October 1999 arXiv papers — page 22

V. D. Ivashchuk, V. N. Melnikov

Black hole generalized p-brane solutions for a wide class of intersection rules are obtained. The solutions are defined on a manifold that contains a product of n - 1 Ricci-flat ``internal'' spaces. They are defined up to a set of functions H_s obeying a non-linear differential equations (equivalent to Toda-type equations) with certain boundary condi

Norman Dombey, Fuad Saradzhev

The relativistic two-body system in (1+1)-dimensional quantum electrodynamics is studied. It is proved that the eigenvalue problem for the two-body Hamiltonian without the self-interaction terms reduces to the problem of solving an one-dimensional stationary Schrödinger type equation with an energy-dependent effective potential which includes the delta-funct

A. J. Bordner, N. S. Manton, R. Sasaki

It is shown that the Calogero-Moser models based on all root systems of the finite reflection groups (both the crystallographic and non-crystallographic cases) with the rational (with/without a harmonic confining potential), trigonometric and hyperbolic potentials can be simply supersymmetrised in terms of superpotentials. There is a universal formula for th

Gerard 't Hooft

When the theory of Quantum Chromodynamics was introduced, it was to explain the observed phenomena of quark confinement and scaling. It was then discovered that the emergence of instantons is an essential consequence of this theory. This led to unanticipated explanations not only for the anomalously high masses of the $η$ and the $η'$ particles, but also

Benjamin Grinstein, Detlef R. Nolte, Ira Z. Rothstein

We show that it is possible to extract the weak mixing angle alpha via a measurement of the rate for B^+(-) -> π^+(-) e^+e^-. The sensitivity to cos(alpha) results from the interference between the long and short distance contributions. The short distance contribution can be computed, using heavy quark symmetry, in terms of semi-leptonic form factors. More i

M. D. Scadron

The ten nonleptonic weak decays $K \to 2π$, $K \to 3π$, $K_L \to 2γ$, $K_S \to 2γ$, $K_L \to π^\circ 2γ$, are predicted for a chiral pole model based on the linear sigma model theory which automatically satisfies the partial conservation of axial current (PCAC) hypothesis. These predictions, agreeing with data to the 5% level and containing no or at most one

M. D. Scadron

We study in various chiral models the pion charge radius, $π_{e3}$ form factor ratio, $π^\circ \to γγ$ amplitude, charge pion polarizabilities, $γγ\to π^\circ π^\circ$ amplitude at low energies and the $ππ$ s-wave I = 0 scattering length. We find that a quark-level linear sigma-model approach (also being consistent with tree-level vector meson dominance) is

R Delbourgo, M D Scadron

The fermion and meson sectors of the quark-level SU(2) linear sigma model are dynamically generated from a meson-quark Lagrangian, with the quark (q) and meson ($σ,π$) fields all treated as elementary, having neither bare masses nor expectation values. In the chiral limit, the masses are predicted to be $m_q = f_πg, m_π= 0, m_σ= 2m_q$, and we also find that

M. Drees, O. J. P. Eboli

We discuss effects of fragmentation and hard gluon radiation on the signal for the pair production of the lighter scalar top eigenstate $\tilde{t}_1$ at e^+e^- colliders. The main emphasis is on scenarios with small stop--LSP mass splitting, where strong interaction effects can considerably modify kinematical properties of the final state.

Nikolaos Kidonakis

I discuss the resummation of soft gluon contributions to direct photon and W + jet production and I present some results for the next-to-next-to-leading order expansions of the resummed cross sections for these processes near threshold.

A. Pineda

We study some general aspects of the formalism of potential NRQCD (pNRQCD), an effective field theory that deals with ultrasoft degrees of freedom in Heavy Quarkonium systems. Specific attention is paid to its effective Lagrangian that it is displayed at the present level of accuracy.

M. Ciuchini, E. Franco, L. Giusti, V. Lubicz

Lattice calculations of matrix elements relevant for kaon decays, and in particular for epsilon'/epsilon, are reviewed. The role of the strange quark mass is also discussed. A comparison with other non-perturbative approaches used to compute kaon decay amplitudes is made.

M. Ciuchini, E. Franco, L. Giusti, V. Lubicz

We perform a combined analysis of the unitarity triangle and of the CP violating parameter epsilon'/epsilon using the most recent determination of the relevant experimental data and, whenever possible, hadronic matrix elements from lattice QCD. We discuss the role of the main non-perturbative parameters and make a comparison with other recent analyses. W

Yong Liu

In this work, the postulation that weak CP phase originates in a certain geometry, is further discussed. Some intrinsic and strict constraints on the mixing angles, weak CP phase, and the Wolfenstein's parameters $ρ$ and $η$ are given by present data and the postulation itself. Especially, we predict $0.0076 \leq |V_{td}| \leq 0.0093, 74.9^o \leq γ\leq 7

S. Pakvasa

The theory and phenomenology of CP violation in hyperon decays is summarized.

V. Azcoiti, A. Galante

An essential assumption in the Vafa and Witten's theorem on P and CT realization in vector-like theories concerns the existence of a free energy density in Euclidean space in the presence of any external hermitian symmetry breaking source. We show how this requires the previous assumption that the symmetry is realized in the vacuum. Even if Vafa and Witt

L. Giusti, M. L. Paciello, S. Petrarca, B. Taglienti

We describe how to overcome some problems that usually prevent from obtaining an efficient algorithm to fix a generic covariant gauge on the lattice. This gauge is the lattice equivalent of the generic gauge usually adopted in perturbative calculations. It depends on a parameter whose value can be varied in order to check the gauge dependence of measured mat

TARO Collaboration, Ph. de Forcrand, M. Garcia Perez, T. Hashimoto

We report our results of the Monte Carlo Renormalization Group analysis in two dimensional coupling space. The qualitative features of the RG flow are described with a phenomenological RG equation. The dependence on the lattice spacing for various actions provides the conditions to determine the parameters entering the RG equation.

S. Capozziello, G. Lambiase, G. Scarpetta

The generalized uncertainty principle of string theory is derived in the framework of Quantum Geometry by taking into account the existence of an upper limit on the acceleration of massive particles.

S. Capozziello, G. Lambiase

The inertial effects on neutrino oscillations induced by the acceleration and angular velocity of a reference frame are calculated. Such effects have been analyzed in the framework of the solar and atmospheric neutrino problem.

S. S. Xulu

Using the symmetric energy-momentum complexes of Landau and Lifshitz, Papapetrou, and Weinberg we obtain the energy of the universe in anisotropic Bianchi type I cosmological models . The energy (due to matter plus field) is found to be zero and this agrees with a previous result of Banerjee and Sen who investigated this problem using the Einstein energy-mom

R. H. Heffner, J. E. Sonier, D. E. MacLaughlin, G. J. Nieuwenhuys

We report new zero-field muon spin relaxation and neutron spin echo measurements in ferromagnetic (FM) (La,Ca)MnO3 which taken together suggest two spatially separated regions in close proximity possessing very different Mn-ion spin dynamics. One region corresponds to an extended cluster which displays 'critical slowing down' near Tc and an increasin

G. Finkelstein, P. I. Glicofridis, S. H. Tessmer, R. C. Ashoori

Using Subsurface Charge Accumulation scanning microscopy we image strips of low compressibility corresponding to several integer Quantum Hall filling factors. We study in detail the strips at Landau level filling factors $ν=$ 2 and 4. The observed strips appear significantly wider than predicted by theory. We present a model accounting for the discrepancy by

Junya Shibata, Shin Takagi

We study macroscopic quantum dynamics of a free domain wall in a quasi-one-dimensional ferromagnet by use of the spin-coherent-state path integral in {\it discrete-time} formalism. Transition amplitudes between typical states are quantitatively discussed by use of {\it stationary-action approximation} with respect to collective degrees of freedom representin

R. Oppermann, H. Feldmann

We report progress in understanding the fermionic Ising spin glass with arbitrary filling. A crossover from a magnetically disordered single band phase via two intermediate bands just below the freezing temperature to a 3-band structure at still lower temperatures - beyond an almost random field instability - is shown to emerge in the magnetic phase. An atte

Chen Zeng, Paul L. Leath, Terence Hwa

We model a planar array of fluxlines as a discrete solid-on-solid model with quenched disorder. Simulations at finite temperatures are made possible by a new algorithm which circumvents the slow glassy dynamics encountered by traditional Metropolis Monte Carlo algorithms. Numerical results on magnetic susceptibility variations support analytic predictions.

Sarmishtha Mandal, S. Tarafdar, Aninda Jiban Bhattacharyya

Ion conducting polymers have a biphasic character with crystalline as well as amorphous phases. There is moreover, a dynamic disorder due to motion of polymer chain segments. The PEO-NH$_4$ClO$_4$ system undergoes a crossover from a DLA-type morphology for low salt fraction (X) to a structure with polygonal spherulites. In the present communication we show t

W. Gotze, M. R. Mayr

The equations of the mode-coupling theory (MCT) for ideal liquid-glass transitions are used for a discussion of the evolution of the density-fluctuation spectra of glass-forming systems for frequencies within the dynamical window between the band of high-frequency motion and the band of low-frequency-structural-relaxation processes. It is shown that the stro

K. Harigaya

Magnetic impurity effects in carbon nanotubes are studied theoretically. The multi channel Kondo effect is investigated with the band structure of the metallic nanotubes. The local non-Fermi liquid behavior is realized at temperatures lower than the Kondo temperature T_K. The density of states of localized electron has a singularity |omega|^1/2 which gives r

N. Dupuis, V. M. Yakovenko

Within the framework of the quantized nesting model, we study the effect of umklapp scattering on the magnetic-field-induced spin-density-wave (SDW) phases which are experimentally observed in the quasi-one-dimensional organic conductors (TMTSF)$_2$X. We discuss the conditions under which umklapp processes may explain the sign reversals (Ribault anomaly) of

F. Bouquet, Y. Wang, H. Wilhelm, D. Jaccard

We have developed a calorimeter able to give a qualitative picture of the specific heat of a sample under high pressure up to approximately 10 GPa. The principle of ac-calorimetry was adapted to the conditions in a high pressure clamp. The performance of this technique was successfully tested with the measurement of the specific heat of CeRu2Ge2 in the tempe

A. Zyuzin, B. Spivak

We consider theoretically a Josephson junction with a superconducting critical current density which has a random sign along the junction's surface. We show that the ground state of the junction corresponds to the phase difference equal to π/2. Such a situation can take place in superconductor- ferromagnet junction.

J. V. Andersen, S. Gluzman, D. Sornette

Starting from the characterization of the past time evolution of market prices in terms of two fundamental indicators, price velocity and price acceleration, we construct a general classification of the possible patterns characterizing the deviation or defects from the random walk market state and its time-translational invariant properties. The classificati

Han-Ching Chu, Gary A. Williams

The superfluid transition of $^3$He-$^4$He mixture films adsorbed on alumina powder is studied, with a $^4$He superfluid coverage near one layer. With up to 1.3 layers of $^3$He added, the transition becomes strongly broadened, indicating a linear increase in the vortex core size for $^3$He coverages below one layer. Annealing of the sample mixture at 4.2 K

Han-Ching Chu, Gary A. Williams

The properties of rapidly quenched superfluid phase transitions are computed for two-dimensional Kosterlitz-Thouless (KT) systems. The decay in the vortex-pair density and the recovery of the superfluid density after a quench are found by solving the Fokker-Planck equation describing the vortex dynamics, in conjunction with the KT recursion relations. The vo

J. Goettker-Schnetmann

Generalizing methods developed by Pinn, Pordt and Wieczerkowski for the hierarchical model with one component (N=1) and dimensions d between 2 and 4 we compute O(N)-symmetric fixed points of the hierarchical renormalization group equation for some N and d with 0 < d < 4 and -2 <= N <= 20. The spectra of the linearized RG equation at the fixed points are calc

Yoshiaki Mizuno, Takami Tohyama, Sadamichi Maekawa

We examine two-spin (2S) and cyclic four-spin (4S) magnetic interactions in insulating ladder and two-dimensional (2D) cuprates. By a comparison of eigenstates between d-p and Heisenberg models, we evaluate magnitudes of these interactions. We find that the 4S interaction is $\sim$10% of nearest neighboring 2S interaction, and a diagonal 2S interaction is co

N. I. Chernov, C. P. Dettmann

The linear super-Burnett coefficient gives corrections to the diffusion equation in the form of higher derivatives of the density. Like the diffusion coefficient, it can be expressed in terms of integrals of correlation functions, but involving four different times. The power law decay of correlations in real gases (with many moving particles) and the random

Gavriel Segre

Martin-Lof&#39;s definition of random sequences of cbits as those not belonging to any set of constructive zero Lebesgue measure is reformulated in the language of Algebraic Probability Theory. The adoption of the Pour-El Richards theory of computability structures on Banach spaces allows us to give a natural noncommutative extension of Martin-Lof&#39;s defi

S. G. Stewart, M. N. Fanelli, G. G. Byrd, J. K. Hill

Far-UV (FUV), H-alpha, and HI observations of dwarf galaxy Holmberg II are used to trace the interaction between sites of massive star formation and the neutral and ionized components of the surrounding ISM. The data emphasize the importance of local conditions in regulating star formation from evidence such as massive stars inside ionized shells, compact HI

R. A. Jansen, D. Fabricant, M. Franx, N. Caldwell

We have obtained integrated and nuclear spectra, as well as U, B, R surface photometry, for a representative sample of 196 nearby galaxies. These galaxies span the entire Hubble sequence in morphological type, as well as a wide range of luminosities (M_B=-14 to -22). Here we present the spectrophotometry for these galaxies. The selection of the sample and th

Lucio M. Buson, Francesco Bertola, Michele Cappellari, Cesare Chiosi

The first UV F300W and F218W WFPC2 observations of the rich galaxy cluster CL0939+4713 at z=0.41 are presented and discussed. UV/optical two-color and c-m diagrams of the sources detected in the F300W waveband are constructed. Thanks to pre-existing HST optical images of the same field a morphological classification for the majority of these objects is also

J. Christopher Howk

Recent optical and submillimeter observations have begun to probe the existence of dust grains in the halos of spiral galaxies. I review our own work in this area which employs high-resolution optical images of edge-on spiral galaxies to trace high-z dust in absorption against the background stellar light of the galaxies. We have found that a substantial fra

Saul Barshay, Georg Kreyerhoff

We examine some general astrophysical results which can be related to the hypothesis that very heavy, metastable particles constitute compact, very massive central entities in QSO&#39;s and the core of galaxies. The mass and lifetime have been calculated in detail previously: the mass is about $10^{10}\GeV$; the lifetime is $\simgt 10^{21} \sec$. The specifi

L. R. Jones, T. J. Ponman, Duncan A. Forbes

The group of galaxies RXJ1340.6+4018 has approximately the same bolometric X-ray luminosity as other bright galaxy groups and poor clusters such as the Virgo cluster. However, 70% of the optical luminosity of the group comes from a dominant giant elliptical galaxy, compared to 5% from M87 in Virgo. The second brightest galaxy in RXJ1340.6+4018 is a factor of

F. Duccio Macchetto

This review addresses one of the important topics of current astrophysical research, namely the role that supermassive black holes play in shaping the morphology of their host galaxies. There is increasing evidence for the presence of massive black holes at the centers of all galaxies and many efforts are directed at understanding the processes that lead to

G. E. Brown, C. -H. Lee, R. A. M. J. Wijers, H. A. Bethe

In this article we consider the formation and evolution of black holes, especially those in binary stars where radiation from the matter falling on them can be seen. We consider a number of effects introduced by some of us, which are not traditionally included in binary evolution of massive stars. These are (i) hypercritical accretion, which allows neutron s

V. Caloi, D. Cardini, F. D&#39;Antona, M. Badiali

The large sample of main sequence stars with Hipparcos parallaxes and estimates of the radial velocity has been used to study the relations among kinematics, age and heavy element content for the solar neighbourhood. The samples with V> -30 km $\rm s^{-1}$, although including stars as old as 10^10 yr, have a very young component (age $\simgt$ 10^7 yr), and h

P. Londrillo, L. Del Zanna

A general method for constructing high order upwind schemes for multidimensional magnetohydrodynamics (MHD), having as a main built-in condition the divergence-free constraint $\divb=0$ for the magnetic field vector $\bb$, is proposed. The suggested procedure is based on {\em consistency} arguments, by taking into account the specific operator structure of M

S. Bardelli, E. Zucca, G. Zamorani, L. Moscardini

(abridged) We present the results of a redshift survey of intercluster galaxies in the central region of the Shapley Concentration supercluster, aimed at determining the distribution of galaxies in between obvious overdensities. Our sample is formed by 442 new redshifts, mainly in the b_J magnitude range 17-18.8. Adding the data from our redshift surveys on

M. Gilfanov, E. Churazov, M. Revnivtsev

We analyzed RXTE/PCA observations of Cyg X-1 from 1996-1998. We found a tight correlation between the characteristic noise frequencies (e.g. the break frequency nu_br) and the spectral parameters in the low spectral state. The amplitude of reflection increases and the spectrum of primary radiation steepens as the noise frequency increases (nu_br changes by a

C. M. Rudge, D. J. Raine

In unified models of active galaxies the direct line of sight to the nucleus is unobscured only within a certain cone of directions. An opening angle for this cone is usually estimated by methods such as the overall ratio of Seyfert 1s to Seyfert2s, the latter assumed to be obscured versions of the former. Here we shall show, as has often been suspected, tha

Martino Romaniello, Maurizio Salaris, Santi Cassisi, Nino Panagia

We have used HST-WFPC2 multiband observations of a field around SN 1987A in the Large Magellanic Cloud to measure its distance from the Sun. The observations allowed us to carefully determine the interstellar extinction along the line of sight to a large number of stars and to measure the LMC distance by using two stellar distance indicators: the Red Clump a

J. Alcolea, V. Bujarrabal, A. Castro-Carrizo, C. Sanchez Contreras

We present our recent results on mm-wave CO observations of proto-planetary nebulae. These include high-resolution interferometric maps of various CO lines in three well known bipolar PPNe: M1-92, M2-56 and OH231.8+4.2. The global properties of the high velocity molecular emission in post-AGB sources have been also studied, by means of high-sensitivity singl

Banibrata Mukhopadhyay

Study of nucleosynthesis in accretion disks around black holes was initiated by Chakrabarti et al. (1987). In the present work we do the similar analysis using the state-of-the-art disk model, namely, Advective Accretion Disks. During the infall, matter temperature and density are generally increased which are first computed. These quantities are used to obt

Y. -J. Moon, H. S. Yun, G. S. Choe, Y. D. Park

The evolution of nonpotential characteristics of magnetic fields in AR 5747 is presented using Mees Solar Observatory magnetograms taken on Oct. 20, 1989 to Oct. 22, 1989. The active region showed such violent flaring activities during the observational span that strong X-ray flares took place including a 2B/X3 flare. The magnetogram data were obtained by th

Y. -J. Moon, H. S. Yun, G. S. Choe, Y. D. Park

We present the evolution of magnetic nonpotentiality associated with an X-class flare in AR 6919 using a set of MSO (Mees Solar Observatory) magnetograms. The magnetogram data were obtained before and after the flare, using the Haleakala Stokes Polarimeter which provides simultaneous Stokes profiles of the Fe I doublet 6301.5 and 6302.5. A nonlinear least sq

Y. -J. Moon, Y. D. Park, H. S. Yun, E. -A. Cho

In this study we present the study of solar active regions based on BOAO vector magnetograms and $Hα$ filtergrams. With the new calibration method we analyzed BOAO vector magnetograms taken from the SOFT observational system to compare with those of other observing systems. In this study it has been demonstrated that (1) our longitudinal magnetogram matches

R. A. Jansen, M. Franx, D. Fabricant, N. Caldwell

We have obtained integrated spectra and multi-filter photometry for a repre- sentative sample of ~200 nearby galaxies. These galaxies span the entire Hubble sequence in morphological type, as well as a wide range of luminosities (M_B = -14 to -22) and colors (B-R=0.4 to 1.8). Here we describe the sample selection criteria and the U, B, R surface photometry f

W. Brandner, E. K. Grebel, Y. -H. Chu, H. Dottori

We report the discovery of three proplyd-like structures in the giant HII region NGC 3603. The emission nebulae are clearly resolved in narrow-band and broad-band HST/WFPC2 observations in the optical and broad-band VLT/ISAAC observations in the near-infrared. All three nebulae are tadpole shaped, with the bright ionization front at the head facing the centr

N. A. Grogin, M. J. Geller

We study the optical properties of a large sample of galaxies in low-density regions of the nearby universe. We make a 5/h Mpc-smoothed map of the galaxy density throughout the Center for Astrophysics Redshift Survey (CfA2) to identify galaxies within three prominent nearby ``voids&#39;&#39; with diameter >30/h Mpc. We augment the CfA2 void galaxy sample wit

G. E. Allen, E. V. Gotthelf, R. Petre

Analyses of the X-ray data of the five young shell-type supernova remnants Cas A, Kepler, Tycho, SN 1006, and RCW 86 suggest that some of the X-ray emission of these sources is non-thermal. This non-thermal emission is qualitatively consistent with models of the broad-band (radio-to-X-ray) synchrotron spectra of remnants and does not seem to be consistent wi

Saul Barshay, Georg Kreyerhoff

We have shown that inflatons with a mass which is calculated to be of the order of $10^{10}\GeV$ can constitute a dominant part of dark matter. They can decay uniquely into a neutrino and antineutrino with a lifetime calculated to be greater than the present age of the universe. We show here that these neutrinos can give rise to a localized bump in the prima

C. B. Moore, R. E. Rutledge, D. W. Fox, R. A. Guerriero

We have identified a likely radio counterpart to the low-mass X-ray binary MXB 1730-335 (the Rapid Burster). The counterpart has shown 8.4 GHz radio on/off behavior correlated with the X-ray on/off behavior as observed by the RXTE/ASM during six VLA observations. The probability of an unrelated, randomly varying background source duplicating this behavior is

Markus Baer, Martin Falcke, Herbert Levine, Lev S. Tsimring

We propose a simple discrete stochastic model for calcium dynamics in living cells. Specifically, the calcium concentration distribution is assumed to give rise to a set of probabilities for the opening/closing of channels which release calcium thereby changing those probabilities. We study this model in one dimension, analytically in the mean-field limit of

Shinji Mukohyama

The stability of the brick wall model is analyzed in a rotating background. It is shown that in the Kerr background without horizon but with an inner boundary a scalar field has complex-frequency modes and that, however, the imaginary part of the complex frequency can be small enough compared with the Hawking temperature if the inner boundary is sufficiently

K. Buckley, T. Fugleberg, A. Zhitnitsky

The development of the early Universe is a remarkable laboratory for the study of most nontrivial properties of particle physics. What is more remarkable is the fact that these phenomena at the QCD scale can be, in principle, experimentally tested in heavy ion collisions. We expect that, in general, an arbitrary theta-state would be created in the heavy ion

V. V. Baru, A. E. Kudryavtsev, V. E. Tarasov, W. J. Briscoe

We discuss the theoretical and experimental situations for charge symmetry violation (CSV) effects in the elastic scattering of pi+ and pi- on deuterium (D) and 3He/3H. Accurate comparison of data for both types of targets provides evidence for the presence of CSV effects. While there are indications of a CSV effect in deuterium, it is much more pronounced i

H. F. Fong, P. Bourges, Y. Sidis, L. P. Regnault

We report a comprehensive polarized and unpolarized neutron scattering study of the evolution of the dynamical spin susceptibility with temperature and doping in three underdoped single crystals of the \YBCO{6+x} high temperature superconductor: \YBCO{6.5} (Tc = 52 K), \YBCO{6.7} (Tc = 67 K), and \YBCO{6.85} (T_c = 87 K). Theoretical implications of these da

I. C. Charret, E. V. Correa Silva, S. M. de Souza, M. T. Thomaz

We investigate the grand potential of the one-dimensional Hubbard model in the high temperature limit, calculating the coefficients of the high temperature expansion ($β$-expansion) of this function up to order $β^4$ by an alternative method. The results derived are analytical and do not involve any perturbation expansion in the hopping constant, being valid

T. P. Vrana, S. A. Dytman, T. -S. H. Lee

A unitary multi-channel approach, first developed by the Carnegie-Mellon- Berkeley group, is applied to extract the pole positions, masses, and partial decay widths of nucleon resonances. Input used are the partial wave amplitudes for the transitions from piN to eight possible final baryon-meson final states. Because the model preserves analyticity, resonanc

D. Belitz, T. R. Kirkpatrick, Thomas Vojta

Local magnetic moments in disordered sytems can be described in terms of annealed magnetic disorder, in addition to the underlying quenched disorder. It is shown that for noninteracting electron systems at zero temperature, the annealed disorder leads to a new mechanism, and a new universality class, for a metal-insulator transition. The transition is driven

A. Capella, I. M. Dremin, J. W. Gary, V. A. Nechitailo

The energy evolution of average multiplicities of quark and gluon jets is studied in perturbative QCD. Higher order (3NLO) terms in the perturbative expansion of equations for the generating functions are found. First and second derivatives of average multiplicities are calculated. The mean multiplicity of gluon jets is larger than that of quark jets and evo

F. T. Brandt, J. Frenkel, F. R. Machado

The approach which relates thermal Green functions to forward scattering amplitudes of on-shell thermal particles is applied to the calculation of the gluon self-energy, in a class of temporal gauges. We show to all orders that, unlike the case of covariant gauges, the exact self-energy of the gluon is transverse at finite temperature. The leading T^2 and th

S. Jadach

A new general purpose Monte Carlo event generator with self-adapting grid consisting of simplices is described. In the process of initialization, the simplex-shaped cells divide into daughter subcells in such a way that: (a) cell density is biggest in areas where integrand is peaked, (b) cells elongate themselves along hyperspaces where integrand is enhanced

J. M. P. Carmelo, J. M. E. Guerra, J. M. B. Lopes dos Santos, A. H. Castro Neto

We use an exact {\it holon} and {\it spinon} Landau-liquid functional which describes the holon - spinon interactions at all scattering orders, to study correlation functions of integrable multicomponent many-particle problems showing both linear and non-linear energy bands. Motivated by recent photoemission experiments, we consider specific cases when the d

N. Ichikawa, S. Uchida, J. M. Tranquada, T. Niemoeller

We report on the phase diagram for charge-stripe order in La(1.6-x)Nd(0.4)Sr(x)CuO(4), determined by neutron and x-ray scattering studies and resistivity measurements. From an analysis of the in-plane resistivity motivated by recent nuclear-quadrupole-resonance studies, we conclude that the transition temperature for local charge ordering decreases monotonic

Adi Armoni

We suggest that orbifold field theories which are obtained from non-commutative N=4 SYM are UV finite. In particular, non-supersymmetric orbifold truncations might be finite even at finite values of Nc.

Richard de Grijs, Robert W. O&#39;Connell, George D. Becker, Roger A. Chevalier

We report the discovery of ten compact H-alpha-bright sources in the post-starburst region northeast of the center of M82, ``M82 B.&#39;&#39; These objects have H alpha luminosities and sizes consistent with Type II supernova remnants (SNRs). They fall on the same H alpha surface brightness-diameter (Sigma-D) relation defined by SNRs in other nearby star-for

F. Kleefeld

A new method for the determination of the spin-1/2-3/2-mixing angle and the range parameter of the quarkmodel wavefunction of the resonance $S^-_{11}(1535)$ is presented. The method ist based on a quantitative calculation of the total cross section of $pp\to ppη$ at threshold. The quantitative on-shell treatment of ISI and FSI is discussed.

J. Fleischer, M. Yu. Kalmykov

Exploring the idea of Broadhurst on the ``sixth root of unity&#39;&#39; we present an ansatz for construction of a basis of transcendental numbers for the epsilon-expansion of single mass scale diagrams with two particle massive cut. As example, several new two- and three-loop master integrals are calculated.

Simon Portegies Zwart, Stephen McMillan

Mergers of black-hole binaries are expected to release large amounts of energy in the form of gravitational radiation. However, binary evolution models predict merger rates too low to be of observational interest. In this paper we explore the possibility that black holes become members of close binaries via dynamical interactions with other stars in dense st

Paolo Zanardi

The dynamical-algebraic structure underlying all the schemes for quantum information stabilization is argued to be fully contained in the reducibility of the operator algebra describing the interaction with the environment of the coding quantum system. This property amounts to the existence of a non-trivial group of symmetries for the global dynamics. We pro

A. Ali, Patricia Ball, L. T. Handoko, G. Hiller

Using improved theoretical calculations of the decay form factors in the Light Cone-QCD sum rule approach, we investigate the decay rates, dilepton invariant mass spectra and the forward-backward (FB) asymmetry in the decays $B \to (K,K^*) \ell^+ \ell^-$ ($\ell^\pm =e^\pm,μ^\pm,τ^\pm$) in the standard model (SM) and a number of popular variants of the supers

R. Deblock, Y. Noat, H. Bouchiat, B. Reulet

In order to investigate the effect of electronic phase coherence on screening we have measured the flux dependent polarizability of isolated mesoscopic rings at 350 MHz. At low temperature (below 100 mK) both non-dissipative and dissipative parts of the polarizability exhibit flux oscillations with a period of half a flux quantum in a ring. The sign and ampl

Antoine Van Proeyen

This is an elementary introduction to basic tools of supersymmetry: the spacetime symmetries, gauge theory and its application in gravity, spinors and superalgebras. Special attention is devoted to conformal and anti-de Sitter algebras.

A. M. Lisewski, W. Hillebrandt, S. E. Woosley

We investigate the possibility of a delayed detonation in a type Ia supernova under the assumption that the transition to detonation is triggered by turbulence only. Our discussion is based on the Zeldovich mechanism and suggests that typical turbulent velocities present during the explosion are not strong enough to allow this transition to occur. Although w

Kostas Skenderis, Sergey N. Solodukhin

We obtain an Einstein metric of constant negative curvature given an arbitrary boundary metric in three dimensions, and a conformally flat one given an arbitrary conformally flat boundary metric in other dimensions. In order to compute the on-shell value of the gravitational action for these solutions, we propose to integrate the radial coordinate from the b

J. Gutowski, G. Papadopoulos

We show that the moduli space of supersymmetric black holes that arise in the five-dimensional N=2 supergravity theory with any number of vector multiplets is a weak HKT manifold. The moduli metric is expressed in terms of a HKT potential which is determined by the associated very special geometry of the supergravity theory. As an example, we give explicitly

Laetitia Paoli, Michelle Schatzman

We consider a mechanical system with impact and n degrees of freedom, written in generalized coordinates. The system is not necessarily Lagrangian. The representative point of the system must remain inside a set of constraints K; the boundary of K is three times differentiable. At impact, the tangential component of the impulsion is conserved, while its norm

B. J. Baelus, F. M. Peeters, V. A. Schweigert

The superconducting state of a thin superconducting disk with a hole is studied within the non-linear Ginzburg-Landau theory in which the demagnetization effect is accurately taken into account. We find that the flux through the hole is not quantized, the superconducting state is stabilized with increasing size of the hole for fixed radius of the disk, and a

Hartmuth Arenhoevel, Frank Ritz, Thomas Wilbois

The influence of relativistic contributions to elastic electron deuteron scattering is studied systematically at low and intermediate momentum transfers ($Q^2\leq 30$ fm$^{-2}$). In a $(p/M)$-expansion, all leading order relativistic $\pi$-exchange contributions consistent with the Bonn OBEPQ models are included. In addition, static heavy meson exchange curr

R. J Sault, J. -P. Macquart

Recently Bower et al. (1999b) have reported the detection of circular polarization from the Galactic Center black hole candidate, Sagittarius A*. We provide an independent confirmation of this detection, and provide some analysis on the possible mechanisms.

D. Controzzi, A. M. Tsvelik

We study the Thermodynamic Bethe Ansatz equations for a one-parameter quantum field theory recently introduced by V.A.Fateev. The presence of chemical potentials produces a kink condensate that modifies the excitation spectrum. For some combinations of the chemical potentials an additional gapless mode appears. Various energy scales emerge in the problem. An

D. Falcone, F. Tramontano

In the standard model, several forms of quark mass matrices which correspond to the choice of weak bases lead to the same left-handed mixings $V_L=V_{CKM}$, while the right-handed mixings $V_R$ are not observable quantities. Instead, in a left-right extension of the standard model, such forms are ansatze and give different right-handed mixings which are now

J. Bec, U. Frisch, K. Khanin

Burgers turbulence subject to a force $f(x,t)=\sum_jf_j(x)δ(t-t_j)$, where the $t_j$&#39;s are ``kicking times&#39;&#39; and the ``impulses&#39;&#39; $f_j(x)$ have arbitrary space dependence, combines features of the purely decaying and the continuously forced cases. With large-scale forcing this ``kicked&#39;&#39; Burgers turbulence presents many of the reg

S. Tsujikawa, K. Maeda, T. Torii

We investigate preheating of an inflaton field $ϕ$ coupled nonminimally to a spacetime curvature. In the case of a self-coupling inflaton potential $V(ϕ)=λϕ^4/4$, the dynamics of preheating changes by the effect of the negative $ξ$. We find that the nonminimal coupling works in two ways. First, since the initial value of inflaton field for reheating becomes

Thomas Mehen, Iain W. Stewart, Mark B. Wise

Momentum space Ward identities are derived for the amputated n-point Green&#39;s functions in 3+1 dimensional non-relativistic conformal field theory. For n=4 and 6 the implications for scattering amplitudes (i.e. on-shell amputated Green&#39;s functions) are considered. Any scale invariant 2-to-2 scattering amplitude is also conformally invariant. However,

J. I. Diaz, J. Negro, L. M. Nieto, O. Rosas-Ortiz

New supersymmetric partners of the modified Poschl-Teller and the Dirac&#39;s delta well potentials are constructed in closed form. The resulting one-parametric potentials are shown to be interrelated by a limiting process. The range of values of the parameters for which these potentials are free of singularities is exactly determined. The construction of hi

Jaehyun Kim, Jae-Seung Lee, Soonchil Lee, Chaejoon Cheong

We implemented the refined Deutsch-Jozsa algorithm on a 3-bit nuclear magnetic resonance quantum computer, which is the meaningful test of quantum parallelism because qubits are entangled. All of the balanced and constant functions were realized exactly. The results agree well with theoretical predictions and clearly distinguish the balanced functions from c