May 1997 arXiv papers — page 16

F. Matera, G. Fabbri, A. Dellafiore

Pairing correlations in symmetric nuclear matter are studied within a relativistic mean-field approximation based on a field theory of nucleons coupled to neutral ($σ$ and $ω$) and to charged ($\varrho$) mesons. The Hartree-Fock and the pairing fields are calculated in a self-consistent way. The energy gap is the result of a strong cancellation between the s

Tomoyuki Maruyama, Koji Niita, Satoshi Chiba, Toshiki Maruyama

We study the photoreaction in the delta energy region using the QMD approach. The proton and pion cross-sections are calculated and compared with experimental data. Through this work we examine the multistep contributions in the cross-sections and the {$π- Δ$} dynamics.

Serguei Tankeev

Let $J$ be an abelian variety over a number field such that the center of its endomorphism ring is equal to the ring of integers. If the endomorphism ring splits at a prime number $l$, then the $l$-adic representation is defined by the minuscule weights (microweights) of simple classical Lie algebras.

Christian Krattenthaler, Paul B. Slater

Clarke and Barron have recently shown that the Jeffreys' invariant prior of Bayesian theory yields the common asymptotic (minimax and maximin) redundancy of universal data compression in a parametric setting. We seek a possible analogue of this result for the two-level {\it quantum} systems. We restrict our considerations to prior probability distributio

Kentaro Hori, Hirosi Ooguri, Yaron Oz

It has been known that the fivebrane of type IIA theory can be used to give an exact low energy description of N=2 supersymmetric gauge theories in four dimensions. We follow the recent M theory description by Witten and show that it can be used to study theories with N=1 supersymmetry. The N=2 supersymmetry can be broken to N=1 by turning on a mass for the

A. A. Bytsenko, L. N. Granda, S. D. Odintsov

We discuss exact renormalization group (RG) in $R^2$-gravity using effective average action formalism. The truncated evolution equation for such a theory on De Sitter background leads to the system of nonperturbative RG equations for cosmological and gravitational coupling constants. Approximate solution of these RG equations shows the appearence of antiscre

Changhyun Ahn

We study N=1 dualities in four dimensional supersymmetric gauge theories in terms of wrapping D 6-branes around 3-cycles of Calabi-Yau threefolds in type IIA string theory. We generalize the recent work of geometrical realization for the models which have the superpotential corresponding to an $A_k$ type singularity, to various models presented by Brodie and

A. J. Baltz, Mark Strikman

Predicted two-photon Higgs production with heavy ions at LHC is shown to be reduced due to the large Coulomb dissociation cross section. Incorporating the effect of dissociation reduces the production of a 100 GeV Higgs by about a factor of three compared to rates in the literature calculated without this effect.

Jiunn-Wei Chen, Gautam Rupak, Martin J. Savage

We compute non-perturbative contributions to b->s l+ l- that are not explicitly suppressed by powers of the b-quark mass. They are proportional to lambda_2 and arise from an interference between the free-quark amplitude and higher order terms in the matrix element of a four-quark operator. This correction is found to be small over most of the dalitz plot exc

A. Signer

I present a general purpose Monte Carlo program for calculating the next-to-leading order corrections to arbitrary four-jet quantities in electron-positron annihilation. In the current version of the program, some subleading in color terms are neglected. As an example, I calculate the four-jet rate in the Durham scheme as well as the Bengtsson-Zerwas angular

Ian G Knowles, George D Lafferty

The confinement transition from the quark and gluon degrees of freedom appropriate in perturbation theory to the hadrons observed by real world experiments is poorly understood. In this strongly interacting transition regime we presently rely on models, which to varying degrees reflect possible scenarios for the QCD dynamics. Because of the absence of beam a

Toshio Hayashi

We investigate CP violation in the purely right-handed b quark to c- and u- quark coupling model under the constraint of right-handed W-gauge boson mass M_R > 720 GeV , which is experimentally obtained recently by D0 Collaboration at Fermilab. By using the data on $K_L-K_S$ mass difference, CP violating parameter $ε$ in the neutral kaon system and $B_d-\bar

F. Buccella, G. Mangano, L. Rosa

We report on some phenomenological implications of a class of unified models based on SO(10) gauge group, with intermediate symmetry group containing SU(2)_R. Interesting predictions for neutrino masses are discussed, which are relevant both for solar neutrino and dark matter problems, as well as a model for the formation of the baryon asymmetry of the unive

G. Mangano, L. Rosa

The cosmological implications of a class of SO(10) models are discussed. In particular we show how a good prediction for neutrino masses is obtained in order to fit with the MSW mechanism to explain the solar neutrino flux deficit and with the predicted amount of the dark matter hot component. A possible scenario for baryogenesis is also considered.

C. Becchi

These lectures present an elementary introduction to quantum gauge fields. The first aim is to show how, in the tree approximation, gauge invariance follows from covariance and unitarity. This leads to the standard construction of the Lagrangian by means of covariant derivatives in a form that unifies the massive and the massless case. Having so identified t

M. Laine, A. Rajantie

3d lattice studies have recently attracted a lot of attention, especially in connection with finite temperature field theories. One ingredient in these studies is a perturbative computation of the 2-loop lattice counterterms, which are exact in the continuum limit. We extend previous such results to SU(N) gauge theories with Higgs fields in the fundamental a

C. Adloff

Two-particle correlations in invariant mass are studied separately for like-sign and unlike-sign charged particles produced in deep inelastic positron-proton scattering in a new kinematical domain. The data were taken with the H1 detector at the HERA storage ring in 1994, in which 27.5 GeV positrons collided with 820 GeV protons at a centre of mass energy sq

Gernot Haager

Two components of spherically symmetric, inhomogeneous dust penetrating each other are introduced as a generalization of the well-known Tolman-Bondi dust solution. The field equations of this model are formulated and general properties are discussed. inhomogeneous Special solutions with additional symmetries - an extra Killing- or homothetic vector - and the

A. J. Markvardsen, N. F. Johnson

It is known experimentally that stable few-body clusters containing negatively-charged electrons (e) and positively-charged holes (h) can exist in low-dimensional semiconductor nanostructures. In addition to the familiar exciton (e+h), three-body 'charged excitons' (2e+h and 2h+e) have also been observed. Much less is known about the properties of su

Stefano Galluccio

We reconsider the Eigen's quasi-species model for competing self-reproductive macromolecules in populations characterized by a single-peaked fitness landscape. The use of ideas and tools borrowed from polymers theory and statistical mechanics, allows us to exactly solve the model for generic DNA lengths d. The mathematical shape of the quasi-species conf

Michiko Yamana, Hidetoshi Nishimori, Tadashi Kadowaki, D. Sherrington

We develop a systematic expansion method of physical quantities for the SK model and the finite-dimensional $\pm J$ model of spin glasses in non-equilibrium states. The dynamical probability distribution function is derived from the master equation using a high temperature expansion. We calculate the expectation values of physical quantities from the dynamic

W. Zwerger

We calculate the backflow current around a fixed impurity in a Fermi liquid. The leading contribution at long distances is radial and proportional to 1/r^2. It is caused by the current induced density modulation first discussed by Landauer. The familiar 1/r^3 dipolar backflow obtained in linear response by Pines and Nozieres is only the next to leading term,

K. Nakanishi, H. Takayama

An approach is proposed to the Hopfield model where the mean-field treatment is made for a given set of stored patterns (sample) and then the statistical average over samples is taken. This corresponds to the approach made by Thouless, Anderson and Palmer (TAP) to the infinite-range model of spin glasses. Taking into account the fact that in the Hopfield mod

S. Nayakshin, F. Melia

An important feature of the EUV spectrum (known as the Big Blue Bump, hereafter BBB) in Seyfert Galaxies is the narrow range in its cutoff energy E0 from source to source, even though the luminosity changes by 4 orders of magnitude. Here we show that if the BBB is due to accretion disk emission, then in order to account for this ``universality'' in t

Adam Frank

Previous studies have explained the shapes of LBV nebulae, such as eta Car, by invoking the interaction of an isotropic fast wind with a previously deposited, slow aspherical wind (a "slow torus"). In this work I focus on the opposite scenario where an aspherical fast wind expands into a previously deposited isotropic slow wind. Using high resolution

Arnon Dar, Ari Laor, Nir J. Shaviv

High energy cosmic ray jets from nearby mergers or accretion induced collapse (AIC) of neutron stars (NS) that hit the atmosphere can produce lethal fluxes of atmospheric muons at ground level, underground and underwater, destroy the ozone layer and radioactivate the environment. They could have caused most of the massive life extinctions on planet Earth in

Hisakazu Minakata, Hiroshi Nunokawa

We investigate, within the framework of three generations of neutrinos, the effects of CP violation in long-baseline neutrino oscillation experiments. We aim at illuminating the global feature of the interplay between genuine effect due to the CP violating phase and a fake one due to the earth matter effect. To this goal, we develop a formalism based on the

Zurab Kakushadze, Gary Shiu, S. -H. Henry Tye, Yan Vtorov-Karevsky

In the 3-family grand unified string models constructed so far, there is only one adjoint (and no higher dimensional representation) Higgs field in the grand unified gauge group. In this preliminary analysis, we address the proton-decay problem in the 3-family E_6 and related SO(10) string models. In particular, we analyze the doublet-triplet splitting (with

M. Baker, James S. Ball, F. Zachariasen

Lattice results and Dual QCD results for all heavy quark potentials through order (quark mass)^${-2}$ are exhibited and compared. The agreement on the whole is quite good, confirming the validity of Dual QCD. NOTE: (The only important change in this replaced version is that Figure 6 has been replotted, because the lattice data used in the original was in the

W. Bardeen, A. Duncan, E. Eichten, H. Thacker

The spectral properties of the Wilson-Dirac operator in 2-dimensional QED responsible for the appearance of exceptional configurations in quenched simulations are studied in detail. The mass singularity structure of the quenched functional integral is shown to be extremely compicated, with multiple branch points and cuts. The connection of lattice topologica

Spenta R. Wadia

S. Chandrasekhar wrote in the prologue to his book on black holes, "The black holes of nature are the most perfect macroscopic objects there are in the universe: the only elements in their construction are our concepts of space and time." In this contribution I briefly discuss recent developments in fundamental theory and black holes that vindicate t

D. A. Trifonov

Three basic properties (eigenstate, orbit and intelligence) of the canonical squeezed states (SS) are extended to the case of arbitrary n observables. The SS for n observables X_i can be constructed as eigenstates of their linear complex combinations or as states which minimize the Robertson uncertainty relation. When X_i close a Lie algebra L the generalize

Tom Bridgeland

We compute a large number of moduli spaces of stable bundles on a general algebraic elliptic surface using a new class of Fourier-Mukai type transforms.

Leticia F. Cugliandolo, David S. Dean, Jorge Kurchan

We show that for stochastic dynamical systems out of equilibrium the violation of the fluctuation-dissipation equality is bounded by a function of the entropy production. The result applies to a much wider situation than `near equilibrium', comprising diffusion as well as glasses and other macroscopic systems far from equilibrium. For aging systems this

A. Kashlinsky

In this paper we evaluate the spectrum of the pregalactic density field on scales $1h^{-1}Mpc < r < 100h^{-1}$Mpc from a variety of astronomical data. APM data on $w(θ)$ in six narrow magnitude is used, after correcting to possible evolutionary effects, to constrain the spectrum of galaxy clustering on scales $10h^{-1}Mpc < r < 50-100h^{-1}Mpc$. Fitting powe

Masahiro Anazawa, Atushi Ishikawa, Hirokazu Tanaka

We discuss the relation among some disk amplitudes with non-trivial boundary conditions in two-dimensional quantum gravity. They are obtained by the two-matrix model as well as the three-matirx model for the case of the tricritical Ising model. We examine them for simple spin configurations, and find that a finite number of insertions of the different spin s

E. Gotsman, E. Levin, U. Maor

A new mechanism for hard inclusive production, which leads to a violation of the factorization theorem, is suggested. The mechanism is illustrated by a detailed discussion of Higgs meson production in high energy deutron-deutron scattering. Numerical estimates for the effect are given for high energy hadron (nucleus) scattering.

Ana Achucarro, Ruth Gregory

It has been pointed out that Nielsen-Olesen vortices may be able to decay by pair production of black holes. We show that when the abelian Higgs model is embedded in a larger theory, the additional fields may lead to selection rules for this process - even in the absence of fermions - due to the failure of a charge quantization condition. We show that, when

S. Aoki, K. Nagai, S. V. Zenkin

We examine the lattice boundary formulation of chiral fermions with either an explicit Majorana mass or a Higgs-Majorana coupling introduced on one of the boundaries. We demonstrate that the low-lying spectrum of the models with an explicit Majorana mass of the order of an inverse lattice spacing is chiral at tree level. Within a mean-field approximation we

Isao Kakebe, Katsuji Yamamoto

Flavor nonconserving and CP violating effects of the quark mixings are investigated in electroweak models incorporating singlet quarks. Especially, the D^0 - {\bar D}^0 mixing and the neutron electric dipole moment, which are mediated by the up-type quark couplings to the neutral Higgs fields, are examined in detail for reasonable ranges of the quark mixings

Steven H. Simon

Paper withdrawn due to errors. Revised version may or may not appear in the future.

Jarmo Hietarinta, Kenji Kajiwara

We study the rational solutions of the discrete version of Painleve&#39;s fourth equation d-PIV. The solutions are generated by applying Schlesinger transformations on the seed solutions -2z and -1/z. After studying the structure of these solutions we are able to write them in a determinantal form that includes an interesting parameter shift that vanishes in

Gilles Brassard, Peter Hoyer, Alain Tapp

In this note, we give a quantum algorithm that finds collisions in arbitrary r-to-one functions after only O((N/r)^(1/3)) expected evaluations of the function. Assuming the function is given by a black box, this is more efficient than the best possible classical algorithm, even allowing probabilism. We also give a similar algorithm for finding claws in pairs

R. Valery Roy, A. J. Roberts, M. E. Simpson

Consider the three-dimensional flow of a viscous Newtonian fluid upon an abitrarily curved substrate when the fluid film is thin as occurs in many draining, coating and biological flows. We derive a model of the dynamics of the film, the model being expressed in terms of the film thickness and the curvature tensor of the substrate. The model accurately inclu

N. Auerbach, N. Van Giai, O. K. Vorov

Exclusive and inclusive $(ν_μ, μ^-), (ν_e, e^-)$ cross-sections and $μ^-$-capture rates are calculated for ^{12}C and ^{16}O using the consistent random phase approximation (RPA) and pairing model. After a pairing correction is introduced to the RPA results the flux-averaged theoretical $(ν_μ, μ^-), (ν_e, e^-)$ cross-sections and $μ^-$-capture rates in $^{12

S. N. Ershov, T. Rogde, B. V. Danilin, J. S. Vaagen

Four-body distorted wave theory appropriate for nucleon-nucleus reactions leading to 3-body continuum excitations of two-neutron Borromean halo nuclei is developed. The peculiarities of the halo bound state and 3-body continuum are fully taken into account by using the method of hyperspherical harmonics. The procedure is applied for A=6 test-bench nuclei; th

I. J. Thompson

Our understanding of halo nuclei has so far relied on high-energy scattering and reactions, but a number of uncertainties remain. I discuss in general terms the new range of observables which will be measured by experiments around the Coulomb barrier, and how some details of the reaction mechanisms still need to be clarified.

Micha Berkooz, Peter Cho, Per Kraus, Matthew J. Strassler

We examine the low energy structure of N=1 supersymmetric SO(10) gauge theory with matter chiral superfields in N_Q spinor and N_f vector representations. We construct a dual to this model based upon an SU(N_f+2N_Q-7) x Sp(2N_Q-2) gauge group without utilizing deconfinement methods. This product theory generalizes all previously known Pouliot-type duals to S

Andrija Rasin

We consider the maximal U(3) horizontal scheme as a handle on fermion masses and mixings. In particular, we attempt to explain the large top Yukawa coupling and the masses and mixing in the two heaviest generations. A simple model is constructed by enlarging the matter content of the Standard Model with that of a $10+\bar{10}$ pair of SU(5). The third genera

T. G. Rizzo

We begin to analyze and contrast the predictions for the decay $b\to s\ell^+\ell^-$ in the Left-Right Symmetric Model(LRM) with those of the Standard Model(SM). In particular, we show that the forward-backward asymmetry of the lepton spectrum can be used to distinguish the SM from the simplest manifestation of the LRM. [To appear in the Proceedings of the 2n

B. C. Allanach, S. F. King

We provide the solutions of the fixed point conditions of the Yukawa sector for a large class of N=1 supersymmetric theories including the minimal and next-to-minimal supersymmetric standard models and their grand unified and other extensions. We also introduce a test which can discriminate between infra-red stable, infra-red unstable and saddle point soluti

Alejandro Gangui, Patrick Peter, Celine Boehm

The modifications of circular cosmic string loop dynamics due to the electromagnetic self-interaction are calculated and shown to reduce the available phase space for reaching classical vorton states, thereby decreasing their remnant abundance. Use is made of the duality between master-function and Lagrangian formalisms on an explicit model.

James M. Cline, Kimmo Kainulainen

We compare two methods of analyzing the finite-temperature electroweak phase transition in the minimal supersymmetric standard model: the traditional effective potential (EP) approach, and the more recently advocated procedure of dimensional reduction (DR). The latter tries to avoid the infrared instabilities of the former by matching the full theory to an e

D. W. Opitz, J. W. Shavlik

An algorithm that learns from a set of examples should ideally be able to exploit the available resources of (a) abundant computing power and (b) domain-specific knowledge to improve its ability to generalize. Connectionist theory-refinement systems, which use background knowledge to select a neural network&#39;s topology and initial weights, have proven to

A. Darwiche, G. Provan

We describe a new paradigm for implementing inference in belief networks, which consists of two steps: (1) compiling a belief network into an arithmetic expression called a Query DAG (Q-DAG); and (2) answering queries using a simple evaluation algorithm. Each node of a Q-DAG represents a numeric operation, a number, or a symbol for evidence. Each leaf node o

S. -H. Lee, C. Broholm, M. F. Collins, L. Heller

We have found weak long range antiferromagnetic order in the quasi-two-dimensional insulating oxide $ KCr_3(OD)_6(SO_4)_2$ which contains Cr$^{3+}$ S=3/2 ions on a kagomé lattice. In a sample with $\approx$ 76% occupancy of the chromium sites the ordered moment is 1.1(3)$μ_B$ per chromium ion which is only one third of the Néel value $gμ_BS=3μ_B$. The magnet

M. Huth, F. B. Anders

The electronic transport properties of heavy-fermion systems were calculated based on a semiphenomenological approach to the lattice non-crossing approximation in the limit of infinite local correlations augmented by crystal-field effects. Within the scope of this calculation using the linearized Boltzmann theory in the relaxation time approximation the qual

John H. Jefferson, Wolfgang Häusler

The electronic properties of nanoscale quantum dots are reviewed. The similarities and differences between these `artificial atoms&#39; and real atoms are discussed and, in particular, the effect of electron correlations is examined. It is shown that for (semiconductor) quantum dots, with only a few electrons, electron correlations can give rise to important

Mangal C. Mahato, A. M. Jayannavar

We study the residence time distributions and explore the possibility of observing stochastic resonance and synchonization of passages in a two-well system driven by a periodic forcing of amplitude larger than a marginal value beyond which one of the two wells become unstable and diasppear. We define and calculate hysteresis loop in the system, the area of w

H. Rieger

An introduction to the application of combinatorial optimization methods to ground state calculations of frustrated, disordered systems is given. We discuss the interface problem in the random bond Ising ferromagnet, the random field Ising model, the diluted antiferromagnet in an external field, the spin glass problem, the solid-on-solid model with a disorde

Mangal C. Mahato, A. M. Jayannavar

Residence times of a particle in both the wells of a double-well system, under the action of zero-mean Gaussian white noise and zero-averaged but temporally asymmetric periodic forcings, are recorded in a numerical simulation. The difference between the relative mean residence times in the two wells shows monotonic variation as a function of asymmetry in the

Th. Busch, J. I. Cirac, V. M. Perez-Garcia, P. Zoller

The dynamics of a two-component dilute Bose gas of atoms at zero temperature is described in the mean field approximation by a two-component Gross-Pitaevskii Equation. We solve this equation assuming a Gaussian shape for the wavefunction, where the free parameters of the trial wavefunction are determined using a moment method. We derive equilibrium states an

M. W. C. Dharma-wardana, Z. Tian, Z. H. Lu, L. J. Lewis

Photoemission (PES) and inverse-photoemission spectra (IPES) for the sulphur-passivated InP(001) surface are compared with theoretical predictions based on density-functional calculations. As a test case for our methods, we also present a corresponding study of the better known Si(111) surface. The reported spectra for InP(001)-S agree well with the calculat

M. R. Evans

A one-dimensional driven lattice gas with disorder in the particle hopping probabilities is considered. It has previously been shown that in the version of the model with random sequential updating, a phase transition occurs from a low density inhomogeneous phase to a high density congested phase. Here the steady states for both parallel (fully synchronous)

P. S. Swain, A. O. Parry

An exact solution of a two dimensional RSOS model of wetting at a corrugated (periodic) wall is found using transfer matrix techniques. In contrast to mean-field analysis of the same problem the wetting transition remains second-order and occurs at a lower temperature than that of the planar system. Comparison with numerical studies and other analytical appr

Leonid S. Braginsky

The phenomenological boundary conditions for the envelope wave function, which is applicable for contacts of semiconductors with the rather different crystal symmetry are proposed. It is shown that the boundary conditions are determined by the number of real values, which are independent of the electron energy. The number of these parameters depends on the s

B. C. Gupta, P. A. Sreeram

We study,numerically, the dynamical behavior of an electron in a two site nonlinear system driven by dc and ac electric field separately. We also study, numerically, the effect of electric field on single static impurity and antidimeric dynamical impurity in an infinite 1D chain to find the strength of the impurities. Analytical arguments for this system hav

Claire Gardent, Michael Kohlhase

Although much has been said about parallelism in discourse, a formal, computational theory of parallelism structure is still outstanding. In this paper, we present a theory which given two parallel utterances predicts which are the parallel elements. The theory consists of a sorted, higher-order abductive calculus and we show that it reconciles the insights

Mark-Jan Nederhof, Gosse Bouma, Rob Koeling, Gertjan van Noord

We argue that grammatical processing is a viable alternative to concept spotting for processing spoken input in a practical dialogue system. We discuss the structure of the grammar, the properties of the parser, and a method for achieving robustness. We discuss test results suggesting that grammatical processing allows fast and accurate processing of spoken

Claire Gardent

Although sloppy interpretation is usually accounted for by theories of ellipsis, it often arises in non-elliptical contexts. In this paper, a theory of sloppy interpretation is provided which captures this fact. The underlying idea is that sloppy interpretation results from a semantic constraint on parallel structures and the theory is shown to predict slopp

Ted Briscoe

A new account of parameter setting during grammatical acquisition is presented in terms of Generalized Categorial Grammar embedded in a default inheritance hierarchy, providing a natural partial ordering on the setting of parameters. Experiments show that several experimentally effective learners can be defined in this framework. Evolutionary simulations sug

Baowen Li

We study numerically the scaling properties of scars in stadium billiard. Using the semiclassical criterion, we have searched systematically the scars of the same type through a very wide range, from ground state to as high as the 1 millionth state. We have analyzed the integrated probability density along the periodic orbit. The numerical results confirm th

Alan M. Watson, Alison L. Coil, Debra S. Shepherd, Peter Hofner

We have observed the ultracompact HII region G29.96-0.02 in the near infrared J, H, and K bands and in the Br-gamma line. By comparison with radio observations, we determine that the extinction to the nebula is AK = 2.14 with a 3 sigma uncertainty of 0.25. We identify the ionizing star and determine its intrinsic K magnitude. The star does not have an infrar

A. Aparicio, C. Gallart, C. Chiosi, G. Bertelli

In this paper, we discuss a method to conduct a quantitative study of the star formation history (SFH) of Local Group (LG) galaxies using (HST) data. This method has proven to be successful in the analysis of the SFH of the same kind of galaxies using ground-based observations. It is based on the comparison of observed CMDs with a set of model CMDs. The latt

A. Aparicio, C. Gallart, G. Bertelli

The star formation history (SFH) and the properties of the dwarf galaxy LGS3 are analyzed using color-magnitude (CM) diagrams plotted from VRI photometry of 736 stars. The distance to the galaxy is estimated through the position of the tip or the red giant branch. Two acceptable results have been obtained: 0.77+/-0.07 Mpc and 0.96+/-0.07 Mpc, although the fi

R. F. Mushotzky

Recent ASCA and ROSAT X-ray observations of active galaxies have revealed a host of new data on the fundamental properties of active galaxies. Amongst these are the discovery and characterization of absorption by ionized gas in Seyfert-I galaxies (the &#34;warm absorber&#34;) , the discovery and parameterization of broad Fe K lines which originate in the cen

Eric V. Linder

Deviations from the Friedmann-Robertson-Walker (FRW) cosmological model in the form of density inhomogeneities induce observational effects on the light propagating through these fluctuations. Using a rigorously parametrized metric whose pseudo-Newtonian potential is related to (possibly nonlinear) density inhomogeneities through a relativistic Green functio

V. D&#39;Odorico, S. Cristiani, S. D&#39;Odorico, A. Fontana

Spectra of the z_em = 3.268 quasar PKS 2126-158 have been obtained in the range lambda lambda 4300-6620 A with a resolution R = 27000 and an average signal-to-noise ratio s/n = 25 per resolution element. The list of the identified absorption lines is given together with their fitted column densities and Doppler widths. The modal value of the Doppler paramete

Michael Finkelberg, Alexander Kuznetsov, Ivan Mirković

Let $C$ be a smooth projective curve of genus 0. Let $B$ be the variety of complete flags in an $n$-dimensional vector space $V$. Given an $(n-1)$-tuple $α\in N[I]$ of positive integers one can consider the space $Q_α$ of algebraic maps of degree $α$ from $C$ to $B$. This space admits some remarkable compactifications $Q^D_α$ (Quasimaps), $Q^L_α$ (Quasiflags

Antony Maciocia

The paper sets out a generalized framework for Fourier-Mukai transforms and illustrates their use via vector bundle transforms. A Fourier-Mukai transform is, roughly, an isomorphism of derived categories of (sheaves) on smooth varieties X and Y. We show that these can only exist if the first Chern class of the varieties vanishes and, in the case of vector bu