July 1999 arXiv papers — page 13

Pankaj Jain, Bijoy Kundu, Hsiang-nan Li, John P. Ralston

We review the current status of perturbative QCD calculation of hadronic electromagnetic form factors.

J. Santiago, F. J. Yndurain

Calculations of deep inelastic processes (DIS) to next-to-next to leading order are discussed. Fitting $ep$ experiment in the range $2.5\leq Q^2\leq 230 GeV^2$, we find the coupling $α_s(M_Z^2)=0.1163\pm0.0023$. We also get the gluon density $xG(x,Q^2\simeq 10 GeV^2)=0.51 x^{-0.44}(1-x)^{8.1}$, and negative evidence for the existence of light gluinos

M. Klasen

We give a pedagogical introduction to hard photoproduction processes at HERA, including the production of jets, hadrons, and prompt photons. Recent theoretical developments in the three areas are reviewed.

Victor Chernyak

1) Hard exclusive processes in QCD: main characteristic properties; 2) Experimental and theoretical status of the J/Psi and Psi^\prime decays.

Guy D. Moore

I review the study of real (Minkowski) time correlators in hot, weakly coupled Yang-Mills theory via lattice methods. I concentrate on the Minkowski time topological susceptibility, which is related to the efficiency of baryon number violation at high temperature. It can be computed by approximating the IR fields as classical and solving their dynamics nonpe

F. Berruto, G. Grignani, G. W. Semenoff, P. Sodano

We review the correspondence between strongly coupled lattice multiflavor Schwinger models and SU(N) antiferromagnetic chains. We show that finding the low lying states of the gauge models is equivalent to solving an SU(N) Heisenberg antiferromagnetic chain. For the two-flavor lattice Schwinger model the massless excitations correspond to gapless states of t

D0 Collaboration, B. Abbott

We present a new measurement of the $W$ mass using the $W\to eν$ data from the DØforward detectors at the Fermilab Tevatron $p \bar p$ Collider. This is the first measurement of the $W$ mass with electron candidates in the range $1.5 < \mid η\mid < 2.5$. We present measurements of the $W$ mass using the transverse mass, the electron transverse momentum and t

C. Adloff

Measurements of transverse energy flow are presented for neutral current deep-inelastic scattering events produced in positron-proton collisions at HERA. The kinematic range covers squared momentum transfers Q^2 from 3.2 to 2,200 GeV^2, the Bjorken scaling variable x from 8.10^{-5} to 0.11 and the hadronic mass W from 66 to 233 GeV. The transverse energy flo

L. G. Landsberg

Experimental results of the SPHINX Collaboration on studying proton diffractive production processes are presented. Evidences for new baryon states with masses >1.8 GeV were obtained in hyperon-kaon effective mass spectra in several reactions. New data for the diffractive reaction p+N->[Sigma0 K+]+N at Ep=70 GeV were obtained with partially upgraded SPHINX s

M. Aglietta, M. Ambrosio, E. Aprile, G. Bologna

A high-density calorimeter, consisting of magnetized iron planes interleaved by RPCs, as tracking and timing devices, is a good candidate for a next generation experiment on atmospheric neutrinos. With 34 kt of mass and in four years of data taking, this experiment will be sensitive to $ν_μ\to ν_x$ oscillation with $Δm^2 > 6 \times 10^{-5}$ and mixing near t

S. E. Perez Bergliaffa, K. E. Hibberd

We present new exact cosmological inhomogeneous solutions for gravity coupled to a scalar field in a general framework specified by the parameter $λ$. The equations of motion (and consequently the solutions) in this framework correspond either to low-energy string theory or Weyl integrable spacetime according to the sign of $λ$. We show that different inflat

S. Q. Wu, X. Cai

Statistical entropies of a general relativistic ideal gas obeying Maxwell-Boltzmann, Bose-Einstein and Fermi-Dirac statistics are calculated in a general axisymmetry space-time of arbitrary dimension. This general formation can be used to discuss the entropy of a quantum field not only in the flat space-time but also in a curved space-time. It can also be us

Emanuele Pianta, Lucia M. Tovena

Natural language generation systems (NLG) map non-linguistic representations into strings of words through a number of steps using intermediate representations of various levels of abstraction. Template based systems, by contrast, tend to use only one representation level, i.e. fixed strings, which are combined, possibly in a sophisticated way, to generate t

Herve Bronnimann, Olivier Devillers

We provide a lower bound construction showing that the union of unit balls in three-dimensional space has quadratic complexity, even if they all contain the origin. This settles a conjecture of Sharir.

Olivier Devillers

We propose a new data structure to compute the Delaunay triangulation of a set of points in the plane. It combines good worst case complexity, fast behavior on real data, and small memory occupation. The location structure is organized into several levels. The lowest level just consists of the triangulation, then each level contains the triangulation of a sm

Olivier Devillers

This paper presents how the space of spheres and shelling may be used to delete a point from a $d$-dimensional triangulation efficiently. In dimension two, if k is the degree of the deleted vertex, the complexity is O(k log k), but we notice that this number only applies to low cost operations, while time consuming computations are only done a linear number

Satoru Kuroda

We define a hierarchy of circuit complexity classes LD^i, whose depth are the inverse of a function in Ackermann hierarchy. Then we introduce extremely weak versions of length induction and construct a bounded arithmetic theory L^i_2 whose provably total functions exactly correspond to functions computable by LD^i circuits. Finally, we prove a non-conservati

Inanc Adagideli, Paul M. Goldbart, Alexander Shnirman, Ali Yazdani

Low-energy quasiparticle states, arising from scattering by single-particle potentials in d-wave superconductors, are addressed. Via a natural extension of the Andreev approximation, the idea that sign-variations in the superconducting pair-potential lead to such states is extended beyond its original setting of boundary scattering to the broader context of

J. Sánchez-Cañizares, F. Sols

We study superconducting transport in homogeneous wires in the cases of both equilibrium and nonequilibrium quasiparticle populations, using the quasiclassical Green&#39;s function technique. We consider superconductors with arbitrary current densities and impurity concentrations ranging from the clean to the dirty limit. Local current conservation is guaran

Gordon Baym, Jean-Paul Blaizot, Jean Zinn-Justin

We calculate explicitly the variation $δT_c$ of the Bose-Einstein condensation temperature $T_c$ induced by weak repulsive two-body interactions to leading order in the interaction strength. As shown earlier by general arguments, $δT_c/T_c$ is linear in the dimensionless product $an^{1/3}$ to leading order, where $n$ is the density and $a$ the scattering len

Andrew M. Martin, Thomas Gramespacher, Markus Buttiker

We show how to calculate the charge noise spectrum in a normal mesoscopic conductor, which is capacitively coupled to a macroscopic gate, when this conductor is attached to L normal leads and M superconducting leads, the only restriction being that the superconducting leads must be at the same chemical potential. We then proceed to examine results for a quan

S. N. Taraskin, S. R. Elliott

A theoretical analysis of the scattering of plane-wave atomic excitations in disordered solids has been made in terms of the spectral densities. Hybridization between transverse and longitudinal waves of approximately the same frequency is demonstrated. The analytic results agree well with the results obtained from computer simulation for a toy linear zig-za

M. J. Konstantinovic, Z. V. Popovic, T. Ruf, M. Cardona

In order to investigate the origin of the phase transition observed in NaV$_2$O$_5$, as well as its electronic structure, we have measured Raman intensities as a function of the laser wavelength above and below the phase transition temperature. In the polarized Raman spectra at room temperature we observe resonant enhancement of the 969 $cm^{-1}$ phonon mode

H. Suderow, E. Bascones, W. Belzig, F. Guinea

We report on the measurement of multiple Andreev resonances at atomic size point contacts between two superconducting nanostructures of Pb under magnetic fields higher than the bulk critical field, where superconductivity is restricted to a mesoscopic region near the contact. The small number of conduction channels in this type of contacts permits a quantita

A. V. Chechkin, V. Yu. Gonchar

The ordinary Levy motion is a random process whose stationary independent increments are statistically self-affine and distributed with a stable probability law characterized by the Levy index alpha, 0 < alpha < 2. The divergence of statistical moments of the order q > alpha leads to an important role of the finite sample effects. The objective of this paper

Masahito Ueda, Anthony J. Leggett

The ground state of a rotating Bose-Einstein condensate with attractive interaction in a quasi-one-dimensional torus is studied in terms of the ratio $γ$ of the mean-field interaction energy per particle to the single-particle energy-level spacing. The plateaus of quantized circulation are found to appear if and only if $γ<1$ with the lengths of the plateaus

A. A. Saharian, A. R. Mkrtchyan, L. A. Gevorgian, L. Sh. Grigorian

Radiation generated by the passage of a monoenergetic electron bunch above the surface wave excited in plane interface between homogeneous media with different dielectric constants is investigated. For the surface wave of general profile the radiation intensity is expressed via the radiated power from a single charge and bunch form factor. Various types of t

Haranath Ghosh

We derive a pair potential from tight binding further neighbours attraction that leads to superconducting gap symmetry similar to that of the phenomenological spin fluctuation theory of high temperature superconductors (Monthoux, Balatsky, Pines, Phys. Rev. Lett. {\bf 67}, 3448). We show that higher anisotropic d-wave than the simpliest d-wave symmetry is on

Ajanta Bhowal Acharyya

The cluster statistics of BTW automata in the SOC states are obtained by extensive computer simulation. Various moments of the clusters are calculated and few results are compared with earlier available numerical estimates and exact results. Reasonably good agreement is observed. An extended statistical analysis has been made.

A. Mourachkine

The phase diagram for hole-doped cuprates is discussed. By examining some recent inelastic neutron scattering data obtained on hole-doped cuprates we conclude that the coherent gap in hole-doped cuprates has most likely the magnetic origin and scales with Tc, on average, as 2Delta/kTc = 5.4.

Zoltan Neufeld, Cristobal Lopez, Emilio Hernandez-Garcia, Tamas Tel

The structure of the concentration field of a decaying substance produced by chemical sources and advected by a smooth incompressible two-dimensional flow is investigated. We focus our attention on the non-uniformities of the Hölder exponent of the resulting filamental chemical field. They appear most evidently in the case of open flows where irregularities

C. Dembowski, H. -D. Graef, R. Hofferbert, H. Rehfeld

The field distributions and eigenfrequencies of a microwave resonator which is composed of 20 identical cells have been measured. With external screws the periodicity of the cavity can be perturbed arbitrarily. If the perturbation is increased a transition from extended to localized field distributions is observed. For very large perturbations the field dist

G. R. Knapp, S. I. Dobrovolsky, Z. Ivezic, K. Young

V Hya, an evolved carbon star with a complex circumstellar envelope, has two variability periods, 530d and 6000d (17 years). We analyze recent light curve data and show that both variations have benn present for at least 100 years and have been regular over this time. The 530d period and its 1.5 - 2 magnitude amplitude show that V Hya is a Mira variable. We

Henry A. Kobulnicky, Kelsey E. Johnson

VLA radio continuum imaging reveals compact (<8 pc) ~1 mJy radio sources in the central 5&#34; starburst region of the blue compact galaxy Henize 2-10. We interpret these radio knots as extremely young, ultra-dense HII regions. We model their luminosities and spectral energy distributions, finding that they are consistent with unusually dense HII regions hav

B. T. Draine

If a gamma ray burst with strong UV emission occurs in a molecular cloud, there will be observable consequences resulting from excitation of the surrounding H2. The UV pulse from the GRB will pump H2 into vibrationally-excited levels which produce strong absorption at wavelengths < 1650 A. As a result, both the prompt flash and later afterglow will exhibit s

Andrea Possenti, Monica Colpi, Ulrich Geppert, Luciano Burderi

We investigate the statistical evolution of magnetic neutron stars, recycled in binary systems, simulating synthetic populations. To bracket uncertainties, we consider a soft (FP) and a stiff (PS) equation of state (EoS) for nuclear matter and explore the hypothesis that the magnetic field is confined in the stellar crust. We follow the magneto-rotational ev

R. D. Jeffries

The current status of observational studies of lithium depletion in open clusters is reviewed, concentrating mainly on G and K type stars. I attempt to answer the following questions: Can the lithium depletion patterns seen in open clusters be explained in terms of standard stellar evolution models? What is the observational evidence for non-standard mixing

N. Kaiser, G. Wilson, G. Luppino, H. Dahle

We describe in detail the processing of a set of images of the z = 0.42 supercluster MS0302 taken with the UH8K camera at CFHT. The result of this is a pair of seamless combined V- and I-band images of the field, along with a characterization of the noise properties and of the point spread function (PSF), and catalogs of about 30,000 faint galaxies. The anal

Y. I. Izotov, F. H. Chaffee, C. B. Foltz, R. F. Green

We present high-quality spectroscopic observations of the two most-metal deficient blue compact galaxies known, I Zw 18 and SBS 0335-052 to determine the helium abundance. The underlying stellar absorption strongly influences the observed intensities of He I emission lines in the brightest NW component of I Zw 18, and hence this component should not be used

L. Wisotzki, N. Christlieb, M. C. Liu, J. Maza

We report the discovery of the new gravitational lens system HE~0230$-$2130, a QSO at redshift $z=2.162$ consisting of at least five distinct components. Three of these are clearly lensed images of the QSO, one is most likely the lensing galaxy, while for the fifth component the identity is unclear: It could be a fourth QSO image (if so, then highly reddened

E. Gourgoulhon, P. Haensel, R. Livine, E. Paluch

Exact models of uniformly rotating strange stars, built of self bound quark matter, are calculated within the framework of general relativity. This is made possible thanks to a new numerical technique capable to handle the strong density discontinuity at the surface of these stars. Numerical calculations are done for a simple MIT bag model equation of state

Luca Amendola, Stefano Corasaniti, Franco Occhionero

We investigate to which extent a time variation of the gravitational constant or other fundamental constants affects the best fit of the Hubble diagram of type Ia supernovae. In particular, we show that a slow increase of $G$ in the past, below experimental constraints, can reconcile the SNe Ia observations with an open zero-$Λ$ universe.

Kari Enqvist, Hannu Kurki-Suonio

We consider the detection possibilities of isocurvature fluctuations in the future CMB satellite experiments MAP and Planck for different cosmological reference models. We present a simultaneous 10 parameter fit (8 for the case of open model) to determine the correlations between the cosmological parameters, including isocurvature cold dark matter contributi

Weihsueh A. Chiu, Jeremiah P. Ostriker

We present a semi-analytic model for the thermal and ionization history of the universe at 1000 >~ z >~ 3. This model incorporates much of the essential physics included in full-scale hydrodynamical simulations, such as (1) gravitational collapse and virialization; (2) star/quasar formation and subsequent ionizing radiation; (3) heating and cooling; (4) atom

Eric Flesch, Halton Arp

NGC3628 is a well-studied starburst/low level AGN galaxy in the Leo Triplet noted for its extensive outgassed plumes of neutral hydrogen. Catalogued QSOs are shown to be concentrated around NGC3628 and aligned with HI plumes. The chance that the three nearest quasars would accidentally fall as close as they do is <= 0.01. The nearest quasar has a redshift of

Takashi Nakamura

A formula for off-axis emissions from the beamed afterglow of GRBs in a synchrotron model is derived. The formula is applied to an inhomogeneous circumstellar matter obeying n proportional to 1/r**2 suggested for SN1998bw/GRB980425. The slow decline rate as well as the X-ray flux similar to the observed values are obtained for appropriate choice of the param

Geoffrey C. Bower, Heino Falcke, Donald C. Backer

We report here the detection of circular polarization in the Galactic Center black hole candidate, Sagittarius A*. The detection was made at 4.8 GHz and 8.4 GHz with the Very Large Array. We find that the fractional circular polarization at 4.8 GHz is $m_c=-0.36 \pm 0.05%$ and that the spectral index of the circular polarization is $α=-0.6 \pm 0.3$ ($m_c \pr

Shin Mineshige, Atsunori Yonehara

Since the radiation from different portions in the central region of a quasar can be successively amplified during a microlensing event, microlensing light curves provide us with fruitful information regarding the emissivity distribution of an accretion disk located at the quasar center. We present a basic methodology how to map the emissivity distribution o

A. Shelankov, M. Ozana

A new method which allows one to study multiple coherent reflection/transmissions by partially transparent interfaces, (e.g., in multi-layer mesoscopic structures or grain boundaries in high-Tc's), in the framework of the quasiclassical theory of superconductivity is suggested. It is argued that in the presence of interfaces, a straight-line trajectory trans

Alexander Soshnikov

We prove universality at the edge for rescaled correlation functions of Wigner random matrices in the limit $n\to +\infty$. As a corollary, we show that, after proper rescaling, the 1st, 2nd, 3rd, etc. eigenvalues of Wigner random hermitian (resp. real symmetric) matrix weakly converge to the distributions established by Tracy and Widom in G.U.E. (G.O.E.) ca

Supriya Kar

We investigate the effective dynamics of an arbitrary Dirichlet p-brane, in a path-integral formalism, by incorporating the massless excitations of closed string modes in open bosonic string theory. It is shown that the closed string background fields in the bosonic sector of type II theories induce invariant extrinsic curvature on the world-volume. In addit

Steven Gratton, Thomas Hertog, Neil Turok

We compute the tensor CMB anisotropy power spectrum for singular and non-singular instantons describing the beginning of an open universe according to the Euclidean no boundary proposal. Singular instantons occur generically, whereas non-singular instantons require more contrived scalar field potentials. For the latter, we consider potentials in which a shar

Clifford Tureman Lewis, Henry D. I. Abarbanel, Matthew B. Kennel, Michael Buhl

We investigate synchronization and subsequently communication using chaotic rare-earth-doped fiber ring lasers, represented by a physically realistic model. The lasers are coupled by transmitting a fraction c of the circulating electric field in the transmitter and injecting it into the optical cavity of the receiver. We then analyze a coupling strategy whic

Masafumi Fukuma, Takeshi Oota, Hirokazu Tanaka

The type IIA/IIB effective actions compactified on T^d are known to be invariant under the T-duality group SO(d, d; Z) although the invariance of the R-R sector is not so direct to see. Inspired by a work of Brace, Morariu and Zumino,we introduce new potentials which are mixture of R-R potentials and the NS-NS 2-form in order to make the invariant structure

W. Lerche, S. Stieberger

We compute certain 2K+4-point, one-loop couplings in the type IIA string compactified on K3 x T^2, which are related to a topological index on this manifold. Their special feature is that they are sensitive to only short and intermediate BPS multiplets. The couplings derive from underlying prepotentials G[K](T,U), which can be nicely summed up into a fundame

Sung-Sik Lee, Sung-Ho Suck Salk

Based on an improved SU(2) slave-boson approach to the t-J Hamiltonian, we derive a phase diagram of high $T_c$ cuprates which displays both the superconducting and pseudogap phases in the plane of temperature vs. hole doping rate. It is shown that the inclusion of phase fluctuations in the order parameters results in a closer agreement with the observed sup

ZEUS Collaboration

A search for the leptonic decays of W bosons produced in the reaction e^+ p\to e^+ W^\pm X at a centre-of-mass energy of 300 GeV has been performed with the ZEUS detector at HERA using an integrated luminosity of 47.7 pb^-1 . Three events consistent with W\to eνdecay are found, giving a cross section of 0.9 +1.0 -0.7 \pm 0.2 pb, in good agreement with the St

Suresh Govindarajan, T. Jayaraman, Tapobrata Sarkar

We consider D-branes wrapped around supersymmetric cycles of Calabi-Yau manifolds from the viewpoint of N=2 Landau-Ginzburg models with boundary as well as by consideration of boundary states in the corresponding Gepner models. The Landau-Ginzburg approach enables us to provide a target space interpretation for the boundary states. The boundary states are ob

Massimo Blasone, Giuseppe Vitiello

We show that the neutrino oscillation formula recently derived in the quantum field theory framework holds true despite the arbitrariness in the mass parameter for the flavor fields. This formula is exact and exhibits new features with respect to the usual Pontecorvo formula, which is however valid in the relativistic limit.

Pedro P. Avelino, Pedro T. P. Viana

The cloud-in-cloud problem is studied in the context of the extension to non-Gaussian density fields of the Press-Schechter approach for the calculation of the mass function. As an example of a non-Gaussian probability distribution functions (PDFs) we consider the Chi-square, with various degrees of freedom. We generate density fields in cubic boxes with per

Steven B. Giddings

The large radius limit in the AdS/CFT correspondence is expected to provide a holographic derivation of flat-space scattering amplitudes. This suggests that questions of locality in the bulk should be addressed in terms of properties of the S-matrix and their translation into the conformal field theory. There are, however, subtleties in this translation rela

S. Bright, R. Winston, E. C. Swallow, A. Alavi-Harati

Using an effective Hamiltonian approach, we obtain expressions for hyperon beta decay final-state baryon polarization. Terms through second order in the energy release are retained. The resulting approximate expressions are much simpler and more compact than the exact expressions, and they agree closely with them.

Xavier Calmet, Thomas Mannel, Ingo Schwarze

We discuss one-particle inclusive B decays in the limit of heavy b and c quarks. Using the large-N_C limit we factorize the non-leptonic matrix elements, and we employ a short distance expansion. Modeling the remaining nonperturbative matrix elements we obtain predictions for various decay channels and compare them with existing data.

Marie-Noëlle Célérier

The magnitude-redshift relation is one of the tools for a direct observational approach to cosmology. The discovery of high redshift Type Ia supernovae (SNIa) and their use as ``standard candles&#39;&#39; has resurrected interest in this approach. Recently collected data have been used to address the problem of measuring the cosmological parameters of the un

Mannque Rho, Sang-Jin Sin, Ismail Zahed

Using the AdS/CFT correspondence and the eikonal approximation, we evaluate the elastic parton-parton scattering amplitude at large $N$ and strong coupling $g^2N$ in N=4 SYM. We obtain a scattering amplitude with a Regge behavior that unitarizes at large $\sqrt{s}$.

A. Fring, C. Korff, B. J. Schulz

By exploiting the properties of q-deformed Coxeter elements, the scattering matrices of affine Toda field theories with real coupling constant related to any dual pair of simple Lie algebras may be expressed in a completely generic way. We discuss the governing equations for the existence of bound states, i.e. the fusing rules, in terms of q-deformed Coxeter

R. Denk, R. Mennicken, L. Volevich

In this paper operator pencils $A(x,D,\lambda)$ are studied which act on a manifold with boundary and satisfy the condition of $N$-ellipticity with parameter, a generalization of the notion of ellipticity with parameter as introduced by Agmon and Agranovich--Vishik. Sobolev spaces corresponding to a Newton polygon are defined and investigated; in particular

Renata Kallosh, Lev Kofman, Andrei Linde, Antoine Van Proeyen

We investigate the production of gravitinos in a cosmological background. Gravitinos can be produced during preheating after inflation due to a combined effect of interactions with an oscillating inflaton field and absence of conformal invariance. In order to get insight on conformal properties of gravitino we reformulate phenomenological supergravity in SU(

L. T. Handoko, C. -F. Qiao

The top quark decay process $\tcups$ is studied in the Standard Model and the Minimal Supersymmetric Standard Model with conserved and violated $R-$parity. In dealing with the heavy quarkonium, $\ups$, production, we take both color-singlet and -octet mechanisms into consideration. With numerical analysis it is found that within the Standard Model the decay

Nobuhiko Shinzawa

Proper lattices for the discrete BKP and the discrete DKP equaitons are determined. Linear Bäcklund transformation equations for the discrete BKP and the DKP equations are constructed, which possesses the lattice symmetries and generate auto-Bäcklund transformations

David H. Adams

Lower bounds on the magnitude of the spectrum of the Hermitian Wilson-Dirac operator H(m) have previously been derived for 0<m<2 when the lattice gauge field satisfies a certain smoothness condition. In this paper lower bounds are derived for 2p-2<m<2p for general p=1,2,...,d where d is the spacetime dimension. The bounds can alternatively be viewed as local

Philippe Sindzingre, Gregoire Misguich, Claire Lhuillier, Bernard Bernu

In this paper, we use a new hybrid method to compute the thermodynamic behavior of the spin-1/2 Kagome antiferromagnet under the influence of a large external magnetic field. We find a T^2 low-temperature behavior and a very low sensitivity of the specific heat to a strong external magnetic field. We display clear evidence that this low temperature magneto-t

J. Bijtebier

We perform a 3D reduction of the two-fermion Bethe-Salpeter equation based on Sazdjian's explicitly covariant propagator, combined with a covariant substitute of the projector on the positive-energy free states. We use this combination in the two fermions in an external potential and in the three-fermion problems. The covariance of the two-fermion propagator

Angel Ballesteros, Francisco J. Herranz, Preeti Parashar

All Lie bialgebra structures for the (1+1)-dimensional centrally extended Schrodinger algebra are explicitly derived and proved to be of the coboundary type. Therefore, since all of them come from a classical r-matrix, the complete family of Schrodinger Poisson-Lie groups can be deduced by means of the Sklyanin bracket. All possible embeddings of the harmoni

R. Flume, E. Kraus

The non-renormalization theorems of chiral vertex functions are derived on the basis of an algebraic analysis. The property, that the interaction vertex is a second supersymmetry variation of a lower dimensional field monomial, is used to relate chiral Green functions to superficially convergent Green functions by extracting the two supersymmetry variations

A. Sibirtsev, W. Cassing

The available data on $ω$ and $ϕ$ production from $πN$ and $pp$ collisions are reanalyzed with respect to an OZI rule violation on the basis of transition matrix elements. The data are found to be compatible with a constant ratio $R$ up to excess energies $ε{\approx}300$ MeV, however, the ratio $R$ deviates substantially from the SU(3) prediction based on th

Gautam Dutta, D. Indumathi, M. V. N. Murthy, G. Rajasekaran

We study the effect of non-vanishing masses and mixings among neutrino flavours on the detection of neutrinos from stellar collapse by a water Cerenkov detector. We consider a realistic framework in which there are three neutrino flavours whose mass squared differences and mixings are constrained by the present understanding of solar and atmospheric neutrino

Katsunori Wakabayashi, Manfred Sigrist

The electronic transport properties through junctions in nanographite ribbons are investigated using the Landauer approach. In the low-energy regime ribbons with zigzag boundary have a single conducting channel of edge states. The conductance as a function of the chemical potential shows a rich structure with sharp dips of zero conductance. Each zero-conduct

Chen Jisheng, Zheng Xiaoping, Li Jiarong

By decomposing the distribution functions and color field to regular and fluctuation parts, the solution of the semi-classical kinetic equations of quark-gluon plasma is analyzed. Through expanding the kinetic equations of the fluctuation parts to third order, the nonlinear permittivity including the self-interaction of gauge field is obtained and a rough nu

F. W. Nijhoff

A universal system of difference equations associated with a hyperelliptic curve is derived constituting the discrete analogue of the Dubrovin equations arising in the theory of finite-gap integration. The parametrisation of the solutions in terms of Abelian functions of Kleinian type (i.e. the higher-genus analogues of the Weierstrass elliptic functions) is

G. A. Prataviera, E. V. Goldstein, P. Meystre

We propose a scheme to measure the cross-correlations and mutual coherence of optical and matter fields. It relies on the combination of a matter-wave detector operating by photoionization of the atoms and a traditional absorption photodetector. We show that the double-detection signal is sensitive to cross-correlation functions of light and matter waves.

Miloslav Znojil

Schroedinger equation with potentials of the Kratzer plus polynomial type (say, quartic V(r) = A r^4 +B r^3 + C r^2+D r + F/r + G/r^2 etc) is considered. A new method of exact construction of some of its bound states is then proposed. it is based on the Taylor series terminated rigorously after N+1 terms at specific couplings and energies. This enables us to

R. E. Grisenti, W. Schoellkopf, J. P. Toennies, G. C. Hegerfeldt

Molecular beams of rare gas atoms and D_2 have been diffracted from 100 nm period SiN_x transmission gratings. The relative intensities of the diffraction peaks out to the 8th order depend on the diffracting particle and are interpreted in terms of effective slit widths. These differences have been analyzed by a new theory which accounts for the long-range v

A. M. Lisewski

We discuss results recently given in an article by M. Tegmark (quant-ph/9907009) where he argues that neurons can be described appropriately by pure classical physics. This letter is dedicated to the question if this is really the case when the role of dissipation and noise -- the two concurrent phenomena present in these biological structures -- is taken in

A. Imamoglu, D. D. Awschalom, G. Burkard, D. P. DiVincenzo

The electronic spin degrees of freedom in semiconductors typically have decoherence times that are several orders of magnitude longer than other relevant timescales. A solid-state quantum computer based on localized electron spins as qubits is therefore of potential interest. Here, a scheme that realizes controlled interactions between two distant quantum do

M. Casalegno, M. Mella, G. Morosi, D. Bressanini

We report ground state energies and structural properties for small helium clusters (4He) containing an H- impurity computed by means of variational and diffusion Monte Carlo methods. Except for 4He_2H- that has a noticeable contribution from collinear geometries where the H- impurity lies between the two 4He atoms, our results show that our 4He_NH- clusters

M. S. Hussein, M. P. Pato

It is shown that an operator can be defined in the abstract space of random matrices ensembles whose matrix elements statistical distribution simulates the behavior of the distribution found in real physical systems. It is found that the key quantity that determines these distribution is the commutator of the operator with the Hamiltonian. Application to sym

L. V. Bravina, E. E. Zabrodin, M. I. Gorenstein, S. A. Bass

The hypothesis of local equilibrium (LE) in relativistic heavy ion collisions at energies from AGS to RHIC is checked in the microscopic transport model. We find that kinetic, thermal, and chemical equilibration of the expanding hadronic matter is nearly reached in central collisions at AGS energy for $t \geq 10$ fm/$c$ in a central cell. At these times the

L. V. Bravina, I. N. Mishustin, J. P. Bondorf, Amand Faessler

The freeze-out conditions in the light (S+S) and heavy (Pb+Pb) colliding systems of heavy nuclei at 160 AGeV/$c$ are analyzed within the microscopic Quark Gluon String Model (QGSM). We found that even for the most heavy systems particle emission takes place from the whole space-time domain available for the system evolution, but not from the thin &#39;&#39;f

Ulrich Heinz

The present status of soft hadron production in high energy heavy-ion collisions is summarized. In spite of strong evidence for extensive dynamical evolution and collective expansion of the fireball before freeze-out I argue that its chemical composition is hardly changed by hadronic final state interactions. The measured hadron yields thus reflect the primo

B. L. Birbrair, V. I. Ryazanov

The doorway states under consideration are eigenstates of the hamiltonian which is the sum of the kinetic energy and the infinite energy limit of the single-particle mass operator. Only Hartree diagrams with the free-space nucleon-nucleon forces contribute to this limit, and therefore the observed doorway state energies carry an important information about b

Thomas Ebertshaeuser, Hartmuth Arenhoevel

Coherent pion electroproduction on the deuteron is studied in the $Δ(1232)$ resonance region in the impulse approximation, i.e., neglecting pion rescattering and two-body effects. The elementary reaction on the nucleon is described in the framework of an effective Lagrangian approach including the dominant $P_{33}(1232)$ resonance and the usual background te

Hamish Short, Bert Wiest

We are concerned with mapping class groups of surfaces with nonempty boundary. We present a very natural method, due to Thurston, of finding many different left orderings of such groups. The construction involves equipping the surface with a hyperbolic structure, embedding the universal cover in the hyperbolic plane, and extending the action of the mapping c

Jean-Francois Burnol

This note adds three annexes to my previous paper math/9904044 Annex 1. A sufficient condition for self-adjointness Annex 2. Invariant closed operators on locally compact abelian groups Annex 3. The trace of Connes for quaternions This last item is a minor variation on the evaluation of Connes&#39;s trace (math/9811068), which is explained here in the settin

Sascha Orlik

The goal of this paper is to give an explicit formula for the l-adic cohomology of period domains over finite fields for arbitrary reductive groups. The result is a generalisation of the computation in math.AG/9907098 which treats the case of the general linear group.

Sascha Orlik

Periodenbereiche sind gewisse offene Unterraeume von verallgemeinerten Flaggenvarietaeten, welche durch Semistabilitaetsbedingungen beschrieben werden. In dem Fall eines endlichen Grundkoerpers bilden diese eine Zariski-offene Untervarietaet, im Fall eines lokalen Koerpers einen zulaessigen offenen Unterraum im Sinne der rigiden algebraischen Geometrie. In d

Toshinori Oaku, Nobuki Takayama, Uli Walther

We present a method to compute the holonomic extension of a $D$-module from a Zariski open set in affine space to the whole space. A particular application is the localization of coherent $D$-modules which are holonomic on the complement of an affine variety.

Jason Fulman

Two notions of riffle shuffling on finite Coxeter groups are given: one using Solomon&#39;s descent algebra and another using random walk on chambers of hyperplane arrangements. These coincide for types $A$,$B$,$C$, $H_3$, and rank two groups. Both notions have the same, simple eigenvalues. The hyperplane definition is especially natural and satisfies a posi

M. Massar, J. Troost

We study a configuration in matrix theory carying longitudinal fivebrane charge, i.e. a D0-D4 bound state. We calculate the one-loop effective potential between a D0-D4 bound state and a D0-anti-D4 bound state and compare our results to a supergravity calculation. Next, we identify the tachyonic fluctuations in the D0-D4 and D0-anti-D4 system. We analyse cla

Z. Bajnok

It is shown that the commutation relations of W-algebras can be recovered from the singular vectors of their simplest nontrivial, completely degenerate highest weight representation.