February 2001 arXiv papers — page 21

I. Bena, R. Kawai, C. Van den Broeck, M. Copelli

We revisit the mean field model of globally and harmonically coupled parametric oscillators subject to periodic block pulses with initially random phases. The phase diagram of regions of collective parametric instability is presented, as is a detailed characterization of the motions underlying these instabilities. This presentation includes regimes not ident

E. V. Sampathkumaran, Subham Majumdar

The results of electrical resistance (1.4 - 300 K), magnetization (2-300 K) and heat-capacity (2 - 50 K) measurements in Y$_2$PdGe$_3$, found to crystallize in a AlB$_2$-derived hexagonalstructure, are reported. The results establish that this compound is superconducting below 3 K. This obervation is interesting considering that this compound is the first su

J. C. Phillips

What is the microscopic interaction responsible for high temperature superconductivity (HTSC)? Here data on temporal relaxation of Tc and the room temperature conductivity in YBa2Cu3O(6+x) after abrupt alteration by light pulses or pressure changes are analyzed. The analysis proves, independently of microscopic details, that only electron-phonon interactions

Leonid P. Rokhinson, L. J. Guo, D. C. Tsui, S. Y. Chou

We investigated electron transport through ultra small Si quantum dots. We found that the $B$-dependence of energy levels is dominated by the Zeeman shift, allowing us to measure the spin difference between two successive ground states directly. In some dots the number of electrons N in the dot can be tuned starting from zero, and the total spin of the dot c

Emmanuele Cappelluti

The standard mean field slave-boson solution for the infinite-$U$ Hubbard model is revised. A slightly modified version is proposed which includes properly the incoherent contribution of the localized states. In contrast to the standard mean field result, this new proposed solution defines a unique spectral function to be used in the calculation of local and

C. J. Pethick, H. T. C. Stoof

We consider the effect of interactions on the line shape of the two-photon 1s-2s transition in a (doubly) spin-polarized atomic hydrogen gas in terms of the interatomic interaction potentials. We show that the frequency-weighted sum rule for the intensity of the line is not given simply in terms of the pseudopotentials that describe the interactions between

J. Zaanen, O. Y. Osman, H. V. Kruis, Z. Nussinov

It is argued that the electron stripes as found in correlated oxides have to do with an unrecognized form of order. The manifestation of this order is the robust property that the charge stripes are at the same time anti-phase boundaries in the spin system. We demonstrate that the quantity which is ordering is sublattice parity, referring to the geometric pr

Alexander Bühler, Ute Löw, Götz S. Uhrig

By high temperature series expansion, exact diagonalisation and temperature density-matrix renormalisation the magnetic susceptibility $χ(T)$ and the specific heat $C(T)$ of dimerised and frustrated $S=1/2$ chains are computed. All three methods yield reliable results, in particular for not too small temperatures or not too small gaps. The series expansion r

R. Golestanian, A. Ajdari, J. -B. Fournier

Fluctuation-induced interactions between anisotropic objects immersed in a nematic liquid crystal are shown to depend on the relative orientation of these objects. The resulting long-range ``Casimir'' torques are explicitely calculated for a simple geometry where elastic effects are absent. Our study generalizes previous discussions restricted to the

E. T. Seppälä, M. J. Alava

The ground state structure of the two-dimensional random field Ising magnet is studied using exact numerical calculations. First we show that the ferromagnetism, which exists for small system sizes, vanishes with a large excitation at a random field strength dependent length scale. This {\it break-up length scale} $L_b$ scales exponentially with the squared

Sher Alam, M. O. Rahman, T. Yanagisawa, H. Oyanagi

Previously we have indicated the relationship between quantum groups and strings via WZWN models. In this note we discuss this relationship further and point out its possible applications to cuprates and related materials. The connection between quantum groups and strings is one way of seeing the validity of our previous conjecture [i.e. that a theory for cu

Xin Zhou, Hu Chen, Ou-Yang Zhong-can

A simple method to calculate the static electric polarization of single-walled carbon nanotube (SWNT) is obtained within the second-order perturbation approximation. The results are in agreement with the previous calculation within the random-phase approximation. We also find that the low energy electronic band structure of SWNT can be affected by an externa

James P. Sethna, Karin A. Dahmen, Christopher R. Myers

Crackling noise arises when a system responds to changing external conditions through discrete, impulsive events spanning a broad range of sizes. A wide variety of physical systems exhibiting crackling noise have been studied, from earthquakes on faults to paper crumpling. Because these systems exhibit regular behavior over many decades of sizes, their behav

Seung-Yeon Kim, Richard J. Creswick

The Q-state Potts model can be extended to noninteger and even complex Q in the FK representation. In the FK representation the partition function,Z(Q,a), is a polynomial in Q and v=a-1(a=e^-T) and the coefficients of this polynomial,Phi(b,c), are the number of graphs on the lattice consisting of b bonds and c connected clusters. We introduce the random-clus

Per Hedegard

It is suggested that modes, observed in recent neutron scattering experiments by Lake {\it et al.}, on La$_{2-x}$Sr$_x$CuO$_4$ in strong magnetic fields ($\approx$ 7 T), are due to the existence of antiferromagnetic moments associated with the cores of vortices generated by the field. These moments form one-dimensional chains along the $c$-axis (the vortex a

S. Chaty, I. F Mirabel, J. Marti, L. F. Rodriguez

We present photometric and spectroscopic optical and near-infrared (NIR) observations (Based on observations collected at the European Southern Observatory, Chile (ESO ID 63.H-0493 and 64.H-0382)) taken during the outburst of the recently flaring source V4641 Sgr = SAX J1819.3-2525 (in't Zand et al., 2000), on September 1999. This source was independentl

Xavier Dupac, M. Giard, J. -P. Bernard, J. -M. Lamarre

We have mapped with the French submillimeter balloon-borne telescope ProNaOS the thermal emission of the dust in the M42 Orion Nebula. The map obtained is 50' by 40' with an angular resolution of about 3' in the four efficient wavelengths 200 $\mic$, 260 $\mic$, 360 $\mic$ and 580 $\mic$. The temperature and index we obtain are highly variable wi

S. Chaty, C. A. Haswell, R. I. Hynes, C. R. Shrader

We report here on multiwavelength observations of the two new soft X-ray transients (SXTs) XTE J1859+226 and XTE J1118+480, which we observed with HST/RXTE/UKIRT. For XTE J1118+480 we also used EUVE since it is located at a very high galactic latitude and suffers from very low extinction. The two sources exhibited very different behaviour. XTE J1859+226 seem

Xavier Dupac, Martin Giard

We present in this article two different ways to make CMB maps in practice, from large timelines. One is to make a simple destriping, fitting the data and using the scan intercepts to remove the low frequency noise (stripes). The second, optimal, is to resolve linearly the map-making problem, which in case of big timelines must be simplified and changed from

Martin Still, Kieran O'Brien, Keith Horne, Danny Hudson

We present RXTE monitoring of the eclipsing X-ray binary Hercules X-1 conducted over the short-high state of July 1998. This was one of the last major short-high states before the source entered an anomalous low-state of activity. A comparison with previous epochs finds no evidence for special behavior during these observations. We determine orbital and puls

Boudewijn F. Roukema

The inner product provides a conceptually and algorithmically simple method for calculating the comoving distance between two cosmological objects given their redshifts, right ascension and declination, and arbitrary constant curvature. The key to this is that just as a distance between two points `on' the surface of the ordinary 2-sphere ${\cal S}^2$ is

Bing Zhang

Soft gamma-ray repeaters (SGRs) and Anomalous X-ray pulsars (AXPs) are generally accepted to be magnetars. Recently, Zhang, Xu & Qiao (2000, ApJ, 545, L127) proposed an alternative viewpoint about the nature of the SGRs (and AXPs). In this picture, SGR bursts are attributed to the impacts of some comet-like objects with the central bare strange star. Here I

Bing Zhang, Alice K. Harding

Photon splitting is a QED process that can potentially suppress pair production in the inner magnetosphere of a pulsar with a super-strong magnetic field, and hence, may quench radio emission from these objects. While it is unknown how many splitting modes really operate in super-critical fields, we derive gap parameters of a high magnetic field pulsar for b

D. Kunth, G. Ostlin

We find no evidence for the presence of genuinely young galaxies in our Local universe. We argue that the metal deficiencies and the behavior of the N/O and C/O ratios meet several plausible explanations involving the primary and secondary nature of these elements and their dispersion and mixing by massive stars and intermediate mass stars. Colors are to be

Boudewijn F. Roukema

Several recent observations using standard rulers and standard candles now suggest, either individually or in combination, that the Universe is close to flat, i.e. that the curvature radius is about as large as the horizon radius (\sim 10h^{-1}Gpc) or larger. Here, a method of distinguishing an almost flat universe from a precisely flat universe using a sing

W. V. Dixon, S. Sallmen, M. Hurwitz, R. Lieu

We have obtained FUV spectra of two clusters of galaxies with FUSE, the Far Ultraviolet Spectroscopic Explorer. The Coma cluster was observed for a total of 28.6 ksec, the Virgo cluster for 10.9 ksec. Neither spectrum shows significant O VI (1032, 1038 A) emission at the cluster redshift. Such emission would be expected from the warm [(5-10) x 10^5 K] compon

T. Bloecker, Y. Balega, K. -H. Hofmann, G. Weigelt

(abridged) NML Cyg is a highly evolved OH/IR supergiant and supposed to be among the most luminous supergiants in the galaxy. We present the first diffraction limited 2.13micron observations of NML Cyg with 73mas resolution. The speckle interferograms were obtained with the SAO 6m telescope, image reconstruction is based on the bispectrum speckle interferome

M. Sikora, M. Blazejowski, M. C. Begelman, R. Moderski

Theories of high energy radiation production in quasar jets can be verified by studies of both time-averaged spectra and variability patterns. While the former has been explored extensively, the latter is in its infancy. In this paper, we study the production of short-term flares in the shock-in-jet model. We examine how the flares' profiles depend on su

Marco Scodeggio

The traditional use of fixed apertures in determining the well known color-magnitude (CM) relation of early type galaxies, coupled with the presence of radial color gradients within these systems, introduces a bias in the CM relation itself. The effect of this bias is studied here deriving a CM relation which is based on color measurements carried out homoge

A. -L. Melchior, S. M. G. Hughes, J. Guibert

We extend the work developed in previous papers on microlensing with a selection of variable stars. We use the Pixel Method to select variable stars on a set of 2.5 x 10**6 pixel light curves in the LMC Bar presented elsewhere. The previous treatment was done in order to optimise the detection of long timescale variations (larger than a few days) and we furt

F. Bocchino, R. S. Warwick, P. Marty, D. Lumb

An \xmm observation of the plerionic supernova remnant 3C58 has allowed us to study the X-ray nebula with unprecedented detail. A spatially resolved spectral analysis with a resolution of 8\arcsec has yielded a precise determination of the relation between the spectral index and the distance from the center. We do not see any evidence for bright thermal emis

A. -L. Melchior, F. Combes, B. Guiderdoni, S. Hatton

The next generation of submillimetre/millimetre instruments will provide us with a deeper insight into the mechanisms that rule galaxy formation. As the brightest starbursts are thought to be heavily obscured at optical wavelengths, the opening of this new window will complement the present observations, and enable a detailed investigation of the hierarchica

W. B. Burton, R. Braun, J. N. Chengalur

Ten isolated compact high-velocity clouds (CHVCs) of the type cataloged by Braun & Burton (1999) have been imaged with the Arecibo telescope and were found to have a nested core/halo morphology. We argue that a combination of high-resolution filled-aperture and synthesis data is crucial to determining the intrinsic properties of the CHVCs. We identify the ha

M. J. Pivovaroff, V. M. Kaspi, F. Camilo, B. M. Gaensler

PSR J1119-6127 is a recently discovered 1700-year-old radio pulsar that has a very high inferred surface dipolar magnetic field. We present a detailed analysis of a pointed ASCA observation and archival ROSAT data of J1119-6127 and its surroundings. Both data sets reveal extended emission coincident with the newly-discovered radio supernova remnant G292.2-0.

Z. -Q. Shen, D. R. Jiang, S. Kameno, Y. J. Chen

We present the results of 5 GHz VLBI observations of a compact steep spectrum source 3C 138. The data are consistent with the western end being the location of the central activity. The observed offset between different frequencies in the central region of 3C 138 can be accounted for by a frequency dependent shift of the synchrotron self-absorbed core. Our n

N. W. Evans

Unhappily, there has been a maelstrom of problems for dark matter theories over the last few years and many serious difficulties still have no resolution in sight. This article reviews the evidence for dark matter in galaxies. The haloes built up by hierarchical merging in dark matter cosmogonies are cusped and dominated by dark matter at the center. Evidenc

J. Gascon, A. Benoit, A. Bonnevaux, L. Berge

The EDELWEISS Dark Matter search uses low-temperature Ge detectors with heat and ionisation read- out to identify nuclear recoils induced by elastic collisions with WIMPs from the galactic halo. Results from the operation of 70 g and 320 g Ge detectors in the low-background environment of the Modane Underground Laboratory (LSM) are presented.

Z. Chacko, Patrick J. Fox

We study the linearized metric perturbation corresponding to the radion for the generalization of the five dimensional two brane setup of Randall and Sundrum to the case when the curvature of each brane is locally constant but non-zero. We find the wave fuction of the radion in a coordinate system where each brane is sitting at a fixed value of the extra coo

Qiang-Hua Wang, Jung Hoon Han, Dung-Hai Lee

The current pattern in the mixed state of high-$T_{c}$ superconductors is studied in the U(1) mean field theory of the t-J model. Our findings are the following. 1) In the absence of antiferromagnetism a robust staggered current pattern exists in the core of vortices if the doping is not too high. 2) At a fixed doping and with increasing magnetic field, the

Manuel Perez-Victoria

We discuss the regularization and renormalization of QED with Lorentz and CPT violation, and argue that the coefficient of the Chern-Simons term is an independent parameter not determined by gauge invariance. We also study these issues in a model with spontaneous breaking of Lorentz and CPT symmetries and find an explicit relation with the ABJ anomaly. This

A. E. Margolin, V. I. Strazhev, A. Ya. Tregubovich

Calculation aspects of holonomic quantum computer (HQC) are considered. Wilczek--Zee potential defining the set of quantum calculations for HQC is explicitly evaluated. Principal possibility of realization of the logical gates for this case is discussed.

L. Homer, P. A. Charles, D. Chakrabarty, L. van Zyl

We report the first extensive set of optical photometric observations of the counterpart to SAX J1808.4-3658 (V4580 Sagittarius) in quiescence. The source was detected at V~21, 5 magnitudes fainter than at the peak of its 1998 outburst. However, a comparable ~6% semi-amplitude 2hr modulation of its flux is revealed. This has the same phasing and approximatel

Michael I. Eides, Valery A. Shelyuto

We derive a compact Yennie gauge representation for the off-shell one-loop electron-photon vertex, and discuss it properties. This expression is explicitly infrared finite, and it has proved to be extremely useful in multiloop calculations in the QED bound state problem.

P. G. Silvestrov, Y. Imry

The role of spin is investigated in the transport through a quantum dot with two overlapping resonances (one having a width larger than the level separation and the other very narrow, cf. Silvestrov and Imry, Phys. Rev. Lett. {\bf 85}, 2565 (2000)). For a series of consecutive charging resonances, one electron from the leads populates one and the same broad

H. Azuma, S. Bose, V. Vedral

We investigate the creation of entanglement by the application of phases whose value depends on the state of a collection of qubits. First we give the necessary and sufficient conditions for a given set of phases to result in the creation of entanglement in a state comprising of an arbitrary number of qubits. Then we analyze the creation of entanglement betw

S. Miyashita, E. Vincent

Aging in spin glasses (and in some other systems) reveals astonishing effects of `rejuvenation and memory' upon temperature changes. In this paper, we propose microscopic mechanisms (at the scale of spin-spin interactions) which can be at the origin of such phenomena. Firstly, we recall that, in a frustrated system, the effective average interaction betw

M. Mihalkovič, I. Al-Lehyani, E. Cockayne, C. L. Henley

Quasicrystals are metal alloys whose noncrystallographic symmetry and lack of structural periodicity challenge methods of experimental structure determination. Here we employ quantum-based total-energy calculations to predict the structure of a decagonal quasicrystal from first principles considerations. We employ Monte Carlo simulations, taking as input the

Mark Alford

I review recent progress in our understanding of the color superconducting phase of matter above nuclear density, giving particular emphasis to the effort to find observable signatures of the presence of this phase in compact stars.

H. W. Diehl, M. Smock

A class of continuum models with a critical end point is considered whose Hamiltonian ${\mathcal{H}}[ϕ,ψ]$ involves two densities: a primary order-parameter field, $ϕ$, and a secondary (noncritical) one, $ψ$. Field-theoretic methods (renormalization group results in conjunction with functional methods) are used to give a systematic derivation of singularitie

I. Eremin, D. Manske, C. Joas, K. H. Bennemann

Using a two-dimensional Hubbard Hamiltonian for the three electronic bands crossing the Fermi level in Sr$_2$RuO$_4$ we calculate the band structure and spin susceptibility $χ({\bf q}, ω)$ in quantitative agreement with nuclear magnetic resonance (NMR) and inelastic neutron scattering (INS) experiments. The susceptibility has two peaks at {\bf Q}$_i = (2π/3,

Jongsoon Park, Vladimir Privman, Egon Matijevic

Ample experimental evidence has been accumulated demonstrating that the formation of monodispersed colloids proceeds through a more complex mechanism, than the generally excepted diffusional "burst nucleation" process. Instead, the synthesis of narrow-size-distribution colloidal dispersions involves several stages, i.e., nuclei produced in a supersat

S. Fukae

I analyzed the CP asymmetry of $B\to X_sl^+l^-$ based on model-independent analysis which includes twelve independent four Fermi operators. The CP asymmetry is suppressed in the Standard Model, however, if some new physics make it much larger, the present or the next generation B factories may catch the CP violation in this decay mode. In this paper, we stud

Christof Wetterich

We propose a simple explanation for the connection between chiral symmetry restoration and deconfinement in QCD at high temperature. In the Higgs description of the QCD vacuum both spontaneous chiral symmetry breaking and effective gluon masses are generated by the condensate of a color octet quark-antiquark pair. The transition to the high temperature state

Kazuhiro Kuboki

Effects of the band structure on the symmetry of superconducting (SC) states are studied. For a square lattice system with a nearest-neighbor attractive interaction, SC states with various symmetries are found by changing the band structure, or, the shape of the Fermi surface. The spin-triplet ($(p_x + ip_y)$-wave) and spin-singlet ($d$- or s-wave) SC states

Erik Kuulkers

I propose that the properties of the two outbursts observed in the X-ray transient XTE J1118+480 in 2000 are akin to superoutbursts of SU UMa stars. In these systems a `normal' outburst immediately precedes a 5-10 times longer (`super')outburst. The optical light curve of the outbursts of XTE J1118+480 is remarkably similar to that seen in some SU UM

A. K. Chaudhuri

We have analyzed the latest NA50 data on transverse energy distributions and $J/ψ$ suppression in Pb+Pb collisions. The transverse energy distribution was analysed in the geometric model of AA collisions. In the geometric model, fluctuations in the number of NN collisions at fixed impact parameter are taken into account. Analysis suggests that in Pb+Pb colli

Jerome Novak

Numerical Relativity is concerned with solving the Einstein equations, as well as any field or matter equations on curved space-time, by means of computer calculations. The methods developed for this purpose up to now, as well as the addressed physical problems are getting more numerous every day. This is a brief summary of the presentations which have been

G. L. Alberghi, R. Casadio, G. P. Vacca, G. Venturi

We study the collapse of a self-gravitating and radiating shell. Matter constituting the shell is quantized and the construction is viewed as a semiclassical model of possible black hole formation. It is shown that the shell internal degrees of freedom are excited by the quantum non-adiabaticity of the collapse and, consequently, on coupling them to a massle

T. A. Lahde, D. O. Riska

The widths for $ππ$ decay of the L=1 charm mesons are calculated by describing the pion coupling to light constituents quarks by the lowest order chiral interaction. The wavefunctions of the charm mesons are obtained as solutions to the covariant Blankenbecler-Sugar equation. These solutions correspond to an interaction Hamiltonian modeled as the sum of a li

H. Jirari, H. Kröger, X. Q. Luo, K. J. M. Moriarty

We suggest how to construct non-perturbatively a renormalized action in quantum mechanics. We discuss similarties and differences with the standard effective action. We propose that the new quantum action is suitable to define and compute quantum instantons and quantum chaos.

G. Hackenbroich, C. Viviescas, B. Elattari, F. Haake

We derive the photocount statistics of the radiation emitted from a chaotic laser resonator in the regime of single-mode lasing. Random spatial variations of the resonator eigenfunctions lead to strong mode-to-mode fluctuations of the laser emission. The distribution of the mean photocount over an ensemble of modes changes qualitatively at the lasing transit

M. Keyl, R. F. Werner

Given N quantum systems prepared according to the same density operator ρ, we propose a measurement on the N-fold system which approximately yields the spectrum of ρ. The projections of the proposed observable decompose the Hilbert space according to the irreducible representations of the permutations on N points, and are labeled by Young frames, whose relat

J. Delgado, E. C. Yustas, L. L. Sanchez-Soto, A. B. Klimov

We explore the role played by the quantum relative phase in a well-known model of atom-field interaction, namely, the Dicke model. We introduce an appropriate polar decomposition of the atom-field relative amplitudes that leads to a truly Hermitian relative-phase operator, whose eigenstates correctly describe the phase properties, as we demonstrate by studyi

Luca Marinatto, Tullio Weber

We analyze in a critical way the mathematical treatment of a quantum teleportation experiment performed with photon particles, showing that a symmetrization operation over both the polarization and spatial degrees of freedom of all the particles involved is necessary in order to reproduce correctly the observed experimental data.

R. F. Werner, M. M. Wolf

We construct a set of 2^(2^n) independent Bell correlation inequalities for n-partite systems with two dichotomic observables each, which is complete in the sense that the inequalities are satisfied if and only if the correlations considered allow a local classical model. All these inequalities can be summarized in a single, albeit non-linear inequality. We

M. Franca Santos, P. Milman, A. Z. Khoury, P. H. Souto Ribeiro

We produce polarization entangled states with variable degree of entanglement for twin photons. Entanglement in polarization is coupled to entanglement in position that produces transverse coincidence interference fringes. We show both theoretically and experimentally that, due to this coupling, we can use the interference pattern to measure the polarization

Dae-Yup Song

For the models of $N$-body identical harmonic oscillators interacting through potentials of homogeneous degree -2, the unitary operator that transforms a system of time-dependent parameters into that of unit spring constant and unit mass of different timescale is found. If the interactions can be written in terms of the differences between positions of two p

Vladimir V. Voronov

The analysis of papers on usage NMR in quantum computations is provided and the probable direction of the future investigations are considered.

M. Sasaki, A. Carlini, R. Jozsa

We consider the quantum analogue of the pattern matching problem, which consists of classifying a given unknown system according to certain predefined pattern classes. We address the problem of quantum template matching in which each pattern class ${\cal C}_i$ is represented by a known quantum state $\hat g_i$ called a template state, and our task is to find

Tony Rothman, E. C. G. Sudarshan

Despite claims that Bell's inequalities are based on the Einstein locality condition, or equivalent, all derivations make an identical mathematical assumption: that local hidden-variable theories produce a set of positive-definite probabilities for detecting a particle with a given spin orientation. The standard argument is that because quantum mechanics

Marc Toussaint

We address a primary question of computational as well as biological research on evolution: How can an exploration strategy adapt in such a way as to exploit the information gained about the problem at hand? We first introduce an integrated formalism of evolutionary search which provides a unified view on different specific approaches. On this basis we discu

Albert M. Chechelnitsky

Invariablly justified representations of the Wave Universe Concept-WU Concept (see monography-Chechelnitsky A.M. Extremum, Stability and Resonance in Astrodynamics..., etc. and other publications) indicate a principle incorrectness of expectations of Standard (Model) cosmology about homogeneity and isotropy of the Universe. It also is connected with observat

P. P. Kulish, N. Manojlovic

The eigenvectors of the osp(1|2) invariant Gaudin hamiltonians are found using explicitly constructed creation operators. Commutation relations between the creation operators and the generators of the loop superalgebra are calculated. The coordinate representation of the Bethe states is presented. The relation between the Bethe vectors and solutions to the K

Tai-Peng Tsai, Horng-Tzer Yau

We consider a linear Schrödinger equation with a small nonlinear perturbation in $R^3$. Assume that the linear Hamiltonian has exactly two bound states and its eigenvalues satisfy some resonance condition. We prove that if the initial data is near a nonlinear ground state, then the solution approaches to certain nonlinear ground state as the time tends to in

Adam S. Sikora

An SL_n-character of a group G is the trace of an SL_n-representation of G. We show that all algebraic relations between SL_n-characters of G can be visualized as relations between graphs (resembling Feynman diagrams) in any topological space X, with pi_1(X)=G. We also show that all such relations are implied by a single local relation between graphs. In thi

J. M. Speight

Harmonic maps from S^2 to S^2 are all weakly conformal, and so are represented by rational maps. This paper presents a study of the L^2 metric gamma on M_n, the space of degree n harmonic maps S^2 -> S^2, or equivalently, the space of rational maps of degree n. It is proved that gamma is Kaehler with respect to a certain natural complex structure on M_n. The

Masatoshi Kokubu, Masaaki Umehara, Kotaro Yamada

In the previous paper, Takahasi and the authors generalized the theory of minimal surfaces in Euclidean n-space to that of surfaces with holomorphic Gauss map in certain class of non-compact symmetric spaces. It also includes the theory of constant mean curvature one surfaces in hyperbolic 3-space. Moreover, a Chern-Osserman type inequality for such surfaces

M. Havlicek, A. U. Klimyk, S. Posta

We study the nonstandard $q$-deformation $U'_q({\rm so}_4)$ of the universal enveloping algebra $U({\rm so}_4)$ obtained by deforming the defining relations for skew-symmetric generators of $U({\rm so}_4)$. This algebra is used in quantum gravity and algebraic topology. We construct a homomorphism $ϕ$ of $U'_q({\rm so}_4)$ to the certain nontrivial e

Masaaki Umehara, Wayne Rossman, Kotaro Yamada

In this work, complete constant mean curvature 1 (CMC-1) surfaces in hyperbolic 3-space with total absolute curvature at most 4 pi are classified. This classification suggests that the Cohn-Vossen inequality can be sharpened for surfaces with odd numbers of ends, and a proof of this is given.

Niranjan Ramachandran

Deligne has conjectured that certain mixed Hodge theoretic invariants of complex algebraic invariants are motivic. This conjecture specializes to an algebraic construction of the Jacobian for smooth projective curves, which was done by A. Weil. The conjecture (and one-motives) are motivated by means of Jacobians, generalized Jacobians of Rosenlicht, and Serr

Benson Farb, Lee Mosher

A survey of problems, conjectures, and theorems about quasi-isometric classification and rigidity for finitely generated solvable groups.

Bruce A. Campbell, Kirk Kaminsky

We examine noncommutative linear sigma models with U(N) global symmetry groups at the one-loop quantum level, and contrast the results with our previous study of the noncommutative O(N) linear sigma models where we have shown that Nambu-Goldstone symmetry realization is inconsistent with continuum renormalization. Specifically we find no violation of Goldsto

Uwe Trittmann

String/Field theory correspondences have been discussed heavily in recent years. Here, we describe a testing scenario involving a non-perturbative field theory calculation using the framework of supersymmetric discrete light-cone quantization (SDLCQ). We consider a Maldacena-type conjecture applied to the near horizon geometry of a D1-brane in the supergravi

Abdur Rahim Choudhary

In this paper we use the analyticity properties of the scattering amplitude in the context of the conformal mapping techniques. The Schwarz-Christoffel and Riemann-Schwarz functions are used to map the upper half -plane onto a triangle. We use the known asymptotic and threshold behaviors of the scattering amplitude to establish a connection between the value

Ilka Brunner, Jacques Distler

In a geometrical background, D-brane charge is classified by topological K-theory. The corresponding classification of D-brane charge in an arbitrary, nongeometrical, compactification is still a mystery. We study D-branes on non-simply-connected Calabi-Yau 3-folds, with particular interest in the D-branes whose charges are torsion elements of the K-theory. W

B. Sathiapalan

In earlier papers on the loop variable approach to gauge invariant interactions in string theory, a ``wave functional'' with some specific properties was invoked. It had the purpose of converting the generalized momenta to space time fields. In this paper we describe this object in detail and give some explicit examples. We also work out the interact

Pierre Ramond

Reminiscences on the String origins of Supersymmetry are followed by a discussion of the importance of confusing bosons with fermions in building superstring theories in 9+1 dimensions. In eleven dimensions, the kinship between bosons and fermions is more subtle, and may involve the exceptional group $F_4$.

Daniel S. Freed

The main new result here is the cancellation of global anomalies in the Type I superstring, with and without D-branes. Our argument here depends on a precise interpretation of the 2-form abelian gauge field using KO-theory; then the anomaly cancellation follows from a geometric form of the full Atiyah-Singer index theorem for families of Dirac operators. Thi

D. H. Beck, B. R. Holstein

We review the area of strange quark contributions to nucleon structure. In particular, we focus on current models of strange quark vector currents in the nucleon and the associated parity-violating elastic electron scattering experiments from which vector- and axial-vector currents are extracted

V. Barger

The physics agenda for future long-baseline neutrino oscillation experiments is outlined and the prospects for accomplishing those goals at future neutrino facilities are considered. Neutrino factories can deliver better reach in the mixing and mass-squared parameters but conventional super-beams with large water or liquid argon detectors can probe regions o

Stanley J. Brodsky

A fundamental goal in QCD is to understand the non-perturbative structure of hadrons at the amplitude level--not just the single-particle flavor, momentum, and helicity distributions of the quark constituents, but also the multi-quark, gluonic, and hidden-color correlations intrinsic to hadronic and nuclear wavefunctions. A natural calculus for describing th

Mario E. Gomez

The cosmological relic density of the lightest supersymmetric particle of the minimal supersymmetric standard model is calculated under the assumption of gauge and Yukawa coupling unification. We employ radiative electroweak breaking with universal boundary conditions from gravity-mediated supersymmetry breaking. Further constraints are imposed by the experi

Massimo Blasone, Antonio Capolupo, Oreste Romei, Giuseppe Vitiello

We consider the quantum field theoretical formulation of boson field mixing and obtain the exact oscillation formula. This formula does not depend on arbitrary mass parameters. We show that the space for the mixed field states is unitarily inequivalent to the state space where the unmixed field operators are defined. We also study the structure of the curren

Paolo Lipari

This work discusses critically the prospects of measuring CP and T violation effects in high energy neutrino factories. For this purpose we develop, in the standard framework with three neutrino flavors, simple expressions for the oscillation probabilities in matter that are valid for high E_nu. All CP violating effects vanish as E_nu^(-3) and are very diffi

Junji Hisano, Mihoko M. Nojiri, Nobuchika Okada

The gauge-mediated SUSY-breaking (GMSB) model needs entropy production at a relatively low temperature in the thermal history of the Universe for the unwanted relics to be diluted. This requires a mechanism for the baryogenesis after the entropy production, and the Affleck and Dine (AD) mechanism is a promising candidate for it. The AD baryogenesis in the GM

Michael G. Schmidt

We argue that the creation of a baryon asymmetry in the early universe is an intriguing case where several aspects of ``Beyond'' physics are needed. We then concentrate on baryogenesis in a strong first-order phase transition and discuss that supersymmetric variants of the electroweak theory (MSSM and some version of NMSSM) rather naturally provide t

Thomas Hebbeker, Charles Timmermans

We collect and combine all published data on the vertical atmospheric muon flux and the muon charge ratio for muon momenta above 10 GeV. At sea level the world average of the momentum spectra agrees with the flux calculated by E.V. Bugaev et al. within 15%. The observed shape of the differential flux versus momentum is slightly flatter than predicted in this

Davison E. Soper

Calculations of observables in quantum chromodynamics are typically performed using a method that combines numerical integrations over the momenta of final state particles with analytical integrations over the momenta of virtual particles. I review a method for performing all of the integrations numerically. In this method, the real-virtual cancellations hap

V. A. Maisheev

The equations for variation of the Stokes parameters and intensity of photons propagating in a medium, whose optical properties may be described by the permittivity tensor, are derived. Classification of different cases of photon propagation is suggested on a basis of these equations.

Hans-Christian Schultz-Coulon

Jet production in electron-proton collisions at HERA provides a unique testing ground for Quantum Chromodynamics (QCD). Apart from the determination of the strong coupling constant $α_s$, ep jet data may especially be used to gain insight into the dynamics of the exchanged parton cascade, whose structure is probed by the high-$E_T$ dijet system; thus informa