August 2001 arXiv papers — page 15

Pranab Ghosh, Nicholas E. White

We discuss the imprints left by a cosmological evolution of the star formation rate (SFR) on the evolution of X-ray luminosities Lx of normal galaxies, using the scheme proposed by White and Ghosh (1998, WG98), wherein the evolution of Lx of a galaxy is driven by the evolution of its X-ray binary population. As indicated in WG98, the profile of Lx with redsh

Vinod B. Johri

We present a realistic scenario of tracking of scalar fields with varying equation of state. The astrophysical constraints on the evolution of scalar fields in the physical universe are discussed. The nucleosynthesis and the galaxy formation constraints have been used to put limits on $Ω_ϕ$ and estimate $ε$ during cosmic evolution. Interpolation techniques h

B. T. Draine, Lei Hao

A gamma ray burst with strong optical-UV emission occuring in a molecular cloud will photodissociate H2, photoionize H2, H, and He, and destroy dust grains. We model these processes, including time-dependent radiative transfer in both continuum radiation and the resonance lines of H2. The UV will pump H2 into vibrationally-excited levels. We calculate the ab

B. Glenn Piner, Dayton L. Jones, Ann E. Wehrle

NGC4261 (3C270) is an elliptical galaxy containing a 300-parsec scale nuclear disk of gas and dust imaged by the Hubble Space Telescope (HST), around a central supermassive black hole. Previous VLBI observations of NGC4261 revealed a gap in emission in the radio counterjet, presumably due to free-free absorption in the inner parsec of the accretion disk. Her

Roger W. Romani, A. J. Miller, B. Cabrera, S. W. Nam

We are developing time- and energy-resolved near-IR/optical/UV photon detectors based on sharp superconducting-normal transition edges in thin films. We report observations of the Crab pulsar made during prototype testing at the McDonald 2.7m telescope with a fiber-coupled transition-edge sensor (TES) system. These data show substantial (d[alpha]~0.3), rapid

J. Liske, G. M. Williger

We present an analysis of the proximity effect in a sample of ten 2 A resolution QSO spectra of the Ly alpha forest at <z> = 2.9. Rather than investigating variations in the number density of individual absorption lines we employ a novel technique that is based on the statistics of the transmitted flux itself. We confirm the existence of the proximity effect

W. E. Harris, G. L. H. Harris

The metallicity distribution function (MDF) for the old red-giant stars in the halo of NGC 5128, the nearest giant elliptical galaxy, is virtually identical with the MDF for the old-disk stars in the LMC and also strongly resembles the halo MDF in M31. These galaxies all have high mean halo metallicities (<m/H> ~ -0.4$) with very small proportions of low-met

O. Barziv, L. Kaper, M. H. van Kerkwijk, J. H. Telting

We measured the radial-velocity curve of HD77581, the B-supergiant companion of the X-ray pulsar Vela X-1, using 183 high-resolution optical spectra obtained in a nine-month campaign. We derive radial-velocity amplitudes for different lines and wavelength regions, and find all are consistent with each other, as well as with values found in previous analyses.

William H. Lee

We present the results of three-dimensional hydrodynamical simulations of the final stages of inspiral in a black hole-neutron star binary, when the separation is comparable to the stellar radius. We use a Newtonian Smooth Particle Hydrodynamics (SPH) code to model the evolution of the system, and take the neutron star to be a polytrope with a soft (adiabati

Nicholas G. Phillips, A. Kogut

We present a neural net algorithm for parameter estimation in the context of large cosmological data sets. Cosmological data sets present a particular challenge to pattern-recognition algorithms since the input patterns (galaxy redshift surveys, maps of cosmic microwave background anisotropy) are not fixed templates overlaid with random noise, but rather are

Annette Ferguson

We discuss the first results from ongoing studies of the resolved stellar populations in the outskirts of our nearest large neighbour, M31. Deep HST/WFPC2 archival observations are used to construct colour-magnitude-diagrams which reach well below the horizontal branch at selected locations in the outer disk and halo, while a panoramic ground-based imaging s

Jos H. J. de Bruijne, Alastair P. Reynolds, Michael . A. C. Perryman, Fabio Favata

Currently operating optical superconducting tunnel junction (STJ) detectors, developed in ESA, can simultaneously measure the wavelength (delta lambda = 50 nm at 500 nm) and arrival time (to within ~5 micros) of individual photons in the range 310-720 nm with an efficiency of ~70%, and with count rates of order 5,000 photons per second per junction. A number

E. M. Drobyshevski, M. V. Beloborodyy, R. O. Kurakin, V. G. Latypov

Detection of negative daemons, DArk Electric Matter Objects, viz. Planckian supermassive (~2*10^-5 g) particles, whose population has been detected in March 2000 to populate near-Earth, almost circular, heliocentric orbits (NEACHOs), is being continued. The NEACHO objects hit the Earth with a velocity ~10-15 km/s. The results of these and new experiments (Ap

Pierre-Henri Chavanis

We investigate the effects of relativity on the gravitational instability of finite isothermal gaseous spheres. In the first part of the paper, we treat the gravitational field within the framework of Newtonian mechanics but we use a relativistic equation of state in the condition of hydrostatic equilibrium. In the second part of the paper, we study the full

Ann E. Hornschemeier, CDF-N Team

The Chandra Deep Field-North survey, which has at its center the Hubble Deep Field-North, has reached an exposure of 1 Ms and is now available to the public for analysis. This great astronomical resource will soon be released to the community in the form of a catalog paper with accurate X-ray fluxes in four bands and astrometry good to approximately 0.6-1.2

S. P. Rajaguru, Sarbani Basu, H. M. Antia

The presence of intense magnetic fields in and around sunspots is expected to modify the solar structure and oscillation frequencies. Applying the ring diagram technique to data from the Michelson Doppler Imager (MDI) on board the Solar and Heliospheric Observatory (SOHO), we analyze the characteristics of high-degree f and p modes near active regions and co

H. M. Antia, Sarbani Basu

Frequency splitting coefficients from Global Oscillation Network Group (GONG) and Michelson Doppler Imager (MDI) observations covering the period 1995--2001 are used to study temporal variations in the solar rotation rate at high latitudes. The torsional oscillation pattern in the Sun is known to penetrate to a depth of about $0.1R_\odot$ with alternate band

Keith R. Dienes

Much recent attention has focused on theories with large extra compactified dimensions. However, while the phenomenological implications of the volume moduli associated with such compactifications are well understood, relatively little attention has been devoted to the shape moduli. In this paper, we show that the shape moduli have a dramatic effect on the c

J. Nakamura, N. Yamada, K. Kuroki, T. A. Callcott

Soft X-ray absorption and emission measurements are performed for the K- edge of B in MB$_2$ (M=Mg, Al, Ta and Nb). Unique feature of MgB$_2$ with a high density of B 2$p_{xy}(σ)$-state below and above the Fermi edge, which extends to 1 eV above the edge, is confirmed. In contrast, the B 2$p$ density of states in AlB$_2$ and TaB$_2$, both of occupied and uno

Marco Ameduri, Richard A. Klemm

At arbitrary temperature $T$, we solve for the dynamics of single molecule magnets composed of three classical Heisenberg spins either on a chain with two equal exchange constants $J_1$, or on an isosceles triangle with a third, different exchange constant $J_2$. As $T\rightrarrow\infty$, the Fourier transforms and long-time asymptotic behaviors of the two-s

J. R. Abo-Shaeer, C. Raman, W. Ketterle

The dynamics of vortex lattices in stirred Bose-Einstein condensates have been studied at finite temperatures. The decay of the vortex lattice was observed non-destructively by monitoring the centrifugal distortions of the rotating condensate. The formation of the vortex lattice could be deduced from the increasing contrast of the vortex cores observed in ba

T. N. Tomaras, N. C. Tsamis, R. P. Woodard

The 1+1 dimensional massive Dirac equation is solved exactly in light-cone coordinates for $x^+ > 0$ and $x^- > -L$, in the presence of an arbitrary $x^+$ dependent electric field. Our solution resolves the ambiguity at $p^+ = 0$. We also obtain the one loop rate for pair production for a positive electric field, compute the expectation values of the vector

Benson Farb, John Franks

Plante-Thurston proved that every nilpotent subgroup of $\Diff^2(S^1)$ is abelian. One of our main results is a sharp converse: $\Diff^1(S^1)$ contains every finitely-generated, torsion-free nilpotent group.

S. F. King, G. G. Ross

We propose a model based on SU(3) family symmetry which leads to a successful description of quark and lepton masses and mixing angles including approximate bi-maximal mixing in the neutrino sector suitable for the LOW or quasi-vacuum solar solutions, with the atmospheric angle predicted to be accurately maximal due to the SU(3) symmetry. The model predicts

Parthapratim Biswas

We present an O(N) algorithm to study the vibrational properties of amorphous silicon within the framework of tight-binding approach. The dynamical matrix elements have been evaluated numerically in the harmonic approximation exploiting the short-range nature of the density matrix to calculate the vibrational density of states which is then compared with the

N. N. Kovaleva, J. L. Gavartin, A. L. Shluger, A. V. Boris

We use the Mott-Littleton approach to evaluate polarisation energies in LaMnO$_3$ lattice associated with holes localized on both Mn$^{3+}$ cation and O$^{2-}$ anion. The full (electronic and ionic) lattice relaxation energy for a hole localized at the O-site is estimated as 2.4 eV which is appreciably greater than that of 0.8 eV for a hole localized at the

Emil Nissimov, Svetlana Pacheva

The recently proposed supersymmetric extensions of reduced Kadomtsev-Petviashvili (KP) integrable hierarchies in $N =1,2$ superspace are shown to contain in the purely bosonic limit new types of ordinary non-supersymmetric integrable systems. The latter are coupled systems of several multi-component non-linear Schr{ö}dinger-like hierarchies whose basic nonli

Johan Bijnens

An overview of the field of Chiral Lagrangians is given. This includes Chiral Perturbation Theory and resummations to extend it to higher energies, applications to the muon anomalous magnetic moment, $ε^\prime/ε$ and others.

Debabrata Goswami

Selective control of decoherence is demonstrated for a multilevel system by generalizing the instantaneous phase of any chirped pulse as individual terms of a Taylor series expansion. In the case of a simple two-level system, all odd terms in the series lead to population inversion while the even terms lead to self-induced transparency. These results also ho

Thomas Keilen

In 1985 Joe Harris proved the long standing claim of Severi that equisingular families of nodal plane curves are irreducible whenever they are non-empty. For families with more complicated singularities this is no longer true. Given a divisor D on a smooth projective surface S it thus makes sense to look for conditions which ensure that the family V_D(S_1,..

T. Asakawa, S. Sugimoto, S. Terashima

In this paper, we study a new matrix theory based on non-BPS D-instantons in type IIA string theory and D-instanton - anti D-instanton system in type IIB string theory, which we call K-matrix theory. The theory correctly incorporates the creation and annihilation processes of D-branes. The configurations of the theory are identified with spectral triples, wh

Kiyoshi Higashijima, Tetsuji Kimura, Muneto Nitta

Using techniques of supersymmetric gauge theories, we present the Ricci-flat metrics on non-compact Kahler manifolds whose conical singularity is repaired by the Hermitian symmetric space. These manifolds can be identified as the complex line bundles over the Hermitian symmetric spaces. Each of the metrics contains a resolution parameter which controls the s

A. A. Penin, M. Steinhauser

In this paper we compute the decay constant of the pseudo-scalar heavy-light mesons in the heavy quark effective theory framework of QCD sum rules. In our analysis we include the recently evaluated three-loop result of order $α_s^2$ for the heavy-light current correlator. The value of the bottom quark mass, which essentially limits the accuracy of the sum ru

Jens O. Andersen

We consider an interacting homogeneous Bose gas at zero temperature in two spatial dimensions. The properties of the system can be calculated as an expansion in powers of g, where g is the coupling constant. We calculate the ground state pressure and the ground state energy density to second order in the quantum loop expansion. The renormalization group is u

V. Berezinsky, M. Lissia

With SNO data on electron-neutrino flux from the sun, it is possible to derive the $ν_e$ survival probability $P_{ee}(E)$ from existing experimental data of Super-Kamiokande, gallium experiments and Homestake. The combined data of SNO and Super-Kamiokande provide boron $ν_e$ flux and the total flux of all active boron neutrinos, giving thus $P_{ee}(E)$ for b

Jihn E. Kim

I briefly review the cosmological constant problem and attempts toward its solution, and present the first nontrivial example for the self-tuning mechanism with a $1/H^2$ term with the antisymmetric field strength $H_{MNPQ}$ in a 5D RS-II setup.

A. F. Kracklauer

Entanglement, including ``quantum entanglement,&#39;&#39; is a consequence of correlation between objects. When the objects are subunits of pairs which in turn are members of an ensemble described by a wave function, a correlation among the subunits induces the mysterious properties of ``cat-states.&#39;&#39; However, correlation between subsystems can be pr

Z. S. Sazonova, Ranjit Singh

We have proposed the construction of optical quantum computer (OQC) on regular domain structure (RDS) crystal. By using RDS crystal, we can perform all the logical operations on one RDS crystal. Moreover, RDS crystals are parctically independent to the heating effects i.e., can perform logic operations constantly without cooling the RDS crystal. Also, we hav

I. Bengtsson, J. Braennlund, K. Zyczkowski

We show that many topological and geometrical properties of complex projective space can be understood just by looking at a suitably constructed picture. The idea is to view CP^n as a set of flat tori parametrized by the positive octant of a round sphere. We pay particular attention to submanifolds of constant entanglement in CP^3 and give a few new results

Christoph Simon, Jian-Wei Pan

Parametric down-conversion can produce photons that are entangled both in polarization and in space. Here we show how the spatial entanglement can be used to purify the polarization entanglement using only linear optical elements. Spatial entanglement as an additional resource leads to a substantial improvement in entanglement output compared to a previous s

Jean-Luc Brylinski, Ranee Brylinski

In this paper we study universality for quantum gates acting on qudits.Qudits are states in a Hilbert space of dimension d where d is at least two. We determine which 2-qudit gates V have the properties (i) the collection of all 1-qudit gates together with V produces all n-qudit gates up to arbitrary precision, or (ii) the collection of all 1-qudit gates tog

Hans Aschauer, Hans J. Briegel

We give a proof that entanglement purification, even with noisy apparatus, is sufficient to disentangle an eavesdropper (Eve) from the communication channel. Our proof applies to all possible attacks (individual and coherent). Due to the quantum nature of the entanglement purification protocol, it is also possible to use the obtained quantum channel for secu

Anatolij Dvurecenskij, Pekka Lahti, Kari Ylinen

The theory of holomorphic functions of several complex variables is applied in proving a multidimensional variant of a theorem involving an exponential boundedness criterion for the classical moment problem. A theorem of Petersen concerning the relation between the multidimensional and one-dimensional moment problems is extended for half-lines and compact su

Rajendra Bhandari

A recent proposal of Sjoqvist et.al. to extend Pancharatnam&#39;s criterion for phase difference between two different pure states to the case of mixed states in quantum mechanics is analyzed and the existence of phase singularities in the parameter space of an interference experiment with particles in mixed states pointed out. In the vicinity of such singul

Heng Fan, Keiji Matsumoto, Xiang-Bin Wang, Hiroshi Imai

A generalized universal quantum cloning machine is proposed which allows the input to be arbitrary states in symmetric subspace. And it reduces to the universal quantum cloning machine (UQCM) if the input are identical pure states. The generalized cloner is optimal in the sense we compare the input and output reduced density operators at a single qubit. The

A. F. Kracklauer, N. A. Kracklauer

Unarticulated, implicit hypotheses in Bell&#39;s analysis of Einstein, Podolsky and Rosen (EPR) correlations are identified and examined. These relate to the mathematical-analytical properties of random variables, the character of the relevant sample spaces and physical interpretations. We shown that continuous hidden variables are not precluded by Bell ineq

Anil K. Patnaik, G. S. Agarwal

The paper has been withdrawn by authors.

Vladimir G. Baryshevsky, Konstantin G. Batrakov

The idea and principles of volume free electron lasers were proposed in [1-4]. It was shown there that volume distributed feedback (VDFB) can essentially reduce the threshold current of generation and provide the possibility of smooth frequency tuning. The present work considers an undulator VFEL with multiwave VDFB. It is shown that dependence of threshold

Vladimir G. Baryshevsky, Konstantin G. Batrakov

Volume Free Electron Laser (VFEL) was proposed in [1-4]. It can operate in the wide spectral range from microwaves to X-rays. To simulate the processes which take place in VFEL the superradiance from a short electron pulse moving in a volume diffraction grating is studied in wavelength range ~4 mm. It is supposed that Bragg condition for emitted photons is f

K. Nakayama

Heavy meson production in nucleon-nucleon collisions is discussed within a meson exchange model of hadronic interactions, paying special attention to the basic dynamics that determine the behavior of the cross sections near the threshold energy. The pp-->ppϕreaction is discussed as an example of the production of vector mesons in NN collisions. For the pseud

N. V. Shevchenko, V. B. Belyaev, S. A. Rakityansky, S. A. Sofianos

A microscopic few-body description of near-threshold coherent photoproduction of the eta-meson on tritium and He3 targets is given. The photoproduction cross-section is calculated using the Finite Rank Approximation (FRA) of the nuclear Hamiltonian. The results indicate a strong final state interaction of the eta-meson with the residual nucleus. Sensitivity

W. H. Dickhoff, E. P. Roth

An overview is given of the theoretical work on nucleon spectral functions in finite nuclei. The consequences of the observed spectral strength distribution are then considered in the context of the nuclear-matter saturation problem. Arguments are presented suggesting that short-range correlations are mainly responsible for the actual value of the observed c

W. H. Dickhoff, E. P. Roth

A brief overview is given of the properties of spectral functions in finite nuclei as obtained from (e,e&#39;p) experiments. Based on recent experimental data from this reaction it is argued that the empirical value of the saturation density of nuclear matter is dominated by short-range correlations. This observation and the observed fragmentation and deplet

W. H. Dickhoff, E. P. Roth, M. Radici

A brief review is given concerning the status of the theoretical work on nucleon spectral functions. A recent concern about the validity of the concept of spectroscopic factors as deduced from (e,e&#39;p) reactions at higher Q^2, is discussed in some detail. The consequences of the observed spectral strength are then considered in the context of nuclear satu

H. Babacan, T. Babacan, A. Gokalp, O. Yilmaz

The $ω$-meson photoproduction, $γ+p\to p+ω$, is studied in the framework of a model, containing $π$-meson exchange in t-channel and nucleon-exchange in s- and u-channels. Considering both $ωNN$-coupling constants in the region of time-like meson four momenta as the free parameters, we find different sets of solutions for these constants from the existing dat

S. A. Merkulov

It is shown that any compact Kähler manifold $M$ gives canonically rise to two strongly homotopy algebras, the first one being associated with the Hodge theory of the de Rham complex and the second one with the Hodge theory of the Dolbeault complex. In these algebras the product of two harmonic differential forms is again harmonic. If $M$ happens to be a Cal

Yonina C. Eldar, H. Bolcskei

We introduce a new class of frames with strong symmetry properties called geometrically uniform frames (GU), that are defined over an abelian group of unitary matrices and are generated by a single generating vector. The notion of GU frames is then extended to compound GU (CGU) frames which are generated by an abelian group of unitary matrices using multiple

Juan B. Gil, Gerardo A. Mendoza

We study the adjointness problem for the closed extensions of a general b-elliptic operator A in x^{-ν}Diff^m_b(M;E), ν>0, initially defined as an unbounded operator A:C_c^\infty(M;E)\subset x^μL^2_b(M;E)\to x^μL^2_b(M;E), μ\in \R. The case where A is a symmetric semibounded operator is of particular interest, and we give a complete description of the domain

Swapneel Mahajan

The random-to-top and the riffle shuffle are two well-studied methods for shuffling a deck of cards. These correspond to the symmetric group $S_n$, i.e., the Coxeter group of type $A_{n-1}$. In this paper, we give analogous shuffles for the Coxeter groups of type $B_n$ and $D_n$. These can be interpreted as shuffles on a ``signed&#39;&#39; deck of cards. Wit

Sung-Yeon Kim, Dmitri Zaitsev

We give a solution to the equivalence and the embedding problems for smooth CR-submanifolds of complex spaces (and, more generally, for abstract CR-manifolds) in terms of complete differential systems in jet bundles satisfied by all CR-equivalences or CR-embeddings respectively (local and global). For the equivalence problem, the manifolds are assumed to be

Joseph P. Previte, Eugene Z. Xia

Let $M$ be a four-holed sphere and $Γ$ the mapping class group of $M$ fixing $\partial M$. The group $Γ$ acts on the space ${\mathcal M}_{\mathcal B}(SU(2))$ of SU(2)-gauge equivalence classes of flat SU(2)-connections on $M$ with fixed holonomy on $\partial M$. We give examples of flat SU(2)-connections whose holonomy groups are dense in SU(2), but whose $Γ

Rimas Norvaisa

The paper develops a calculus for a class of real-valued functions having a quadratic variation. The main result is a solution of the representation problem for a class of evolutions having a quadratic variation. The result is applied to build up an asset pricing model. Also in the paper there are some results concerning an extension of the class of all semi

Yucai Su, Xiaoping Xu

Classical contact Lie algebras are the fundamental algebraic structures on the manifolds of contact elements of configuration spaces in classical mechanics. In this paper, we determine the structure of the currently largest known category of contact simple Lie algebras introduced earlier by the second author. These algebras are in general not finitely-graded

Tomasz Brzezinski, Stefaan Caenepeel, Gigel Militaru

A definition of a Doi-Koppinen datum over a noncommutative algebra is proposed. The idea is to replace a bialgebra in a standard Doi-Koppinen datum with a bialgebroid. The corresponding category of Doi-Koppinen modules over a noncommutative algebra is introduced. A weak Doi-Koppinen datum and module of [G. Bohm. Comm. Algebra, 28:4687--4698, 2000] are shown

Nima Arkani-Hamed, Andrew Cohen, Howard Georgi

We construct four dimensional gauge theories in which the successful supersymmetric unification of gauge couplings is preserved but accelerated by N-fold replication of the MSSM gauge and Higgs structure. This results in a low unification scale of $10^{13/N}$ TeV.

C. D. Palmer, M. E. Carrington

The calculation of the symmetry factor corresponding to a given Feynman diagram is well known to be a tedious problem. We have derived a simple formula for these symmetry factors. Our formula works for any diagram in scalar theory ($ϕ^3$ and $ϕ^4$ interactions), spinor QED, scalar QED, or QCD.

Dan Radu Grigore

We introduce the concept of general gauge theory which includes Yang-Mills models. In the framework of the causal approach and show that the anomalies can appear only in the vacuum sector of the identities obtained from the gauge invariance condition by applying derivatives with respect to the basic fields. Then we provide a general result about the absence

R. S. Ward

The holonomy of an SU(2) N-instanton in the x^4-direction gives a map from R^3 into SU(2), which provides a good model of an N-Skyrmion. Combining this map with the standard Hopf map from SU(2)=S^3 to S^2 gives a configuration for a Hopf soliton of charge N. In this way, one may define a collective-coordinate manifold for Hopf solitons. This paper deals with

Sergio Zerbini

Some issues related to quantum anomaly induced effects due to matter are considered. Explicit examples corresponding to quantum creation of d4 dilatonic AdS Universe and of d2 dilatonic AdS Black Hole (BH) are discussed. Motivated by holographic RG, in a similar approach, it is shown that, starting from a 5 dimensional AdS Universe, 4-dimensional de Sitter o

Frederik Denef

We explain microscopically why split attractor flows, known to underlie certain stationary BPS solutions of four dimensional N=2 supergravity, are the relevant data to describe wrapped D-branes in Calabi-Yau compactifications of type II string theory. We work entirely in the context of the classical geometry of A-branes, i.e. special Lagrangian submanifolds,

G. Tavares-Velasco, J. J. Toscano

We present a complete calculation of the singly and doubly charged gauge bosons (bileptons) contribution to the static properties of the W boson in the framework of the minimal 331 model, which accommodates the bileptons in an SU_L(2) doublet. A nonlinear R_ξgauge is used and a slightly modified version of the Passarino-Veltman reduction scheme is employed a

Daniel Boyanovsky, Hector J. de Vega, Richard Holman, Matthew R. Martin

The non-equilibrium dynamics of a Yukawa theory with N fermions coupled to a scalar field is studied in the large N limit with the goal of comparing the dynamics predicted from the renormalization group improved effective potential to that obtained including the fermionic backreaction. The effective potential is of the Coleman-Weinberg type. Its renormalizat

J. Burguet-Castell, O. Mena

In this talk, based on the work \cite{cpviolation}, we refine our previous analysis \cite{golden} of the sensitivity to leptonic CP violation and $\tetaot$ at a neutrino factory in the LMA-MSW scenario, by exploring the full range of these two parameters. We have discovered that there exist, at fixed neutrino energy, $E_ν$, and baseline, $L$, degenerate solu

E. T. Tomboulis

We reconsider the question of mass generation for fermions coupled to a set of gauge bosons when the latter get their masses through the Goldstone bosons originating in a simple (i.e. not extended) technicolor sector. The fermion global chiral symmetries are broken by including four-fermion interactions. We find that the system can be nonperturbatively unsta

Hitoshi Murayama, Aaron Pierce

We make explicit the statement that Minimal Supersymmetric SU(5) has been excluded by the Super-Kamiokande search for the process $p \to K^{+} \overlineν$. This exclusion is made by first placing limits on the colored Higgs triplet mass, by forcing the gauge couplings to unify. We also show that taking the superpartners of the first two generations to be ver

Stephan Dürr

Given the increasing availability of lattice data for (unquenched) QCD with $N_f=2$, it is worth while to check whether the generated vacuum significantly deviates from the quenched one. I discuss a specific attempt to do this on the basis of topological susceptibility data gained at various sea-quark masses, since for this observable detailed predictions ar

Martin Lüscher, Peter Weisz

In non-abelian gauge theories without matter fields, expectation values of large Wilson loops and loop correlation functions are difficult to compute through numerical simulation, because the signal-to-noise ratio is very rapidly decaying for increasing loop sizes. Using a multilevel scheme that exploits the locality of the theory, we show that the statistic

Gail G. Hanson

The experimental results presented at the XXXVI Rencontres de Moriond Electroweak Interactions and Unified Theories are summarized. The results range from possible evidence for the Standard Model Higgs boson at LEP2 to searches for new physics at LEP, the Tevatron and HERA, to precision electroweak and weak decay measurements, and to the strong evidence for

Milind V. Diwan, Hong Ma, T. L. Trueman

We have examined the decay $K^0_L \to π^0 μ^+ μ^-$ in which the branching ratio, the muon energy asymmetry and the muon decay asymmetry could be measured. In particular, we find that within the Standard Model the longitudinal polarization ($P_L$) of the muon is proportional to the direct CP violating amplitude. On the other hand the energy asymmetry and the

V. Dzhunushaliev, D. Singleton

In this article we use the idea of algorithmic complexity (AC) to study various cosmological scenarios, and as a means of quantizing the gravitational interaction. We look at 5D and 7D cosmological models where the Universe begins as a higher dimensional Planck size spacetime which fluctuates between Euclidean and Lorentzian signatures. These fluctuations ar

Jarmo Makela

We suggest that all horizons of spacetime, no matter whether they are black hole, Rindler or de Sitter horizons, have certain microscopic properties in common. We propose that these propertues may be used as the starting points, or postulates, of a microscopic theory of gravity.

G. Carapella, N. Martucciello, G. Costabile, C. Ferdeghini

We report the demonstration of dc and ac Josephson effects as well as tunneling spectroscopy measurements on Nb/Al2O3/Al/MgB2 thin films heterostructures. Data on dc Josephson effect suggest the presence of two characteristic critical currents possibly accounted for the presence of two gaps in the MgB2 film. Tunneling spectroscopy measurements confirm this t

Ana L. C. Pereira, P. A. Schulz

The evolution of extended states with magnetic field and disorder intensities is investigated for 2D lattice models. The floating-up picture is revealed when the shift of the extended state, relative to the density of states, is properly taken into account, either for white-noise or correlated disorder.

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

We report unexpected fluctuations in the positions of Coulomb blockade peaks at high magnetic fields in a small Si quantum dot. The fluctuations have a distinctive saw-tooth pattern: as a function of magnetic field, linear shifts of peak positions are compensated by abrupt jumps in the opposite direction. The linear shifts have large slopes, suggesting forma

Roberto C. Alamino, Carmen P. C. Prado

In this paper we discuss some features of the BCRE model. We show that this model can be understood as a mapping from a two-dimensional to a one-dimensional problem, if some conditions are satisfied. We propose some modifications that (a) guarantee mass conservation in the model (what is not assured in its original form) and (b) correct undesired behaviors t

L. A. Openov

We consider a simple model of an electron moving in a T-shaped confinement potential. This model allows for an analytical solution that explicitly demonstrates the existence of laterally bound electron states in quantum wires obtained by the cleaved edge overgrowth technique.

A. A. Chabanov, A. Z. Genack

We report measurements of microwave transmission over the first five Mie resonances of alumina spheres randomly positioned in a waveguide. Though precipitous drops in transmission and sharp peaks in the photon transit time are found near all resonances, measurements of transmission fluctuations show that localization occurs only in a narrow frequency window

Niels Asger Mortensen, Karsten Flensberg, Antti-Pekka Jauho

We study Coulomb drag between two parallel disordered mesoscopic 1D-wires. By numerical ensemble averaging we calculate the statistical properties of the transconductance G_21 including its distribution. For wires with mutually uncorrelated disorder potentials we find that the mean value is finite, but with comparable fluctuations so that sign-reversal is po

Niels Asger Mortensen, Karsten Flensberg, Antti-Pekka Jauho

We present a theory for Coulomb drag between two mesoscopic systems which expresses the drag in terms of scattering matrices and wave functions. The formalism can be applied to both ballistic and disordered systems and the consequences can be studied either by numerical simulations or analytic means such as perturbation theory or random matrix theory. The ph

X. S. Chen, V. Dohm

The singular part of the finite-size free energy density $f_s$ of the O(n) symmetric $ϕ^4$ field theory in the large-n limit is calculated at finite cutoff for confined geometries of linear size L with periodic boundary conditions in 2 < d < 4 dimensions. We find that a sharp cutoff $Λ$ causes a non-universal leading size dependence $f_s \sim Λ^{d-2} L^{-2}$

Alexander K. Hartmann

A new method to simulate probability distributions in regions where the events are VERY unlikely (e.g. p ~ 10^{-40}) is presented. The basic idea is to represent the underlying probability space by the phase space of a physical system. The system is held at a temperature T, which is chosen such that the system preferably generates configurations which origin

Yu. S. Barash, I. V. Bobkova

The Josephson current in S-F-S junctions is described by taking into account different reflection (transmission) amplitudes for quasiparticles with spin up and down. We show that the 0-$π$ transition in the junctions can take place at some temperature only for sufficiently strong spin-activity of the interface. In particular, Andreev interface bound state en

Jani Lahtinen, János Kertész, Kimmo Kaski

In this study we have carried out computer simulations of random walks on Watts-Strogatz-type small world networks and measured the mean number of visited sites and the return probabilities. These quantities were found to obey scaling behavior with intuitively reasoned exponents as long as the probability $p$ of having a long range bond was sufficiently low.

Federico Becca, Luca Capriotti, Sandro Sorella

Structural distortions in cuprate materials give a natural origin for anisotropies in electron properties. We study a modified one-band t-J model in which we allow for different hoppings and antiferromagnetic couplings in the two spatial directions ($t_x \ne t_y$ and $J_x \ne J_y$). Incommensurate peaks in the spin structure factor show up only in the presen

P. Maragakis, Jose M. Soler, Efthimios Kaxiras

A potential disadvantage of real-space-grid electronic structure methods is the lack of a variational principle and the concomitant increase of total energy with grid refinement. We show that the origin of this feature is the systematic underestimation of the kinetic energy by the finite difference representation of the Laplacian operator. We present an alte

S. Sivasubramanian, A. Widom

We present the circuit equivalent of the Landau-Khalatnikov dynamical ferroelectric model. The differential equation for hysteretic behavior is subject to numerical computer simulations. The size and shape of the simulated hysteretic loops depends strongly on the frequency and the amplitude of the driving electric field. This dependence makes the experimenta

G. A. Ummarino

In this paper I calculate the possible alteration of the gravitational field in a superconductor by using the time-dependent Ginzburg-Landau equations (TDGL). I compare the behaviour of a high-Tc superconductor (HTCS) like YBa_2Cu_3O_7 (YBCO) with a classical low-Tc superconductor (LTCS) like Pb. Finally, I discuss what values of the parameters characterizin

M. A. W. Verheijen

The Tully-Fisher relations for a complete sample of spirals in the Ursa Major cluster is investigated. The merits of combining B, R, I and K&#39; photometry with HI rotation curves (RCs) have been exploited. In addition to the corrected HI global profile widths W_{R,I}^i, the HI RCs allow direct measurements of the maximum rotation Vmax and the amplitudes Vf

R. Benton Metcalf, Piero Madau

We show how observations of multiply-imaged quasars at high redshift can be used as a probe of dark matter clumps (subhalos with masses ~ 10^9 solar masses) within the virialized extent of more massive lensing halos. A large abundance of such satellites is predicted by numerical simulations of galaxy formation in cold dark matter (CDM) cosmogonies. Small-sca

L. Verdes-Montenegro, M. S. Yun, B. A. Williams, W. K. Huchtmeier

We have analyzed the total HI contents of 72 Hickson compact groups of galaxies (HCGs) and the detailed spatial distributions and kinematics of HI within a subset of 16 groups using the high angular resolution observations obtained with the VLA in order to investigate a possible evolutionary scenario for these densest systems in the present day galaxy hierar