February 1996 arXiv papers — page 3

J. L. Chkareuli, I. G. Gogoladze, A. B. Kobakhidze

We show that in some SU(N) type GUTs with the complementary pairs of the conjugated fermion multiplets there naturally appear the relatively light ($M\ll M_{GUT}$) vectorlike fermions which considerably modify the desert physics. In the non-SUSY case they can provide for the unification of the standard coupling constant $α_1$, $α_2$ and $α_S$ whereas in the

H. Anlauf

We describe a simple algorithm that calculates the distributions of electrons and positrons under multiphoton beamstrahlung at a future linear collider. The evolution equation as given by Chen is solved by a Monte Carlo algorithm. Explicit multiple beamstrahlung photons are generated. We present first results from an implementation of beamstrahlung into the

B. Bajc, A. H. Blin, B. Hiller, M. C. Nemes

We calculate the one-quark-loop amplitude for the low energy $γγ\toππ$ collision in the context of the Nambu and Jona-Lasinio model with scalar and pseudoscalar four quark couplings to all orders in the external momenta. We show that the NJL predictions for the $γγ\toπ^+π^-$ reaction are not far from the Born amplitude, which is close to the data, and is com

S. Jadach, O. Nicrosini, H. Anlauf, A. Arbuzov

The results obtained by the "Event Generators for Bhabha Scattering" working group during the CERN Workshop "Physics at LEP2" (1994/1995) are presented.

Ch. Hoelbling, C. B. Lang

We study the 2D Ising model on three different types of lattices that are topologically equivalent to spheres. The geometrical shapes are reminiscent of the surface of a pillow, a 3D cube and a sphere, respectively. Systems of volumes ranging up to O($10^5$) sites are simulated and finite size scaling is analyzed. The partition function zeros and the values

Viqar Husain

The vacuum Einstein equations for spacetimes with two commuting spacelike Killing field symmetries are studied using the Ashtekar variables. The case of compact spacelike hypersurfaces which are three-tori is considered, and the determinant of the Killing two-torus metric is chosen as the time gauge. The Hamiltonian evolution equations in this gauge may be r

Radu P. Mondescu, M. Muthukumar

An effective medium approach together with a multiple scattering formalism is considered to study the steady-state dynamics of suspensions of spheres and rigid stiff polymer chains (Gaussian) without excluded volume interactions. The translational diffusion coefficients of the moving probe sphere and of the probe polymer chain, and the shear viscosity of the

C. E. Creffield, P. E. Kornilovitch, E. G. Klepfish, E. R. Pike

A Quantum Monte Carlo calculation of dynamical spin susceptibility in the half-filled 2D Hubbard model is presented for temperature $T=0.2t$ and an intermediate on-site repulsion $U=4t$. Using the singular value decomposition technique we succeed in analytically continuing the Matsubara Green's function into the real frequency domain and in deriving the

J. Sanchez-Canizares, F. Sols

We study the nonequilibrium transport properties of a normal-superconductor-normal structure, focussing on the effect of adding an impurity in the superconducting region. Current conservation requires the superfluid velocity to be nonzero, causing a distortion of the quasiparticle dispersion relation within the superconductor. For weakly reflecting interface

Mark Abney, Richard I Epstein, Angela V Olinto

We show that the short spin-up time observed for the Vela pulsar during the 1988 ``Christmas'' glitch implies that the coupling time of the pulsar core to its crust is less than $\sim$ 10 seconds. Ekman pumping cannot explain the fast core-crust coupling and a more effective coupling is necessary. The internal magnetic field of the Vela pulsar can pr

Xiangdong Shi

We investigate in detail the parameter space of active-sterile neutrino oscillations that amplifies neutrino chemical potentials at the epoch of Big Bang Nucleosynthesis. We calculate the magnitude of the amplification and show evidences of chaos in the amplification process. We also discuss the implications of the neutrino chemical potential amplification i

R. Juszkiewicz, F. R. Bouchet

Since the appearance of the classical paper of Lifshitz almost half a century ago, linear stability analysis of cosmological models is textbook knowledge. Until recently, however, little was known about the behavior of higher than linear order terms in the perturbative expansion. These terms become important in the weakly nonlinear regime of gravitational cl

David Muller, Satyanarayan Nandi

We consider an extended electroweak gauge group: SU(2)$_1 \times$ SU(2)$_2 \times$ U(1)$_Y$ where the first and second generation of fermions couple to SU(2)$_1$ and the third generation couples to SU(2)$_2$. Bounds based on heavy gauge boson searches and current precision electroweak measurements are placed on the masses of the new heavy gauge bosons. In pa

S. S. Gubser, I. R. Klebanov, A. W. Peet

We consider slightly non-extremal black 3-branes of type IIB supergravity and show that their Bekenstein-Hawking entropy agrees, up to a mysterious factor, with an entropy derived by counting non-BPS excitations of the Dirichlet 3-brane. These excitations are described in terms of the statistical mechanics of a 3+1 dimensional gas of massless open string sta

Mar Bastero-Gil, Biswajoy Brahmachari

Two-loop evolutions of the gauge couplings in a class of intermediate scale supersymmetric SO(10) models including the effect of third generation Yukawa couplings are studied. The unification scale, the intermediate scale and the value of the unification gauge coupling in these models are calculated and the gauge boson mediated proton decay rates are estimat

S. Yu. Shmakov, A. M. Zadorozhny

We present an algorithm for simulation of $SU(2)$ lattice gauge theory under the MA gauge and first numerical results for the theory without abelian monopoles. The results support the idea that nonperturbative interaction arises between monopoles and residual abelian field and the other interactions are perturbative. It is shown that the Gribov region for th

Jose M. Gracia-Bondia

We briefly sketch the noncommutative geometry approach to the Standard Model, with attention to what can be inferred about particle masses.

K. Tamvakis

We address the question whether it is possible in GUTs to obtain R-parity violation with a large ${ΔL{/}ΔB}$ hierarchy of strengths so that the proton is stable while phenomenologically interesting $L$-violation is present. We consider versions of SU(5) with a built-in Peccei-Quinn symmetry spontaneously broken at an intermediate scale. The P-Q symmetry and

J. Sexton, A. Vaccarino, D. Weingarten

We evaluate the partial decay widths of the lightest scalar glueball to pairs of pseudoscalar quark-antiquark states. The calculation is done in the valence (quenched) approximation on a $16^3 \time 24$ lattice at $β= 5.7$. These predictions and values obtained earlier for the infinite volume continuum limit of the scalar glueball's mass are in good agre

O. Agam, A. V. Andreev, B. L. Altshuler

We demonstrate that beyond the universal regime correlators of quantum spectral determinants $Δ(ε)=\det (ε-\hat{H})$ of chaotic systems, defined through an averaging over a wide energy interval, are determined by the underlying classical dynamics through the spectral determinant $1/Z(z)=\det (z- {\cal L})$, where $e^{-{\cal L}t}$ is the Perron-Frobenius oper

M. M. Fogler, A. A. Koulakov

We compare the energies of the Laughlin liquid and a charge density wave in a weak magnetic field for the upper Landau level filling factors $ν_N = 1/3$ and $1/5$. The charge density wave period has been optimized and was found to be $\simeq 3R_c$, where $R_c$ is the cyclotron radius. We conclude that the optimal charge density wave is more energetically pre

Nitin Nitsure

For conic bundles on a smooth variety (over a field of characteristic $\ne 2$) which degenerate into pairs of distinct lines over geometric points of a smooth divisor, we prove a theorem which relates the Brauer class of the non-degenerate conic on the complement of the divisor to the covering class (Kummer class) of the 2-sheeted cover of the divisor define

Alok Kumar, Gautam Sengupta

A family of type IIB superstring backgrounds involving Ramond-Ramond fields are obtained in ten dimensions starting from a K-model through a generalization of our recent results. The unbroken global $SL(2,R)$ symmetry of the type IIB equations of motion are implemented in this context as a solution generating transfromation. A geometrical analysis, based on

Y. S. Myung

We perform consistently the Gupta-Bleuler quantization combined with Dirac procedure for a chiral boson with the parameter ($α$) on the circle, the boundary of the circular droplet. For $α=1$, we obtain the holomorphic constraints. Using the representation of Bargmann-Fock space and the Schrödinger equation, we construct the holomorphic wave functions. In or

As. Abada, M. B. Gavela, O. Pène

The thermal average of the Polyakov line is non-zero at high temperature. It has been suggested that its phase could be relevant for baryogenesis within the standard model, providing a source of spontaneously broken CP violation. This scenario suffers from a causal domain problem which cannot be cured by inflation: quantum fluctuations in de Sitter space ove

K. Huitu, J. Maalampi, M. Raidal

Single $W$-boson production in $e^-γ$ collisions with polarized beams is investigated. In the framework of the Standard Model the updated estimates for the measurement precision of photon anomalous coupling parameters $ κ_{ γ},$ $ λ_{ γ}$ at the Next Linear Collider with $ \sqrt{s_{ eγ}}=420$ GeV are obtained. The production of right-handed gauge bosons $ W^

Osamu Yasuda, Hisakazu Minakata

We discuss constraints on three flavor neutrino mixings from the accelerator and reactor experiments, the Kamiokande multi-GeV data, and the solar neutrino observations. The LSND result is excluded at 90\%CL by the constraints imposed by all the data of reactor and accelerator experiments and the Kamiokande multi-GeV data if the mass scale required for the s

J. Jurkiewicz

The analogue of the loop-loop correlation function in 2d gravity for the planar connected $ϕ^3$ diagrams is calculated. It is shown that although the discretized formulas are different the scaling limit is the same as for the loop-loop correlation function. The derivation may serve as an alternative definition of the volume-volume correlator of Euclidean qua

Kouichirou Hirata, Yoshi Fujiwara, Jiro Soda

The thermodynamic second law in the evaporating black hole space-time is examined in the context of two-dimensional dilaton black hole. The dynamical evolution of entropy is investigated by using the analytical perturbation method and the numerical method. It is shown that the thermodynamic second law holds in the vicinity of infalling shell %analytically an

Somendra M. Bhattacharjee

We propose a theory for the observed tricriticality in the orientational phase diagram of Si(113) misoriented towards [001]. The systems seems to be at or close to a very special point for long range interactions.

M. W. Ortalano, Song He, S. Das Sarma

We perform an exact spherical geometry finite-size diagonalization calculation for the fractional quantum Hall ground state in three different experimentally relevant GaAs-Al_{x}Ga_{1-x}As systems: a wide parabolic quantum well, a narrow square quantum well, and a heterostructure. For each system we obtain the Coulomb pseudopotential parameters entering the

G. E. Volovik

The friction force on the moving interface between two different vacuum states of superfluid 3He is considered at low temperature. Since the dominating mechanism of the friction is the Andreev reflection of the massless "relativistic" fermions, which live on the A-phase side of the interface, the results are similar to that for the perfectly reflecti

Steven R. White, Ian Affleck

Using the density matrix renormalization group and a bosonization approach, we study a spin-1/2 antiferromagnetic Heisenberg chain with near-neighbor coupling $J_1$ and frustrating second-neighbor coupling $J_2$, particularly in the limit $J_2 >> J_1$. This system exhibits both dimerization and incommensurate spiral spin correlations. We argue that this syst

Thomas Appelquist, John Terning, L. C. R. Wijewardhana

We investigate the zero temperature chiral phase transition in an SU(N) gauge theory as the number of fermions $N_f$ is varied. We argue that there exists a critical number of fermions $N_f^c$, above which there is no chiral symmetry breaking or confinement, and below which both chiral symmetry breaking and confinement set in. We estimate $N_f^c$ and discuss

Abhay Ashtekar, Jerzy Lewandowski

A new functional calculus, developed recently for a fully non-perturbative treatment of quantum gravity, is used to begin a systematic construction of a quantum theory of geometry. Regulated operators corresponding to areas of 2-surfaces are introduced and shown to be self-adjoint on the underlying (kinematical) Hilbert space of states. It is shown that thei

D. Bailin, A. Love, W. A. Sabra, S. Thomas

Convergence of the standard model gauge coupling constants to a common value at around $2\times 10^{16}$ GeV is studied in the context of orbifold theories where the modular symmetry groups for $T$ and $U$ moduli are broken to subgroups of $PSL(2, Z)$. The values of the moduli required for this unification of coupling constants are studied for this case and

James Robinson, Andrew Yates

We examine the statistical properties of defects formed by the breaking of a U(1) symmetry when the Higgs field has a power spectrum $P(k) \propto k^n$. We find a marked dependence of the amount of infinite string on the spectral index $n$ and empirically identify an analytic form for this quantity. We also confirm that this result is robust to changes in th

R. Balbinot, A. Fabbri

Analytical extensions and resulting Penrose diagrams are given for the solutions of a simple 2d dilaton gravity theory describing black holes which are static as viewed by asymptotically accelerated observers.

I. Racz, J. Zsigrai

Stationary perfect-fluid configurations of Einstein's theory of gravity are studied. It is assumed that the 4-velocity of the fluid is parallel to the stationary Killing field, and also that the norm and the twist potential of the stationary Killing field are functionally independent. It has been pointed out earlier by one of us (I.R.) that for these per

B. de Carlos, P. L. White

We present full renormalisation group equations for the MSSM with R-parity violation, including all soft supersymmetry breaking terms. The inclusion of dimensionless R-parity violating couplings can generate many possible low energy effects through the generation of off-diagonal soft masses violating lepton and quark flavour, and through the generation of le

M. Maul, B. Ehrnsperger, E. Stein, A. Schäfer

We perform a systematic operator product expansion of the most general form of the nucleon scattering tensor $W_{μν}$ including electro-magnetic and weak interaction processes. Finite quark masses are taken into account and a number of higher-twist corrections are included. In this way we derive relations between the lowest moments of all 14 structure functi

Marco Lenci

It is proven that, under some conditions on $f$, the non-compact flat billiard $Ω= \{ (x,y) \in \R_0^{+} \times \R_0^{+};\ 0\le y \le f(x) \}$ has no orbits going {\em directly} to $+\infty$. The relevance of such sufficient conditions is discussed.

C. D. Fosco, T. Matsuyama

We study the Schwinger-Dyson equation for the fermion self-energy in massless and massive $QED_2$, in the ladder approximation. When the fermion is massless (and the photon massless or massive), we check the reliability of this approximation by comparing its solutions with the exact ones. They agree only when the photon is massless. For a massive fermion and

G. Santi, T. Jarlborg, M. Peter, M. Weger

We examine the different possible symmetries of the superconducting gap obtained by solving the Eliashberg equations. We consider an electron-phonon interaction in a strong coupling scenario. The Coulomb pseudopotential plays the crucial role of providing the repulsion needed to favour the d-wave symmetry. But the key parameter that allows very anisotropic s

Jan de Gier, Bernard Nienhuis

We consider the two-dimensional random tiling model introduced by Cockayne, i.e. the ensemble of all possible coverings of the plane without gaps or overlaps with squares and various hexagons. At the appropriate relative densities the correlations have eight-fold rotational symmetry. We reformulate the model in terms of a random tiling ensemble with identica

M. S. Marinov, Bilha Segev

Time dependence for barrier penetration is considered in the phase space. An asymptotic phase-space propagator for nonrelativistic scattering on a one - dimensional barrier is constructed. The propagator has a form universal for various initial state preparations and local potential barriers. It is manifestly causal and includes time-lag effects and quantum

Erik Aurell, Sergey N. Gurbatov, Sergey I. Simdyankin

We study the statistical properties of solutions to Burgers' equation, $v_t + vv_x = νv_{xx}$, for large times, when the initial velocity and its potential are stationary Gaussian processes. The initial power spectral density at small wave numbers follows a steep power-law $E_0(k) \sim |k|^n$ where the exponent $n$ is greater than two. We compare results

V. F. Dmitriev, V. B. Telitsin

The many body contributions to the nuclear anapole moment of $^{133}$Cs, $^{205}$Tl, $^{207,209}$PB, and $^{209}$Bi from the core polarization are calculated in the random-phase approximation with the effective residual interaction. Strong reduction of a valence nucleon contribution was found provided by the core polarization effects. The contribution of the

C. D. Fosco, T. Matsuyama

We investigate some properties of a first-order polynomial formulation of the U(1) non-linear sigma-model in two Euclidean dimensions. The variables in this description are a 1-form field plus a 0-form Lagrange multiplier field. The usual spin variables are non-local functions of the new fields. As this construction incorporates O(2) invariance ab initio, on

Min-Ho Lee, Jae Kwan Kim

We calculate the entropies of the system of classical particles and a quantum scalar field by using the brick wall method in thermal bath in a charged Kerr black hole spacetime. Their leading terms at Hartle-Hawking temperature $T_H = κ/(2 π) $ are given by $ S_{cl} \approx N \ \ln \left( \frac{A_b}{ε^2} \right)$, and $S \approx N' \frac{A_H}{ε^2}$, wher

Anna Rossi

We present the evolution equation describing MSW conversion, derived in the framework of the Schrödinger approach, in the presence of matter density fluctuations. Then we analyse the effect of such fluctuations in the MSW scenario as a solution to the solar neutrino problem. It is shown that the non-adiabatic MSW parameter region is rather stable (especially

S. M. Bilenky, C. Giunti, C. W. Kim

We show in a simple and general way that matter effects do not contribute to the averaged value of the probabilities of transition of solar $ν_e$'s into other states in the case of maximal mixing of any number of massive neutrinos. We also show that future solar neutrino experiments (Super-Kamiokande and SNO) will allow to test the model with maximal mix

Jan Govaerts, Marc Van Caillie

Whether in the Standard Model or beyond it, neutrinos contribute to the invisible decay mode of orthopositronium but practically not at all to that of parapositronium. Although this remark does not resolve the orthopositronium decay puzzle, it allows for upper bounds to be set on neutrino magnetic moments.

W. Hollik

In these lectures we give a discussion of the structure of the electroweak standard model and its quantum corrections for tests of the electroweak theory. The predictions for the vector boson masses, neutrino scattering cross sections and the $Z$ resonance observables are presented in some detail. We show comparisons with the recent experimental data and the

D. Indumathi

We compute nuclear spin dependent structure functions using a dynamical model for bound nucleon densities and hence calculate nuclear modifications to asymmetries observed in recent doubly polarised deep inelastic scattering experiments. We conclude that while the individual densities are changed substantially by nuclear effects, the asymmetries themselves a

W. Beenakker, R. Höpker, P. M. Zerwas

The partial widths are determined for squark decays to gluinos and quarks, and gluino decays to squarks and quarks, respectively. The widths are calculated including one-loop SUSY-QCD corrections. The corrections amount to $+$30\% to $+$50\% for squark decays and $-$10\% to $+$10\% for gluino decays. We have derived the results in the \DR ~and \MS ~renormali

W. F. Palmer, E. A. Paschos, P. H. Soldan

The parton model as developed for semileptonic B decays is applied to the inclusive decay B to J/Psi+X. We calculate the momentum spectrum of the J/Psi using a one-parameter distribution function for the heavy quark, taken from production experiments, and compare our results with recent data from CLEO which fixes the distribution parameter epsilon_p. An anal

Dmitri Diakonov

This is a review of the QCD instanton vacuum. After introducing instantons and their physical meaning, I show that the number of instantons in the vacuum fluctuates in accordance with the QCD trace anomaly. The main properties of the instanton ensemble are given. Chiral symmetry breaking by instantons is explained in three different though mathematically equ

E. Braaten, S. Fleming, T. C. Yuan

Recent data from the Tevatron has revealed that the production rate of prompt charmonium at large transverse momentum is orders of magnitude larger than the best theoretical predictions of a few years ago. These surprising results can be understood by taking into account two recent developments that have revolutionized the theoretical description of heavy qu

S. Aid

The total cross sections for the elastic electroproduction of $\rh0$ and $J/Ψ$ mesons for $Q^2$ $>$ 8 GeV$^2$ and $<W > \simeq 90$ GeV/c$^2$ are measured at HERA with the H1 detector. The measurements are for an integrated electron$-$proton luminosity of $\simeq$~3~pb$^{-1}$. The dependences of the total virtual photon$-$proton ($γ^* p$) cross sections on $Q

Vicenç Mendez, Josep Triginer

The Einstein&#39;s field equations of Friedmann-Robertson-Walker universes filled with a dissipative fluid described by both the {\em truncated} and {\em non-truncated} causal transport equations are analyzed using techniques from dynamical systems theory. The equations of state, as well as the phase space, are different from those used in the recent literat

Francisco Dominguez-Adame, Enrique Macia

We study motion and capture of excitons in self-similar linear systems in which interstitial traps are arranged according to an aperiodic sequence, focusing our attention on Fibonacci and Thue-Morse systems as canonical examples. The decay of the fluorescence intensity following a broadband pulse excitation is evaluated by solving the microscopic equations o

Francois David, Kay J. Wiese

The scaling properties of selfavoiding polymerized membranes are studied using renormalization group methods. The scaling exponent νis calculated for the first time at two loop order. νis found to agree with the Gaussian variational estimate for large space dimension d and to be close to the Flory estimate for d=3.

Carsten Timm

The Berezinskii-Kosterlitz-Thouless theory for superfluid films is generalized in a straightforward way that (a) corrects for overlapping vortex-antivortex pairs at high pair density and (b) utilizes a dielectric approximation for the polarization of the vortex system and a local field correction. Generalized Kosterlitz equations are derived, containing high

M. Maul, A. Schäfer, W. Greiner, P. Indelicato

We discuss the prospects for parity non-conservation experiments with highly charged heavy ions. Energy levels and parity mixing for heavy ions with two to five electrons are calculated. We investigate two-photon-transitions and the possibility to observe interference effects between weak-matrix elements and Stark matrix elements for periodic electric field

H. F. Chau

Is pulsar make up of strange matter? The magnetic field decay of a pulsar may be able to give us an answer. Since Cooper pairing of quarks occurs inside a sufficiently cold strange star, the strange stellar core is superconducting. In order to compensate the effect of rotation, different superconducting species inside a rotating strange star try to set up di

E. Ford, P. Kaaret, B. A. Harmon, M. Tavani

We have monitored a sample of 27 nearby globular clusters in the hard X-ray band (20-120 keV) for approximately 1400 days using the BATSE instrument on board the Compton Gamma-Ray Observatory. Globular clusters may contain a large number of compact objects (e.g., pulsars or X-ray binaries containing neutron stars) which can produce hard X-ray emission. Our s

Winfried Zimdahl

A universe consisting of two interacting perfect fluids with the same 4-velocity is considered. A heuristic mean free time argument is used to show that the system as a whole cannot be perfect as well but neccessarily implies a nonvanishing bulk viscosity. A new formula for the latter is derived and compared with corresponding results of radiative hydrodynam

G. Fritz Benedict, Beverly J. Smith, Jeffrey D. P. Kenney

NGC 4314 is an early-type barred galaxy containing a nuclear ring of recent star formation. We present CO(1-0) interferometer data of the bar and circumnuclear region with 2.3 x 2.2 arcsec spatial resolution and 13 km/s velocity resolution acquired at the Owens Valley Radio Observatory . These data reveal a clumpy circumnuclear ring of molecular gas. We also

Gregory A. Shields

The broad absorption lines (BALs) of QSOs indicate abundances of heavy elements, relative to hydrogen, that are 1 to 2 orders of magnitude higher than the solar values. In at least one QSO, an especially large enhancement of phosphorus is observed. These abundances resemble those in Galactic novae, and this suggests that novae may produce the BAL gas. The ne

R. Pain, I. Hook, S. Perlmutter, S. Deustua

We present the first measurement of the rate of Type Ia supernovae at high redshift. The result is derived using a large subset of data from the Supernova Cosmology Project as described in more detail at this meeting by Perlmutter et al. (1996). We present our methods for estimating the numbers of galaxies and the number of solar luminosities to which the su

G. Goldhaber, S. Deustua, S. Gabi, D. Groom

This work is based on the first results from a systematic search for high redshift Type Ia supernovae. Using filters in the R-band we discovered seven such SNe, with redshift z = 0.3 - 0.5, before or at maximum light. Type Ia SNe are known to be a homogeneous group of SNe, to first order, with very similar light curves, spectra and peak luminosities. In this

A. Kim, S. Deustua, S. Gabi, G. Goldhaber

Cross-filter K corrections for a sample of &#34;normal&#34; Type Ia supernovae (SNe) have been calculated for a range of epochs. With appropriate filter choices, the combined statistical and systematic K correction dispersion of the full sample lies within 0.05 mag for redshifts z<0.7. This narrow dispersion of the calculated K correction allows the Type Ia

S. Perlmutter, S. Deustua, S. Gabi, G. Goldhaber

Our search for high-redshift Type Ia supernovae discovered, in its first years, a sample of seven supernovae. Using a &#34;batch&#34; search strategy, almost all were discovered before maximum light and were observed over the peak of their light curves. The spectra and light curves indicate that almost all were Type Ia supernovae at redshifts z = 0.35 -- 0.5

H. K. C. Yee, E. Ellingson, J. Bechtold, R. Carlberg

A protogalaxy candidate at z=2.72 has been discovered serendipitously by the CNOC cluster redshift survey. The candidate is an extremely luminous (V=20.5 mag, absolute mag -26) and well resolved disk-like galaxy. The redshift is identified from a dozen strong UV absorption lines. No emission lines are found between 1000 and 2000A (rest), including Ly alpha.

F J Summers

High resolution gravity plus smoothed particle hydrodynamics simulations are used to study the formation of galaxies within the context of hierarchical structure formation. The simulations have sufficient dynamic range to resolve from ten kpc scale galactic disks up to many Mpc scale filaments. Over this range of scales, we find that hierarchical structure d

Th. Gallay, G. Raugel

We consider a nonlinear damped hyperbolic equation in $\real^n$, $1 \le n \le 4$, depending on a positive parameter $\epsilon$. If we set $\epsilon=0$, this equation reduces to the well-known Kolmogorov-Petrovski-Piskunov equation. We remark that, after a change of variables, this hyperbolic equation has the same family of one-dimensional travelling waves as

D. Amati, J. G. Russo

In the context of a two-dimensional exactly solvable model, the dynamics of quantum black holes is obtained by analytically continuing the description of the regime where no black hole is formed. The resulting spectrum of outgoing radiation departs from the one predicted by the Hawking model in the region where the outgoing modes arise from the horizon with

J. G. Russo

From the postulate that a black hole can be replaced by a boundary on the apparent horizon with suitable boundary conditions, an unconventional scenario for the evolution emerges. Only an insignificant fraction of energy of order $(mG)^{-1}$ is radiated out. The outgoing wave carries a very small part of the quantum mechanical information of the collapsed bo

Jordi Comellas, Jose I. Latorre

We present a line of reasoning based on the analysis of scale variations of the Wilsonian partition function and the trace of the stress tensor in a curved manifold which results in a statement of irreversibility of Wilsonian renormalization group flow for unitary theories. We also analyze subtleties related to subtractions in the case of the 1PI effective a

Michael J. Mehl, Dimitrios A. Papaconstantopoulos

A recent tight-binding scheme provides a method for extending the results of first principles calculations to regimes involving $10^2 - 10^3$ atoms in a unit cell. The method uses an analytic set of two-center, non-orthogonal tight-binding parameters, on-site terms which change with the local environment, and no pair potential. The free parameters in this me

Hideo Suganuma, Sei Umisedo, Shoich Sasaki, Hiroshi Toki

Monopole dominance for the nonperturbative features in QCD is studied both in the continuum and the lattice gauge theories. First, we study the dynamical chiral-symmetry breaking (D$\chi $SB) in the dual Higgs theory using the effective potential formalism. We find that the main driving force for D$\chi $SB is brought from the confinement part in the nonpert

J. A. de Azcarraga, J. C. Perez Bueno

The $\hatκ$-deformed extended Galilei Hopf group algebra, ${\rm Fun}_{\hatκ}(\tilde G_{(m)})$, is introduced. It provides an example of a cocycle bicrossproduct structure, and is shown to be the contraction limit of a pseudoextension of the $κ$-Poincaré group algebra. The possibility of obtaining another deformed extended Galilei groups is discussed, includi

David R. Morrison, Cumrun Vafa

We study compactifications of F-theory on certain Calabi--Yau threefolds. We find that $N=2$ dualities of type II/heterotic strings in 4 dimensions get promoted to $N=1$ dualities between heterotic string and F-theory in 6 dimensions. The six dimensional heterotic/heterotic duality becomes a classical geometric symmetry of the Calabi--Yau in the F-theory set

Bijan Sheikholeslami Sabzevari

A four dimensional systematic mathematical approach for investigating propagation and coupling of wave modes in a slowly varying (in all space directions and time) anisotropic, absorbing plasma is represented. The formalism is especially useful for energy considerations of the waves. It is applicable to general cases of mode conversion in plasmas with genera

A. Delfino, M. Malheiro, T. Frederico

The link between non-linear chiral effective Lagrangians and the Walecka model description of bulk nuclear matter [1] is questioned. This fact is by itself due to the Mean Field Approximation (MFA) which in nuclear mater makes the picture of a nucleon-nucleon interaction based on scalar(vector) meson exchange, equivalent to the description of a nuclear matte

F. de Jong, K. Nakayama

We investigate the effect of negative-energy states on proton-proton bremsstrahlung using a manifestly covariant amplitude based on a T-matrix constructed in a spectator model. We show that there is a large cancellation among the zeroth-order, single- and double-scattering diagrams involving negative-energy nucleonic currents. We thus conclude that it is ess

S. C. Li, S. Kuyucak

We present a study of deformed nuclei in the framework of the sdg interacting boson model utilizing both numerical diagonalization and analytical $1/N$ expansion techniques. The focus is on description of high-spin states which have recently become computationally accessible through the use of computer algebra in the $1/N$ expansion formalism. A systematic s

Jorge Kohanoff, Jean-Pierre Hansen

The metallic regime of the hydrogen plasma is studied by ab initio Molecular Dynamics simulations, for classical protons and fully degenerate electrons, in the strong coupling regime of the protons. The breakdown of linear screening observed for decreasing density gives rise to a surprisingly rich low-temperature phase diagram, showing in particular a dramat

Akihiko Yukie

Throughout this paper, k is a number field. We fix a quadratic extension k_1=k(a_0) of k, where a_0=sqrt(B_0) for a certain B_0 in k^\times/(k^\times)^2. In this paper, we consider the zeta function defined for the space of pairs of binary Hermitian forms. This is the prehomogeneous vector space we discussed in section 2 [1] and is a non-split form of the D_

V. V. Tugai, A. A. Zheltukhin

A supersymmetric formulation of the classical action of interacting charged and neutral fermions with arbitrary anomalous magnetic moment is considered. This formulation generalizes the known action for scalar charged particles investigated in papers by Fokker, Schwarzschild, Tetrode, Wheeler and Feynman. The superfield formulation of the electrodynamics of

G. Grignani, P. Sodano, C. A. Scrucca

The free quantum states of topologically massive electrodynamics and gravity in 2+1 dimensions, are explicitly found. It is shown that in both theories the states are described by infrared-regular polarization tensors containing a regularization phase which depends on the spin. This is done by explicitly realizing the quantum algebra on a functional Hilbert

Robert Caldwell, Andrew Chamblin, Gary Gibbons

In this paper we study the production of pairs of neutral and charged black holes by domain walls, finding classical solutions and calculating their classical actions. We find that neutral black holes whose creation is mediated by Euclidean instantons must be produced mutually at rest with respect to one another, but for charged black holes a new type of ins

Roman Jackiw

Quantum field theory offers physicists a tremendously wide range of application; it is both a language with which a vast variety of physical processes can be discussed and also it provides a model for fundamental physics, the so-called ``standard-model,&#39;&#39; which thus far has passed every experimental test. No other framework exists in which one can ca

J. F. Donoghue, T. Torma

A class of loop diagrams in general relativity appears to have a behavior which would upset the utility of the energy expansion for quantum effects. We show through the study of specific diagrams that cancellations occur which restore the expected behaviour of the energy expansion. By considering the power counting in a physical gauge we show that the appare

B. Bailey, Edmond L. Berger, L. E. Gordon

A second order, $O(α^2_s)$, calculation in perturbative quantum chromodynamics of the two particle inclusive cross section is presented for the reaction $p +\bar{p}\rightarrow γ+ c + X$ for large values of the transverse momentum of the prompt photon and charm quark. The combination of analytic and Monte Carlo integration methods used here to perform phase-s

M. A. Ivanov, M. P. Locher, V. E. Lyubovitskij

We report the calculation of electromagnetic form factors of nucleons within a relativistic three-quark model with Gaussian shape for the nucleon-quark vertex. The allowed region for two adjustable parameters, the range parameter $Λ_N$ in the Gaussian and the constituent quark mass $m_q$, is obtained from fitting the data for magnetic moments and electromagn

Raj Gandhi, Chris Quigg, M. H. Reno, Ina Sarcevic

Recent measurements of the small-$x$ deep-inelastic regime at HERA translate to new expectations for the neutrino-nucleon cross section at ultrahigh energies. We present event rates for large underground neutrino telescopes based on the new cross section for a variety of models of neutrino production in Active Galactic Nuclei, and we compare these rates with

M. Malheiro, Mira Dey, A. Delfino, Jishnu Dey

It is known now that chiral symmetry restoration requires the meson-nucleon coupling to be density dependent in nuclear-matter mean-field models. We further show that quite generally, the quark and gluon condensates in medium are related to the trace of energy-momentum tensor of nuclear matter and in these models the incompressibility, K, must be less than t

J. W. F. Valle

A brief sketch is made of the present observational status of neutrino properties, with emphasis on the hints from solar and atmospheric neutrinos, as well as cosmological data on the amplitude of primordial density fluctuations. Implications of neutrino mass in particle accelerators, astrophysics and cosmology are discussed.