May 2002 arXiv papers — page 11

Aaron D. Lewis, John T. Stocke, David A. Buote

We have obtained high spatial resolution temperature and abundance profiles for the galaxy cluster Abell 2029 with the Chandra ACIS-S instrument. Our observations reveal that the spectra are well-fit by a single-phase gas in each annulus. While the temperature of the intracluster medium drops from ~9 keV at 3 arcmin (260 kpc) to 3 keV in the central 5 arcsec

Stefan Immler, Andrew S. Wilson, Yuichi Terashima

We present two high-resolution Chandra X-ray observations of supernova (SN) 1994I which show, for the first time, that the interaction of the blast wave from a Type Ic SN with its surrounding circumstellar material (CSM) can give rise to soft X-ray emission. Given a 0.3-2 keV band X-ray luminosity of L_x ~ 1 x 10^{37} ergs/s between six and seven years after

P. E. Nissen, F. Primas, M. Asplund, D. L. Lambert

A study of the O/Fe ratio in metal-poor main sequence and subgiant stars is presented using the [OI] 6300A line, the OI 7774A triplet, and a selection of weak FeII lines observed on high-resolution spectra acquired with the VLT UVES spectrograph. The [OI] line is detected in the spectra of 18 stars with -0.5 < [Fe/H] < -2.4, and the triplet is observed for 1

Georges Meynet, Andre Maeder

We calculate a grid of star models with and without the effects of axial rotation for stars in the mass range between 2 and 60 M$_{\odot}$ for the metallicity $Z = 10^{-5}$. Star models with initial masses superior or equal to 9 M$_\odot$ were computed up to the end of the carbon--burning phase. Star models with masses between 2 and 7 M$_\odot$ were evolved

W. A. Traub, K. W. Jucks

Terrestrial planetary systems may exist around nearby stars as the Earth-sized counterparts to the many giant planets already discovered within the solar neighborhood. In this chapter we first discuss the numerous techniques which have been suggested to search for extrasolar terrestrial planets. We then focus on the expected results from that technique in wh

Yu. N. Efremov, S. A. Pustilnik, A. Y. Kniazev, B. G. Elmegreen

We describe the results of a long-slit spectroscopic study of an unusual star complex in the nearby spiral galaxy NGC 6946 using the SAO 6-m telescope and the Keck 10-m telescope. The complex resembles a circular bubble 600 pc in diameter with a young super star cluster (SSC) near the center. The kinematics of ionized gas is studied through Ha emission with

Hideyuki Umeda, Ken&#39;ichi Nomoto

We calculate evolution and nucleosynthesis in massive Pop III stars with M = 13 ~ 270Msun, and compare the results with abundances of very metal-poor halo stars. The observed abundances can be explained by the energetic core-collapse supernovae with M < ~ 130Msun (``hypernovae&#39;&#39;) but not by pair-instability supernovae (PISNe) with M ~ 140-270 Msun. T

Christopher J. Conselice

Clusters of galaxies have an observed over-density of low-luminosity systems in comparison to the field, although it is not yet agreed whether this effect is the result of initial galaxy mass functions that vary with environment or galaxy evolutionary effects. In this letter we argue that this over-density is the result of low-mass systems with red colors th

T. Kato, D. Nogami, S. Masuda

We discovered that RX And, one of prototypical Z Cam-type dwarf novae, underwent a deep, extended faint state in 1996-1997. Time-resolved photometry at the bottom of the fading revealed the presence of strong flickering, and the absence of detectable orbital modulation. This finding indicates that the mass-transfer remained even at the deepest minimum of the

Tonatiuh Matos, Dario Nunez, F. Siddhartha Guzman, Erandy Ramirez

In an arbitrary axisymmetric stationary spacetime, we determine the expression for the tangential velocity of test objects following a circular stable geodesic motion in the equatorial plane, as function of the metric coefficients. Next, we impose the condition, observed in large samples of disks galaxies, that the magnitude of such tangential velocity be ra

Barbara M. Terhal, David P. DiVincenzo

We present evidence that there exist quantum computations that can be carried out in constant depth, using 2-qubit gates, that cannot be simulated classically with high accuracy. We prove that if one can simulate these circuits classically efficiently then the complexity class BQP is contained in AM.

Richard Wigmans

It is shown that a variety of characteristic features of the high-energy hadronic cosmic ray spectra, in particular the abrupt changes in the spectral index that occur around 3 PeV and 300 PeV, as well as the corresponding changes in elemental composition that are evident from kinks in the $<X_{\max}>$ distribution, can be explained in great detail from inte

Andreas S. Kronfeld

Several physical problems in particle physics, nuclear physics, and astrophysics require information from non-perturbative QCD to gain a full understanding. In some cases the most reliable technique for quantitative results is to carry out large-scale numerical calculations in lattice gauge theory. As in any numerical technique, there are several sources of

V. M. Pudalov, M. E. Gershenson, H. Kojima, G. Brunthaler

We compare the temperature dependence of resistivity ρ(T) of Si MOSFETs with the recent theory by Zala et al. This comparison does not involve any fitting parameters: the effective mass m* and g*-factor for mobile electrons have been found independently. An anomalous increase of ρwith temperature, which has been considered a signature of the &#34;metallic&#3

P. C. de Holanda, A. Yu. Smirnov

We perform global analysis of the solar neutrino data including the day and night spectra of events at SNO. In the context of two active neutrino mixing, the best fit of the data is provided by the LMA MSW solution with Delta m^2 = 6.15 10^{-5} eV^2, tan^2θ= 0.41, f_B = 1.05, where f_B is the boron neutrino flux in units of the corresponding flux in the Stan

Chong-Sun Chu, Pei-Ming Ho, Feng-Li Lin

We study Witten open string field theory in the pp-wave background in the tensionless limit, and construct the N-string vertex in the basis which diagonalizes the string perturbative spectrum. We found that the Witten *-product can be viewed as infinite copies of the Moyal product with the same noncommutativity parameter $θ=2$. Moreover, we show that this Mo

Christopher T. Hill, Adam K. Leibovich

We consider the Wilson Line PNGB which arises in a U(1)^N gauge theory, abstracted from a latticized, periodically compactified extra dimension U(1). Planck scale breaking of the PNGB&#39;s global symmetry is suppressed, providing natural candidates for the axion and quintessence. We construct an explicit model in which the axion may be viewed as the 5th com

Y. Nahmad-Molinari, G. Canul-Chay, J. C. Ruiz-Suarez

The rise dynamics of a large spherical particle, in a granular bed under vertical vibrations, is experimentally studied. An inductive device has been designed to track the particle while it climbs through the bed under different conditions. A simple model based in energy considerations is presented to explain our experimental data, drawing important conclusi

Steven Corley, Sanjaye Ramgoolam

A class of exact non-renormalized extremal correlators of half-BPS operators in N=4 SYM, with U(N) gauge group, is shown to satisfy finite factorization equations reminiscent of topological gauge theories. The finite factorization equations can be generalized, beyond the extremal case, to a class of correlators involving observables with a simple pattern of

S. Kachru, L. McAllister

We study the cosmology induced on a brane probing a warped throat region in a Calabi-Yau compactification of type IIB string theory. For the case of a BPS D3-brane probing the Klebanov-Strassler warped deformed conifold, the cosmology described by a suitable brane observer is a bouncing, spatially flat Friedmann-Robertson-Walker universe with time-varying Ne

Elizabeth Winstanley

The Einstein-conformally coupled scalar field system is studied in the presence of a cosmological constant. We consider a massless or massive scalar field with no additional self-interaction, and spherically symmetric black hole geometries. When the cosmological constant is positive, no scalar hair can exist and the only solution is the Schwarzschild-de Sitt

Gautam Trivedi

We use Berkovits&#39; pure spinor quantization to compute various three-point tree correlation functions in position-space for the Type IIB superstring. We solve the constraint equations for the vertex operators and obtain explicit expressions for the graviton and axion components of the vertex operators. Using these operators we compute tree level correlati

Etienne Balan, Francesco Mauri, Celine Lemaire, Christian Brouder

Chrysotile asbestos is formed by densely packed bundles of multiwall hollow nanotubes. Each wall in the nanotubes is a cylindrically wrapped layer of $Mg_3 Si_2 O_5 (OH)_4$. We show by experiment and theory that the infrared spectrum of chrysotile presents multiple plasmon resonances in the Si-O stretching bands. These collective charge excitations are unive

Emiliano Imeroni

We obtain the correct all-loop beta-function of pure N=1 super Yang-Mills theory from the supergravity solution of the warped deformed conifold, including also some nonperturbative corrections. The crucial ingredient is the gauge-gravity relation that can be inferred by taking into account the phenomenon of gaugino condensation.

Paolo Aschieri, Branislav Jurco, Peter Schupp, Julius Wess

Noncommutative Yang-Mills theories are sensitive to the choice of the representation that enters in the gauge kinetic term. We constrain this ambiguity by considering grand unified theories. We find that at first order in the noncommutativity parameter θ, SU(5) is not truly a unified theory, while SO(10) has a unique noncommutative generalization. In view of

G. Bonelli

We formulate matrix models for strings in ten dimensional pp-wave backgrounds and for particles in eleven dimensional ones. This is done by first characterizing the deformations of ten dimensional {\cal N}=1 SYM which are induced by a constant bispinorial coupling $\int \barΨHΨ$ plus a minimal purely bosonic completition and then by the appropriate dimension

Charis Anastopoulos

Quantum theory predicts probabilities as well as relative phases between different alternatives of the system. A unified description of both probabilities and phases comes through a generalisation of the notion of a density matrix for histories; this object is the decoherence functional of the consistent histories approach. If we take phases as well as proba

E. Christova, H. Eberl, S. Kraml, W. Majerotto

Supersymmetric loop contributions can lead to different decay rates of H+\to t\bar b and H-\to b\bar t. We calculate the decay rate asymmetry δ^CP = \frac{Γ(H+\to t\bar b)-Γ(H-\to b\bar t)}{{Γ(H+\to t\bar b)+Γ(H-\to b\bar t)} at next-to-leading order in the MSSM with complex parameters. We analyse the parameter dependence of δ^CP with emphasis on the phases

N. V. Dobrodey, A. I. Streltsov, L. S. Cederbaum, C. Villani

The two available Mg2p^{-1} spectra of the recently discovered high-temperature superconducting MgB_2 crystal exhibit interesting structures, but contradict each other. This motivated us to perform ab initio calculations on the core-level spectra of cluster models. The computed spectra reveal unusual rich and intense structures triggered by a B2p_z->Mg3s,3p

Xu-Bo Zou, Hai-Woong Lee, Jaewan Kim, Jae-Weon Lee

By applying Hardy&#39;s argument, we demonstrate the violation of local realism in a gedanken experiment using independent and separated particle sources.

J. P. Mbelek, M. Lachièze-Rey

We explore the possibility that the reported time variation of the fine structure constant $α$ is due to a coupling between electromagnetism and gravitation. This may reconcile the claimed results on $α$ with the upper limit from the Oklo naturel Uranium fission reactor.

A. Bassetto, G. Nardelli, A. Torrielli

Commutative Yang-Mills theories in 1+1 dimensions exhibit an interesting interplay between geometrical properties and U(N) gauge structures: in the exact expression of a Wilson loop with $n$ windings a non trivial scaling intertwines $n$ and $N$. In the non-commutative case the interplay becomes tighter owing to the merging of space-time and ``internal&#39;&

Jiro Soda, Kazuya Koyama

First, we will study the cosmological perturbations from the brane point of view. It turns out that two types of the extra data are necessary to know the evolution of the system. To fix these data, the analysis of the bulk is needed. So, we have solved equations of motion for the bulk gravity and determined the extra data. We would like to stress that, both

J. W. Moffat

A possible causal solution to the problem of providing a spacetime description of the transmission of signals in quantum entangled states is described using a `bimetric&#39; spacetime structure, in which the quantum entanglement measurements alter the structure of spacetime. Possible experimental tests to verify the suggested spacetime interpretation of quan

Karl L. F. Bane

Beginning with the general Bjorken-Mtingwa solution for intrabeam scattering (IBS) we derive an accurate, greatly simplified model of IBS, valid for high energy beams in normal storage ring lattices. In addition, we show that, under the same conditions, a modified version of Piwinski&#39;s IBS formulation (where dispersion squared over beta has been replaced

N. Marwan, N. Wessel, U. Meyerfeldt, A. Schirdewan

The knowledge of transitions between regular, laminar or chaotic behavior is essential to understand the underlying mechanisms behind complex systems. While several linear approaches are often insufficient to describe such processes, there are several nonlinear methods which however require rather long time observations. To overcome these difficulties, we pr

Shantilal G. Goradia

The gravitational inverse square law is microscopic approximation. I suggest that it should be modified for elementary particles to use the surface-to-surface separation of the particles rather than the center-to-center separations. For small particles at macroscopic separations, the ratio between the center-to-center distance D and the surface-to-surface di

A. Capella

We show that the baryon stopping observed in heavy ion collisions both at CERN-SPS and at RHIC can be derived from the one observed in proton-proton collisions. No increase in the size of the baryon junction component is required between small size $(pp)$ and large size (AA) systems.

J. Dudek, A. Gozdz, N. Schunck, M. Miskiewicz

More than half a century after the fundamental, spherical shell structure in nuclei has been established, theoretical predictions indicate that the shell-gaps comparable or even stronger than those at spherical shapes may exist. Group-theoretical analysis supported by realistic mean-field calculations indicate that the corresponding nuclei are characterized

U. van Kolck, L. J. Abu-Raddad, D. M. Cardamone

We present a simple introduction to the techniques of effective field theory (EFT) and their application to QCD. For problems with more than one energy scale, the EFT approach is a useful alternative to more traditional model-building strategies. The most relevant such problem for this discussion is that of making contact between QCD and the hadronic phase o

S. Zschocke, O. P. Pavlenko, B. Kampfer

QCD sum rules are evaluated at finite nucleon densities and temperatures to determine the change of mass parameters for the lightest vector mesons $ρ$, $ω$ and $ϕ$ in a strongly interacting medium. For conditions relevant for the starting experiments at HADES we find that the in-medium mass shifts of the $ρ$ and $ω$ mesons are governed, within the Borel QCD

A. Shudo, Y. ishii, K. S. Ikeda

We find that characteristics of quantum tunneling in the presence of chaos can be regarded as a manifestation of the Julia set of the complex dynamical system. Several numerical evidences for the standard map together with a rigorous statement for the Hénon map are presented demonstrating that the complex classical paths which contribute to the semiclassical

D. G. W. Parfitt, M. E. Portnoi

The bound state energy eigenvalues for the two-dimensional Kepler problem are found to be degenerate. This &#34;accidental&#34; degeneracy is due to the existence of a two-dimensional analogue of the quantum-mechanical Runge-Lenz vector. Reformulating the problem in momentum space leads to an integral form of the Schroedinger equation. This equation is solve

J. Bruening, V. Geyler

The quantum-mechanical scattering on a compact Riemannian manifold with semi-axes attached to it (hedgehog-shaped manifold) is considered. The complete description of the spectral structure of Schroedinger operators on such a manifold is done, the proof of existence and uniqueness of scattering states is presented, an explicit form for the scattering matrix

S. V. Kozyrev

Representation of the Cuntz algebra in the space of (complex valued) functions on p-adic disk is introduced. The relation of this representation and the free coherent states is investigated.

Michael Kunzinger, Roland Steinbauer, James A. Vickers

The concept of generalized functions taking values in a differentiable manifold is extended to a functorial theory. We establish several characterization results which allow a global intrinsic formulation both of the theory of manifold-valued generalized functions and of generalized vector bundle homomorphisms. As a consequence, a characterization of equival

R. T. Faizullin, A. V. Prolubnikov

We consider heuristic algorithm for solving graph isomorphism problem. The algorithm based on a successive splitting of the eigenvalues of the matrices which are modifications (to positive defined) of graphs&#39; adjacency matrices. Modification of the algorithm allows to find a solution for Frobenius problem. Formulation of the Frobenius problem is followin

Robert Brooks, Orit Davidovich

We give a number of examples of pairs of non-compact surfaces which are isoscattering, and which are exceptionally simple in one or more senses. We give examples which are of small genus with a small number of ends, and also examles which are congruence surfaces.

Rahim Moosa, Thomas Scanlon

Motivated by the problem of determining the structure of integral points on subvarieties of semiabelian varieties defined over finite fields, we prove a quantifier elimination result for certain modules over finite simple extensions of the integers given together with predicates for orbits of the distinguished generator of the ring.

A. Khorunzhy

We generalise the Erdos-Renyi limit theorem on the maximum of the partial sums of random variables to the case when the number of terms in these sums is randomly distributed. Certain relations between the limiting theorems of this type and the spectral theory of random graphs and random matrices are discussed.

A. Khorunzhy, W. Kirsch

We consider the family of N-dimensional real symmetric matrices H with random independent entries whose variance is determined by a function U((x-y)/b). In the limit of (relatively) narrow band width 1<<b<<N, we obtain explicitly first terms of 1/b-expansion of the resolvent of H. The expressions derived show that the rate of decay of U(t) determines several

Kirill Melnikov, Marvin Weinstein

We develop a Hamiltonian formalism which can be used to discuss the physics of a massless scalar field in a gravitational background of a Schwarzschild black hole. Using this formalism we show that the time evolution of the system is unitary and yet all known results such as the existence of Hawking radiation can be readily understood. We then point out that

Massimo Giovannini, Jean-Vincent Le Be, Stephane Riederer

We analyze the fluctuations of Nielsen-Olesen vortices arising in the six-dimensional Abelian-Higgs model. The regular geometry generated by the defect breaks spontaneously six-dimensional Poincaré symmetry leading to a warped space-time with finite four-dimensional Planck mass. As a consequence, the zero mode of the spin two fluctuations of the geometry is

Alain Riazuelo, Filippo Vernizzi, Danièle Steer, Ruth Durrer

We derive the gauge invariant perturbation equations for a 5-dimensional bulk spacetime in the presence of a brane. The equations are derived in full generality, without specifying a particular energy content of the bulk or the brane. We do not assume Z_2 symmetry, and show that the degree of freedom associated with brane motion plays a crucial role. Our for

Ioannis Giannakis

In this paper we discuss deformations of the BRST operator of the fermionic string. These deformations preserve nilpotency of the BRST operator and correspond to turning on infinitesimal Gravitino and Ramond-Ramond spacetime fields.

Yan V Fyodorov, Eugene Strahov

We calculate a general spectral correlation function of products and ratios of characteristic polynomials for a $N\times N$ random matrix taken from the chiral Gaussian Unitary Ensemble (chGUE). Our derivation is based upon finding an Itzykson-Zuber type integral for matrices from the non-compact manifold ${\sf{Gl(n,{\mathcal{C}})/U(1)\times ...\times U(1)}}

M. Cadoni, P. Carta, M. Cavaglia&#39;, S. Mignemi

We investigate de Sitter/conformal field theory (dS/CFT) correspondence in two dimensions. We define the conserved mass of de Sitter spacetime and formulate the correspondence along the lines of anti-de Sitter/conformal field theory duality. Asymptotic symmetry group, mass, and central charge of de Sitter spacetime are equal to those of anti-de Sitter spacet

Steven B. Giddings

If TeV-scale gravity describes nature, black holes will be produced in particle accelerators, perhaps even with impressive rates at the Large Hadron Collider. Their decays, largely via the Hawking process, will be spectacular. Black holes also would be produced in cosmic ray collisions with our atmosphere, and their showers may be observable. Such a scenario

Thomas G. Rizzo

The radion may be the lightest new state present in the Randall-Sundrum(RS) model. We examine the couplings of the radion to the Standard Model(SM) fields in the scenario where they propagate in the bulk and expand into Kaluza-Klein towers. These couplings are then contrasted with those of the more familiar case where the SM fields are confined to the TeV br

Mariana Frank, Shuquan Nie

We analyze the FCNC semileptonic decay $B \to X_s l^+l^-$ in a fully left-right supersymmetric model. We give explicit expressions for all the amplitudes involved in the process, and compare the numerical results with experimental bounds, in both the constrained case (where the only flavor violation comes from the Cabibbo-Kobayashi-Maskawa matrix) and the un

A. P. Contogouris, Z. Merebashvili

For processes involving structure functions and/or fragmentation functions, arguments that, over a range of a proper kinematic variable, there is a part that dominates the next-to-leading order (NLO) corrections are briefly reviewed. The arguments are tested against more recent NLO and in particular complete next-to-next-to-leading order (NNLO) calculations.

R. S. Thorne

I discuss the issue of uncertainties in parton distributions and in the physical quantities which are determined in terms of them. While there has been significant progress on the uncertainties associated with errors on experimental data, there are still outstanding questions. Also, I demonstrate that in many circumstances this source of errors may be less i

M. Jezabek

A large hierarchy of the Dirac masses can result in a small hierarchy for the low energy masses of the active neutrinos. This can happen even if the Majorana masses of right-handed neutrinos are all equal. A realistic description of the observed neutrino masses and mixing can be obtained starting from a large hierarchy in the Dirac masses. A large mixing for

R. S. Thorne, H. Boettcher, A. M. Cooper-Sarkar, B. Reisert

A discussion is presented of the manner in which uncertainties in parton distributions and related quantities are determined. One of the central problems is the criteria used to judge what variation of the parameters describing a set of partons is acceptable within the context of a global fit. Various ways of addressing this question are outlined.

B. Ananthanarayan, B. Moussallam

Chiral perturbation theory in the anomaly sector for $N_f=2$ is extended to include dynamical photons, thereby allowing a complete treatment of isospin breaking. A minimal set of independent chiral lagrangian terms is determined and the divergence structure is worked out. There are contributions from irreducible and also from reducible one-loop graphs, a fea

K. J. Eskola, H. Honkanen, V. J. Kolhinen, C. A. Salgado

The $Q^2$ dependence of the ratios of nuclear structure functions $F_2^A$ is studied by performing QCD evolution of nuclear parton distribution functions. The log $Q^2$ slope of these ratios is very sensitive to the nuclear gluon distribution function. Taking different parametrizations, we show that the NMC data on the $Q^2$ dependence of $F_2^{\rm Sn}/F_2^{

C. Barbot, M. Drees, F. Halzen, D. Hooper

Top-down models of cosmic rays produce more neutrinos than photons and more photons than protons. In these models, we reevaluate the fluxes of neutrinos associated with the highest energy cosmic rays in light of mounting evidence that they are protons and not gamma rays. While proton dominance at EeV energies can possibly be achieved by efficient absorption

Rainer W. Kuhne

Several years ago, I suggested a quantum field theory which has many attractive features. (1) It can explain the quantization of electric charge. (2) It describes symmetrized Maxwell equations. (3) It is manifestly covariant. (4) It describes local four-potentials. (5) It avoids the unphysical Dirac string. Here I will review the ideas which led to my model

Holger Gies, Christof Wetterich

Within the framework of exact renormalization group flow equations, a scale-dependent transformation of the field variables provides for a continuous translation of UV to IR degrees of freedom. Using the gauged NJL model as an example, this translation results in a construction of partial bosonization at all scales. A fixed-point structure arises which makes

A. B. Lahanas, D. V. Nanopoulos, V. C. Spanos

In this talk we discuss the impact of recent experimental information, like the revised bound from E821 Brookhaven experiment on $g_μ-2$ and light Higgs boson mass bound from LEP, in delineating regions of the parameters of the Constrained Minimal Supersymmetric Standard Model which are consistent with the cosmological data. The effect of these to Dark Matte

Jun Xiao, Enke Wang

Based on the closed time path formalism, a new Feynman rule for directly calculating the retarded and advanced Green functions is deduced. This Feynman rule is used to calculate the two-point self-energy and three-point vertex correction in $ϕ^3$ theory. The generalized fluctuation-dissipation theorem for three-point nonlinear response function is verified.

F. M. L. Almeida, Y. A. Coutinho, J. A. Martins Simões, M. A. B. do Vale

We study the discovery potential for detecting new neutral heavy Majorana leptons as suggested by some extentions of the Standard Model in recently proposed electron-proton colliders. Since 1998-1999 the option of an electron-proton collider for the Very Large Hadron Collider at Fermilab operating with the proton booster has been considered. We study the rea

Antonio Gonzalez-Arroyo

Dirac operators in non-trivial topology backgrounds in a finite box are reviewed. We analyze how the formalism translates to the lattice, with special emphasis on uniform field backgrounds.

Alexis Pompili

Preliminary limits on the D^0 mixing parameter y = ΔΓ/ 2 Γare obtained using about 57.8 fb^-1 of data collected by BaBar in 2000 and 2001:y = (1.4 \pm 1.0 (stat.) +0.6 -0.7 (syst.))%. y is extracted, provided that CP is conserved, by measuring separately the D^0 lifetime for the Cabibbo-suppressed decay modes K- K+, π- π+ and the Cabibbo-favoured mode K- π+.

Giacomo Graziani

The NA48 experiment, conceived primarily to look for direct CP violation in neutral kaon decays, has recently published the so far most precise determination of the epsilon&#39;/epsilon parameter. After reviewing shortly this result, we report on the 2001 data-taking, which concluded the epsilon&#39; program by collecting a substantial amount of data with di

A. Vaiciulis

Multivariate data analysis techniques have the potential to improve physics analyses in many ways. The common classification problem of signal/background discrimination is one example. The Support Vector Machine learning algorithm is a relatively new way to solve pattern recognition problems and has several advantages over methods such as neural networks. Th

M. N. Achasov, K. I. Beloborodov, A. V. Berdyugin, A. G. Bogdanchikov

The e+e- -> pi0 pi0 gamma process was studied in the SND experiment at VEPP-2M e+e- collider in the energy region 0.60-0.97 GeV. From the analysis of the energy dependence of measured cross section the branching ratios B(omega -> pi0 pi0 gamma)= (6.6 +1.4-0.8(stat) +-0.6(syst))x10^-5 and B(rho -> pi0 pi0 gamma)=(4.1 +1.0-0.9(stat) +-0.3(syst))x10^-5 were obt

Jim Wiss

We present two topics on charm meson semileptonic decay. Evidence for interference in the decay K*munu and new results on the D+ to K*munu/K2pi branching fraction.

T. J. Gershon

Results on a number of rare hadronic B decays are presented. A data sample of $29.1 {\rm fb}^{-1}$ accumulated using the Belle detector at the KEKB asymmetric $e^+e^-$ collider operating at the $Υ(4S)$ resonance is used.

N. R. Pantoja, H. Rago, R. O. Rodriguez

For the non-rotating BTZ black hole, the distributional curvature tensor field is found. It is shown to have singular parts proportional to a $δ$-distribution with support at the origin. This singularity is related, through Einstein field equations, to a point source. Coordinate invariance and independence on the choice of differentiable structure of the res

Piret Kuusk, Margus Saal

The field equations derived from the low energy string effective action with a matter tensor describing a perfect fluid with a barotropic equation of state are solved iteratively using the long-wavelength approximation, i.e. the field equations are expanded by the number of spatial gradients. In the zero order, a quasi-isotropic solution is presented and com

T. Padmanabhan

I provide a general proof of the conjecture that one can attribute an entropy to the area of {\it any} horizon. This is done by constructing a canonical ensemble of a subclass of spacetimes with a fixed value for the temperature $T=β^{-1}$ and evaluating the {\it exact} partition function $Z(β)$. For spherically symmetric spacetimes with a horizon at $r=a$,

Alexei Novikov

We propose centralized algorithm of data distribution in the unicast p2p network. Good example of such networks are meshes of WWW and FTP mirrors. Simulation of data propogation for different network topologies is performed and it is shown that proposed method performs up to 200% better then common apporaches

Mathias Creutz, Krista Lagus

We present two methods for unsupervised segmentation of words into morpheme-like units. The model utilized is especially suited for languages with a rich morphology, such as Finnish. The first method is based on the Minimum Description Length (MDL) principle and works online. In the second method, Maximum Likelihood (ML) optimization is used. The quality of

Michael R. Fellows, Jens Gramm, Rolf Niedermeier

We show that Closest Substring, one of the most important problems in the field of biological sequence analysis, is W[1]-hard when parameterized by the number k of input strings (and remains so, even over a binary alphabet). This problem is therefore unlikely to be solvable in time O(f(k)\cdot n^{c}) for any function f of k and constant c independent of k. T

Allison Woodruff, Margaret H. Szymanski, Rebecca E. Grinter, Paul M. Aoki

We present a case study of an iterative design process that includes a conversation analyst. We discuss potential benefits of conversation analysis for design, and we describe our strategies for integrating the conversation analyst in the design process. Since the analyst on our team had no previous exposure to design or engineering, and none of the other me

Allison Woodruff, Paul M. Aoki, Rebecca E. Grinter, Amy Hurst

We describe an electronic guidebook, Sotto Voce, that enables visitors to share audio information by eavesdropping on each other&#39;s guidebook activity. We have conducted three studies of visitors using electronic guidebooks in a historic house: one study with open air audio played through speakers and two studies with eavesdropped audio. An analysis of vi

Paul M. Aoki, Rebecca E. Grinter, Amy Hurst, Margaret H. Szymanski

In addition to providing information to individual visitors, electronic guidebooks have the potential to facilitate social interaction between visitors and their companions. However, many systems impede visitor interaction. By contrast, our electronic guidebook, Sotto Voce, has social interaction as a primary design goal. The system enables visitors to share

T. Nikuni, J. E. Williams, C. W. Clark

An ultra-cold Bose gas of two-level atoms can be thought of as a spin-1/2 Bose gas. It supports spin-wave collective modes due to the exchange mean field. Such collective spin oscillations have been observed in recent experiments at JILA with ${}^{87}$Rb atoms confined in a harmonic trap. We present a theory of the spin-wave collective modes based on the mom

Andri M. Gretarsson

Some references for the breaking strength of fused silica fibers compiled in 1999.

M. Eliashvili, Z. F. Ezawa, G. Tsitsishvili

Considering the system of interacting electrons in the lowest Landau level we show that the corresponding four-fermion Hamiltonian is invariant with respect to the local area-preserving transformations. Testing a certain class of interaction potentials, we find that this symmetry is universal with respect to a concrete type of potentials.

F. Leonard, J. Tersoff

Calculations of quantum transport in a carbon nanotube transistor show that such a device offers unique functionality. It can operate as a ballistic field-effect transistor, with excellent characteristics even when scaled to 10 nm dimensions. At larger gate voltages, channel inversion leads to resonant tunneling through an electrostatically defined nanoscale

Guang-Hong Chen, Yong-Shi Wu

We present an analytic study of the phase diagram of the one-dimensional t-J model and a couple of its cousins. To deal with the interactions induced by the no double occupancy constraints, we introduce a deformation of the Hubbard operators. When the deformation parameter $Δ$ is small, the induced interactions are softened, accessible by perturbation theory

J. Bruening, S. Yu. Dobrokhotov, V. A. Geyler, K. V. Pankrashkin

We have proposed a semiclassical explanation of the geometric structure of the spectrum for the two-dimensional Landau Hamiltonian with a two-periodic electric field without any additional assumptions on the potential. Applying an iterative averaging procedure we approximately, with any degree of accuracy, separate variables and describe a given Landau band

Na Sai, Karin M. Rabe, David Vanderbilt

We have developed and implemented a formalism for computing the structural response of a periodic insulating system to a homogeneous static electric field within density-functional perturbation theory (DFPT). We consider the thermodynamic potentials E(R,eta,e) and F(R,eta,e) whose minimization with respect to the internal structural parameters R and unit cel

Alex P Taylor, Angus MacKinnon

In the most popular approach to the numerical study of the Anderson metal-insulator transition the transfer matrix method is combined with finite-size scaling ideas. This approach requires large computer resources to overcome the statistical fluctuations and to accumulate data for a sufficient range of different values of disorder or energy. In this paper we

Guang-Hong Chen, Yong-Shi Wu

We present the general lattice model for a multi-component atomic Bose-Einstein system in the optical lattice. Using the model, we analytically study the quantum phase transition between Mott insulator and superfluid. A mean-field theory is developed from the Mott insulator ground state. When the inter-species interactions are strong enough, the Mott insulat

Victor M. Eguiluz, Konstantin Klemm

We analyze the spreading of viruses in scale-free networks with high clustering and degree correlations, as found in the Internet graph. For the Suscetible-Infected-Susceptible model of epidemics the prevalence undergoes a phase transition at a finite threshold of the transmission probability. Comparing with the absence of a finite threshold in networks with

V. V. Afonin, J. Bergli, Y. M. Galperin, V. L. Gurevich

The first-principle theory of electron dephasing by disorder-induced two state fluctuators is developed. There exist two mechanisms of dephasing. First, dephasing occurs due to direct transitions between the defect levels caused by inelastic electron-defect scattering. The second mechanism is due to violation of the time reversal symmetry caused by time-depe

M. Raczkowski, B. Normand, A. M. Oles

We extend previous real-space Hartree-Fock studies of static stripe stability to determine the phase diagram of the Hubbard model with anisotropic nearest-neighbor hopping t, by varying the on-site Coulomb repulsion U and investigating locally stable structures for representative hole doping levels x=1/8 and x=1/6. We also report the changes in stability of