October 1998 arXiv papers — page 15

D. Lacroix, Ph. Chomaz, S. Ayik

A method is presented for numerical implementation of the extended TDHF theory in which two-body correlations beyond the mean-field approximation are incorporated in the form of a quantal collision term. The method is tested in a model problem in which the exact solution can be obtained numerically. Whereas the usual TDHF fails to reproduce the long time evo

L. V. Bravina, M. Brandstetter, M. I. Gorenstein, E. E. Zabrodin

Thermodynamical variables and their time evolution are studied for central relativistic heavy ion collisions from 10.7 to 160 AGeV in the microscopic Ultrarelativistic Quantum Molecular Dynamics model (UrQMD). The UrQMD model exhibits drastic deviations from equilibrium during the early high density phase of the collision. Local thermal and chemical equilibr

D. Lacroix, Ph. Chomaz

A recent interpretation of the caloric curve based on the expansion of the abraded spectator nucleus is re-analysed in the framework of the Time-Dependent Hartree-Fock (TDHF) evolution. It is shown that the TDHF dynamics is more complex than a single monopolar collective motion at moderate energy. The inclusion of other important collective degrees of freedo

A. I. L'vov

Spin polarizabilities of the nucleon are discussed in the framework of fixed-t and backward-angle dispersion relations, chiral perturbation theory, and the non-relativistic quark model. Calculations with the dispersion relations generally confirm findings from HBChPT and disagree with a recent experimental result from LEGS for the backward spin polarizabilit

Nikita Sidorov, Anatoly Vershik

We study the arithmetic codings of hyperbolic automorphisms of the 2-torus, i.e. the continuous mappings acting from a certain symbolic space of sequences with a finite alphabet endowed with an appropriate structure of additive group onto the torus which preserve this structure and turn the two-sided shift into a given automorphism of the torus. This group i

Alexander Polishchuk

This paper is devoted to the function introduced by M. P. Appell in connection with decomposition of elliptic functions of the third kind into simple elements. We show that this function (which appeared as a Fukaya triple product in math.AG/9803017) is related to global sections of rank-2 vector bundles on elliptic curves. We derive analogues of theta-identi

E. Vassiliou

In the framework of Abstract Differential Geometry, we show that to a given principal sheaf and a representation of its stuctural sheaf in $A^n$, where A is a sheaf of associative, commutative, unital algebras (over R or C), we associate a vector sheaf. Moreover, under some natural assumptions on the compatibility of the representation with the Maurer-Cartan

Kevin P. Scannell, Michael Wolf

Grafting is a method of obtaining new projective structures from a hyperbolic structure, basically by gluing a flat cylinder into a surface along a closed geodesic in the hyperbolic structure, or by limits of that procedure. This induces a map of Teichmuller space to itself. We prove that this map is a homeomorphism by analyzing harmonic maps between pairs o

Jianxun Hu

In this paper, using the gluing formula of Gromov-Witten invariants under symplectic cutting, due to Li and Ruan, we studied the Gromov-Witten invariants of blow-ups at a smooth point or along a smooth curve. We established some relations between Gromov-Witten invariants of M and its blow-ups at a smooth point or along a smooth curve.

Jean-Claude Hausmann, Allen Knutson

The ``symplectic cut'' construction [Lerman] produces two symplectic orbifolds $C_-$ and $C_+$ from a symplectic manifold $M$ with a Hamiltonian circle action. We compute the rational cohomology ring of $C_+$ in terms of those of $M$ and $C_-$.

S. Kharchev

The review is devoted to the integrable properties of the Generalized Kontsevich Model which is supposed to be an universal matrix model to describe the conformal field theories with $c<1$. It is shown that the deformations of the &#34;monomial&#34; phase to &#34;polynomial&#34; one have the natural interpretation in context of so-called equivalent hierarchi

M. Quandt, H. Reinhardt, A. Schafke

We express the Pontryagin index in Polyakov gauge completely in terms of magnetically charged gauge fixing defects, namely magnetic monopoles, lines, and domain walls. Open lines and domain walls are topologically equivalent to monopoles, which are the genuine defects. The emergence of non-genuine magnetically charged closed domain walls can be avoided by ch

D. J. Broadhurst, D. Kreimer

It was recently shown that the renormalization of quantum field theory is organized by the Hopf algebra of decorated rooted trees, whose coproduct identifies the divergences requiring subtraction and whose antipode achieves this. We automate this process in a few lines of recursive symbolic code, which deliver a finite renormalized expression for any Feynman

Klaus Hasselmann

A conceptual summary is given of a deterministic unified field and particle theory (the metron model) developed in more mathematical detail in a four-part paper published in Physics Essays (1996/97). The model is developed from Einsteins vacuum gravitational equations, Ricci tensor $R_{LM}=0$, in a higher dimensional space. It is postulated that the equation

Andrzej J. Staruszkiewicz

The theory of the quantum Coulomb field associates with each Lorentz frame, i. e., with each unit, future oriented time-like vector $u$, the operator of the number of transversal infrared photons $N(u)$ and the phase $S(u)$ which is the coordinate canonically conjugated with the total charge $Q: [Q, S(u)] = ie, e$ being the elementary charge. It is shown tha

Andrzej J. Staruszkiewicz

A simple argument against the existence of magnetic monopoles is given. The argument is an important part of the quantum theory of the electric charge developed by the author.

Christofer Cronstrom

I consider the problem of defining canonical coordinates and momenta in pure Yang-Mills theory, under the condition that Gauss&#39; law is identically satisifed. This involves among other things particular boundary conditions for certain dependent variables. These boundary conditions are not postulated a priori, but arise as consistency conditions related to

T. Ioannidou, B. Piette, W. J. Zakrzewski

Due to a computational mistake this paper has been withdrawn.

T. Ioannidou, B. Piette, W. J. Zakrzewski

Due to a computational mistake this paper has been withdrawn.

Alan Kostelecky

This talk summarizes some theoretical features and experimental implications of a general Lorentz-violating extension of the minimal SU(3) x SU(2) x U(1) standard model that allows for both CPT-even and CPT-odd effects. The theory would arise as the low-energy limit of a fundamental theory that is Lorentz and CPT covariant but in which spontaneous Lorentz br

Harry J. Lipkin

A useful inequality is obtained if charmless strange B decays are assumed to be dominated by a $ΔI = 0$ transition like that from the gluonic penguin diagram and the contributions of all other diagrams including the tree, electroweak penguin and annihilation diagrams are small but not negligible. The interference contributions which are linear in these other

I. V. Andreev

Modification of the particles in the course of the source evolution is considered. Influence of this effect on multiplicities and correlations of the particles is displayed, including an enhancement of the production rates and identical particle correlations and also back-to-back particle-antiparticle correlations.

D. S. Isert, S. P. Klevansky, P. Rehberg

We investigate the nature of transition rates for the hadronization process of q q bar -> Pi Pi Pi as opposed to the transition rates for q q bar -> Pi Pi, within the Nambu--Jona-Lasinio model that has manifest chiral symmetry. Feynman diagrams appropriate to this process can be classified according to the expansion in the inverse number of colors 1/N_c. Two

M. Sirera, A. Perez

In this work we study the propagation of massive Dirac neutrinos in matter with flavor mixing, using statistical techniques based on Relativistic Wigner Functions. First, we consider neutrinos in equilibrium within the Hartree approximation, and obtain the corresponding relativistic dispersion relations and effective masses. After this, we analyze the same s

E. Di Salvo, M. Pallavicini, E. Robutti

We employ QCD sum rules, implemented with two numerical algorithms already tested in two different channels of Charmonium, in order to predict masses of resonances just above the ground states in the $^3 P$ channels. We find that such masses are above the threshold of open charm. We calculate also the partial decay widths of the ground states into light hadr

G. G. Devidze, G. R. Jibuti

B_s-meson double radiative decay $B \to γγ$ is investigated in frame of supersymmetric extension of the standard model. The branching ratio is calculated. It is shown that for light Higgs particle and heigh $\tanβ$ supersymmetric contribution into branching ratio is significunt large than standard model estimate.

Uma Mahanta

Supersymmetry implies that the trilinear couplings between gauge bosons and gauginos are equal to all orders in perturbation theory. However if SUSY is broken and some of the superpartners have large SUSY breaking masses then they can induce non-decoupling deviations in this relation through radiative corrections. In this article we show that the deviation i

M. Franz, P. V. Pobylitsa, M. V. Polyakov, K. Goeke

Recently in the context of studies of the intrinsic charm content of the nucleon and of the eta&#39; meson two groups have arrived at different results for the 1/m^3 term of the heavy quark expansion for operator $\bar Qγ_5Q$ differing by the factor of six. We show that the form of both results violates certain general conditions. Using the expression for th

V. Ch. Zhukovskii, A. E. Grigoruk, K. G. Levtchenko, P. A. Eminov

Production of a massive neutrino-antineutrino pair by a virtual polarized photon in the Weiberg-Salam model with mixing is studied. The rate of the neutrino production by photons with various polarizations is found at values of the magnetic field intensity lower than critical.

A. Ster, T. Csorgo, B. Lorstad

Analytic and numeric approximations are studied in detail for a hydrodynamic parameterization of single-particle spectra and two-particle correlation functions in high energy hadron-proton and heavy ion reactions. Two very different sets of model parameters are shown to result in similarly shaped correlation functions and single particle spectra in a rather

Debajyoti Choudhury, Anirban Kundu, Biswarup Mukhopadhyaya

The $b$ and the $c$ quark compete with each other in decays of the $B_c$-meson. We emphasize the need of obtaining reliable signals of $c \to s$ in order to assess the merits of the spectator approximation in calculating the relative strengths of the two types of decays. This, we argue, can be done by considering the decay $B_c \to B_s (B_s^*) l \bar{ν_l}$,

R. Rückl

Exclusive decays of B and D mesons are discussed with the focus on the theoretical problem how to calculate the relevant hadronic matrix elements of weak operators in the framework of QCD sum rules. The three lectures are devoted to 1. leptonic decays and decay constants 2. semileptonic decays and form factors 3. nonleptonic decays and nonfactorizable amplit

P. Zenczykowski

We study the question whether the phenomenologically successful VMD approach to weak radiative hyperon decays can be made consistent with Hara&#39;s theorem and still yield the pattern of asymmetries exhibited by experimental data. It appears that an essential ingredient which governs the pattern of asymmetries is the off-shell behaviour of the input electro

Salvatore Mele

The precise measurements of the Bd oscillation frequency and the limit on the Bs one one as well as the determination of the Cabibbo-Kobayashi-Maskawa matrix element Vub improve the constraints on the other elements of this matrix. A fit to the experimental data and the theory calculations leads to the determination of the vertex of the unitarity triangle as

Massimo Blasone

I report on recent theoretical results about neutrino mixing and oscillations. I show that in Quantum Field Theory, mixing transformations are not trivial and the vacuum for the mixed fields has a condensate structure. This fact has phenomenological consequences on neutrino oscillations: the oscillation formula turns out to have an additional oscillating pie

A. E. Dorokhov, Lauro Tomio

The leading-twist valence-quark distribution function in the pion is obtained at a low normalization scale of an order of the inverse average size of an instanton $ρ_c$. The momentum dependent quark mass and the quark-pion vertex are constructed in the framework of the instanton liquid model, using a gauge invariant approach. The parameters of instanton vacu

Attilio Cucchieri, Tereza Mendes, Roberto Petronzio

We discuss a comparative analysis of unimproved and nonperturbatively improved quenched hadron spectroscopy, on a set of 104 gauge configurations, at beta=6.2. We also present here our results for meson decay constants, including the constants f_D and f_Ds in the charm-quark region.

Attilio Cucchieri, Tereza Mendes, Andrea Pelissetto

We define a set of orthogonal functions on the complex projective space CP^{N-1}, and compute their Clebsch-Gordan coefficients as well as a large class of 6-j symbols. We also provide all the needed formulae for the generation of high-temperature expansions for U(N)-invariant spin models defined on CP^{N-1}.

G. P. Perry, F. I. Cooperstock

Recent work on gravitational geons is extended to examine the stability properties of gravitational and electromagnetic geon constructs. All types of geons must possess the property of regularity, self-consistency and quasi-stability on a time-scale much longer than the period of the comprising waves. Standard perturbation theory, modified to accommodate tim

S. D. Biller, A. C. Breslin, J. Buckley, M. Catanese

We have used data from the TeV gamma-ray flare associated with the active galaxy Markarian 421 observed on 15 May 1996 to place bounds on the possible energy-dependence of the speed of light in the context of an effective quantum gravitational energy scale. The possibility of an observable time dispersion in high energy radiation has recently received attent

Masakatsu Kenmoku, Hiroto Kubotani, Eiichi Takasugi, Yuki Yamazaki

We study the quantum theory of the Einstein-Maxwell action with a cosmological term in the spherically symmetric space-time, and explored quantum black hole solutions in Reissner-Nordstrom-de Sitter geometry. We succeeded to obtain analytic solutions to satisfy both the energy and momentum constraints.

Giorgio Satta, William Schuler

Several methods are known for parsing languages generated by Tree Adjoining Grammars (TAGs) in O(n^6) worst case running time. In this paper we investigate which restrictions on TAGs and TAG derivations are needed in order to lower this O(n^6) time complexity, without introducing large runtime constants, and without losing any of the generative power needed

Judith L. Klavans, Kathleen R. McKeown, Min-Yen Kan, Susan Lee

We report on two corpora to be used in the evaluation of component systems for the tasks of (1) linear segmentation of text and (2) summary-directed sentence extraction. We present characteristics of the corpora, methods used in the collection of user judgments, and an overview of the application of the corpora to evaluating the component system. Finally, we

David R. Hanson

The Abstract Syntax Description Language (ASDL) is a language for specifying the tree data structures often found in compiler intermediate representations. The ASDL generator reads an ASDL specification and generates code to construct, read, and write instances of the trees specified. Using ASDL permits a compiler to be decomposed into semi-independent compo

Chen Zeng, Paul L. Leath

A randomly pinned elastic medium in two dimensions is modeled by a disordered fully-packed loop model. The energetics of disorder-induced dislocations is studied using exact and polynomial algorithms from combinatorial optimization. Dislocations are found to become unbound at large scale, and the elastic phase is thus unstable giving evidence for the absence

Richard J. Creswick, Seung-Yeon Kim

The microcanonical transfer matrix is used to study the zeros of the partition function of the Q-state Potts model. Results are presented for the Yang-Lee zeros of the 3-state model, the Fisher zeros of the 3-state model in an external field $H_q<0$, and the spontaneous magnetization of the 2-state model. In addition, we are able to calculate the ground-stat

J. L. Cohn, J. Karpinski

We report measurements of the in-plane thermal conductivity ($κ$) of YBa_2Cu_4O_8 (Y-124) single crystals in the temperature range $4K\leq T\leq 300K$ and compare them with previous results on YBa_2Cu_3O_{6+x} (Y-123). For transport perpendicular to the CuO chains, $κ_a(300K)\simeq 10$W/mK, and along the chains, $κ_b(300K)\simeq 40$W/mK. The temperature depe

Eduardo Fradkin, Steven A. Kivelson

Mean-field calculations for the two dimensional electron gas (2DEG) in a large magnetic field with a partially filled Landau level with index $N\geq 2$ consistently yield ``stripe-ordered&#39;&#39; charge-density wave ground-states, for much the same reason that frustrated phase separation leads to stripe ordered states in doped Mott insulators. We have stud

S. J. Lee, B. Kim, J. -R. Lee

We present Monte Carlo simulation results on the equilibrium relaxation of the two dimensional lattice Coulomb gas with fractional charges, which exhibits a close analogy to the primary relaxation of fragile supercooled liquids. Single particle and collective relaxation dynamics show that the Stokes-Einstein relation is violated at low temperatures, which ca

H. Niggemann, J. Zittartz

We present a class of optimum ground states for spin-3/2 models on the Cayley tree with coordination number 3. The interaction is restricted to nearest neighbours and contains 5 continuous parameters. For all values of these parameters the Hamiltonian has parity invariance, spin-flip invariance, and rotational symmetry in the xy-plane of spin space. The glob

John Schliemann, Franz G. Mertens

We use spin-coherent states as a time-dependent variational ansatz for a semiclassical description of a large family of Heisenberg models. In addition to common approaches we also evaluate the square variance of the Hamiltonian in terms of coherent states. This quantity turns out to have a natural interpretation with respect to time-dependent solutions of th

Oleg Derzhko, Johannes Richter

We extend the consideration of the spin-1/2 transverse XY chain with correlated Lorentzian disorder (Phys. Rev. B {\bf 55,} 14298 (1997)) for the case of additional Dzyaloshinskii-Moriya interspin interaction. It is shown how the averaged density of states can be calculated exactly. Results are presented for the density of states and the transverse magnetiza

Damian Marinaro, Oleg Sushkov

To investigate relations between long-range antiferromagnetic (AF) order, superconductivity and two particle triplet collective excitations we consider a modified two dimensional t-J model at doping close to half filling. The model includes additional hopping t&#39;&#39; and nearest sites Coulomb repulsion V. The additional parameters allow us to control clo

Jan W. Kantelhardt, Armin Bunde, L. Schweitzer

We investigate the localization behavior of vibrational modes of infinite percolation clusters above the critical concentration in two and three dimensions using the method of level statistics. We find that all eigenstates are localized in d=2, including the low frequency phonon states. In d=3 we obtain evidence for a localization-delocalization transition.

Yoshimi Tanaka, Koji Fukao, Yoshihisa Miyamoto, Ken Sekimoto

The relation between fracture surface morphology and the three-dimensional structure of crack fronts is investigated through direct observation of brittle cracks in gels. A key notion in this investigation is the discontinuity of the crack front, whose advancement creates the fracture surface. We discuss the significance of our findings in the studies of gen

L. W. Bernardi, K. Hukushima, H. Takayama

Using extensive Monte Carlo simulations, we clarify the critical behaviour of the 3 dimensional simple cubic Ising Fully Frustrated system. We find two transition temperatures and two long range ordered phases. Within the present numerical accuracy, the transition at higher temperature is found to be second order and we have extracted the standard critical e

H. Okamura, S. Kimura, H. Shinozaki, T. Nanba

Optical reflectivity experiments have been conducted on single crystals of the Kondo insulator YbB_12 in order to obtain its optical conductivity, σ(ω). Upon cooling below 70 K, a strong supression of σ(ω) is seen in the far-infrared region, indicating the opening of an energy gap of ~ 25 meV. This gap development is coincident with a rapid decrease in the m

G. Biczo

It is suggested that the appearance of Jordan blocks in the normal form of the recursion (transfer) matrix is responsible for high temperature superconductivity and related phenomena. Several published observations are discussed to support this idea. The draft of a quantum chemical theory is given for a more complete verification. Keywords: Jordan scenario,

Richard P. Sear

It has been shown by Stell [J. Stat. Phys. 63, 1203 (1991)] that at low temperature monodisperse sticky spheres collapse to form coexisting close-packed solid and infinitely dilute gases. We show that polydisperse sticky spheres also collapse and calculate the collapse temperature. The polydisperse spheres separate into fractions with narrower polydispersiti

P. V. Coveney, J. -B. Maillet, J. L. Wilson, P. W. Fowler

We develop our existing two-dimensional lattice-gas model to simulate the flow of single-phase, binary-immiscible and ternary-amphiphilic fluids. This involves the inclusion of fixed obstacles on the lattice, together with the inclusion of ``no-slip&#39;&#39; boundary conditions. Here we report on preliminary applications of this model to the flow of such fl

Bruce M. Boghosian, Peter V. Coveney

A thermohydrodynamic lattice-BGK model for the ideal gas was derived by Alexander et al. in 1993, and generalized by McNamara et al. in the same year. In these works, particular forms for the equilibrium distribution function and the transport coefficients were posited and shown to work, thereby establishing the sufficiency of the model. In this paper, we re

Martin R. Zirnbauer

The color-flavor transformation is a mathematical result that has applications to problems as diverse as lattice gauge theory, random network models, and dynamical systems. Several variants are described, and an outline of the proof is given. It is then shown how to use the transformation to set up a field theoretic formalism for quantum chaotic maps.

Ales Raidl

The correlation dimension and K2-entropy are estimated from meteorological time- series. The results lead us to claim that seasonal variability of weather is under influence of low dimensional dynamics, whereas changes of weather from day to day are governed by high dimensional system(s). Error-doubling time of this system is less than 3 days. We suggest tha

E. Gaztanaga, J. Barriga, A. Romeo, P. Fosalba

Data on board the future PLANCK Low Frequency Instrument (LFI), to measure the Cosmic Microwave Background (CMB) anisotropies, consist of $N$ differential temperature measurements, expanding a range of values we shall call $R$. Preliminary studies and telemetry allocation indicate the need of compressing these data by a ratio of $c_r \simgt 10$. Here we pres

R. A. Battye, J. Weller

A wide class of inflationary models, known as Hybrid Inflation models, may produce topological defects during a phase transition at the end of the inflationary epoch. We point out that, if the energy scale of these defects is close to that of Grand Unification, then their effect on cosmic structure formation and the generation of microwave background anisotr

Bruce Margon, Eric W. Deutsch

Four high-latitude slow variable stars have been noted by Meinunger (1972) as &#34;nicht rote&#34; (&#34;not red&#34;) objects and thus curious. We have previously reported (Margon & Deutsch 1997) that one of these objects, CC Boo, is in fact a QSO. Here we present observations demonstrating that the remaining three are also highly variable active galactic n

E. Salvador-Sole, A. Manrique, J. M. Solanes

High resolution cosmological N-body simulations show that the density profiles of dark matter halos in hierarchical cosmogonies are universal, with low mass halos typically denser than more massive ones. This mass-density correlation is interpreted as reflecting the earlier formation of less massive objects. We investigate this hypothesis in the light of for

MP Hobson, AW Jones, AN Lasenby

We investigate the use of wavelet transforms in detecting and characterising non-Gaussian structure in maps of the cosmic microwave background (CMB). We apply the method to simulated maps of the Kaiser-Stebbins effect due to cosmic strings onto which Gaussian signals of varying amplitudes are superposed. We find the method significantly outperforms standard

Luca Amendola

I present here a generalization of the maximum likelihood method and the $χ^2$ method to the cases in which the data are {\it not} assumed to be Gaussian distributed. The method, based on the multivariate Edgeworth expansion, can find several astrophysical applications. I mention only two of them. First, in the microwave background analysis, where it cannot

A. N. Lasenby, A. W. Jones, Y. Dabrowski

Observations of the Cosmic Microwave Background (CMB) are discussed, with particular emphasis on current ground-based experiments and on future satellite, balloon and interferometer experiments. Observational techniques and the effects of contaminating foregrounds are highlighted. Recent CMB data is used with large scale structure (LSS) data to constrain cos

John F. Kartje, Arieh Konigl, Moshe Elitzur

Recent spectroscopic and VLBI-imaging observations of bright extragalactic water maser sources have revealed that the megamaser emission often originates in thin circumnuclear disks near the centers of active galactic nuclei (AGNs). Using general radiative and kinematic considerations and taking account of the observed flux variability, we argue that the mas

Lam Hui, Enrique Gaztanaga

Nonlinear combinations of direct observables are often used to estimate quantities of theoretical interest. Without sufficient caution, this could lead to biased estimations. An example of great interest is the skewness $S_3$ of the galaxy distribution, defined as the ratio of the third moment $\xibar_3$ and the variance squared $\xibar_2^2$. Suppose one is

John S. Arabadjis, Douglas O. Richstone

We report the results of simulations of dense rotating stellar systems whose members suffer collisions and undergo stellar evolution processes. The initial configuration for each experiment is an isotropic Kuzmin-Kutuzov model. The dynamical evolution is simulated with the N-body tree code of Hernquist, modified to incorporate physical stellar collisions, st

John S. Arabadjis, Douglas O. Richstone

This paper, and its companion, investigate the evolution of dense stellar systems due to the influence of two-body gravitational encounters, physical collisions and stellar evolution. Our goal is the simulation of the densest centers of galaxies, like M32, which reach stellar densities near a million solar masses per cubic parsec and which may harbor black h

Stefan Gottloeber, Anatoly Klypin, Andrey Kravtsov

A significant fraction of mass in the universe is believed to be in the form of dark matter (DM). Due to gravitational instability, the DM collapses hierarchically into DM halos. In this contribution we present a study of the formation and evolution of such DM halos in a COBE-normalized spatially flat LCDM model (Omega_0=1-Omega_L=0.3; h=0.7) using high-reso

Istvan Szapudi, Thomas Quinn, Joachim Stadel, George Lake

Higher order statistics are investigated in ($Ω$)CDM universes by analyzing $500\mpc$ high resolution tree N-body simulations with both $Ω= 1$, and $Ω< 1$. The amplitudes of the N-point correlation functions are calculated from moments of counts-in-cells determined by a pair of new algorithms especially developed for large simulations. This approach enables

F. Governato, A. Babul, T. Quinn, P. Tozzi

We analyse parallel N-body simulations of three Cold Dark Matter (CDM) universes to study the abundance and clustering of galaxy clusters. The simulations cover a volume comparable to the forthcoming SDSS. We are able to make robust measurements of cluster properties to a redshift larger than unity. We extract halos using two independent, public domain group

Erik van Nimwegen, James P. Crutchfield

Epochal dynamics, in which long periods of stasis in an evolving population are punctuated by a sudden burst of change, is a common behavior in both natural and artificial evolutionary processes. We analyze the population dynamics for a class of fitness functions that exhibit epochal behavior using a mathematical framework developed recently. In the latter t

Don H. Kim, Patrick A. Lee

We consider the magnetic properties of high Tc cuprates from a gauge theory point of view, with emphasis on the underdoped regime. Underdoped cuprates possess certain antiferromagnetic correlations, as evidenced, for example, by different temperature dependence of the Cu and O site NMR relaxation rates, that are not captured well by slave boson mean field th

M. Catanese

We present multi-wavelength observations of the very high energy (VHE, E >250 GeV) gamma-ray sources Mrk 421 and Mrk 501. The VHE data presented here were taken with the Whipple Observatory 10m gamma-ray telescope. In the Mrk 421 campaign, conducted in 1995 April-May, correlations were observed between VHE gamma-ray, X-ray, extreme ultraviolet (EUV) and poss

David A. Lowe

The consistency of Matrix theory with supergravity requires that in the large N_c limit terms of order v^4 in the SU(N_c) Matrix effective potential are not renormalized beyond one loop in perturbation theory. For SU(2) gauge group, the required non-renormalization theorem was proven recently by Paban, Sethi and Stern. In this paper we consider the constrain

Jean Letessier, Johann Rafelski

Strange particles produced in S-Au/W/Pb 200 A GeV and Pb-Pb 158 A GeV reactions are described invoking final hadronic phase space in thermal equilibrium, but allowing chemical non-equilibrium. Several sets of statistical freeze-out parameters are obtained for each system, invoking different models of dense matter. We show that only when allowing for strange

M. Asakawa, T. Csorgo, M. Gyulassy

Huge back-to-back correlations are shown to arise for thermal ensembles of bosonic states with medium-modified masses. The effect is experimentally observable in high energy heavy ion collisions.

L. Alvero, L. Frankfurt, M. Strikman

We evaluate nuclear shadowing of the total cross section of charm particles production in DIS within the framework of the Gribov theory of nuclear shadowing using as input the recent QCD Pomeron parton density analysis of the HERA diffractive data. Assuming that the QCD factorization theorem is applicable to the charm production off nuclei we also calculate

A. I. Sokolov, E. V. Orlov, V. A. Ul&#39;kov, S. S. Kashtanov

The field-theoretical renormalization group approach in three dimensions is used to estimate the universal critical values of renormalized coupling constants g_6 and g_8 for the O(n)-symmetric model. The RG series for g_6 and g_8 are calculated in the four-loop and three-loop approximations respectively and then resummed by means of the Pade-Borel-Leroy tech

Johann Rafelski

The study of strange and also charmed hadronic particle production in nuclear relativistic collisions offers an opportunity to explore the physical properties of the deconfined quark-gluon phase. We survey the recent accomplishments and the future directions of this research program.

Clement Sire, Satya N. Majumdar, Andreas Rudinger

In this paper, we present the detailed calculation of the persistence exponent $θ$ for a nearly-Markovian Gaussian process $X(t)$, a problem initially introduced in [Phys. Rev. Lett. 77, 1420 (1996)], describing the probability that the walker never crosses the origin. New resummed perturbative and non-perturbative expressions for $θ$ are obtained, which sug

P. S. Howe, O. Raetzel, I. Rudychev, E. Sezgin

The superembedding approach to $p$-branes is used to study a class of $p$-branes which have linear multiplets on the worldvolume. We refer to these branes as L-branes. Although linear multiplets are related to scalar multiplets (with 4 or 8 supersymmetries) by dualising one of the scalars of the latter to a $p$-form field strength, in many geometrical situat

Shi-Lin Zhu

The light cone QCD sum rules are derived for $ωNN$ vector and tensor couplings simultaneously. The vacuum gluon field contribution is taken into account. Our results are $g_ω=(18\pm 8), κ_ω=(0.8\pm 0.4)$.

H. Kaya, A. Erzan

A new position-space renormalization group approach is investigated for bond directed percolation in two dimensions. The threshold value for the bond occupation probabilities is found to be $p_c=0.6443$. Correlation length exponents on time (parallel) and space (transverse) directions are found to be $ν_\parallel=1.719$ and $ν_\perp=1.076$, respectively, whi

H. Nikolic

The relativistic motion of an arbitrary point of an accelerated rigid rod is discussed for the case when velocity and acceleration are directed along the rod&#39;s length. The discussion includes the case of a time-dependent force applied to a single point, as well as a time-independent force arbitrary distributed along the rod. The time dependence of the ro

C. Hoeppler, W. Zwerger

Based on the recent free electron model for cohesion in narrow metallic constrictions by Stafford et al., we calculate the quantum fluctuations in the cohesive force versus elongation. The fluctuations are dominated by states near the Fermi energy, thus explaining their apparently universal magnitude of order epsilon_F/lambda_F. We present numerical results

Dan Radu Grigore

We continue our study of non-Abelian gauge theories in the framework of Epstein-Glaser approach to renormalisation theory. We consider the case when massive spin-one Bosons are present into the theory and we modify appropriately the analysis of the origin of gauge invariance performed in a preceding paper in the case of null-mass spin-one Bosons. Then we are

Ph. Boucaud, J. P. Leroy, J. Micheli, O. Pène

We compute the flavorless running coupling constant of QCD from the three gluon vertex in the (regularisation independent) momentum subtraction renormalisation scheme. This is performed on the lattice with high statistics. The expected color dependence of the Green functions is verified. There are significant $O(a^2μ^2)$ effects which can be consistently con

Zhou Mian-Lai, Ma Wen-Gan, Han Liang, Jiang Yi

The complete analysis of the CP violation in the process $γγ\to t \bar{t}$ in frame of the Minimal Supersymmetric Model(MSSM) is presented. The CP-odd observables for describing the CP violating effects in polarized and unpolarized photon collisions, are calculated. We investigate the possible CP violation sources induced by the complex soft breaking paramet

Dong-Shin Shin

We report the result of our evaluation of the Feynman diagrams appearing in the determination of the four-loop renormalization group functions in the two-dimensional lattice O($n$) $σ$-model by Caracciolo and Pelissetto. In the list of the integrals used for the determination of those functions, we find that three entries were not correctly evaluated. We giv

CDF collaboration, F. Abe

We report on a search for second generation leptoquarks (Phi_2) using a data sample corresponding to an integrated luminosity of 110 pb^{-1} collected at the Collider Detector at Fermilab. We present upper limits on the production cross section as a function of Phi_2 mass, assuming that the leptoquarks are produced in pairs and decay into a muon and a quark

Zhou Haijun, Ou-Yang Zhong-can

Simple expressions for the bending and the base-stacking energy of double-stranded semiflexible biopolymers (such as DNA and actin) are derived. The distribution of the folding angle between the two strands is obtained by solving a Schrödinger equation variationally. Theoretical results based on this model on the extension versus force and extension versus d

Christopher A. Fuchs

From the perspective of quantum information theory, a system so simple as one restricted to just two nonorthogonal states can be surprisingly rich in physics. In this paper, we explore the extent of this statement through a review of three topics: (1) ``nonlocality without entanglement&#39;&#39; as exhibited in binary quantum communication channels, (2) the

J. C. Garrison, M. W. Mitchell, R. Y. Chiao, E. L. Bolda

Recent results demonstrating superluminal group velocities and tachyonic dispersion relations reopen the question of superluminal signals and causal loop paradoxes. The sense in which superluminal signals are permitted is explained in terms of pulse reshaping, and the self-consistent behavior which prevents causal loop paradoxes is illustrated by an explicit