostka functions

T. T. S. Kuo, H. Müther, K. Amir-Azimi-Nili

We study halo nuclei using a two-frequency shell-model approach employing wave functions of two different oscillator constants $\hbarω_{in}$ and $\hbarω_{out}$, the former for the inner orbits and the latter for the halo (outer) orbits. An initial application has been made for the halo nuclei $^6$He and $^6$Li, with $0s_{1/2}$ taken as the inner and ( $0p_{3

M. S. Baouendi, Xiaojun Huang, Linda Preiss Rothschild

In this paper we prove a general result of the ``Hopf lemma&#39;&#39; type for CR mappings, with nonidentically vanishing Jacobians, between real hypersurfaces in C^n with smooth or real analytic boundaries. Applications of this result to finiteness and holomorphic extendibility of such mappings are also given. The novelty here is that we make no assumption

Rajamani Narayanan, Herbert Neuberger

We consider anomaly free combinations of chiral fermions coupled to $U(1)$ gauge fields on a 2D torus first in the continuum and then on the lattice in the overlap formulation. Both in the continuum and on the lattice, when the background consists of sufficiently large constant gauge potentials the action induced by the fermions varies significantly under ce

L. H. Kauffman, H. P. Noyes

We rewrite the 1+1 Dirac equation in light cone coordinates in two significant forms, and solve them exactly using the classical calculus of finite differences. The complex form yields ``Feynman&#39;s Checkerboard&#39;&#39;---a weighted sum over lattice paths. The rational, real form can also be interpreted in terms of bit-strings.

G. Bimonte, G. Lozano

We study the finite temperature symmetry behaviour of O(N_1) \times O(N_2) scalar models on the lattice and we prove that at sufficiently high temperatures and in arbitrary dimensions their full symmetry is always restored or, equivalently, that the phenomenon of Symmetry Non Restoration which, according to lowest order perturbation theory, takes place in th

Omduth Coceal, Wafic A. Sabra, Steven Thomas

The theory of magnetohydrodynamics is extended to the cases of a plasma of separate magnetic and electric charges, as well as to a plasma of dyons respectively. In both these cases the system possesses electric-magnetic duality symmetry. In the former case we find that because of the existence of two independent generalized Ohm&#39;s law equations, the limit

Artemio Gonzalez-Lopez, Rafael Hernandez Heredero, Gloria Mari Beffa

In this paper we find an explicit formula for the most general vector evolution of curves on $RP^{n-1}$ invariant under the projective action of $SL(n,R)$. When this formula is applied to the projectivization of solution curves of scalar Lax operators with periodic coefficients, one obtains a corresponding evolution in the space of such operators. We conject

Chien-Hao Liu

The interest in string Hamiltonian system has recently been rekindled due to its application to target-space duality. In this article, we explore another direction it motivates. In Sec.\ 1, conformal symmetry and some algebraic structures of the system that are related to interacting strings are discussed. These lead one naturally to the study of Lorentz sur

Chang-Yeong Lee

We study topological Yang-Mills-Higgs theories in two and three dimensions and topological Yang-Mills theory in four dimensions in a unified framework of superconnections. In this framework, we first show that a classical action of topological Yang-Mills type can provide all three classical actions of these theories via appropriate projections. Then we obtai

G. T. Horowitz, D. A. Lowe, J. M. Maldacena

We identify the states in string theory which are responsible for the entropy of near-extremal rotating four-dimensional black holes in $N=8$ supergravity. For black holes far from extremality (with no rotation), the Bekenstein-Hawking entropy is exactly matched by a mysterious duality invariant extension of the formulas derived for near-extremal black holes

Mohammad R. Garousi, Robert C. Myers

We derive fully covariant expressions for all two-point scattering amplitudes of two massless closed strings from a Dirichlet $p$-brane. This construction relies on the observation that there is a simple relation between these D-brane amplitudes in type II superstring theory and four-point scattering amplitudes for type I open superstrings. From the two-poin

A. Mondragon, E. Hernandez

We derive closed analytical expressions for the complex Berry phase of an open quantum system in a state which is a superposition of resonant states and evolves irreversibly due to the spontaneous decay of the metastable states. The codimension of an accidental degeneracy of resonances and the geometry of the energy hypersurfaces close to a crossing of reson

Felix M. Lev

We consider restrictions imposed on the electromagnetic and weak current operators by Poincare invariance and show that some assumptions used in deriving the sum rules in deep inelastic scattering (DIS) have no physical ground. In particular there is no ground to neglect the contribution of nonperturbative effects to these operators, even in the Bjorken limi

D. Gomez Dumm

We analyze the phenomenological consequences of assuming spontaneous CP violation in an SU(3) x U(1) model with three Higgs triplets and one sextuplet. After the identification of the relevant physical scalars, we estimate the contributions to the parameters $Δm_K$, $ε$ and $ε&#39;$ coming from the Higgs-fermion couplings.

Andrea Petrelli

In this paper we present a complete next-to-leading order QCD calculation of the $χ_J$ ($^3P_J\; ;J=0,1,2$) hadronic decay width. We include the NLO colour-octet contribution, as defined in the Bodwin, Braaten and Lepage formalism. We extract an estimate of the colour-octet parameter \height\ from the charmonium decay data.

D. Bardin, D. Lehner, A. Leike, T. Riemann

We describe the program package gentle/4fan, which consists of the Fortran codes gentle\_4fan.f, 4fan.f, and gentle\_nc\_qed.f and is devoted to the description of e+ e- annihilation into four fermions. The codes are based on the semi-analytical approach. Initial state QED corrections are taken into account. The program versions, which are described here wer

H. Stremnitzer

Within the context of a viable and economical SUSY preon model, two vector--like families $Q_{L,R} = (U,D,N,E)_{L,R}$ and $Q^\prime_{L,R} = (U^\prime,D^\prime,N^\prime,E^\prime)_{L,R}$ with masses of order 1 TeV, one of which is a doublet of $SU(2)_L$ and the other a doublet of $SU(2)_R$, have been predicted to exist together with the three observed chiral f

C. D. Froggatt, H. B. Nielsen, D. J. Smith

We investigate the possibility of adding a fourth generation of quarks. We also extend the Standard Model gauge group by adding another SU(N) component. In order to cancel the contributions of the fourth generation of quarks to the gauge anomalies we must add a generation of fermions coupling to the SU(N) group. This model has many features similar to the St

S. Aoki, H. Hirose

We investigate a U(1) chiral gauge model in 4+1 dimensions formulated on the lattice via the domain-wall method. We calculate an effective action for smooth background gauge fields at a fermion one loop level. From this calculation we discuss properties of the resulting 4 dimensional theory, such as gauge invariance of 2 point functions, gauge anomalies and

S. Frittelli, C. N. Kozameh, E. T. Newman, C. Rovelli

The null-surface formulation of general relativity -- recently introduced -- provides novel tools for describing the gravitational field, as well as a fresh physical way of viewing it. The new formulation provides ``local&#39;&#39; observables corresponding to the coordinates of points --- which constitute the spacetime manifold --- in a {\em geometrically d

Roberto Go'mez, Pablo Laguna, Philippos Papadopoulos, Jeff Winicour

A Cauchy-characteristic initial value problem for the Einstein-Klein-Gordon system with spherical symmetry is presented. Initial data are specified on the union of a space-like and null hypersurface. The development of the data is obtained with the combination of a constrained Cauchy evolution in the interior domain and a characteristic evolution in the exte

Mustapha Azreg-Ainou, Gérard Clément

We make a systematic investigation of stationary cylindrically symmetric solutions to the five-dimensional Einstein and Einstein-Gauss-Bonnet equations. Apart from the five-dimensional neutral cosmic string metric, we find two new exact solutions which qualify as cosmic strings, one corresponding to an electrically charged cosmic string, the other to an exte

Anton Yu. Alekseev, Anton Z. Malkin

Let $G$ be a simple complex Lie group, $\alg{g}$ be its Lie algebra, $K$ be a maximal compact form of $G$ and $\alg{k}$ be a Lie algebra of $K$. We denote by $X\rightarrow \overline{X}$ the anti-involution of $\alg{g}$ which singles out the compact form $\alg{k}$. Consider the space of flat $\alg{g}$-valued connections on a Riemann sphere with three holes wh

J. J. Palacios, D. Yoshioka, A. H. MacDonald

We consider the charged exciton complexes of an ideal two-dimensional electron-hole system in the limit of strong magnetic fields. A series of charged multiple-exciton states is identified and variational and finite-size exact diagonalization calculations are used to estimate their binding energies. We find that, because of a hidden symmetry, bound states of

G. T. Barkema, S. Flesia

Oriented self-avoiding walks (OSAWs) on a square lattice are studied, with binding energies between steps that are oriented parallel across a face of the lattice. By means of exact enumeration and Monte Carlo simulation, we reconstruct the shape of the partition function and show that this system features a first-order phase transition from a free phase to a

D. Yoshioka, A. H. MacDonald

We develop a theory of edge state transport in separately contacted double-layer quantum Hall systems which are tuned close to the resonance condition for tunneling between the layers. When applied to the case where contact is made to only one layer, the theory gives a quantized Hall resistance and zero longitudinal resistance in both weak and strong inter-l

V. Ferrari, G. Chiappe

We study the effects of correlations on a one dimensional ring threaded by a uniform magnetic flux. In order to describe the interaction between particles, we work in the framework of the U $\infty$ Hubbard and $t$-$J$ models. We focus on the dilute limit. Our results suggest the posibility that the persistent current has an anomalous periodicity $ϕ_{0}/p$,

S. Jain

The nearest-neighbour XY spin glass on a hypercubic lattice in four dimensions is studied by Monte Carlo simulations. A finite- size scaling analysis of the data leads to a finite temperature spin glass transition at $T_c=0.95\pm 0.15$. The critical exponents are estimated to be $ν_{sg}=0.70\pm 0.10$ and η_{sg}=-0.28\pm 0.38$. The results imply that the lowe

T. Raafat, J. P. Hulin, H. J. Herrmann

We report experimental measurements of density waves in granular materials flowing down in a capillary tube. The density wave regime occurs at intermediate flow rates between a low density free fall regime and a high compactness slower flow.

Hiroshi Kontani, M. E. Zhitomirsky, Kazuo Ueda

We present a theoretical model for CaV$_3$O$_7$: the $1/4$-depleted square spin-$1/2$ Heisenberg model which includes both the nearest-neighbor coupling ($J$) and the next-nearest-neighbor coupling ($J&#39;$), where $J$ and $J&#39;$ are antiferromagnetic. Recent experiments of the neutron diffraction by Harashina et.al. report the magnetic ordering at low te

W. Z. Wang, J. Tinka Gammel, A. R. Bishop, M. I. Salkola

We study nonlinear phonon excitations in a one-dimensional quantum nonlinear lattice model using numerical exact diagonalization. We find that multi-phonon bound states exist as eigenstates which are natural counterparts of breather solutions of classical nonlinear systems. In a translationally invariant system, these quantum breather states form particle-li

S. Leseduarte, J. Sellares, A. Travesset

Collective excitations in simple metal systems can be described successfully in terms of a local one-body excitation operator Q, due to the long range nature of the coulomb interaction. For the plasmon modes of a simple-metal slab, momentum expansions of Q are calculated using a variational procedure, equivalent to a restricted RPA calculation. The dispersio

Wm. R. Greenberg, Abraham Klein, Ivalyo Zlatev, C. T. Li

Despite the seminal connection between classical multiply-periodic motion and Heisenberg matrix mechanics and the massive amount of work done on the associated problem of semiclassical (EBK) quantization of bound states, we show that there are, nevertheless, a number of previously unexploited aspects of this relationship that bear on the quantum-classical co

Marko Robnik, Luca Salasnich

We calculate the WKB series for the angular momentum and the non--relativistic 3-dim Kepler problem. This is the first semiclassical treatment of the angular momentum for terms beyond the leading WKB approximation. We explain why the torus quantization (the leading WKB term) of the full problem is exact, even if the individual torus quantization of the angul

M. A. Malkov

The asymptotic travelling wave solution of the KdV-Burgers equation driven by the long scale periodic driver is constructed. The solution represents a shock-train in which the quasi-periodic sequence of dispersive shocks or soliton chains is interspersed by smoothly varying regions. It is shown that the periodic solution which has the spatial driver period u

Anupam Garg

The {\it intrinsic} decoherence from vibrational coupling of the ions in the Cirac-Zoller quantum computer [Phys. Rev. Lett. {\bf 74}, 4091 (1995)] is considered. Starting from a state in which the vibrational modes are at a temperature $T$, and each ion is in a superposition of an excited and a ground state, an adiabatic approximation is used to find the in

Giuliano Giuricin, Dario Fadda, Marino Mezzetti

Using recent high-resolution radio observations of a large sample of Seyfert galaxies (Roy et al. 1994), we analyze the relations between the compact radio core emission and several nuclear and host galaxy properties. Seyfert nuclei hosted in early-type galaxies or in object with nearby companions show stronger radio cores than the norm. Radio core emission

Ethan T. Vishniac, J. Craig Wheeler

We examine the speed of inward traveling cooling fronts in accretion disks. We show that their speed is determined by the rarefaction wave that precedes them and is approximately $α_F c_{F} (H/r)^q$, where $α_F$ is the dimensionless viscosity, $c_{F}$ is the sound speed, $r$ is the radial coordinate, $H$ is the disk thickness, and all quantities are evaluate

Khac Viet Nguyen, Masa-Hiko Saito

We study the problem of $d$-gonality of the modular curve $X_0(N)$. As a result, we can give an upperbound of the level $N$ by means of $d$. This generalizes Ogg&#39;s result on hyperelliptic modular curves ($d = 2$). As a corollary of this result, we prove an analogue of the strong Uniform Boundedness Conjecture for elliptic curves defined over the function

N. Arkani-Hamed, H. -C. Cheng, J. L. Feng, L. J. Hall

Supersymmetric theories with significant lepton flavor violation have $\tilde{e}$ and $\tildeμ$ nearly degenerate. In this case, pair production of $\tilde{e}^+ \tilde{e}^-$ and $\tildeμ^+ \tildeμ^-$ at LEPII and at the Next Linear Collider leads to the phenomenon of slepton oscillations, which is analogous to neutrino oscillations. The reach in $Δm^2$ and $

J. Michael Owen, Jens V. Villumsen

We investigate the properties of hybrid gravitational/hydrodynamical simulations, examining both the numerics and the general physical properties of gravitationally driven, hierarchical collapse in a mixed baryonic/dark matter fluid. We demonstrate that, under certain restrictions, such simulations converge with increasing resolution to a consistent solution

Lev Vaidman, Lior Goldenberg, Stephen Wiesner

It is shown that a simplified version of the error correction code recently suggested by Shor exhibits manifestation of the quantum Zeno effect. Thus, under certain conditions, protection of an unknown quantum state is achieved. Error prevention procedures based on four-particle and two-particle encoding are proposed and it is argued that they have feasible

V. Moretti

Photons and thermal photons are studied in the Rindler Wedge employing Feynman&#39;s gauge and canonical quantization. A Gupta-Bleuler-like formalism is explicitly implemented. Non thermal Wightman functions and related (Euclidean and Lorentzian) Green functions are explicitly calculated and their complex time analytic structure is analyzed using the Fulling

Rafael Ferraro, Daniel M. Sforza

The BRST generator is realized as a Hermitian nilpotent operator for a finite-dimensional gauge system featuring a quadratic super-Hamiltonian and linear supermomentum constraints. As a result, the emerging ordering for the Hamiltonian constraint is not trivial, because the potential must enter the kinetic term in order to obtain a quantization invariant und

Dmitri Sorokin, Francesco Toppan

It is shown that an alternative supersymmetric version of the Liouville equation extracted from D=3 Green-Schwarz superstring equations naturally arises as a super-Toda model obtained from a properly constrained supersymmetric WZNW theory based on the $sl(2, R)$ algebra. Hamiltonian reduction is performed by imposing a nonlinear superfield constraint which t

H. Dorn, H. -J. Otto

We discuss T-duality for open strings in general background fields both in the functional integral formulation as well as in the language of canonical transformations. The Dirichlet boundary condition in the dual theory has to be treated as a constraint on the functional integration. Furthermore, we give meaning to the notion of matrix valued string end poin

S. Ciechanowicz, Z. Oziewicz, N. Popov

The characteristics of the partial nuclear muon capture with massive left-handed Dirac neutrino and relativistic component of the muon wave function have been derived. The multipole amplitudes are given as a function of neutrino mass parameter and reduced nuclear matrix elements which are modified by the small component of the muon wave function. As an examp

P. Mitra

Major developments in the history of the subject are critically reviewed in this talk.

S. Sakoda, M. Omote

The scattering problem under the influence of the Aharonov-Bohm (AB) potential is reconsidered. By solving the Lippmann-Schwinger (LS) equation we obtain the wave function of the scattering state in this system. In spite of working with a plane wave as an incident wave we obtain the same wave function as was given by Aharonov and Bohm. Another method to solv

B. Sriram Shastry, Diptiman Sen

We study the 1-dimensional Heisenberg antiferromagnet with s=1/2 using a Majorana representation of the s=1/2 spins. A simple Hartree-Fock approximation of the resulting model gives a bilinear fermionic description of the model. This description is rotationally invariant and gives power-law correlations in the ``ground state&#39;&#39; in a natural fashion. T

Stephen D. J. Gwyn, F. D. A. Hartwick

Photometric redshifts have been determined for the galaxies in the Hubble Deep Field. The resulting redshift distribution shows two peaks: one at z~0.6 and one at z~2.2. Luminosity functions derived from the redshifts show strong luminosity evolution as a function of redshift. This evolution is consistent with the Babul & Rees (1992) scenario wherein massive

T. Opatrny, D. -G. Welsch, W. Vogel

A new method is described for determining the quantum correlations at different times in optical pulses by using balanced homodyne detection. The signal pulse and sequences of ultrashort test pulses are superimposed, where for chosen distances between the test pulses their relative phases and intensities are varied from measurement to measurement. The correl

Daniel Henry Gottlieb

We study the &#34;Lie Algebra&#34; of the group of Gauge Transformations of Space-time. We obtain topological invariants arising from this Lie Algebra. Our methods give us fresh mathematical points of view on Lorentz Transformations, orientation conventions, the Doppler shift, Pauli matrices , Electro-Magnetic Duality Rotation, Poynting vectors, and the Ener

M. Gyulassy, V. Topor Pop, X. N. Wang

The Comment of Gazdzicki and Heinz is flawed because their assumed baryon stopping power in $pA$ is inconsistent with data and because they ignored half the analysis based on the VENUS model. The Comment continues the misleading presentation of strangeness enhancement by focusing on ratios of integrated yields. Those ratios discard essential experimental inf

T. Hatsuda, H. Shiomi, H. Kuwabara

We summarize the current theoretical and experimental status of the spectral changes of vector mesons ($ρ$, $ω$, $ϕ$) in nuclear medium. Various approaches including QCD sum rules, effective theory of hadrons and bag models show decreasing of the vector meson masses in nuclear matter. Possibility to detect the mass shift through lepton pairs in $γ-A$, $p-A$

Boris Apanasov

The paper sketches a recent progress and formulates several open problems in studying equivariant quasiconformal and quasisymmetric homeomorphisms in negatively curved spaces as well as geometry and topology of noncompact geometrically finite negatively curved manifolds and their boundaries at infinity having Carnot--Carathéodory structures. Especially, the

Anthony Gaglione, Dennis Spellman

Sacerdote [Sa] has shown that the non-Abelian free groups satisfy precisely the same universal-existential sentences Th(F$_2$)$\cap \forall \exists $ in a first-order language L$_o$ appropriate for group theory. It is shown that in every model of Th(F$_2$)$\cap \forall \exists $ the maximal Abelian subgroups are elementarily equivalent to locally cyclic grou

B. de Wit

We study the symplectic reparametrizations that are possible for theories of N=2 supersymmetric vector multiplets in the presence of a chiral background and discuss some of their consequences. One of them concerns an anomaly arising from a conflict between symplectic covariance and holomorphy.

Jonathan M. Evans, Timothy J. Hollowood

The complete spectrum of states in the supersymmetric principal chiral model based on SU(n) is conjectured, and an exact factorizable S-matrix is proposed to describe scattering amongst these states. The SU(n)_L*SU(n)_R symmetry of the lagrangian is manifest in the S-matrix construction. The supersymmetries, on the other hand, are incorporated in the guise o

S. P. Gavrilov, D. M. Gitman

On the example of the quantized spinor field, interacting with arbitrary external electromagnetic field, the commutation function is studied. It is shown that a proper time representation is available in any dimensions. Using it, all the light cone singularities of the function are found explicitly, generalizing the Fock formula in four dimensions, and a pat

Chan Hong-Mo, Jacqueline Faridani, Jakov Pfaudler, Tsou Sheung Tsun

Dual Feynman rules for Dirac monopoles in Yang-Mills fields are obtained by the Wu-Yang (1976) criterion in which dynamics result as a consequence of the constraint defining the monopole as a topological obstruction in the field. The usual path-integral approach is adopted, but using loop space variables of the type introduced by Polyakov (1980). An anti-sym

F. Aldabe

As shown by Hořava and Witten, there are gravitational anomalies at the boundaries of $M^{10}\times S^1/Z_2$ of 11 dimensional supergravity. They showed that only 10 dimensional vector multiplets belonging to $E_8$ gauge group can be consistently coupled to this theory. Thus, the dimensional reduction of this theory should be the low energy limit of the $E_8

C. R. Hu, S. Matinyan, B. Muller

We investigate the restoration of spontaneously broken gauge symmetry in collisions of gauge boson wave packets in the SU(2) Higgs model.