March 2001 arXiv papers — page 20

Hans-Christian Pauli

The effective interaction between a quark and an anti-quark as obtained previously with by the method of iterated resolvents is replaced by the up-down-model and applied to flavor off-diagonal mesons including the positive pion. The only free parameters are the canonical ones, the coupling constant and the masses of the quarks.

Hans-Christian Pauli

The effective quark-antiquark-interaction is derived from Lagrangian QCD in the front form by means of the flow equations. It coincides with previous results.

Hans-Christian Pauli

For the purpose of consistent notation and easy reference the most important relations in light-cone quantization are compiled from a recent review (Brodsky, Pauli Pinsky, Physics Reports 301 (1998) 299), where all further details and derivations can be found. Some further typos are removed.

Hael Collins, Bob Holdom

We investigate a scenario with two four-branes embedded in six dimensions. When the metric is periodic and compact in one of the dimensions parallel to the branes, the value of the effective cosmological constant for the remaining five dimensions can assume a variety of values, determined by the dependence of the metric on the sixth dimension. The picture th

K. K. Gan

An optical package of novel design has been developed for the ATLAS pixel detector. The package contains two VCSELs and one PIN diode to transmit and receive optical signals. The design is based on a simple connector-type concept and is made of radiation-hard material. Several packages have been fabricated and show promising results.

K. K. Gan

This is a review of some of the highlights of the 6th workshop on the physics of the tau lepton and its neutrino. This includes the test of lepton universality, measurement of Lorentz Structure, study of hadronic decays, direct evidence of tau neutrino, status of neutrino oscillations, and search for neutrinoless decays. This review concludes with a look at

M. Ashida, Y. Taguchi, Y. Tokura, R. T. Clay

Femtosecond pump-probe measurements find pronounced dimensionality dependence of the optical nonlinearity in cuprates. Although the coherent two-photon absorption (TPA) and linear absorption bands nearly overlap in both quasi-one and two-dimensional (1D and 2D) cuprates, the TPA coefficient is one order of magnitude smaller in 2D than in 1D. Furthermore, pic

Raul Cruz Hidalgo, Ferenc Kun, Hans. J. Herrmann

We study the creep rupture of bundles of viscoelastic fibers occurring under uniaxial constant tensile loading. A novel fiber bundle model is introduced which combines the viscoelastic constitutive behaviour and the strain controlled breaking of fibers. Analytical and numerical calculations showed that above a critical external load the deformation of the sy

Hirokazu Tsunetsugu

The ground state of the S=1/2 Heisenberg antiferromagnet on the pyrochlore lattice is theoretically investigated. Starting from the limit of isolated tetrahedra, I include interactions between the tetrahedra and obtain an effective model for the spin-singlet ground state multiplet by third-order perturbation. I determine its ground state using the mean-field

Yukitoshi Motome, Nobuo Furukawa

Critical phenomena of ferromagnetic transition at finite temperatures are studied in double-exchange systems. In order to investigate strong interplay between charge and spin degrees of freedom, Monte Carlo technique is applied to include fluctuations in a controlled and unbiased manner. By using finite-size scaling analysis, critical exponents and transitio

O. Naaman, W. Teizer, R. C. Dynes

We demonstrate Josephson tunneling in vacuum tunnel junctions formed between a superconducting scanning tunneling microscope tip and a Pb film, for junction resistances in the range 50-300 k$Ω$. We show that the superconducting phase dynamics is dominated by thermal fluctuations, and that the Josephson current appears as a peak centered at small finite volta

C. H. Chung, J. B. Marston, Subir Sachdev

We study possible paramagnetic phases of antiferromagnets on the Shastry-Sutherland lattice by a gauge-theoretic analysis of fluctuations in a theory with Sp(2N) symmetry. In addition to the familiar dimer phase, we find a confining phase with plaquette order, and a topologically ordered phase with deconfined S=1/2 spinons and helical spin correlations. The

C. M. Baugh, A. J. Benson, S. Cole, C. S. Frenk

There is now compelling evidence in favour of the hierarchical structure formation paradigm. Semi-analytic modelling is a powerful tool which allows the formation and evolution of galaxies to be followed in a hierarchical framework. We review some of the latest developments in this area before discussing how such models can help us to interpret observations

J. Machalski, M. Jamrozy, S. Zola

A new sample of very large angular size radio sources has been selected from the 1.4 GHz VLA surveys: FIRST and NVSS. This sample will be very useful for an observational constraint on the time evolution of double radio sources, especially their size, predicted by numerous analytical models of such evolution (cf. Introduction). In this paper we present radio

Peter A. Sturrock, Mark A. Weber

We carry out a comparative analysis of the GALLEX-GNO solar neutrino data and estimates of the solar internal rotation rate derived from the MDI helioseismology experiment on the SOHO spacecraft. We introduce a statistic, which we evaluate as a function of radius and latitude, that is a measure of the degree of "resonance" of oscillations in the neut

Peter Arnold, Guy D. Moore

Using standard numerical Monte Carlo lattice methods, we study non-universal properties of the phase transition of three-dimensional phi^4 theory of a 2-component real field phi = (phi_1,phi_2) with O(2) symmetry. Specifically, we extract the renormalized values of <phi^2>/u and r/u^2 at the phase transition, where the continuum action of the theory is \int

Peter Arnold, Guy D. Moore

The leading-order effect of interactions on a homogeneous Bose gas is theoretically predicted to shift the critical temperature by an amount Δ\Tc = # a_{scatt} n^{1/3} T_0 from the ideal gas result T_0, where a_{scatt} is the scattering length and n is the density. There have been several different theoretical estimates for the numerical coefficient #. We cl

K. Zarembo

The AdS/CFT correspondence establishes a string representation for Wilson loops in N=4 SYM theory at large N and large 't Hooft coupling. One of the clearest manifestations of the stringy behaviour in Wilson loop correlators is the string-breaking phase transition. It is shown that resummation of planar diagrams without internal vertices predicts the strong-

F. Cachazo, K. Intriligator, C. Vafa

We propose a large N dual of 4d, N=1 supersymmetric, SU(N) Yang-Mills with adjoint field Φand arbitrary superpotential W(Φ). The field theory is geometrically engineered via D-branes partially wrapped over certain cycles of a non-trivial Calabi-Yau geometry. The large N, or low-energy, dual arises from a geometric transition of the Calabi-Yau, where the bran

William A. Ponce, Juan B. Florez, Luis A. Sanchez

Six different models, straightforward extensions of the standard model to SU(3)_c X SU(3)_L X U(1)_X, which do not contain particles with exotic electric charges are described. Two of the models are one family and four are three family models. In two of the three family models one of the families transforms different from the others, and in the other two all

Edward Malec, Gerhard Schaefer

Gravitational waves in the linear approximation propagate in the Schwarzschild spacetime similarly as electromagnetic waves. A fraction of the radiation scatters off the curvature of the geometry. The energy of the backscattered part of an initially outgoing pulse of the quadrupole gravitational radiation is estimated by compact formulas depending on the ini

Daniel F. Litim, Cristina Manuel

QCD with two light quark flavors at high baryonic density and low temperature is a color superconductor. The diquark condensate partially breaks the SU(3) gauge symmetry down to an SU(2) subgroup. We study thermal fluctuations of the superconductor for temperatures below the gap. These are described by a simple transport equation, linked to a quasiparticle b

Michael Haack, Jan Louis

We perform the Kaluza-Klein reduction of M-theory on warped Calabi-Yau fourfolds with non-trivial four-form flux turned on. The resulting scalar- and superpotential is computed and compared with the superpotential obtained by Gukov, Vafa and Witten using different methods.

A. Bianconi, D. Di Castro, S. Agrestini, G. Campi

We have studied the variation of Tc with charge density and lattice parameters in Mg1-xAlxB2 superconducting samples at low Al doping x<8%. We show that high Tc occurs where the chemical potential is tuned at a &#34;superconducting shape resonance&#34; near the energy Ec of the quantum critical point (QCP) for the dimensional transition from 2D to 3D electro

H. Garcia-Compean, O. Obregon, C. Ramirez

Abelian Chern-Simons gauge theory is known to possess a `$S$-self-dual&#39; action where its coupling constant $k$ is inverted {\it i.e.} $k \leftrightarrow {1 \over k}$. Here a vector non-abelian duality is found in the pure non-abelian Chern-Simons action at the classical level. The dimensional reduction of the dual Chern-Simons action to two-dimensions co

J. I. Kapusta, S. M. H. Wong

One and two loop self-energies are worked out explicitly for a heavy scalar field interacting weakly with a light self-interacting scalar field at finite temperature. The ring/daisy diagrams and a set of necklace diagrams can be summed simultaneously. This simple model serves to illustrate the connection between multi-loop self-energy diagrams and multiple s

J. C. Montero, C. A. de S. Pires, V. Pleitez

In a version of the 3-3-1 model proposed by Duong and Ma the introduction of the scalar sextet for giving mass to the charged leptons is avoided by adding a singlet charged lepton. We show that in this case the $τ$ lepton gains mass through a seesaw--like mechanism. Besides we show how to generate neutrino masses at the tree and at the 1-loop level with the

Yukitaka Ishimoto

There exist logarithmic CFTs(LCFTs) such as the $c_{p,1}$ models. It is also well known that it generally contains Jordan cell structure. In this paper, we obtain the boundary Ishibashi state for a rank-2 Jordan cell structure and, with these states in $c=-2$ rational LCFT, we derive boundary states in the closed string picture, which correspond to boundary

J. Chovan, N. Papanicolaou, S. Komineas

The magnetic compound Ba_2CuGe_2O_7 has recently been shown to be an essentially two-dimensional spiral antiferromagnet that exhibits an incommensurate-to-commensurate phase transition when a magnetic field applied along the c-axis exceeds a certain critical value H_c. The T=0 dynamics is described here in terms of a continuum field theory in the form of a n

Abdesslam Arhrib, Chun-Khiang Chua, Wei-Shu Hou

If one has Abelian flavor symmetry, $s_R$-$b_R$ mixing could be near maximal. This can drive a &#34;strange-beauty&#34; squark ($\widetilde{sb}_{1}$) to be rather light, but still evade the $b\to sγ$ constraint. Low energy constraints imply that all other superpartners are at TeV scale, except for a possibly light neutralino, $\widetilde χ_1^0$. Whether ligh

R. P. Vasquez, C. U. Jung, Min-Seok Park, Heon-Jung Kim

A c-axis oriented thin film and a high density sintered pellet of MgB2 have been studied by x-ray photoemission spectroscopy, and compared to measurements from MgO and MgF2 single crystals. The as-grown surface has a layer which is Mg-rich and oxidized, which is effectively removed by a nonaqueous etchant. The subsurface region of the pellet is Mg-deficient.

Gen Yoneda, Hisa-aki Shinkai

The current important issue in numerical relativity is to determine which formulation of the Einstein equations provides us with stable and accurate simulations. Based on our previous work on &#34;asymptotically constrained&#34; systems, we here present constraint propagation equations and their eigenvalues for the Arnowitt-Deser-Misner (ADM) evolution equat

Qingjuan Yu, David N. Spergel, Jeremiah P. Ostriker

During the recombination epoch, cosmic background photons couple not only to free electrons through Thompson scattering, but also to the neutral hydrogen through Rayleigh scattering. This latter is ~2% effect for photons near the peak of the photon energy distribution at z=800 and a ~0.2% effect at z=1100. Including Rayleigh scattering in the calculation red

F. Donato, D. Maurin, P. Salati, A. Barrau

Cosmic ray antiprotons provide an important probe for the study of the galactic Dark Matter, as they could be produced by exotic sources. On the other hand, antiprotons are anyway produced by standard nuclear reactions of cosmic ray nuclei on interstellar matter. This process is responsible for a background flux that must be carefully determined to estimate

Peter Tinyakov, Katarzyna Zuleta

We show that in 6d models localizing gravity on stringlike defects and satisfying the dominant energy condition, the metric exterior to the string inevitably depends on the string&#39;s thickness. As a consequence, in the limit of thin string either the gravity delocalizes, or the six-dimensional Planck scale must be much larger that the four-dimensional one

W. Detmold, W. Melnitchouk, J. W. Negele, D. B. Renner

We present the resolution of a long-standing discrepancy between the moments of parton distributions calculated from lattice QCD and their experimental values. We propose a simple extrapolation formula for the moments of the nonsinglet quark distribution u-d, as a function of quark mass, which embodies the general constraints imposed by the chiral symmetry o

Ashok Das, Ziemowit Popowicz

The Moyal-Lax representation and the Moyal momentum algebra are introduced and systematically investigated. It is shown that the Moyal-Lax equation can be interpreted as a Hamiltonian equation and can be derived from an action. We show that the parameter of non-commutativity, in this case, is related to the central charge of the second Hamiltonian structure

T. Mito, S. Kawasaki, G. -q. Zheng, Y. Kawasaki

We report $^{115}$In nuclear-quadrupole-resonance (NQR) measurements of the pressure($P$)-induced superconductor CeRhIn$_5$ in the antiferromagnetic (AF) and superconducting (SC) states. In the AF region, the internal field $H_{int}$ at the In site is substantially reduced from $H_{int}=1.75$ kOe at P=0 to 0.39 kOe at $P=1.23$ GPa, while the Néel temperature

H. Eberle

We apply Kadanoff&#39;s theory of marginal deformations of conformal field theories to twistfield deformations of Z_2 orbifold models in K3 moduli space. These deformations lead away from the Z_2 orbifold sub-moduli-space and hence help to explore conformal field theories which have not yet been understood. In particular, we calculate the deformation of the

Tsunehiro Kobayashi, Toshiki Shimbori

All two-dimensional Schrödinger equations with symmetric potentials \break $(V_a(ρ)=-a^2g_a ρ^{2(a-1)/2} {with} ρ=\sqrt{x^2+y^2} {and} a\not=0)$ is shown to have zero energy states contained in conjugate spaces of Gel&#39;fand triplets. For the zero energy eigenvalue the equations for all $a$ are reduced to the same equation representing two-dimensional free

Toan T. Nguyen, Boris I. Shklovskii

Adsorption of multivalent counterions on the charged surface of a macroion is known to lead to inversion of the macroion charge due to the strong lateral correlations of counterions. We consider a nontrivial role of the excluded volume of counterions on this effect. It is shown analytically that when the bare charge of macroion increases, its net charge incl

Abhay Ashtekar, Christopher Beetle, Jerzy Lewandowski

Black hole mechanics was recently extended by replacing the more commonly used event horizons in stationary space-times with isolated horizons in more general space-times (which may admit radiation arbitrarily close to black holes). However, so far the detailed analysis has been restricted to non-rotating black holes (although it incorporated arbitrary disto

Eugene Demler, Subir Sachdev, Ying Zhang

We argue that recent neutron scattering measurements by Lake et. al. (Science 291, 1759 (2001)) of the spin excitation spectrum of LSCO in a magnetic field can be understood in terms of proximity to a phase with co-existing superconductivity and spin density wave order. We present a general theory for such quantum transitions, and argue that their low energy

Leo Radzihovsky, A. M. Ettouhami, Karl Saunders, John Toner

Ferromagnetic order in superconductors can induce a {\em spontaneous} vortex (SV) state. For external field ${\bf H}=0$, rotational symmetry guarantees a vanishing tilt modulus of the SV solid, leading to drastically different behavior than that of a conventional, external-field-induced vortex solid. We show that quenched disorder and anharmonic effects lead

Roya Zandi, Joseph Rudnick, Ramin Golestanian

We study the effect of electrostatic interactions on the distribution function of the end-to-end distance of a single polyelectrolyte chain in a rodlike configuration. We investigate the validity of the concept of electrostatic persistence length for uniformly charged wormlike chains for both screened and unscreened Coulomb interactions. We find that the dis

Harald Weinfurter, Marek Zukowski

Double-pair emission from type-II parametric down conversion results in a highly entangled 4-photon state. Due to interference, which is similar to bunching from thermal emission, this state is not simply a product of two pairs. The observation of this state can be achieved by splitting the two emission modes at beam splitters and subsequent detection of a p

Serge Massar, Stefano Pironio

We show how to construct states for which a Greenberger-Horne-Zeilinger type paradox occurs if each party measures either the position or momentum of his particle. The paradox can be ascribed to the anticommutation of certain translation operators in phase space. We then rephrase the paradox in terms of modular and binary variables. The origin of the paradox

Gennaro Auletta

As it is well known, classical mechanics consists of several basic features like determinism, reductionism, completeness of knowledge and mechanicism. In this article the basic assumptions are discussed which underlie those features. It is shown that these basic assumptions - though universally assumed up the beginnings of the XX century - are far from being

S. Prvanovic, Z. Maric

The symmetrized product for quantum mechanical observables is defined. It is seen as consisting of the ordinary multiplication and the application of the superoperator that orders the operators of coordinate and momentum. This superoperator is defined in a way that allows obstruction free quantization when the observables are considered from the point of vie

Alberto Casado, Ramon Risco-Delgado, Emilio Santos

In this article we present a local hidden variables model for all experiments involving photon pairs produced in parametric down conversion, based on the Wigner representation of the radiation field. A modification of the standard quantum theory of detection is made in order to give a local realist explanation of the counting rates in photodetectors. This mo

S. Prvanovic, Z. Maric

The algebra of polynomials in operators that represent generalized coordinate and momentum and depend on the Planck constant is defined. The Planck constant is treated as the parameter taking values between zero and some nonvanishing $h_0$. For the second of these two extreme values, introduced operatorial algebra becomes equivalent to the algebra of observa

Henry P. Stapp

Orthodox Copenhagen quantum theory renounces the quest to understand the reality in which we are imbedded, and settles for practical rules describing connections between our observations. Many physicist have regarded this renunciation of our effort to describe nature herself as premature, and John von Neumann reformulated quantum theory as a theory of an evo

G. Alber, Th. Beth, Ch. Charnes, A. Delgado

A new class of error-correcting quantum codes is introduced capable of stabilizing qubits against spontaneous decay arising from couplings to statistically independent reservoirs. These quantum codes are based on the idea of using an embedded quantum code and exploiting the classical information available about which qubit has been affected by the environmen

D. Bernard, H. Delagrange, D. G. d&#39;Enterria, M. Le Guay

We present an original design for large area gaseous detectors based on the MICROMEGAS technology. This technology incorporates an insulating grid, sandwiched between the micro-mesh and the anode-pad plane, which provides an uniform 200 $μ$m amplification gap. The uniformity of the amplification gap thickness has been verified under several experimental cond

Tomislav Ivezic

Different formulations of special relativity are theoretically discussed. First an invariant formulation, i.e., the &#39;&#39;true transformations (TT) relativity,&#39;&#39; is exposed. There a physical quantity is represented by a true tensor which comprises both components and a basis. Also the usual covariant formulation and the &#39;&#39;apparent transfo

F. Doveil, M-C. Firpo, Y. Elskens, D. Guyomarc&#39;h

Effects induced by the finite number $N$ of particles on the evolution of a monochromatic electrostatic perturbation in a collisionless plasma are investigated. For growth as well as damping of a single wave, discrete particle numerical simulations show a $N$-dependent long time behavior which differs from the numerical errors incurred by vlasovian approache

B. G. Sidharth

In some recent theories including Quantum SuperString theory we encounter duality - it arises due to a non commutative geometry which in effect adds an extra term to the Heiserberg Uncertainity Principle. The result is that the micro world and the macro universe seem to be linked. We show why this is so in the context of a recent cosmological model and a phy

Claus O. Wilke

We investigate the competition between two quasispecies residing on two disparate neutral networks. Under the assumption that the two neutral networks have different topologies and fitness levels, it is the mutation rate that determines which quasispecies will eventually be driven to extinction. For small mutation rates, we find that the quasispecies residin

Rudolph C. Hwa, Jan Pisut, Neva Pisutova

The enhanced suppression of $J/ψ$ production at large $x_F$ in $pA$ collisions is studied in the framework of gluon depletion at large $x_1$. The nonperturbative process that modifies the gluon distribution as the gluons propagate in nuclear matter is described by an evolution equation with a kernal to be determined by phenomenology. With nuclear shadowing a

Klaus Morawetz

The numerical solutions of nonlocal and local Boltzmann kinetic equations for the simulation of peripheral and central heavy ion reactions are compared. The experimental finding of enhancement of mid-rapidity matter shows the necessity to include nonlocal corrections. While the in-medium cross section changes the number of collisions and not the transferred

J-G. Caputo, J. Leon, A. Spire

Numerical simulations of the scattering of a linear plane wave incoming onto a nonlinear medium (sine-Gordon) reveals that: i) nonlinearity allows energy transmission in the forbidden band, ii) this nonlinear transmission occurs beyond an energy threshold of the incoming wave, iii) the process begins (at the threshold) with large amplitude breathers, and the

T. Kanna, M. Lakshmanan

We present the exact bright one-soliton and two-soliton solutions of the integrable three coupled nonlinear Schroedinger equations (3-CNLS) by using the Hirota method, and then obtain them for the general $N$-coupled nonlinear Schroedinger equations (N-CNLS). It is pointed out that the underlying solitons undergo inelastic (shape changing) collisions due to

Andrey A. Sukhorukov, Adrian Ankiewicz, Nail N. Akhmediev

We derive exact analytical solutions describing multi-soliton complexes and their interactions on top of a multi-component background in media with self-focusing or self-defocusing Kerr-like nonlinearities. These results are illustrated by numerical examples which demonstrate soliton collisions and field decomposition between localized and radiation modes.

U. D. Jentschura, J. Zinn-Justin

The energy levels of the double-well potential receive, beyond perturbation theory, contributions which are non-analytic in the coupling strength; these are related to instanton effects. For example, the separation between the energies of odd- and even-parity states is given at leading order by the one-instanton contribution. However to determine the energie

Chin-Lung Wang

We show that for smooth complex projective varieties the most general combinations of chern numbers that are invariant under the K-equivalence relation consist of the complex elliptic genera. Combined with a recent result of Totaro, we deduce that up to complex cobordism any K-equivalence can be decomposed into a sequence of classical flops.

David Borthwick, Alejandro Uribe

For a symplectic manifold with quantizing line bundle, a choice of almost complex structure determines a Laplacian acting on tensor powers of the bundle. For high tensor powers Guillemin-Uribe showed that there is a well-defined cluster of low-lying eigenvalues, whose distribution is described by a spectral density function. We give an explicit computation o

Laurent Freidel, Kirill Krasnov

We analyze the expansion of the fuzzy sphere non-commutative product in powers of the non-commutativity parameter. To analyze this expansion we develop a graphical technique that uses spin networks. This technique is potentially interesting in its own right as introducing spin networks of Penrose into non-commutative geometry. Our analysis leads to a clarifi

L. Alvarez-Gaume, J. L. F. Barbon, R. Zwicky

We propose a physical interpretation of the perturbative breakdown of unitarity in time-like noncommutative field theories in terms of production of tachyonic particles. These particles may be viewed as a remnant of a continuous spectrum of undecoupled closed-string modes. In this way, we give a unified view of the string-theoretical and the field-theoretica

Gerald V. Dunne, Kumar Rao

We analyze the phemomenon of induced fermion number at finite temperature. At finite temperature, the induced fermion number $<N>$ is a thermal expectation value, and we compute the finite temperature fluctuations, $(ΔN)^2=<N^2>-<N>^2$. While the zero temperature induced fermion number is topological and is a sharp observable, the finite temperature induced

M. D. Maia, E. M. Monte

The stability conditions for coordinate gauge independent perturbations of brane-worlds are analyzed. It is shown that, these conditions lead to the Einstein-Hilbert dynamics and to a confined gauge potential, independently of models and metric ansatzes. The size of the extra dimensions are estimated without assuming a fixed topology. The quantum modes corre

E. Vaz, M. E. Carrington, R. Kobes, G. Kunstatter

We use a combination of perturbation theory and numerical techniques to study the equilibration of two interacting fields which are initially at thermal equilibrium at different temperatures. Using standard rules of quantum field theory, we examine the master equations that describe the time evolution of the distribution functions for the two coupled systems

D. Bailin, G. V. Kraniotis, A. Love

The phenomenological implications of the M-theory limit in which supersymmetry is broken by the auxiliary fields of five-brane moduli is investigated. Assuming that the lightest neutralino provides the dark matter in the universe, constraints on the sparticle spectrum are obtained. Direct detection rates for dark matter are estimated.

Howard E. Haber

The structure of low-energy supersymmetric models of fundamental particles and interactions is reviewed, with an emphasis on the minimal supersymmetric extension of the Standard Model (MSSM) and some of its variants. Various approaches to the supersymmetry-breaking mechanism are considered. The implications for the phenomenology of Higgs bosons and supersymm

A. Jakovac, A. Patkos, Zs. Szep

The effective equations of motion for low-frequency mean gauge fields in the Abelian Higgs model are investigated in the presence of a scalar condensate, near the high temperature equilibrium. We determine the current induced by an inhomogeneous background gauge field in the linear response approximation up to order $e^4$, assuming adiabatic variation of the

M. Klasen

We demonstrate that a future high-energy electron-proton collider like THERA could largely extend the current HERA program in jet photoproduction of testing QCD and determining the partonic structure of the proton and the photon. Depending on the electron beam energy (250-500 GeV) and the collider mode ($ep$ or $γp$), the range in the hard transverse energy

E. Boos, A. De Roeck, I. F. Ginzburg, K. Hagiwara

We review the most important topics and objectives of the physics program of the gamma-gamma, gamma-electron collider (photon collider) option for an e+e- linear collider.

Anna Kulesza, W. James Stirling

The distribution of W and Z bosons produced with small transverse momentum (pt) at hadron colliders receives important contributions from large logarithms arising from soft gluon emission. Although conventionally the all-orders resummation of these `Sudakov&#39; logarithms is performed in impact parameter (Fourier transform) space, pt-space resummation is al

J. M. Carmona, M. D&#39;Elia, A. Di Giacomo, B. Lucini

It is demonstrated that monopole condensation in the confined phase of SU(2) and SU(3) gauge theories is independent of the specific Abelian projection used to define the monopoles. Hence the dual excitations which condense in the vacuum to produce confinement must have magnetic U(1) charge in all the Abelian projections. Some physical implications of this r

Wolfgang Beirl, Bernd A. Berg

We re-examine results of the Liouville theory and provide arguments that a {\it negative} bare cosmological constant is essential to define two-dimensional quantum gravity. From this we are naturally led to a regularization of quantum gravity within the Regge approach such that it is described by small fluctuations around equilateral triangles, whose average

T. Ferbel

We report on a search for extra spatial dimensions compactified at radii that are vast compared to those of the Planck length, and even larger than the distance corresponding to the scale of electroweak symmetry breaking. The study is based on the suggestion that there may be only a single mass scale appropriate to particle phenomena, this being the effectiv

Hisa-aki Shinkai, Gen Yoneda

In order to perform accurate and stable long-term numerical integration of the Einstein equations, several hyperbolic systems have been proposed. We here report our numerical comparisons between weakly hyperbolic, strongly hyperbolic, and symmetric hyperbolic systems based on Ashtekar&#39;s connection variables. The primary advantage for using this connectio

Sergio Dain

We prove the existence of a family of initial data for the Einstein vacuum equation which can be interpreted as the data for two Kerr-like black holes in arbitrary location and with spin in arbitrary direction. This family of initial data has the following properties: (i) When the mass parameter of one of them is zero or when the distance between them goes t

Janusz Garecki

It is known that General Relativity ({\bf GR}) uses Lorentzian Manifold $(M_4;g)$ as a geometrical model of the physical space-time. $M_4$ means here a four-dimensional differentiable manifold endowed with Lorentzian metric $g$. The metric $g$ satisfies Einstein equations. Since the 1970s many authors have tried to generalize this geometrical model of the ph

Miroslav Sukenik, Jozef Sima

Stemming from relationships between a number of information describing a system and entropy content of the system it is possible to determine maximal cosmological time. The contribution manifests a compatibility of the superstring theory and the model of Expansive Nondecelerative Universe.

Jozef Sima, Miroslav Sukenik

The contribution provides a comparison of consequences stemming from D-brane theories and Expansive Nondecelerative Universe model, and calls attention to coincidence of the results arising from the mentioned approaches to a description of the Universe. It follows from the comparison that the effects of quantum gravitation should appear at the energy near to

Zhong Fang, Kiyoyuki Terakura

To gain insights into the fundamental and characteristic features of the surface of doped manganites, we constructed a general magnetic phase diagram of La$_{1-x}$Sr$_{x}$MnO$_3$ (001) surfaces in the plane spanned by $x$ and the bulk tetragonal distortion $c/a$, from the first-principles calculations. We found that the surfaces are quite different from the

M. Lawrence Glasser

This note examines the second virial coefficient for an imperfect gas subject to a 2n-n interparticle potential in any dimension d between 0 and n. A compact analytic expression is presented for this quantity which shows that, apart from a numerical factor, its temperature dependence is a universal function parameterized by d/n.

Zhong Fang, Kiyoyuki Terakura

We constructed, by the first-principles calculations, a magnetic phase diagram of Sr$_{2}$RuO$_4$ in the space spanned by structural distortions. Our phase diagram can qualitatively explain the experimental one for Ca$_{2-x}$Sr$_x$RuO$_4$. We found that the rotation and the tilting of RuO$_6$ octahedron are responsible for the ferro- and antiferro-magnetism,

P. G. Silvestrov

The decay of a quasiparticle in an isolated quantum dot is considered. At relatively small time the probability to find the system in the initial state decays exponentially: $P(t)\sim \exp(-Γt)$, in accordance with the golden rule. However, the contributions to $P(t)$ accounting for the discreteness of final three-particle states, five-particle states, etc.

K-t. Leung, L. Jozsa, M. Ravasz, Z. Neda

A fascinating class of patterns, often encountered in nature as meandering cracks on rocks, dried-out fields and tectonic plates is produced by the fracture of solids. Here we report the observation and modeling of an unusual type of patterns consisting of spiral cracks within fragments of a thin layer of drying precipitate. We find that this symmetry-breaki

J. M. Schwarz, Ron Maimon

We present a heuristic derivation of the first passage time exponent for the integral of a random walk [Y. G. Sinai, Theor. Math. Phys. {\bf 90}, 219 (1992)]. Building on this derivation, we construct an estimation scheme to understand the first passage time exponent for the integral of the integral of a random walk, which is numerically observed to be $0.22

Horacio M. Pastawski, Ernesto Medina

We discuss the steady-state electronic transport in solid-state and molecular devices in the quantum regime. The decimation technique allows a comprehensive description of the electronic structure. Such a method is used, in conjunction with the generalizations of Landauer&#39;s tunneling formalism, to describe a wide range of transport regimes. We analize me

Giancarlo Cappellini, Guido Satta, Maurizia Palummo, Giovanni Onida

Linear optical functions of cubic and hexagonal BN have been studied within first principles DFT-LDA theory. Calculated energy-loss functions compare well with experiments and previous theoretical results both for h-BN and for c-BN. Discrepancies arise between theoretical results and experiments in the imaginary part of the dielectric function for c-BN. Poss

Youichi Yanase, Kosaku Yamada

The pseudogap phenomena in High-$T_{\rm c}$ cuprates are investigated on the basis of the Hubbard model which includes only the on-site repulsive interaction $U$. We consider the pairing scenario for the pseudogap. The pseudogap arises from the resonance scattering due to the strong superconducting fluctuations. First, the electronic state and the anti-ferro

Stephan Roche, Francois Triozon, Angel Rubio, D. Mayou

We report on a numerical study of quantum diffusion over micron lengths in defect-free multi-walled nanotubes. The intershell coupling allows the electron spreading over several shells, and when their periodicities along the nanotube axis are incommensurate, which is likely in real materials, the electronic propagation is shown to be non ballistic. This resu

Yadong Wei, Jian Wang, Hong Guo, Hatem Mehrez

Resonant Andreev reflection through superconductor-carbon-nanotube devices was investigated theoretically with a focus on the superconducting proximity effect. Consistent with a recent experiment, we find that for high transparency devices on-resonance, the Andreev current is characterized by a large value and a resistance dip; low-transparency off-resonance

P. G. Bolhuis, A. A. Louis, J. P. Hansen

We calculate the two, three, four, and five-body (state independent) effective potentials between the centers of mass (CM) of self avoiding walk polymers by Monte-Carlo simulations. For full overlap, these coarse-grained n-body interactions oscillate in sign as (-1)^n, and decrease in absolute magnitude with increasing n. We find semi-quantitative agreement

N. -C. Yeh, C. -T. Chen, G. Hammerl, J. Mannhart

Scanning tunneling spectroscopy (STS) studies reveal long-range (~100 nm) spatial homogeneity in optimally and underdoped superconducting YBa_2Cu_3O_{7-δ} (YBCO) single crystals and thin films, and macroscopic spatial modulations in overdoped (Y_{0.7}Ca_{0.3})Ba_2Cu_3O_{7-δ} (Ca-YBCO) epitaxial films. In contrast, STS on an optimally doped YBa_2(Cu_{0.9934}Z

Shao-ying Zhang, Jian Zhang, Tong-yun Zhao, Chuan-bing Rong

In this paper, we reported the structural properties and superconductivity of Mg(B1-xCx)2 compounds. Powder x-ray diffraction results indicate that the samples crystallize in a hexagonal AlB2-type structure. Due to the chemical activity of Mg powders, a small amount of MgO impurity phase was detected by x-ray diffraction. The lattice parameters decrease slig

W. N. Kang, Hyeong-Jin Kim, Eun-Mi Choi, C. U. Jung

We report the growth of high-quality epitaxial MgB2 thin films on (1102) Al2O3 and (001) SrTiO3 substrates by using a pulsed laser deposition technique. The thin films grown on Al2O3 substrates show a Tc of 39 K with a sharp transition width of ~ 0.7 K. The critical current density in zero field is ~ 8 x 10^6 A/cm^2 at 5 K, suggesting that this compound has