March 2002 arXiv papers — page 7

Laurent Bartholdi, Rostislav I. Grigorchuk

We construct a group acting on a binary rooted tree; this discrete group mimics the monodromy action of iterates of $f(z)=z^2-1$ on associated coverings of the Riemann sphere. We then derive some algebraic properties of the group, and describe for that specific example the connection between group theory, geometry and dynamics. The most striking is probably

Allan Adams, Jarah Evslin

We examine the conjecture that an 11d E_8 bundle, appearing in the calculation of phases in the M-Theory partition function, plays a physical role in M-Theory, focusing on consequences for the classification of string theory solitons. This leads for example to a classification of IIA solitons in terms of that of LE_8 bundles in 10d. Since K(Z,2) approximates

Sergei Gukov, Shing-Tung Yau, Eric Zaslow

We argue that G_2 manifolds for M-theory admitting string theory Calabi-Yau duals are fibered by coassociative submanifolds. Dual theories are constructed using the moduli space of M5-brane fibers as target space. Mirror symmetry and various string and M-theory dualities involving G_2 manifolds may be incorporated into this framework. To give some examples,

W. J. Huo

We review our works on the sequential fourth generation model and focus on the constriants of $4\times 4$ quark mixing matrix elements. We investigate the quark mixing matrix elements from the rare $K,B$ meson decays. We talk about the $ hierarchy$ of the $4\times 4$ matrix and the existence of fourth generation.

A. Ferroglia, G. Ossola, M. Passera, A. Sirlin

The calculation of the partial widths of the Z boson in the effective scheme is discussed. Simple formulae for Sin^2 theta_eff^lept, M_W, and Gamma_l in the on-shell, MS, and effective renormalization schemes are presented. Their domain of validity extends to low M_H values probed by current experiments, and to the range of Delta alpha_hadr results from rece

E. B. Myers, F. J. Albert, J. C. Saneky, E. Bonet

We have measured the statistical properties of magnetic reversal in nanomagnets driven by a spin-polarized current. Like reversal induced by a magnetic field, spin-transfer-driven reversal near room temperature exhibits the properties of thermally-activated escape over an effective barrier. However, the spin-transfer effect produces qualitatively different b

Martin Andersson, Stellan Ostlund

We have numerically investigated whether or not a mean-field theory of spin textures generate fictitious flux in the doped two dimensional $t-J$-model. First we consider the properties of uniform systems and then we extend the investigation to include models of striped phases where a fictitious flux is generated in the domain wall providing a possible source

C. T. Liang, C. F. Huang, Yu-Ming Cheng, Tsai-Yu Huang

We have performed low-temperature transport experiments on a Si/SiGe hole system. The measured transverse and longitudinal condductivities $σ_{xx}$ and $σ_{xy}$ allow us to study the magnetic-field-induced transitions in the system. In particular, we present the first study of the temperature-driven flow lines in the "anomalous Hall insulator" regime

P. S. Letelier, A. E. Motter

The Melnikov method is applied to periodically perturbed open systems modeled by an inverse--square--law attraction center plus a quadrupolelike term. A compactification approach that regularizes periodic orbits at infinity is introduced. The (modified) Smale-Birkhoff homoclinic theorem is used to study transversal homoclinic intersections. A larger class of

S. Cristiani, S. Arnouts, A. Fontana, P. Saracco

The addition of deep near infrared images to the database provided by the HDF-S WFPC2 is essential to monitor the SEDs of the objects on a wide baseline and address a number of key issues including the total stellar content of baryonic mass, the effects of dust extinction, the dependence of morphology on the rest frame wavelength, the photometric redshifts,

Alex Kim, Peter Nugent

The relative brightnesses of standard candles have long been known to be potentially powerful probes of distance. The distance modulus, the difference between observed and absolute magnitudes, has been associated with the values of the cosmological parameters: Hubble's constant H_0, the mass density Omega_M and the cosmological constant Omega_Lambda. In

Adan Cabello

Three apparently unrelated problems which have no solution using classical tools are described: the "N-strangers," "secret sharing," and "liar detection" problems. A solution for each of them is proposed. Common to all three solutions is the use of quantum states of total spin zero of N spin-(N-1)/2 particles.

N. Regnault, Th. Jolicoeur, R. Sessoli, D. Gatteschi

The magnetic properties of the molecular cluster Mn12Ac are due to the four Mn3+ ions which have spins S=3/2 and the eight Mn4+ ions with spins S=2. These spins are coupled by superexchange mechanism. We determine the four exchange couplings assuming a Heisenberg-type interaction between the ions. We use exact diagonalization of the spin Hamiltonian by a Lan

Panagiota Kanti, John March-Russell

In the context of brane-world theories, the production cross-section for black holes may be greatly enhanced. Such black holes can in principle lead to detectable signals via their Hawking evaporation to brane-localized modes. We calculate, in the semiclassical approximation, the leading corrections to the energy spectrum (the greybody factors) for decay int

K. Cunha, V. V. Smith, N. B. Suntzeff, J. E. Norris

Copper abundances are presented for 40 red-giant stars in Omega Cen as well as 15 red-giant members of the globular clusters NGC288, NGC362, NGC3201, NGC6752, and M4. A comparison with the halo field star pattern indicates that, unlike the field stars, Omega Cen displays a constant ratio of [Cu/Fe] -0.5 all the way from [Fe/H]=-2.0 to -0.8. At the metallicit

M. V. Sadovskii, N. A. Strigina

We consider a two-dimensional model of the pseudogap state, based on the scenario of strong electron scattering by fluctuations of ``dielectric'' (AFM, CDW) short-range order. We construct a system of recurrence equations both for one-particle Green's function and vertex part, describing electron interaction with an external field, which take int

Ashoke Sen

We discuss construction of classical time dependent solutions in open string (field) theory, describing the motion of the tachyon on unstable D-branes. Despite the fact that the string field theory action contains infinite number of time derivatives, and hence it is not a priori clear how to set up the initial value problem, the theory contains a family of t

Eduard Masso, Francesc Rota, Gabriel Zsembinszki

We reanalyze the conditions under which we have a primordial thermal population of axions. Compared with previous studies, we find other processes, involving gluons and quarks, that dominate at high temperatures. We conclude that if the Peccei-Quinn scale fulfills $F_a < 1.2 \times 10^{12} \GeV$ there is thermal axion production. In this case, a period in th

J. Alfaro, A. A. Andrianov, L. Balart, D. Espriu

While it is clear that in some kinematic regime QCD can be described by an effective (as opposed to fundamental) string theory, it is not at all clear how this string theory should be. The `natural&#39; candidate, the bosonic string, leads to amplitudes with the usual problems related to the existence of the tachyon, absence of the adequate Adler zero, and m

Sergei Gukov, Cumrun Vafa

We study the geometric interpretation of two dimensional rational conformal field theories, corresponding to sigma models on Calabi-Yau manifolds. We perform a detailed study of RCFT&#39;s corresponding to T^2 target and identify the Cardy branes with geometric branes. The T^2&#39;s leading to RCFT&#39;s admit ``complex multiplication&#39;&#39; which charact

V. I. Kuvshinov, V. A. Shaparau, V. V. Marmysh

We study evolution of colour gluon states in isolated QCD jet at the non-perturbative stage. Fluctuations of gluons are less than those for coherent states under specific conditions. This fact suggests that there gluon squeezed states can arise. The angular and rapidity dependencies of the normalized second-order correlation function for present gluon states

Jayendra N. Bandyopadhyay, Arul Lakshminarayan

Previous results indicate that while chaos can lead to substantial entropy production, thereby maximizing dynamical entanglement, this still falls short of maximality. Random Matrix Theory (RMT) modeling of composite quantum systems, investigated recently, entails an universal distribution of the eigenvalues of the reduced density matrices. We demonstrate th

Armen E. Allahverdyan, Roger Balian, Theo M. Nieuwenhuizen

A hamiltonian model is solved, which satisfies all requirements for a realistic ideal quantum measurement. The system S is a spin-$\half$, whose $z$-component is measured through coupling with an apparatus A=M+B, consisting of a magnet $\RM$ formed by a set of $N\gg 1$ spins with quartic infinite-range Ising interactions, and a phonon bath $\RB$ at temperatu

M. V. Cheremisin

The resistivity components of 3D electron gas placed in quantizing magnetic field are calculated taking into account the correction caused by combined action of the Peltier and Seebeck thermoelectric effects. The longitudinal, transverse and the Hall magnetoresistivities exhibit familiar 1/H-period oscillations being universal functions of magnetic field and

Kikuo Harigaya

Optical excitations in hexagonal nanonetwork materials, for example, Boron-Nitride (BN) sheets and nanotubes, are investigated theoretically. The bonding of BN systems is positively polarized at the B site, and is negatively polarized at the N site. There is a permanent electric dipole moment along the BN bond, whose direction is from the B site to the N sit

W. -Y. Hwang, K. Matsumoto

We show that the entanglement of cost and entanglement of distillation can be vague when we consider a more general form of entanglement manipulation in which we collectively deal with not only states of our concern but also other states. We introduce the most general entanglement manipulation in which the formation and distillation can be simultaneously per

S. Vrielmann, Rae F. Stiening, Warren Offutt

We analyse simultaneous UBVR quiescent light curves of the cataclysmic variable V2051 Oph using the Physical Parameter Eclipse Mapping method in order to map the gas temperature and surface density of the disc for the first time. The disc appears optically thick in the central regions and gradually becomes optically thin towards the disc edge or shows a more

Y. Nambu, K. Usami, Y. Tsuda, K. Matsumoto

We report the generation of polarization-entangled photons by femtosecond-pulse-pumped spontaneous parametric down-conversion in a cascade of two type-I crystals. Highly entangled pulsed states were obtained by introducing a temporal delay between the two orthogonal polarization components of the pump field. They exhibited high-visibility quantum interferenc

Takuji Nomura, Kosaku Yamada

We discuss a microscopic mechanism of the spin-tiplet superconductivity in the quasi-two-dimensional ruthenium oxide Sr2RuO4 on the basis of two-dimensional three-band Hubbard model. We solve the linearized Eliashberg equation by taking into account the full momentum-frequency dependence of the order parameter for the spin-triplet and the spin-singlet states

Kenji Kawamura, Naomichi Hatano

We introduce a simple and generic model that reproduces Zipf&#39;s law. By regarding the time evolution of the model as a random walk in the logarithmic scale, we explain theoretically why this model reproduces Zipf&#39;s law. The explanation shows that the behavior of the model is very robust and universal.

Yuri V. Kovchegov, Kirill L. Tuchin

We calculate the contribution to the elliptic flow observable v2 from two-particle correlations in minijet production in ultrarelativistic heavy ion collisions. We use a minijet production cross section derived in a model inspired by saturation approach to high energy scattering. Resulting differential elliptic flow v2(pT) is an increasing function of pT for

We-Fu Chang, I-Lin Ho, John N. Ng

We investigate the constraint on the split fermions in extra dimensions by considering the universality of $W$ leptonic decays $W\to l_i ν_i$, the charged lepton decays $l_i \ra l_jν_i\barν_j$, and the lepton flavor violating process $l_i\ra \bar{l}_j l_k l_h$ where $l_i= e,μ$ or $τ$. For the Standard Model (SM) background of $W\ra l_i ν_i$, we extended the

F. J. Rodriguez, L. Quiroga, N. F. Johnson

We propose an unambiguous signature for detecting quantum superposition states in a nanostructure, based on current ultrafast spectroscopy techniques. The reliable generation of such superposition states via Hadamard-like quantum gates is crucial for implementing solid-state based quantum information schemes. The signature originates from a remarkably strong

J. S. Bloom, S. R. Kulkarni, P. A. Price, D. Reichart

Using observations from an extensive monitoring campaign with the Hubble Space Telescope we present the detection of an intermediate-time flux excess which is redder in color relative to the afterglow of GRB 011121, currently distinguished as the gamma-ray burst with the lowest known redshift. The red ``bump,&#39;&#39; which exhibits a spectral roll-over at

D. Stucki, N. Gisin, O. Guinnard, G. Ribordy

We present a fibre-optical quantum key distribution system. It works at 1550nm and is based on the plug & play setup. We tested the stability under field conditions using aerial and terrestrial cables and performed a key exchange over 67 km between Geneva and Lausanne.

Masahide Sasaki, Masashi Ban, Stephen M. Barnett

We investigate strategies for estimating a depolarizing channel for a finite dimensional system. Our analysis addresses the double optimization problem of selecting the best input probe state and the measurement strategy that minimizes the Bayes cost of a quadratic function. In the qubit case, we derive the Bayes optimal strategy for any finite number of inp

D. Iftimie, M. C. Lopes Filho, H. J. Nussenzveig Lopes

In this article we study the asymptotic behavior of incompressible, ideal, time-dependent two dimensional flow in the exterior of a single smooth obstacle when the size of the obstacle becomes very small. Our main purpose is to identify the equation satisfied by the limit flow. We will see that the asymptotic behavior depends on $γ$, the circulation around t

F. Moulin, D. Bernard

Semiclassical methods are used to study the nonlinear interaction of light in vacuum in the context of four wave mixing. This study is motivated by a desire to investigate the possibility of using recently developed powerful ultrashort (femtosecond) laser pulses to demonstrate the existence of nonlinear effects in vacuum, predicted by quantum electrodynamics

Masashi Hase, Hiroshi Miyazaki, Mitsuru Egashira, Norio Shinya

We measured and calculated transmission spectra of two-dimensional quasiperiodic photonic crystals (PCs) based on a 5-fold (Penrose) or 8-fold (octagonal) symmetric quasiperiodic pattern. The photonic crystal consisted of dielectric cylindrical rods in air placed normal to the basal plane on vertices of tiles composing the quasiperiodic pattern. An isotropic

Y. G. Ma

The features of the emissions of light particles (LP), charged particles (CP), intermediate mass fragments (IMF) and the largest fragment (MAX) are investigated for $^{129}Xe$ as functions of temperature and &#39;freeze-out&#39; density in the frameworks of the isospin-dependent lattice gas model and the classical molecular dynamics model. Definite turning p

Jacek Dobaczewski

The present-day nuclear structure theory exhibits a great degree of synergy with respect to methods that are used to describe various phenomena in heavy nuclear systems. From few-body methods, through the shell model to mean-field approaches, the bridges are being built between different ways of describing the stable as well as the most exotic nuclei. In the

Joakim Nystrand, Anthony J. Baltz, Spencer R. Klein

Coherent vector meson production in peripheral nucleus-nucleus collisions is discussed. These interactions may occur for impact parameters much larger than the sum of the nuclear radii. Since the vector meson production is always localized to one of the nuclei, the system acts as a two-source interferometer in the transverse plane. By tagging the outgoing nu

I. Vidana, I. Bombaci

Properties of spin polarized isospin asymmetric nuclear matter are studied within the framework of the Brueckner--Hartree--Fock formalism. The single-particle potentials of neutrons and protons with spin up and down are determined for several values of the neutron and proton spin polarizations and the asymmetry parameter. It is found an almost linear and sym

STAR Collaboration, C. Adler

We report the first measurement of strange ($Λ$) and anti-strange ($\barΛ$) baryon production from $\sqrt{s_{_{NN}}}=130$ GeV Au+Au collisions at the Relativistic Heavy Ion Collider (RHIC). Rapidity density and transverse mass distributions at mid-rapidity are presented as a function of centrality. The yield of $Λ$ and $\barΛ$ hyperons is found to be approxi

K. Adcox, PHENIX Collaboration

Distributions of event-by-event fluctuations of the mean transverse momentum and mean transverse energy near mid-rapidity have been measured in Au+Au collisions at sqrt(s_NN) = 130 GeV at RHIC. By comparing the distributions to what is expected for statistically independent particle emission, the magnitude of non-statistical fluctuations in mean transverse m

R. Klages

Rajagopalan and Sabir [nlin.CD/0104021 and Phys. Rev. E 63, 057201 (2001)] recently discussed deterministic diffusion in a piecewise linear map using an approach developed by Fujisaka et al. We first show that they rederived the random walk formula for the diffusion coefficient, which is known to be the exact result for maps of Bernoulli type since the work

Xingang Wang, Gang Hu

Transitions to measure synchronization in two coupled $ϕ^{4}$ lattices are investigated based on numerical simulations. The relationship between measure synchronization (MS), phase locking and system&#39;s total energy is studied both for periodic and chaotic states. Two different scalings are discovered during the process to MS according to phase locking. R

J. Yamamoto

We studied that arbitrary 2-dimensional maps are Hamilton system if a initial value of map is a &#34;time&#34; variable. In this paper, we generalize this correspondence, and show that an n-dimensional map is a Nambu system in which one of initial values of the map play a role of &#34;time&#34; variable.

Stefan Teufel

The Schroedinger equation for N particles interacting through effective pair potentials is derived from the massless Nelson model with ultraviolet cutoffs. We consider a scaling limit where the particles are slow and heavy, but, in contrast to earlier work [6], no ``weak coupling&#39;&#39; is assumed. To this end we prove a space-adiabatic theorem without ga

J. Cortes, S. Martinez, F. Cantrijn

The geometric approach to autonomous classical mechanical systems in terms of a canonical first-order system on the Whitney sum of the tangent and cotangent bundle, developed by R. Skinner and R. Rusk, is extended to the time-dependent framework.

Tohru Koma, Bruno Nachtergaele, Shannon Starr

We investigate the spectrum above the kink ground states of the spin J ferromagnetic XXZ chain. Our main theorem is that there is a non-vanishing gap above all ground states of this model for all values of J. Using a variety of methods, we obtain additional information about the magnitude of this gap, about its behavior for large Δ, about its overall behavio

Lev A. Borisov, Paul E. Gunnells

In two previous papers we used the geometry of complete polyhedral fans to construct a subring $\TTT (l)$ of the modular forms on $Γ_{1} (l)$, and showed that for weight two the cuspidal part of $\TTT (l)$ coincides with the space of cusp forms of analytic rank zero. In this paper we show that in weights greater than two, the cuspidal part of $\TTT (l)$ coin

K. Hulek, G. K. Sankaran

We determine the cone of nef divisors on the Igusa and Voronoi compactifications of the moduli space of principally polarised abelian 4-folds. We also show that the canonical bundle on the Igusa compactification of A_4(n) is ample for n at least 3. Analogous results for A_2 and A_3 were earlier obtained by the first author but the case of A_4 is far less sim

Daniel Azagra, Manuel Cepedello Boiso

We prove that every continuous mapping from a separable infinite-dimensional Hilbert space $X$ into $\mathbb{R}^{m}$ can be uniformly approximated by $C^\infty$ smooth mappings {\em with no critical points}. This kind of result can be regarded as a sort of very strong approximate version of the Morse-Sard theorem. Some consequences of the main theorem are as

Martin Markl

In this note we introduce an action of cyclohedra on the free loop space. We will then discuss how this action can be used for an appropriate recognition principle in the same manner as the action of Stasheff&#39;s associahedra can be used to recognize based loop spaces. We will also interpret one result of R.L. Cohen as an approximation theorem, in the spir

Mircea Mustata

We generalize a result of Ein-Lazarsfeld-Smith (math.AG/0202303), proving that for an arbitrary sequence of zero-dimensional ideals, the multiplicity of the sequence is equal with its volume. This is done using a deformation to monomial ideals. As a consequence of our result, we obtain a formula which computes the multiplicity of an ideal I in terms of the m

Emilio De Santis, Charles M. Newman

We consider stochastic processes, S^t \equiv (S_x^t : x \in Z^d), with each S_x^t taking values in some fixed finite set, in which spin flips (i.e., changes of S_x^t) do not raise the energy. We extend earlier results of Nanda-Newman-Stein that each site x has almost surely only finitely many flips that strictly lower the energy and thus that in models witho

Jobst Heitzig

It is shown that each continuous transformation $h$ from Euclidean $m$-space ($m>1$) into Euclidean $n$-space that preserves the equality of distances (that is, fulfils the implication $|x-y|=|z-w|\Rightarrow|h(x)-h(y)|=|h(z)-h(w)|$) is a similarity map. The case of equal dimensions already follows from the Beckman--Quarles Theorem.

Jaroslaw Kedra

Moduli spaces of stable pseudoholomorphic curves can be defined parametrically, i.e. over total spaces of symplectic fibrations. This imposes several restrictions on the spectral sequence of a symplectic fibration. We prove that, under certain assumptions, a Hamiltonian fibration c-splits, i.e. the spectral sequence associated to the fibration collapses at E

Michael Levitin, Rustem Yagudin

We conduct extensive numerical experiments aimed at finding the admissible range of the ratios of the first three eigenvalues of a planar Dirichlet Laplacian. The results improve the previously known theoretical estimates of M Ashbaugh and R Benguria. We also prove some properties of a maximizer of the ratio $λ_3/λ_1$.

S. Ole Warnaar

We present alternative, q-hypergeometric proofs of some polynomial analogues of classical q-series identities recently discovered by Alladi and Berkovich, and Berkovich and Garvan.

Martin Ulrich Schmidt

A proof of the Willmore conjecture is presented. With the help of the global Weierstrass representation the variational problem of the Willmore functional is transformed into a constrained variational problem on the moduli space of all spectral curves corresponding to periodic solutions of the Davey-Stewartson equation. The subsets of this moduli space, whic

Michael Lacey, Sarah Ferguson

Let b be a function on the plane. Let H_j, j=1,2, be the Hilbert transform acting on the j-th coordinate on the plane. We show that the operator norm of the double commutator [[ M_b, H_1], H_2] is equivalent to the Chang-Fefferman BMO norm of b. Here, M_b denotes the operator which is multiplication by b. This result extends a well known theorem of Nehari on

Danny Calegari

A taut foliation of a hyperbolic 3-manifold has the continuous extension property for leaves in almost every direction; that is, for each leaf of the universal cover of the foliation and almost every geodesic ray in the leaf, the limit of the ray in the universal cover of the 3-manifold is a well-defined point in the ideal boundary.

Frederic Leblond, Luc Marleau

We find examples in string theory of locally wrapped D-branes. These excitations mimic skyrmions in that they correspond to topological excitations of the scalar fields parametrizing the brane motion in the space transverse to its world-volume. While these brane excitations appear to be point-like, evidence is provided that curvature corrections to the probe

J. Kijowski, G. Rudolph, C. Śliwa

The lattice model of scalar quantum electrodynamics (Maxwell field coupled to a complex scalar field) in the Hamiltonian framework is discussed. It is shown that the algebra of observables ${\cal O}(Λ)$ of this model is a $C^*$-algebra, generated by a set of gauge-invariant elements satisfying the Gauss law and some additional relations. Next, the faithful,

A. I. Davydychev, M. Yu. Kalmykov

Some problems related to the structure of higher terms of the epsilon-expansion of Feynman diagrams are discussed.

Pedro F. Gonzalez-Diaz

After reviewing the main characteristics of the spacetime of accelerating universes driven by a quintessence scalar field with constant equation of state $ω$, we investigate in this paper the classical stability of such spaces to cosmological perturbations, particularizing in the case of a closed geometry and equation of state $ω=-2/3$. We conclude that this

Masahiro Anazawa, Atushi Ishikawa

We study a disk amplitude which has a complicated heterogeneous matter configuration on the boundary in a system of the (3,4) conformal matter coupled to two-dimensional gravity. It is analyzed using the two-matrix chain model in the large N limit. We show that the disk amplitude calculated by Schwinger-Dyson equations can completely be reproduced through pu

Mattia Jona-Lasinio

The loop expansion of the effective action is used to evaluate quantum corrections to a scalar field theory (massive phi^4 model) on AdS. We evaluate one loop corrections and show that they preserve conformal invariance of the boundary theory as conjectured by AdS/CFT correspondence.

Ruth Durrer

In this note I try to clarify the problem of perturbations in the ekpyrotic universe. I write down the most general matching conditions and specify the choices taken by the two debating sides. I also bring up the problem of surface stresses which always have to be present when a transition from a collapsing to an expanding phase is made.

Gautam Dutta

The neutrino oscillation experiments increasingly point towards a mixing pattern that can be parametrised with two near maximal and one small mixing angle. We investigate whether such a mixing pattern can be generated as a fixed point of renormalisation group evolution.

J. Fleischer, J. Fujimoto, T. Ishikawa, A. Leike

Radiative corrections to the process e+ e- to t tbar are calculated in one-loop approximation of the Standard Model. There exist results from several groups. This talk provides further comparisons of the complete elektroweak contributions, including hard bremsstrahlung. The excellent final agreement of the different groups allows to continue by working on a

Sudhir K. Vempati

Supersymmetric Standard Model has been built to solve the hierarchy problem which is encountered whenever Standard Model is incorporated into a theory with a larger mass scale. Experimentally, one of the first signals of physics beyond Standard Model is provided by the atmospheric neutrino experiments which indicate the existence of at least one non-zero neu

Z. Was

In the future high energy physics experiments, the question of properly matching the phenomenological programs that describe different parts of the physics processes (such as hard scattering, hadronization, decay of resonances, detector response, etc.) is very important. In the past, FORTAN common blocks filled with lists of objects (particles, strings, clus

Alberto Giovannini, Roberto Ugoccioni

Particle correlations and particle multiplicity distributions cannot be approached independently: a unified description of correlations and multiplicity distributions is always needed in order to understand the underlying dynamics in high energy collisions. In this light, we review the most recent and interesting results on rapidity and momentum correlations

Alberto Giovannini, Roberto Ugoccioni

ALICE is a unique opportunity for studying low Pt physics and minimum bias events, and consequently for hunting substructures in strong interactions. The general question concerning global event properties in pp and ppbar physics is indeed whether substructures can be seen in the data in a model-independent way. In other terms, can we identify the interface

Wu-Jun Huo, Tai-Fu Feng

We investigate the lepton flavor violation decays, $τ\to μγ$, $τ\to eγ$ and $μ\to eγ$, in the framwork of a squential fourth generation model with a heavy fourth neutrino, $ν&#39;$. Using the recent experimental bounds, we can obtain the constraints of the $4\times 4$ leptonic mixing matrix element factors, $V_{1ν&#39;},V_{2ν&#39;}$ and $V_{3ν&#39;}$. We fin

L. Del Debbio, A. Di Giacomo, B. Lucini, G. Paffuti

The abelian projection in SU(N) gauge theories is discussed in detail, as well as the construction of a disorder parameter to study dual superconductivity as a mechanism for color confinement. If the ideas of the large N limit are correct, a universal N-independent behavior is expected for the suitable rescaled disorder parameter as a function of lambda = g^

Luke Jones

A search for slepton production via the decay of pair-produced neutralinos has been performed under the assumption that the sleptons have observable lifetime in the detector before each decays to a lepton and a gravitino. Sleptons, neutralinos and gravitinos are particles predicted by the theory of supersymmetry, and are the supersymmetric partners of the St

R. Aldrovandi, J. Gariel, G. Marcilhacy

Physics, as known from our local, around--earth experience, meets some of its applicability limits at the time just preceding the period of primeval nucleosynthesis. Attention is focussed here on the effects of the nucleon size. Radiation--belonging nucleons are found to produce an extremely high pressure at kT of the order of some tens or hundreds of MeV. Q

Brien C. Nolan, Filipe C. Mena

We derive some more results on the nature of the singularities arising in the collapse of inhomogeneous dust spheres. (i) It is shown that there are future-pointing radial and non-radial time-like geodesics emerging from the singularity if and only if there are future-pointing radial null geodesics emerging from the singularity. (ii) Limits of various space-

Sergio M. C. V. Goncalves, Sanjay Jhingan

We find analytical solutions describing the collapse of an infinitely long cylindrical shell of counter-rotating dust. We show that--for the classes of solutions discussed herein--from regular initial data a curvature singularity inevitably develops, and no apparent horizons form, thus in accord with the spirit of the hoop conjecture.

Maurice H. P. M. van Putten

Upcoming gravitational wave-experiments promise a window for discovering new physics in astronomy. Detection sensitivity of the broadband laser interferometric detectors LIGO/VIRGO may be enhanced by matched filtering with accurate wave-form templates. Where analytic methods break down, we have to resort to numerical relativity, often in Hamiltonian or vario

Osvaldo M. Moreschi, Sergio Dain

The notion of center of mass for an isolated system has been previously encoded in the definition of the so called nice sections. In this article we present a generalization of the proof of existence of solutions to the linearized equation for nice sections, and formalize a local existence proof of nice sections relaxing the radiation condition. We report on

L. J. Boya, M. A. Per, A. J. Segui

We study the apparition of event horizons in accelerated expanding cosmologies. We give a graphical and analytical representation of the horizons using proper distances to coordinate the events. Our analysis is mainly kinematical. We show that, independently of the dynamical equations, all the event horizons tend in the future infinity to a given expression

Chris Doran, Anthony Lasenby, Joan Lasenby

Projective geometry provides the preferred framework for most implementations of Euclidean space in graphics applications. Translations and rotations are both linear transformations in projective geometry, which helps when it comes to programming complicated geometrical operations. But there is a fundamental weakness in this approach - the Euclidean distance

Hao Li, Chao Tang, Ned Wingreen

We study the designability of all compact 3x3x3 and 6x6 lattice-protein structures using the Miyazawa-Jernigan (MJ) matrix. The designability of a structure is the number of sequences that design the structure, i.e. sequences that have that structure as their unique lowest-energy state. Previous studies of hydrophobic-polar (HP) models showed a wide distribu

Zoltan Adam Nemeth, Jean-Louis Pichard

We consider three spinless fermions free to move on 2d square lattice with periodic boundary conditions and interacting via a U/r Coulomb repulsion. When the Coulomb energy to kinetic energy ratio r_s is large, a rigid Wigner molecule is formed. As r_s decreases, we show that melting proceeds via an intermediate regime where a floppy two particle molecule co

F. Alonso-Marroquin, H. J. Herrmann

The constitutive relation of the quasi-static deformation on two dimensional packed samples of polygons is calculated using molecular dynamic simulations. The stress values at which the system remains stable are bounded by a failure surface, that shows a power law dependence on the pressure. Below the failure surface, non linear elasticity and plastic deform

D. A. Contreras-Solorio, J. A. de la Cruz-Alcaz, S. T. Pavlov

The &#34;one-dimensional&#34; coherent states are applied to describe the Shubnikov - de Haas and the de Haas-van Alphen oscillation effects in metals, semimetals, and degenerate semiconductors. The oscillatory part of the electron density of states in a magnetic field is calculated. A substantial simplification of calculations is achieved.

Egidijus Anisimovas, F. M. Peeters

We investigate the ground and excited states of a bipolar artificial molecule composed of two vertically coupled quantum dots containing different type of carriers -- electrons and holes -- in equilibrium. The approach based on exact diagonalization is used and reveals an intricate pattern of ground-state angular momentum switching and a rearrangement of app

Burkhard Duenweg, Dirk Reith, Martin Steinhauser, Kurt Kremer

We discuss the hydrodynamic radius $R_H$ of polymer chains in good solvent, and show that the leading order correction to the asymptotic law $R_H \propto N^ν$ ($N$ degree of polymerization, $ν\approx 0.59$) is an ``analytic&#39;&#39; term of order $N^{-(1 - ν)}$, which is directly related to the discretization of the chain into a finite number of beads. This

Tamara S. Nunner, Philipp Brune, Thilo Kopp, Marco Windt

We investigate the influence of a cyclic spin exchange J_{cyc} on the one- and two-triplet excitations of an undoped two-leg S=1/2 ladder, using the density matrix renormalization group (DMRG). The dispersion of the S=0 two-triplet bound state is dramatically reduced by J_{cyc} due to a repulsion between triplets on neighboring rungs. In (La,Ca)_{14}Cu_{24}O

Alice Ruini, Marilia J. Caldas, Giovanni Bussi, Elisa Molinari

We perform ab initio calculations of optical properties for a typical semiconductor conjugated polymer, poly-para-phenylenevinylene, in both isolated chain and crystalline packing. In order to obtain results for excitonic energies and real-space wavefunctions we explicitly include electron-hole interaction within the density-matrix formalism. We find that th

Thomas Schwager, Thorsten Poeschel

In a recent paper an implicit equation for contacting viscoelastic spheres was derived (Brilliantov et al. PRE 53, 5382 (1996)). Integrating this equation it can be shown that the coefficient of normal restitution depends on the impact velocity as 1-ε\sim g^{1/5}.

M. A. Moore

The energy of a droplet of linear extent L in the ``droplet theory&#39;&#39; of spin glasses goes as $L^θ$ for large L. It is argued that this formula needs to be modified by the addition of a scaling correction $L^{-ω}$ in order to accurately describe droplet energies at the length scales currently probed in numerical simulations. With this simple modificat

H. Portales, L. Saviot, E. Duval, M. Gaudry

Low-frequency Raman scattering experiments have been performed on thin films consisting of nickel-silver composite nanoparticles embedded in alumina matrix. It is observed that the Raman scattering by the quadrupolar modes, strongly enhanced when the light excitation is resonant with the surface dipolar excitation, is mainly governed by the silver electron c

Thorsten Poeschel, Werner Ebeling, Helge Rose

We propose a new method for the calculation of the statistical properties, as e.g. the entropy, of unknown generators of symbolic sequences. The probability distribution p(k) of the elements k of a population can be approximated by the frequencies f(k) of a sample provided the sample is long enough so that each element k occurs many times. Our method yields

V. M. Loktev, V. Turkowski

Zero temperature crossover from superfluidity to superconductivity with carrier density increasing is studied for a two-dimensional system in the s-wave and d-wave pairing channels. It was assumed that the particle attraction correlation length depends on carrier density $n_f$ as $r_0\sim1/\sqrt{n_f}$. Such a dependence was found experimentally for the radiu