March 1997 arXiv papers — page 3

Z. Németh

The interaction of a spin 1/2 particle (described by the non-relativistic "Dirac" equation of Lévy-Leblond) with Chern-Simons gauge fields is studied. It is shown, that similarly to the four dimensional spinor models, there is a consistent possibility of coupling them also by axial or chiral type currents. Static self dual vortex solutions together w

I. Brunner, M. Lynker, R. Schimmrigk

We review several aspects of heterotic, type II, F-theory, and M-theory compactifications on Calabi-Yau threefolds and fourfolds. In the context of dualities we focus on the heterotic gauge structure determined by the various types of fibration relevant in the framework of heterotic/type II duality in D=4 as well as 4D F-theory. We also consider transitions

C. S. Aulakh, K. Benakli, G. Senjanovic

We construct the minimal supersymmetric left-right theory and show that at the renormalizable level it requires the existence of an intermediate $B-L$ breaking scale. The subsequent symmetry breaking down to MSSM automatically preserves R-symmetry. Furthermore, unlike in the nonsupersymmetric version of the theory, the see-saw mechanism takes its canonical f

T. Plehn, H. Spiesberger, M. Spira, P. M. Zerwas

The cross sections for the formation of scalar resonances, leptoquarks or squarks, in electron/positron-proton collisions at HERA are presented including next-to-leading order QCD corrections. Depending mildly on the mass of the resonances, the K-factors increase the production cross sections by up to 30% if the target quarks are valence quarks. The QCD corr

A. V. Belitsky

We review the recent theoretical progress in the construction and solution of the evolution equations which govern the scale dependence for the twist-three structure and fragmentation functions of the nucleon.

Jan Kalinowski

If the sneutrino mass is below the chargino mass, the dominant decay mode of the lightest chargino is via a two-body decay channel $χ^{\pm}_1 \ra \tildeν + l^{\pm}$. Sneutrinos are invisible in $R$-parity conserving supersymmetric models and, if the mass gap $m(χ^{\pm}_1)-m(\tildeν)$ is sufficiently small, the soft decay lepton may escape detection leading t

E. M. Gregores, M. C. Gonzalez-Garcia, S. F. Novaes

We explore the potential of the Next Linear Collider (NLC), operating in the $eγ$ mode, to disentangle new physics scenarios on single $W$ production. We study the effects related with the exchange of composite fermion in the reaction $eγ\to W ν_e$, and compare with those arising from trilinear gauge boson anomalous couplings. We stress the role played by th

M. Beneke

I review recent progress in understanding inclusive quarkonium production in hadron collisions. The first part focuses on non-relativistic QCD as an effective theory. I discuss its differences from and similarities with effective theories describing bound states of a single heavy quark, as far as matching calculations beyond tree-level and power counting are

Paul Langacker, Jens Erler

The status of precision electroweak data, tests of the standard model, determination of its parameters, and constraints on new physics, are surveyed.

Z. Kunszt, W. J. Stirling

The excess of high-$Q^2$ events found by H1 and ZEUS at HERA in $e^+p$ deep-inelastic scattering above the Standard Model prediction motivates us to calculate the NLO QCD corrections to the HERA scalar leptoquark (or squark) production cross sections. We find that the corrections are significant, of order 50% in the mass range of interest. We also calculate

Z. Berezhiani

We briefly review the GIFT (Goltstones instead of Fine Tuning) mechanism which provides a promising solution to the doublet-triplet splitting problem and some other puzzles of the supersymmetric grand unification as are the $μ$-problem, the fermion mass problem, etc. It can be naturally implemented by extending the minimal SUSY SU(5) model to the gauge SU(6)

Fyodor V. Tkachov

The pinched/non-pinched classification of intersections of causal singularities of propagators in Minkowski space is reconsidered in the context of the theory of asymptotic operation as a first step towards extension of the latter to non-Euclidean asymptotic regimes. A highly visual distribution-theoretic technique of singular wave fronts is tailored to the

D. Boyanovsky, H. J. de Vega, R. Holman, S. Prem Kumar

We study production of photons via the non-equilibrium relaxation of a Disoriented Chiral Condensate with the chiral order parameter having a large initial amplitude along the π^0 direction. Assuming the validity of the low energy coupling of the neutral pion to photons via the U_A(1) anomalous vertex, we find that for large initial amplitudes along the π^0

Gerhard K. Mallot

In this paper the experimental status of unpolarised structure functions is reviewed. In particular the latest results from the NMC, E665, CCFR, and HERA experiments are discussed. Emphasis is put on the fixed-target experiments, which cover with high precision the x region relevant for the present polarised DIS experiments.

James D. E. Grant, Ian G. Moss

A generalised canonical formulation of gravity is devised for foliations of spacetime with codimension $n\ge1$. The new formalism retains n-dimensional covariance and is especially suited to 2+2 decompositions of spacetime. It is also possible to use the generalised formalism to obtain boundary contributions to the 3+1 Hamiltonian.

Reinhard Meinel

The exact global solution of the Einstein equations [Neugebauer & Meinel, Phys. Rev. Lett. 75 (1995) 3046] describing a rigidly rotating, self-gravitating disk is discussed. The underlying matter model is a perfect fluid in the limit of vanishing pressure. The solution represents the general-relativistic analogue of the classical Maclaurin disk. It was deriv

B. Reznik

An effective black-hole-like horizon occurs, for electromagnetic waves in matter, at a surface of singular electric and magnetic permeabilities. In a physical dispersive medium this horizon disappears for wave numbers with $k>k_c$. Nevertheless, it is shown that Hawking radiation is still emitted if free field modes with $k>k_c$ are in their ground state.

A. Gopakumar, Bala R. Iyer, Sai Iyer

Starting from the recently obtained 2PN accurate forms of the energy and angular momentum fluxes from inspiralling compact binaries, we deduce the gravitational radiation reaction to 2PN order beyond the quadrupole approximation - 4.5PN terms in the equation of motion - using the refined balance method proposed by Iyer and Will. We explore critically the fea

P. G. Grinevich, M. U. Schmidt

If a curve in R^3 is closed, then the curvature and the torsion are periodic functions satisfying some additional constraints. We show that these constraints can be naturally formulated in terms of the spectral problem for a 2x2 matrix differential operator. This operator arose in the theory of the self-focusing Nonlinear Schrodinger Equation. A simple spect

Ennio Gozzi

In this paper we explore the idea of looking at the Dirac quantisation conditions as $\hbar$-dependent constraints on the tangent bundle to phase-space. Starting from the path-integral version of classical mechanics and using the natural Poisson brackets structure present in the cotangent bundle to the tangent bundle of phase- space, we handle the above cons

A. Gutin, V. Abkevich, E. Shakhnovich

In this brief reply we point out to some misconceptions in C.Camacho's comment (cond-mat/9701210).

R. N. Silver, H. Roder

We present an efficient algorithm for calculating spectral properties of large sparse Hamiltonian matrices such as densities of states and spectral functions. The combination of Chebyshev recursion and maximum entropy achieves high energy resolution without significant roundoff error, machine precision or numerical instability limitations. If controlled stat

G. E. Volovik, V. M. Yakovenko

In this Comment on the paper by W. Apel and Yu. A. Bychkov, cond-mat/9610040 and Phys. Rev. Lett. 78, 2188 (1997), we draw attention to our prior microscopic derivations of the Hopf term for various systems and to shortcomings of the Apel-Bychkov derivation. We explain how the value of the Hopt term prefactor $Θ$ is expressed in terms of a topological invari

O. Sommelius

The kinetic behavior of a three-dimensional off-lattice heteropolymer model is studied in terms of the time dependence of the average mean-square displacement between configurations. It is found that at short time-scales similar behavior is obtained even for sequences with very different thermodynamic properties. Furthermore, the degree of cooperativity in t

Daniel Stariolo

By considering the Langevin dynamics of the SK spin glass with a spherical constraint we calculate the asymptotic distance between two real replicas that evolve with the same thermal noise from different initial conditions. Despite the simplicity of the model its dynamics is known to be non trivial and presents aging phenomena. We find that the asymptotic di

Ikuo Ichinose, Akira Sekiguchi

Topological solitons in CP^{N-1} models coupled with Chern-Simons gauge theory and a Hopf term are studied both analytically and numerically.These models are low-energy effective theories for the quantum Hall effect with internal degrees of freedom, like that in bilayer electron systems. We explicitly show that the CP^{N-1} models describe quite well spin te

P. V. Shevchenko, O. P. Sushkov

The implications of the two-pocket Fermi surface for macroscopic quantum phenomena are considered. We demonstrate that in the case of the two-pocket Fermi surface the g-wave pairing is closely related to the d-wave one. As a result two macroscopic condensates arise. The Josephson tunneling for such two-component system has very special properties. We prove t

Ekkehard Reibold, Wolfram Just, Hartmut Benner

We report the first experimental observation of noise-free stochastic resonance by utilizing the intrinsic chaotic dynamics of the system. To this end we have investigated the effect of an external periodic modulation on intermittent signals observed by high power ferromagnetic resonance in yttrium iron garnet spheres. Both the signal-to-noise ratio and the

Wolfram Just

A mean-field formulation is used to investigate the bifurcation diagram for globally coupled tent maps by means of an analytical approach. It is shown that the period doubling sequence of the single site map induces a continuous family of periodic states in the coupled system. This type of collective motion breaks the ergodicity of the coupled map lattice. T

M. H. Cohen, R. C. Vermeulen, P. M. Ogle, H. D. Tran

Polarimetry of the narrow-line radio galaxy PKS 0116+082 at the W.M. Keck telescope shows that it has high and variable optical polarization, presumably due to synchrotron radiation. It is not a BL Lac object because it has strong narrow lines, and it is not an OVV quasar because it has no broad lines and the extended galaxy is prominent. VLA and VLBA images

Hale Bradt

The Rossi X-ray Timing Explorer (RXTE) was successfully launched on 1995 December 30 and has been operational since that time. Its three instruments are probing regions close to compact objects, degenerate dwarfs, neutron stars, stellar black holes and the central engines of AGN. Temporal studies with the ASM and PCA have already yielded rich results which p

Michael S. Turner

The Hubble constant sets the size and age of the Universe, and, together with independent determinations of the age, provides a consistency check of the standard cosmology. The Hubble constant also provides an important test of our most attractive paradigm for extending the standard cosmology, inflation and cold dark matter.

August E. Evrard

In this brief contribution, I outline hopes of understanding the origin of galaxy scaling relations using numerical simulations as a tool to gain understanding. The case of the Tully--Fisher relation for disk galaxies is used as an example to illustrate the modest achievements to date and the difficult tasks ahead.

Mordecai-Mark Mac Low, Michael D. Smith

We compute the nonlinear development of the instabilities in C-shocks first described by Wardle, using a version of the ZEUS code modified to include a semi-implicit treatment of ambipolar diffusion. We find that, in three dimensions, thin sheets parallel to the shock velocity and perpendicular to the magnetic field lines form. High resolution, two-dimension

Michael D. Smith, Mordecai-Mark Mac Low

Shock waves in molecular clouds should evolve into continuous or C-type structures due to the magnetic field and ion-neutral friction. We here determine whether and how this is achieved through plane-parallel numerical simulations using an extended version of ZEUS. We first describe and test the adapted code against analytical results, laying the necessary f

Tim Ebbels, Richard Ellis, Jean-Paul Kneib, Jean-Francois Le Borgne

We present deep spectroscopic measurements of 18 distant field galaxies identified as gravitationally-lensed arcs in a Hubble Space Telescope image of the cluster Abell 2218. Redshifts of these objects were predicted by Kneib et al. (1996) using a lensing analysis constrained by the properties of two bright arcs of known redshift and other multiply-imaged so

Somak Raychaudhury, Kaspar von Braun, Gary M. Bernstein, Puragra Guhathakurta

We investigate the amount of scatter in the Tully-Fisher relation (TFR) when using optical long-slit H-alpha rotation curves to determine the velocity widths of spiral galaxies. We study a sample of 25 galaxies in the Coma region of the sky which were shown in Bernstein et al. (1994) to exhibit an extraordinarily low scatter of 0.10 mag RMS in the I magnitud

W. Eholzer, T. Ibukiyama

Let H_n be the Siegel upper half space and let F and G be automorphic forms on H_n of weights k and l, respectively. We give explicit examples of differential operators D acting on functions on H_n x H_n such that the restriction of D(F(Z_1) G(Z_2)) to Z = Z_1 = Z_2 is again an automorphic form of weight k+l+v on H_n. Since the elliptic case, i.e. n=1, has a

H. Aoki, H. Kawai

Baryogenesis scenarios at the string scale are considered. The observed baryon to entropy ratio, $n_B /s \sim 10^{-10}$, can be explained in these scenarios.

Giorgio Parisi

In this note we present numerical simulations of binary mixtures. We study the diffusion of particles and the response to an external driving force. We find evidence for the validity of the Cugliandolo Kurchan off-equilibrium fluctuation dissipation relation. The results are in agreement with the predictions of one step replica symmetry breaking and the depe

Alejandro Corichi, Kirill Krasnov

We consider the loop quantization of Maxwell theory. A quantization of this type leads to a quantum theory in which the fundamental excitations are loop-like rather than particle-like. Each such loop plays the role of a quantized Faraday's line of electric flux. We find that the quantization depends on an arbitrary choice of a parameter e that carries th

J. M. Isidro, A. Mukherjee, J. P. Nunes, H. J. Schnitzer

A concise presentation of the PF equations for N=2 Seiberg-Witten theories for the classical groups of rank r with N_f massless hypermultiplets in the fundamental representation is provided. For N_f=0, all r PF equations can be given in a generic form. For certain cases with N_f\neq zero, not all equations are generic. However, in all cases there are at leas

Taekoon Lee

This paper has been replaced by hep-ph/9908225.

Paul Federbush

I now agree with conclusion of author that there is a problem with unitarity in discussed models.

Frank B. Estabrook, R. Steve Robinson, Hugo D. Wahlquist

By adopting Nester's higher dimensional special orthonormal frames (HSOF) the tetrad equations for vacuum gravity are put into first order symmetric hyperbolic (FOSH) form with constant coefficients, independent of any time slicing or coordinate specialization.

Jens Reinbach, Hermann Schulz

The consistency condition, which guarantees a well organized small-coupling asymptotic expansion for the thermodynamics of massless $ϕ^4$-theory, is generalized to any desired order of the perturbative treatment. Based on a strong conjecture about forbidden two-particle reducible diagrams, this condition is derived in terms of functions of four-momentum in p

R. D. Ball, S. Forte

We describe the application of renormalization group improved perturbative QCD to inelastic lepton-hadron scattering at high center-of-mass energy but comparatively low photon virtuality. We construct a high energy factorization theorem which complements the mass factorization theorem used for processes with high virtualities. From it we derive a renormaliza

I. M. McHardy, L. R. Jones, M. R. Merrifield, K. O. Mason

We present the results of the deepest optically identified X-ray survey yet made. The X-ray survey was made with the ROSAT PSPC and reaches a flux limit of 1.6x10^-15 erg cm^-2 s^-1 (0.5--2.0 keV). Above a flux limit of 2x10^-15 erg cm^-2 s^-1 we define a complete sample of 70 sources of which 59 are identified. Some (5) other sources have tentative identifi

Lee Smolin

A Chern-Simons theory in 11 dimensions, which is a piece of the 11 dimensional supergravity action, is considered as a quantum field theory in its own right. We conjecture that it defines a non-perturbative phase of M theory in which the metric and gravitino vanish. The theory is diffeomorphism invariant but not topological in that there are local degrees of

Shu-Quan Nie, Yu-Ping Kuang, Qing Wang, Yu-Ping Yi

Taking the sum rule for the rho meson as an example, we study the possibility of explaining the phenomenological enhamcement factors for certain terms in the vacuum expectation value of the operator product expansion in the QCD sum rule. We take a QCD motivated extended Nambu-Jona-Lasinio (ENJL) model as the low energy effective Lagrangian for QCD with which

S. Groote, J. G. Körner, J. A. Leyva

We calculate the linear polarization of gluons radiated off top quarks produced in e^+e^- annihilations. For typical top pair production energies at the Next-Linear-Collider (NLC) the degree of linear polarization remains close to its soft gluon value of 100% over almost the whole energy spectrum of the gluon. The massive quark results are compared with the

Hongfei Xi, ALADIN collaboration

Breakup temperatures were deduced from double ratios of isotope yields for target spectators produced in the reaction Au + Au at 1000 MeV per nucleon. Pairs of $^{3,4}$He and $^{6,7}$Li isotopes and pairs of $^{3,4}$He and H isotopes (p, d and d, t) yield consistent temperatures after feeding corrections, based on the quantum statistical model, are applied.

Andres Jordan, Matias Libedinsky

We give here a covariant definition of the path integral formalism for the Lagrangian, which leaves a freedom to choose anyone of many possible quantum systems that correspond to the same classical limit without adding new potential terms nor searching for a strange measure, but using as a framework the geometry of the spaces considered. We focus our attenti

Ranjan K. Ghosh, Sumathi Rao

We construct many particle Hamiltonians for which the Laughlin and Jain wavefunctions are exact ground states. The Hamiltonians involve fermions in a magnetic field and with inter-particle interactions. For the Laughlin wave-functions,the interactions involve two- and three-body correlations similar to the Chern-Simons interactions, whereas for the projected

Michael S. Turner

The case is simple: there is no compelling theoretical argument against a cosmological constant and LambdaCDM is the only CDM model that is consistent with all present observations. LambdaCDM has two noteworthy features: it can be falsified in the near future (the prediction q_0 sim -0.5 is an especially good test), and, if correct, it has important implicat

E. Moya de Guerra, P. Sarriguren, L. Zamick

We present an analytical proof and a generalization of the Fayache-Sharon-Zamick relation between single particle energy splittings and the SU(3) limit in Elliott's model.

M. Quiros

We review the constraints on Higgs boson properties from effective potential methods. In the Standard Model, the requirement of stability (or metastability) of the standard electroweak minimum puts an upper bound on the scale of new physics as a function of the Higgs mass. This upper bound is below the Planck scale if the Higgs weights $\simlt$ 130 GeV. In s

F. del Aguila, J. A. Aguilar-Saavedra, G. C. Branco

We characterize CP violation in the SU(2)xU(1) model due to an extra vector-like quark or sequential family, giving special emphasis to the chiral limit m_{u,d,s}=0. In this limit, CP is conserved in the three generation Standard Model (SM), thus implying that all CP violation is due to the two new CP violating phases whose effects may manifest either at hig

V. A. Rubakov

We argue that sufficiently complex grand unified theories involving extra strong intractions that confine at very short distances, may lead to a heavy axion solution of the CP problem of QCD. This axion may have a mass within accessible energy range, and its low energy interactions emerge through mixing with axial Higgs boson(s). Another signature of this sc

Suresh Govindarajan

Using the differential equation approach to W-algebras, we discuss the inclusion of punctures in W-string theory. The key result is the existence of different kinds of punctures in W-strings. This is similar to the NS and R punctures occuring in superstring theories. We obtain the moduli associated with these punctures and present evidence in existing W-stri

V. V. Flambaum, D. W. Murray

From the recent measurement of parity nonconservation (PNC) in the Cs atom we have extracted the constant of the nuclear spin dependent electron-nucleon PNC interaction, $κ= 0.442 (63)$; the anapole moment constant, $κ_a = 0.364 (62)$; the strength of the PNC proton-nucleus potential, $g_p = 7.3 \pm 1.2 (exp.) \pm 1.5 (theor.)$; the $π$-meson-nucleon interac

H. -W. Hammer, M. J. Ramsey-Musolf

We estimate the 3 πcontinuum contribution to the nucleon strange quark vector current form factors, including the effect of a 3 π<----> ρπresonance. We find the magnitude of this OZI-violating contribution to be comparable to that of typical OZI-allowed contributions. We also study the isoscalar electromagnetic form factors, and find that the presence of a ρ

Robert Carroll

We show how the WDVV equations and the DZM system can be characterized via a background family of functions.

Eric M. Rains

We present several results on quantum codes over general alphabets (that is, in which the fundamental units may have more than 2 states). In particular, we consider codes derived from finite symplectic geometry assumed to have additional global symmetries. From this standpoint, the analogues of Calderbank-Shor-Steane codes and of GF(4)-linear codes turn out

G. A. Kotel&#39;nikov

On the basis of the invariance of Dirac equation Lu(x,c)=0 with respect to the inversion of the speed of light Q:(x,c)=(x,-c), it is shown that the relationship [C,PTQ]u(x,c)=0 between the transformations of the charge conjugation C, the space inversion P, the time reversal T and the inversion of the speed of light Q is true. The charge conjugation in quantu

G. M. Moy, C. M. Savage

We calculate the spectrum of a beam of atoms output from a single mode atomic cavity. The output coupling uses an internal state change to an untrapped state. We present an analytical solution for the output energy spectrum from a broadband coupler of this type. An example of such an output coupler, which we discuss in detail uses a Raman transition to produ

Alessandro Drago, Manuel Fiolhais, Ubaldo Tambini

The electromagnetic form factors are computed using eigenstates of linear momentum for the nucleon. The latter is described in the framework of the chiral color-dielectric model, projecting the hedgehog ansatz on eigenstates of angular momentum and isospin. Form factors are well reproduced, with the exception of the magnetic one for the proton, up to $q^2 \s

Miklós Bóna

We give a combinatorial proof of the result of Hetyei and Reiner that there are exactly $n!/3$ permutations of length $n$ in the minmax tree representation of which the $i$th node is a leaf. We also prove the new result that the number of $n$-permutations in which this node has one child is $n!/3$ as well, implying that the same holds for those in which this

Paul Hewitt

Recently, Meierfrankenfeld has published three theorems on the cohomology of a finitary module. They cover the local determination of complete reducibility; the local splitting of group extensions; and the representation of locally split extensions in the double dual. In this note we derive all three by combining a certain duality between homology and cohomo

Noureddine Hambli

This paper illustrates the derivation of the low-energy background field solutions of D2-branes and D4-branes intersecting at non-trivial angles by solving directly the bosonic equations of motion of II supergravity coupled to a dilaton and antisymmetric fields. We also argue for how a similar analysis can be performed for any similar Dp-branes oriented at a

V. P. Frolov, D. V. Fursaev

The mechanism of generation of the Bekenstein-Hawking entropy $S^{BH}$ of a black hole in the Sakharov&#39;s induced gravity is proposed. It is suggested that the &#34;physical&#34; degrees of freedom, which explain the entropy $S^{BH}$, form only a finite subset of the standard Rindler-like modes defined outside the black hole horizon. The entropy $S_R$ of

Andreas Karch

We analyze three dimensional gauge theories with $Sp$ gauge group. We find that in some regime the theory should be described in terms of a dual theory, very much in the spirit of Seiberg duality in four dimensions. This duality does not coincide with mirror symmetry.

ByungKoo Lee, Soonkeon Nam

The instanton-induced effective vertex is derived for N=2 supersymmetric QCD (SQCD) with arbitrary mass matter hypermultiplets for the case of SU(2). The leading term of the low energy effective lagrangian obtained from this vertex agrees with one-instanton effective term of the Seiberg-Witten result.

H. Arodz

We show that collective dynamics of a curved domain wall in a (3+1)-dimensional relativistic scalar field model is represented by Nambu-Goto membrane and (2+1)-dimensional scalar fields defined on the worldsheet of the membrane. Our argument is based on a recently proposed by us version of the expansion in the width. Derivation of the expansion is significan

D. I. Diakonov, V. Yu. Petrov, P. V. Pobylitsa, M. V. Polyakov

The isosinglet unpolarized and isovector polarized twist-2 quark distributions of the nucleon at low normalization point are calculated in the large-Nc limit. The nucleon is described as a soliton of the effective chiral theory. We derive the expressions for the distribution functions in the large-Nc limit starting from their definition as numbers of partons

C. Dib, O. Espinosa, P. D. Morley, I. Schmidt

We investigate whether the total number of electrons per collision, as a function of beam energy, is a potential quark-gluon-plasma (QGP) signature. At high beam energies, we find that, after experimental removal of the noise induced by Dalitz decays, the number of produced electrons is increased many times fold from the existence of the QGP. The robustness

W. M. Alberico, M. B. Barbaro, S. M. Bilenky, J. A. Caballero

Possibilities to extract information on the strange form factors of the nucleon from neutrino (antineutrino) inelastic scattering on nuclei, in an energy range from 200 MeV to 1 GeV and more, are investigated in detail. All calculations are performed within two relativistic independent particle models (Fermi gas and shell model); the final state interactions

V. A. Miransky

The conception of the conformal phase transition (CPT), which is relevant for the description of non-perturbative dynamics in gauge theories, is discussed.

I. Schmidt, J. Soffer

By making use of the effect of the Melosh rotation, we show that one can estimate, in a simple way, the nucleon tensor charge in a relativistic quark model formulated on the light-cone. We discuss the physical significance of our results and compare them with those recently obtained in different phenomenological models.

Susumu Koretune

Implication of the modified Gottfried sum rule is discussed by focusing its theoretical bases, the range of validity, and physical interpretation.

C. Balazs, C. -P. Yuan

We propose the measurement of the ratio $R_{CSS}(Q_T^{\min}) \equiv \frac{σ(Q_T>Q_T^{\min})}{σ_{Total}}$ to study the effects of the multiple soft gluon radiation, predicted by QCD, on the transverse momentum ($Q_T$) distribution of the weak gauge bosons $W^{\pm }$ and $Z^0$ produced at the Tevatron. We compare the prediction of the extended Collins-Soper-St

A. H. Hoang

Two-loop contributions to the electromagnetic form factors are calculated in the kinematic regime close to the fermion-antifermion threshold. The results are presented in an expansion in the velocity $β$ of the fermions in the c.m. frame up to next-to-next-to leading order in $β$. The existence of a new Coulomb singularity logarithmic in $β$, which is closel

P. Butera, M. Comi

We compute the 2n-point renormalized coupling constants in the symmetric phase of the 3d Ising model on the sc lattice in terms of the high temperature expansions O(beta^{17}) of the Fourier transformed 2n-point connected correlation functions at zero momentum. Our high temperature estimates of these quantities, which enter into the small field expansion of

CLEO Collaboration, J. Bartelt

Using 4.8 fb$^{-1}$ of data taken with the CLEO II detector, the branching fraction for the Cabibbo-suppressed decay $D^+\toπ^0\ell^+ν$ measured relative to the Cabibbo favored decay $D^+\to\bar{K^0}\ell^+ν$ is found to be $0.046\pm 0.014\pm 0.017$. Using $V_{cs}$ and $V_{cd}$ from unitarity constraints, we determine $| f_+^π(0)/f_+^K(0)|^2=0.9\pm 0.3\pm 0.3

Milan Mijic

An analysis of the decoherence of quantum fluctuations shows that production of classical adiabatic density perturbations may not take place in models of power-law inflation with power 1< p < 3. Some consequences for models of extended inflation are pointed out. In general, the condition for decoherence places new constraint on inflationary models, which doe

Hing Tong Cho

Using an energy-momentum tensor for spinning particles due to Dixon and Bailey-Israel, we develop the post-Newtonian approximation for N spinning particles in a self-contained manner. The equations of motion are derived directly from this energy-momentum tensor. Following the formalism of Epstein- Wagoner, we also obtain the waveform and the luminosity of th

Luis P. Chimento, Alejandro S. Jakubi

The exact general solution to the Einstein equations in a homogeneous Universe with a full causal viscous fluid source for the bulk viscosity index $m=1/2$ is found. We have investigated the asymptotic stability of Friedmann and de Sitter solutions, the former is stable for $m\ge 1/2$ and the latter for $m\le 1/2$. The comparison with results of the truncate

M. Hummel, C. Pich, F. Schwabl

We report on the properties of a dipolar, antiferromagnetic chain in the framework of linear spin-wave theory. The phase diagram is calculated for an arbitrary ratio of dipolar interaction to exchange interaction and for fields both parallel and perpendicular to the chain direction. The calculated magnetization is compared with experimental measurements for

Ph. Brune, C. Bruder, H. Schoeller

We study transport through one or two ultrasmall quantum dots with discrete energy levels to which a time-dependent field is applied (e.g., microwaves). The AC field causes photon-assisted tunneling and also transitions between discrete energy levels of the dot. We treat the problem by introducing a generalization of the rotating-wave approximation to arbitr

M. V. Feigel&#39;man, M. A. Skvortsov

The model Hamiltonian of a two-dimensional Bose liquid (proposed earlier by Kane, Kivelson, Lee and Zhang as the Hamiltonian which has Jastrow-type wavefunctions as the ground-state solution), is shown to possess nonrelativistic supersymmetry. For the special value of the coupling constant $α=1/2$ the quantum mechanics described by this Hamiltonian is shown

B. Normand, K. Penc, M. Albrecht, F. Mila

We present a theoretical study of the magnetic phase diagram of the frustrated coupled ladder structure realized recently in several materials. This system displays a nondegenerate spin-gap state in the dimer limit and an infinitely degenerate spin-gap state in the regime of weakly-coupled zig-zag chains. Between these we demonstrate the existence of gapless

Biplab Chattopadhyay, D. M. Gaitonde

We consider an extended Hubbard model of interacting fermions on a lattice. The fermion kinetic energy corresponds to a tight binding Hamiltonian with nearest neighbour (-t) and next nearest neighbour (t&#39;) hopping matrix elements. In addition to the onsite Hubbard interaction (U) we also consider a nearest neighbour repulsion (V). We obtain the zero temp

M. Tatsuno, Y. Aizawa

A new description of the neural activity is introduced by the neuro-flow dynamics and the extended Hebb rule. The remarkable characteristics of the neuro-flow dynamics, such as the primacy and the recency effect during awakeness or sleep, are pointed out.

V. J. Emery, S. A. Kivelson, O. Zachar

Mobile holes in an antiferromagnetic insulator form a slowly fluctuating array of quasi one-dimensional metallic stripes, which induce a spin gap or pseudogap in the intervening Mott-insulating regions. The mobile holes on an individual stripe acquire a spin gap via pair hopping between the stripe and its environment; i.e. via a magnetic analog of the usual

Henning Schomerus, Fritz Haake

We determine semiclassical quasienergy spectra from periodic orbits for a system with a mixed phase space, the kicked top. Throughout the transition from integrability to well developed chaos the standard error incurred for the quasienergies is a small percentage of their mean spacing. Such fine accuracy does not even require the angular momentum quantum num

A. C. Marti, J. M. Sancho, F. Sagues, A. Careta

We present an analytical scheme, easily implemented numerically, to generate synthetic Gaussian turbulent flows by using a linear Langevin equation, where the noise term acts as a stochastic stirring force. The characteristic parameters of the velocity field are well introduced, in particular the kinematic viscosity and the spectrum of energy. As an applicat

Eduardo Bica, Horacio Dottori, Irapuan Rodrigues de Oliveira F., Sergio Ortolan

The recent detection of a double Red Giant Branch in the optical color-magnitude diagram (CMD) of the bulge globular cluster HP1 (Ortolani et al. 1997), a more populated metal-poor steep one corresponding to the cluster itself, and another metal-rich curved, led us to explore in the present Letter the possibility of capture of field stars by a globular clust

George F. Smoot

This is a very exciting time for the CMB field. It is widely recognized that precision measurements of the CMB can provide a definitive test of cosmological models and determine their parameters accurately. At present observations give us the first rough results but ongoing experiments promise new and improved results soon and eventually satellite missions (

Sidney van den Bergh

The present paper presents a discussion of classification systems for galaxies, with special emphasis on possible modifications of the Hubble &#34;tuning fork&#34; diagram, and on galaxy types not included in Hubble&#39;s original scheme. Hubble&#39;s morphological types were defined in terms of standards observed at small look-back times that were mostly lo

Edward L. Fitzpatrick

An empirical determination of the f-values of the far-UV Mg II lines at 1239 A and 1240 A is reported. The strong near-UV Mg II lines at 2796 A and 2803 A are generally highly saturated along most interstellar sightlines outside the local ISM and usually yield extremely uncertain estimates of Mg II column densities in interstellar gas. Since Mg II is the dom