December 2001 arXiv papers — page 10

A. Merloni, A. C. Fabian

The spectral energy distributions of galactic black holes in the low/hard state and of low-luminosity AGN possess many common features, the most prominent being: compact, flat (or inverted) spectrum radio cores with high brightness temperatures; excess red and infrared emission, often correlated with the radio flux; an extremely weak (or absent) quasi-therma

S. Recchi, F. Matteucci, A. D'Ercole, M. Tosi

In this paper we present some results concerning the effects of two instantaneous starbursts, separated by a quiescent period, on the dynamical and chemical evolution of blue compact dwarf galaxies. In particular, we compare the model results to the galaxy IZw18, which is a very metal-poor, gas-rich dwarf galaxy, possibly experiencing its first or second bur

Peter A. Thomas, Orrarujee Muanwong, Scott T. Kay, Andrew R. Liddle

It has become increasingly apparent that traditional hydrodynamical simulations of galaxy clusters are unable to reproduce the observed properties of galaxy clusters, in particular overpredicting the mass corresponding to a given cluster temperature. Such overestimation may lead to systematic errors in results using galaxy clusters as cosmological probes, su

A. J. Cenarro, J. Gorgas, N. Cardiel, A. Vazdekis

Using a near-IR stellar library of 706 stars with a wide coverage of atmospheric parameters, we study the behaviour of the Ca II triplet strength in terms of effective temperature, surface gravity and metallicity. Empirical fitting functions for recently defined line-strength indices, namely CaT*, CaT and PaT, are provided. These functions can be easily impl

Stephan D. Price, G. C. Sloan, Kathleen E. Kraemer

Spectra from the Short Wavelength Spectrometer (SWS) on ISO exhibit artifacts at 4.5 and 8 um. These artifacts appear in spectra from a recent data release, OLP 10.0, as spurious broad emission features in the spectra of stars earlier than ~F0, such as alpha CMa. Comparison of absolutely calibrated spectra of standard stars to corresponding spectra from the

G. Domogatsky

We review the present status of the Baikal Neutrino Project and present the results obtained with the deep underwater neutrino telescope NT-200.

M. A. Thompson, J. Hatchell, G. H. Macdonald, T. J. Millar

We present the preliminary results of a sub-mm imaging survey of ultracompact HII regions, conducted with the SCUBA bolometer array on JCMT.

G. I. Ogilvie

An important and widely neglected aspect of the interaction between an accretion disc and a massive companion with a coplanar orbit is the vertical component of the tidal force. As shown by Lubow, the response of the disc to vertical forcing is resonant at certain radii, at which a localized torque is exerted, and from which a compressive wave (p mode) may b

Arnold O. Benz, Pascal Saint-Hilaire, Nicole Vilmer

Narrowband spikes of the decimeter type have been identified in dynamic spectrograms of Phoenix-2 of ETH Zurich and located in position with the Nancay Radioheliograph at the same frequency. The spike positions have been compared with the location of hard X-ray emission and the thermal flare plasma in soft X-rays and EUV lines. The decimetric spikes are foun

Sonja Vrielmann, Frederic V. Hessman, Keith Horne

We have reconstructed the temperatures and surface densities in the quiescent accretion disc in HT Cas by performing a "Physical Parameter Eclipse Mapping" analysis of archival UBVR observations. Using a simple hydrogen slab model and demanding a smooth, maximally artefact-free reconstruction, we derive a formal distance to HT Cas of 207 +- 10 pc, si

D. E. Gruber, W. A. Heindl, R. E. Rothschild, W. Coburn

Five observations of the hard X-ray spectrum of Her X-1 from \xte show that the $\sim 41$ keV energy of the cyclotron scattering line is constant within statistics of a few percent per observtion. Comparison with other observations over many years indicates strongly that the centroid energy of this absorption line has increased some time between 1991 and 199

Joel K. Erickson, R. R. Caldwell, Paul J. Steinhardt, C. Armendariz-Picon

Quintessence, a time-varying energy component that may account for the accelerated expansion of the universe, can be characterized by its equation of state and sound speed. In this paper, we show that if the quintessence density is at least one percent of the critical density at the surface of last scattering the cosmic microwave background anisotropy can di

Hiroko Koyama, Tetsuro Konishi

Long-time behavior of spatial power-law correlation in one-dimensional self-gravitating system is numerically investigated. It is found that the power-law structure persists even after the system is virialized. The structure gradually disappears owing to energy exchange among particles. Energy distribution is quasi-stationary after the system is virialized.

Vadim A. Naumov

The impact of neutrino mixing, refraction and absorption on high-energy neutrino propagation through a thick medium is studied using the MSW evolution equation with complex indices of refraction. It is found that, owing to the mixing with sterile neutrinos, the penetrability of active neutrinos may be many orders of magnitude larger than it would be in the a

LHPC Collaboration, D. G. Richards, QCDSF Collaboration, :

We discuss the extraction of negative-parity baryon masses from lattice QCD calculations. The mass of the lowest-lying negative-parity $J = 1/2^{-}$ state is computed in quenched lattice QCD using an ${\cal O}(a)$-improved clover fermion action, and a splitting found with the nucleon mass. The calculation is performed on two lattice volumes, and three lattic

Kevin Eng, X. G. Feng, Dragana Popovic, S. Washburn

The temperature dependence of conductivity $σ(T)$ of a two-dimensional electron system in silicon has been studied in parallel magnetic fields B. At B=0, the system displays a metal-insulator transition at a critical electron density $n_c(0)$, and $dσ/dT >0$ in the metallic phase. At low fields ($B\lesssim 2$ T), $n_c$ increases as $n_c(B) - n_c(0) \propto B

J. C. Montero, V. Pleitez, M. C. Rodriguez

We consider the mass generation for both charginos and neutralinos in a 3-3-1 supersymmetric model. We show that R-parity breaking interactions leave the electron and one of the neutrinos massless at the tree level. However the same interactions induce masses for these particles at the 1-loop level. Unlike the similar situation in the MSSM the masses of the

J. C. Montero, C. A. de S. Pires, V. Pleitez

Some years ago it was shown by Ma that in the context of the electroweak standard model there are, at the tree level, only three ways to generate small neutrino masses by the see-saw mechanism via one effective dimension-five operator. Here we extend this approach to 3-3-1 chiral models showing that in this case there are several dimension-five operators and

Kirill Krasnov

We consider the theory of pure gravity in 2+1 dimensions, with negative cosmological constant. The theory contains simple matter in the form of point particles; the later are classically described as lines of conical singularities. We propose a formalism in which quantum amplitudes for process involving black holes and point particles are obtained as Liouvil

Andrei G. Bytsko

Integrable Hamiltonians for higher spin periodic XXZ chains are constructed in terms of the spin generators; explicit examples for spins up to 3/2 are given. Relations between Hamiltonians for some U_q(sl_2)-symmetric and U(1)-symmetric universal r-matrices are studied; their properties are investigated. A certain modification of the higher spin periodic cha

R. A. Barankov

The boundary of two mixed Bose-Einstein condensates interacting repulsively was considered in the case of spatial separation at zero temperature. Analytical expressions for density distribution of condensates were obtained by solving two coupled nonlinear Gross-Pitaevskii equations in cases corresponding weak and strong separation. These expressions allow to

Giancarlo Franzese, Manuel I. Marques, H. Eugene Stanley

We study a model for water with a tunable intra-molecular interaction $J_σ$, using mean field theory and off-lattice Monte Carlo simulations. For all $J_σ\geq 0$, the model displays a temperature of maximum density.For a finite intra-molecular interaction $J_σ> 0$,our calculations support the presence of a liquid-liquid phase transition with a possible liqui

W. Fulton, C. Woodward

We give a formula for the smallest powers of the quantum parameters q that occur in a product of Schubert classes in the (small) quantum cohomology of general flag varieties G/P. We also include a complete proof of Peterson's quantum version of Chevalley's formula, also for general G/P's.

G. Barbiellini, A. Celotti, F. Longo

The energetics of the long duration GRB phenomenon is compared with models of a rotating Black Hole (BH) in a strong magnetic field generated by an accreting torus. A rough estimate of the energy extracted from a rotating BH with the Blandford-Znajek mechanism is obtained with a very simple assumption: an inelastic collision between the rotating BH and the t

J. Ananias Neto, C. Neves, W. Oliveira

We propose a new procedure to embed second class systems by introducing Wess-Zumino (WZ) fields in order to unveil hidden symmetries existent in the models. This formalism is based on the direct imposition that the new Hamiltonian must be invariant by gauge-symmetry transformations. An interesting feature in this approach is the possibility to find a represe

Hai-Yang Cheng, Kwei-Chou Yang

We present a systematical study of two-body and three-body charmless baryonic B decays. Branching ratios for two-body modes are in general very small, typically less than $10^{-6}$, except that $\B(B^-\to p \barΔ^{--})\sim 1\times 10^{-6}$. In general, $\bar B\to N\barΔ>\bar B\to N\bar N$ due to the large coupling constant for $Σ_b\to BΔ$. For three-body mod

Sergey M. Klishevich, Mikhail S. Plyushchay

Recently, it was noticed by us that the nonlinear holomorphic supersymmetry of order $n\in\N, n>1$, ($n$-HSUSY) has an algebraic origin. We show that the Onsager algebra underlies $n$-HSUSY and investigate the structure of the former in the context of the latter. A new infinite set of mutually commuting charges is found which, unlike those from the Dolan-Gra

Cailin A. Nelson, Kem H. Cook, Tim S. Axelrod, Jeremy R. Mould

We have performed a search for halo white dwarfs as high proper motion objects in a second epoch WFPC2 image of the Groth-Westphal strip. We identify 24 high proper motion objects with mu > 0.014 ''/yr. Five of these high proper motion objects are identified as strong white dwarf candidates on the basis of their position in a reduced proper motion di

Marek A. Abramowicz, Luciano Rezzolla, Shin'ichirou Yoshida

We show that, at first order in the angular velocity, the general relativistic description of Rossby-Haurwitz waves (the analogues of r-waves on a thin shell) can be obtained from the corresponding Newtonian one after a coordinate transformation. As an application, we show that the results recently obtained by Rezzolla and Yoshida (2001) in the analysis of N

Kasper Peeters, Pierre Vanhove, Anders Westerberg

We report on progress made in the construction of higher-derivative superinvariants for type-II theories in ten dimensions. The string amplitude calculations required for this analysis exhibit interesting features which have received little attention in the literature so far. We discuss two examples from a forthcoming publication: the construction of the (H_

Gil Ariel, David Andelman

The persistence length of a single, strongly charged, stiff polyelectrolyte chain is investigated theoretically. Path integral formulation is used to obtain the effective electrostatic interaction between the monomers. We find significant deviations from the classical Odijk, Skolnick and Fixman (OSF) result. An induced attraction between monomers is due to t

Marcus Berg, Henning Samtleben

We describe a supersymmetric RG flow between conformal fixed points of a two-dimensional quantum field theory as an analytic domain wall solution of the three-dimensional SO(4) x SO(4) gauged supergravity. Its ultraviolet fixed point is an N=(4,4) superconformal field theory related, through the double D1-D5 system, to theories modeling the statistical mecha

Norman Dombey, Piers Kennedy

It is shown that the amplitude for reflection of a Dirac particle with arbitrarily low momentum incident on a potential of finite range is -1 and hence the transmission coefficient T=0 in general. If however the potential supports a half-bound state at k=0 this result does not hold. In the case of an asymmetric potential the transmission coefficient T will b

Mitsuru Hamada

Tradeoffs between the information rate and fidelity of quantum error-correcting codes are discussed. Quantum channels to be considered are those subject to independent errors and modeled as tensor products of copies of a general completely positive linear map, where the dimension of the underlying Hilbert space is a prime number. On such a quantum channel, t

F. Patras

The Gerstenhaber and Schack cohomology comparison theorem asserts that there is a cochain equivalence between the Hochschild complex of a certain algebra and the usual singular cochain complex of a space. We show that this comparison theorem preserves the brace algebra structures. This result gives a structural reason for the recent results establishing fine

L. Brey, C. Tejedor

We study spin textures in a quantum Hall Ising ferromagnet. Domain walls between ferro and unpolarized states at $ν=2$ are analyzed with a functional theory supported by a microscopic calculation. In a neutral wall, Hartree repulsion prevents the appearance of a fan phase provoked by a negative stiffness. For a charged system, electrons become trapped as sol

Dario Martelli, Andre Miemiec

We consider holographic RG flows which interpolate between non-trivial ultra-violet (UV) and infra-red (IR) conformal fixed points. We study the ``superpotentials'' which characterize different flows and discuss their expansions near the fixed points. Then we focus on the holographic $c$-function as defined from the two-point function of the stress-energy te

Lorenzo Giada, Achille Giacometti, Maurice Rossi

We discuss a numerical scheme to solve the continuum Kardar-Parisi-Zhang equation in generic spatial dimensions. It is based on a momentum-space discretization of the continuum equation and on a pseudo-spectral approximation of the non-linear term. The method is tested in (1+1)- and (2+1)- dimensions, where it is shown to reproduce the current most reliable

L. E. Hartley, J. E. Drew, K. S. Long, C. Knigge

To confront the predictions of the most recent line-driven disk wind models with observational evidence, we have obtained HST STIS (1180--1700A) echelle spectra of the nova-like variables IX Vel and V3885 Sgr at three epochs. The targets were observed in timetag mode for ~2000sec on each occasion, allowing us to study the spectral time evolution on timescale

A. Acin, V. Scarani, M. M. Wolf

We consider quantum systems composed of $N$ qubits, and the family of all Bell's correlation inequalities for two two-valued measurements per site. We show that if a $N$-qubit state $ρ$ violates any of these inequalities, then it is at least bipartite distillable. Indeed there exists a link between the amount of Bell's inequality violation and the de

Dmitriy V. Uvarov

Possible ways of generalization of the superembedding approach for the supersurfaces with the number of Grassmann directions being less than the half of that for the target superspace are considered on example of Type II superstrings. Focus is on n=(1,1) superworldsheet embedded into D=10 Type II superspace that is of the interest for establishing a relation

Sergei Sakovich

The gauge-invariant description of zero-curvature representations of evolution equations is applied to the problem of how to distinguish the fake Lax pairs from the true Lax pairs. The main difference between the true Lax pairs and the fake ones is found in the structure of their cyclic bases.

Jinsung Park, Krzysztof P. Wojciechowski

We review the work of the authors and their collaborators on the decomposition of the zeta-determinant of the Dirac operator into the contribution coming from different parts of a manifold.

Chien-Wen Hwang

We calculate the electromagnetic (EM) form factors of the pseudoscalar mesons in the light-front framework. Specifically, these form factors are extracted from the relevant matrix elements directly, instead of choosing the Breit frame. The results show that the charge radius of the meson is related to both the first and second longitudinal momentum square de

Qi-Shu Yan, Dong-Sheng Du

We use the external field method to study the electroweak chiral Lagrangian of the extra dimension model with brane fluctuation. Under the assumption that the contact terms between the matters of the standard model and KK excitations are heavily suppressed, we use the standard procedure to integrate out the quantum fields of KK excitations and the equation o

Keiichi Nagao

The domain wall fermion formalism in lattice gauge theory is much investigated recently. This is set up by reducing 4+1 dimensional theory to low energy effective 4 dimensional one. In order to look around other possibilities of realizing chiral fermion on the lattice, we construct vortex fermion by reducing 4+2 dimensional theory to low energy effective 4 d

Daniel R. Nelson, George T. Fleming, Gregory W. Kilcup

A standing mystery in the Standard Model is the unnatural smallness of the strong CP violating phase. A massless up quark has long been proposed as one potential solution. A lattice calculation of the constants of the chiral Lagrangian essential for the determination of the up quark mass, 2 alpha_8 - alpha_5, is presented. We find 2 alpha_8 - alpha_5 = 0.29

Hideo Iguchi, Takashi Nakamura, Ken-ichi Nakao

Even for the observed luminosity distance D_L(z), which suggests the existence of dark energy, we show that an inhomogeneous dust universe solution without dark energy is possible in general. Future observation of D_L(z) for 1 \lesssim z < 1.7 may confirm or refute this possibility.

Gustavo Burdman, Eugene Golowich, JoAnne Hewett, Sandip Pakvasa

We perform a comprehensive study of a number of rare charm decays, incorporating the first evaluation of the QCD corrections to the short distance contributions, as well as examining the long range effects. For processes mediated by the $c\to u\ell^+\ell^-$ transitions, we show that sensitivity to short distance physics exists in kinematic regions away from

Shin&#39;ichi Nojiri, Sergei D. Odintsov

We calculate Wilson loop (quark anti-quark potential) in dS/CFT correspondence. The brane-world model is considered where bulk is two 5d Euclidean de Sitter spaces and boundary (brane) is 4d de Sitter one. Starting from the Nambu-Goto action, the calculation of the effective tension (average energy) is presented. Unlike to the case of supergravity calculatio

Jinlan Wang, Guanghou Wang, Jijun Zhao

We have investigated the lowest-energy structures and electronic properties of the Au$_n$(n=2-20) clusters based on density functional theory (DFT) with local density approximation. The small Au$_n$ clusters adopt planar structures up to n=6. Tabular cage structures are preferred in the range of n=10-14 and a structural transition from tabular cage-like stru

Benjamin Schumacher, Michael D. Westmoreland

The errors that arise in a quantum channel can be corrected perfectly if and only if the channel does not decrease the coherent information of the input state. We show that, if the loss of coherent information is small, then approximate error correction is possible.

A. Galindo, M. A. Martin-Delgado

Quantum theory has found a new field of applications in the realm of information and computation during the recent years. This paper reviews how quantum physics allows information coding in classically unexpected and subtle nonlocal ways, as well as information processing with an efficiency largely surpassing that of the present and foreseeable classical com

R. Lazauskas, J. Carbonell

The low energy scattering of heavy positively charged particles on hydrogen atoms (H) are investigated by solving the Faddeev equations in configuration space. A resonant value of the pH scattering length, $a=750\pm 5$ a.u., in the pp antisymmetric state was found. This large value indicates the existence of a first excited state with a binding energy B=1.14

A. Gilchrist, A. G. White, W. J. Munro

We present some applications of high efficiency quantum interrogation (&#34;interaction free measurement&#34;) for the creation of entangled states of separate atoms and of separate photons. The quantum interrogation of a quantum object in a superposition of object-in and object-out leaves the object and probe in an entangled state. The probe can then be fur

M. Fannes, P. Spincemaille

For chaotic classical systems, the distribution of return times to a small region of phase space is universal. We propose a simple tool to investigate multiple returns in quantum systems. Numerical evidence for the baker map and kicked top points, also in the quantum case, at a universal distribution.

Mark P. Davidson

The origin of the algebra of the non-commuting operators of quantum mechanics is explained in the general Fenyes-Nelson stochastic models in which the diffusion constant is a free parameter. This is achieved by continuing the diffusion constant to imaginary values, a continuation which destroys the physical interpretation, but does not affect experimental pr

Yu. Dabaghian, R. V. Jensen, R. Blümel

We consider a class of simple quasi one-dimensional classically non-integrable systems which capture the essence of the periodic orbit structure of general hyperbolic nonintegrable dynamical systems. Their behavior is simple enough to allow a detailed investigation of both classical and quantum regimes. Despite their classical chaoticity, these systems exhib

I. Brevik, J. B. Aarseth, J. S. Høye

The Casimir mutual free energy F for a system of two dielectric concentric nonmagnetic spherical bodies is calculated, at arbitrary temperatures. Whereas F has recently been evaluated for the special case of metals (refractive index n=\infty), here analogous results are presented for dielectrics, and shown graphically when n=2.0. Our calculational method rel

J. Niel de Beaudrap, Richard Cleve, John Watrous

We obtain the strongest separation between quantum and classical query complexity known to date -- specifically, we define a black-box problem that requires exponentially many queries in the classical bounded-error case, but can be solved exactly in the quantum case with a single query (and a polynomial number of auxiliary operations). The problem is simple

V. J. Menon, B. K. Patra

It is pointed out that for a general short-ranged potential the Lippmann-Schwinger-Low scattering state $|ψ^L_k>$ does not strictly satisfy the Schrodinger eigen equation, and the pair $|ψ^L_n>$, $|ψ^L_k>$ is mutually nonorthogonal if $E_n=E_k$. For this purpose, we carefully use an infinitesimal adiabatic parameter $ε$, a nonlinear relation among transition

A. V. Rykov

The photoeffect, (vacuum analogue of the photoelectric effect,) is used to study the structure of the physical vacuum, the outcome of which is the basis for an hypothesis on the nature of gravitation and inertia. The source of gravitation is the vacuum which has a weak massless elementary electrical dipole (+/-) charge. Inertia is the result of the elastic f

Jijun Zhao, Bingchen Liu, Huajin Zhai, Rufang Zhou

We study the carbon-dope aluminum clusters by using time-of-flight mass spectrum experiments and {\em ab initio} calculations. Mass abundance distributions are obtained for anionic aluminum and aluminum-carbon mixed clusters. Besides the well-known magic aluminum clusters such as Al$_{13}^-$ and Al$_{23}^-$, Al$_7$C$^-$ cluster is found to be particularly st

E. Tiesinga, S. Kotochigova, P. S. Julienne

We have constructed the X 1SIGMAg+ potential for the collision between two ground state Mg atoms and analyzed the effect of uncertainties in the shape of the potential on scattering properties at ultra-cold temperatures. This potential reproduces the experimental term values to 0.2 inverse cm and has a scattering length of +1.4(5) nm where the error is prodo

E. Bjorklund

Experience using hardware knobs as an operator interface for controlling equipment has varied considerably at different facilities. Reactions have ranged from &#34;indispensable&#34; at some facilities, to &#34;virtually useless&#34; at others. In this paper, we will attempt to outline some basic principles for successful knob implementation. These principle

T. Gaitanos, C. Fuchs, H. H. Wolter, Amand Faessler

We investigate differential in-plane and out-of-plane flow observables in heavy ion reactions at intermediate energies from $0.2÷2$ AGeV within the framework of relativistic BUU transport calculations. The mean field is based on microscopic Dirac-Brueckner-Hartree-Fock (DBHF) calculations. We apply two different sets of DBHF predictions, those of ter Haar an

P. Bartsch, D. Baumann, J. Bermuth, R. Boehm

In a p(e_pol,e&#39;p)pi_0 out-of-plane coincidence experiment at the 3-spectrometer setup of the Mainz Microtron MAMI, the beam-helicity asymmetry has been precisely measured around the energy of the Delta(1232) resonance and Q^2 = 0.2 (GeV/c)^2. The results are in disagreement with three up-to-date model calculations. This is interpreted as lack of understa

E. Bogomolny, O. Giraud, C. Schmit

The exact computation of the nearest-neighbor spacing distribution P(s) is performed for a rectangular billiard with point-like scatterer inside for periodic and Dirichlet boundary conditions and it is demonstrated that for large s this function decreases exponentially. Together with the results of [Bogomolny et al., Phys. Rev. E 63, 036206 (2001)] it proves

Wen-Xiu Ma

Binary symmetry constraints are applied to the nonlinearization of spectral problems and adjoint spectral problems into so-called binary constrained flows, which provide candidates for finite-dimensional Liouville integrable Hamiltonian systems. The resulting constraints on the potentials of spectral problems give rise to a kind of involutive solutions to ze

Tooru Taniguchi, Gary P. Morriss

The structure of Lyapunov spectra for many particle systems with a random interaction between the particles is discussed. The dynamics of the tangent space is expressed as a master equation, which leads to a formula that connects the positive Lyapunov exponents and the time correlations of the particle interaction matrix. Applying this formula to one and two

Pierre Martinetti

Cette these etudie l&#39;aspect metrique de la geometrie non commutative a travers la formulation de Connes de la distance entre etats d&#39;une algebre. Sont etudies des exemples d&#39;espaces finis et le modele standard ou le champs de Higgs s&#39;interprete comme coefficient d&#39;une metrique dans une dimension interne discrete.

Vadim V. Varlamov

An algebraic description of basic physical fields (neutrino field, electron-positron field and electromagnetic field) is studied. It is sown that the electromagnetic field can be described within a quotient representation of the proper orthochronous Lorentz group. The relation of such a description with Majorana-Oppenheimer quantum electrodynamics and de Bro

Craig A. Jensen

We calculate the homology of automorphism groups of free groups in various cases. The author would like to thank his thesis advisor Karen Vogtmann.

Craig A. Jensen

For odd primes p, we examine $\hat H^*(Aut(F_{2(p-1)}); \Z_{(p)})$, the Farrell cohomology of the group of automorphisms of a free group $F_{2(p-1)}$ on $2(p-1)$ generators, with coefficients in the integers localized at the prime $(p) \subset \Z$. This extends results by Glover and Mislin, whose calculations yield $\hat H^*(Aut(F_n); \Z_{(p)})$ for $n \in \

Henry H Glover, Craig A. Jensen

We examine the palindromic automorphism group $ΠA(F_n)$ of a free group $F_n$, a group first defined by Collins which is related to hyperelliptic involutions of mapping class groups, congruence subgroups of $SL_n(\Z)$, and symmetric automorphism groups of free groups. Cohomological properties of the group are explored by looking at a contractible space on wh

Craig A. Jensen

We show that for every finite subgroup $G$ of $Aut(F_n)$, the fixed point subcomplex $X_n^G$ is contractible, where $F_n$ is the free group on $n$ letters and $X_n$ is the spine of ``auter space&#39;&#39; constructed by Hatcher and Vogtmann. In more categorical language, $X_n =\underline{E}Aut(F_n)$. This is useful because it allows one to compute the cohomo

Craig A. Jensen

It is not known whether or not the stable rational cohomology groups $\tilde H^*(Aut(F_\infty);\Q)$ always vanish. We show that either the rational cohomology does not vanish in certain dimensions, or the integral cohomology of a moduli space of pointed graphs does not stabilize in certain other dimensions. Similar results are stated for groups of outer auto

Adam Van Tuyl

We describe the eventual behaviour of the Hilbert function of a set of distinct points in P^{n_1} x ... x P^{n_k}. As a consequence of this result, we show that the Hilbert function of a set of points in P^{n_1} x ... x P^{n_k} can be determined by computing the Hilbert function at only a finite number of values. Our result extends the result that the Hilber

Victor Guillemin, Tara Holm, Catalin Zara

Let $T$ be a torus of dimension $n>1$ and $M$ a compact $T-$manifold. $M$ is a GKM manifold if the set of zero dimensional orbits in the orbit space $M/T$ is zero dimensional and the set of one dimensional orbits in $M/T$ is one dimensional. For such a manifold these sets of orbits have the structure of a labelled graph and it is known that a lot of topologi

Boris Chorny

In this work we develop a cellular equivariant homology functor and apply it to prove an equivariant Euler-Poincare formula and an equivariant Lefschetz theorem.

Beata Randrianantoanina

We give a characterization of conditional expectation operators through a disjointness type property similar to band preserving operators. We say that the operator $T:X\to X$ on a Banach lattice $X$ is semi band preserving if and only if for all $f, g \in X$, $f \perp Tg$ implies that $Tf \perp Tg$. We prove that when $X$ is a purely atomic Banach lattice, t

Fedor Duzhin

In this paper the problem of estimating the number of periodical billiard trajectories is considered. The main result is the theorem on Morse theory for periodical billiard trajectories.

Boris Chorny

We show that the model category of diagrams of spaces generated by a proper class of orbits is not cofibrantly generated. In particular the category of maps between spaces may be given a non-cofibrantly generated model structure.

Richard P. Stanley

We extend work of McKay, Morse, and Wilf by giving exact formulas and asymptotic formulas for the number of skew Young tableaux T in two situations: (1) the &#34;inside shape&#34; and total number of cells of T are fixed, and (2) the inside shape of T is fixed. The proofs use the theory of symmetric functions and estimates for irreducible characters of the s

Andrzej Weber

We present several approaches to equivariant intersection cohomology. We show that for a complete algebraic variety acted by a connected algebraic group $G$ it is a free module over $H^*(BG)$. The result follows from the decomposition theorem or from a weight argument.

P. A. Grassi, G. Policastro, M. Porrati, P. van Nieuwenhuizen

We construct a covariant quantum superstring, extending Berkovits&#39; approach by introducing new ghosts to relax the pure spinor constraints. The central charge of the underlying Kac-Moody algebra, which would lead to an anomaly in the BRST charge, is treated as a new generator with a new b-c system. We construct a nilpotent BRST current, an anomalous ghos

Roberto Contino, Andrea Gambassi

We discuss a systematic way to dimensionally regularize divergent sums arising in field theories with an arbitrary number of physical compact dimensions or finite temperature. The method preserves the same symmetries of the action as the conventional dimensional regularization and allows an easy separation of the regulated divergence from the finite term tha

Nathan Berkovits, Paul Howe

It has recently been shown that the ten-dimensional superstring can be quantized using the BRST operator $Q=\ointλ^αd_α$ where $λ^α$ is a pure spinor satisfying $λγ^m λ=0$ and $d_α$ is the fermionic supersymmetric derivative. In this paper, the pure spinor version of superstring theory is formulated in a curved supergravity background and it is shown that ni

Davoud Kamani

We consider open strings attached to a moving D$_p$-brane with motion along itself, in the presence of the backgrounds $B_{μν}$-field and a U(1) gauge field $A_α$. The effects of the motion of the brane on the open string propagator and on the open string variables are studied. We observe that some free parameters appear in the open string variables and in t

B. Juliá-Díaz, J. Haidenbauer, A. Valcarce, F. Fernández

The three-nucleon bound state problem is studied employing a nucleon-nucleon potential obtained from a basic quark-quark interaction in a five-channel Faddeev calculation. The obtained triton binding energy is comparable to those predicted by conventional models of the $NN$ force.

Christian W. Bauer

In this talk I review the status of our ability to extract the CKM matrix elements |Vub| and |Vcb| from semileptonic decays. I will review both exclusive and inclusive methods and put a strong emphasis on how to ensure keeping the extractions model independent.

E. Martynov, E. Predazzi, A. Prokudin

A model based on a dipole Pomeron framework for vector meson exclusive photoproduction by real and virtual photons shows very good agreement with the experimental data. The model does not violate unitarity constrains and describes in a universal manner all the available data for $ρ$, $ω$, $ϕ$, $J/ψ$ and $Υ$ vector meson photoproduction in the region of energ

G. L. Fogli, G. Lettera, E. Lisi

Variations around the average density and composition of the Earth mantle may affect long-baseline (anti)neutrino oscillations through matter effects. For baselines not exceeding a few thousand km, such effects are known to be very small, and can be practically regarded as fractional contributions to the theoretical uncertainties. We perturbatively derive co

Kai Hencken

Using the strong electromagnetic fields in peripheral heavy ion collisions gives rise to a number of interesting possibilities of applications in both photon-photon and photon-hadron physics. We look at the theoretical foundations of the equivalent photon approximation and the specific problems in the heavy ion case. The interesting physics processes that ca

G. Baur

Due to coherence, there are strong electromagnetic fields of short duration in very peripheral heavy ion collisions. They give rise to photon-photon and photon-nucleus collisions with high flux. Photon-photon and photon-hadron physics at various invariant mass scales are discussed.

A. Bottino, N. Fornengo, S. Scopel

Phenomenology of relic neutralinos is analyzed in an effective supersymmetric scheme at the electroweak scale. It is shown that current direct experiments for WIMPs, when interpreted in terms of relic neutralinos, are indeed probing regions of supersymmetric parameter space compatible with all present experimental bounds.

Mustafa Nasr, Omran Trifees

We present and discuss results on multiplicity and angular distributions of shower particles produced in silicon-nucleus collisions at 4.5 A GeV/c. These results are compared with those obtained for different values of impact parameter. Shower width distribution has also been investigated .

Christian W. Bauer, Zoltan Ligeti, Michael Luke

We review how to determine |Vub| from inclusive semileptonic B decay using combined cuts on the leptonic and hadronic invariant masses to eliminate the b -> c background. This leads to a determination of |Vub| with theoretical uncertainty at the 5 -10% level.

A. Duncan, E. Eichten

Quark propagators with arbitrary sources and sinks can be obtained more efficiently using a pseudofermion method with a mode-shifted action. Mode-shifting solves the problem of critical slowing down (for light quarks) induced by low eigenmodes of the Dirac operator. The method allows the full physical content of every gauge configuration to be extracted, and

B. Meadows

Results are presented for the 500 GeV/c pion production asymmetry and polarization of the Lambda_c (anti-Lanbda_c) charmed baryon from Fermilab experiment E791. An analysis of the decay to the p anti-K pi final state is described. Resonant sub-channel fractions and phases are given and possible resonant effects in the low mass p anti-K system discussed. Sign