November 1997 arXiv papers — page 8

C. T. Sachrajda

I review the status of theoretical aspects of B-decays. The principal difficulty in interpreting the wealth of experimental data is the control of non-perturbative QCD effects, and the talk is focused on attempts to control these effects. Lattice results for the decay constants, B-$\bar B$ mixing and semileptonic form-factors are summarized. The discrepancy

D. Boyanovsky, C. Destri, H. J. de Vega, R. Holman

We analyze the dynamics of dissipation and relaxation in the unbroken and broken symmetry phases of scalar theory in the nonlinear regime for large initial energy densities, and after linear unstabilities (parametric or spinodal) are shut-off by the quantum backreaction. A new time scale emerges that separates the linear from the non-linear regimes. This sca

R. Engel, J. Ranft

Hadron production in single and central diffraction dissociation is studied in a model which includes soft hadron interaction as controlled by a supercritical pomeron parametrization and hard diffraction. Within this model, particle production in collisions with pomerons exhibit properties like multiple soft interactions and multiple minijets, quite similar

G. Radel, A. De Roeck

We investigate the possibility to identify photon-gluon fusion (PGF) events in polarised deep inelastic ep scattering, assuming the kinematics of the HERA collider, by a pair of charged high p_t particles. In a Monte Carlo study we find possible selection criteria and show the expected measurable asymmetries. We discuss the sensitivity to $ΔG(x)$ and compare

Yong Liu, Jing-Ling Chen, Mo-Lin Ge

We suppose that the solar neutrino problem is only due to the mechanism introduced by Ellis, Hagelin, Nanopoulos and Srednicki (EHNS), then a lower limit constraint on EHNS parameters is obtained. We find that gamma > 7.4 10^(-22)GeV if alpha < 2 gamma and alpha > 1.5 10^(-21)GeV if alpha > 2 gamma, this limit is consistent with the upper limits extract from

Gregory Gabadadze

We study whether the pseudoscalar glueball mass in full QCD can differ from the prediction of quenched lattice calculations. Using properties of the correlator of the vacuum topological susceptibility we derive an expression for the upper bound on the QCD glueball mass. We show that the QCD pseudoscalar glueball is lighter than the pure Yang-Mills theory glu

J. Y. Cui, J. M. Wu, H. Y. Jin

The mass of the glueballs is calculated in the B.S. equation framework. Under instantaneous approximation, the wave function of B.S. equations are obtained. The kernel is chosen as the sum of an one-gluon exchange potential, a contact interaction and a linear confining potential. The numerical results are in agreement with that of recent lattice calculation.

Yu. S. Kalashnikova, A. V. Nefediev

The system of light quark and heavy antiquark source is studied in 1+1 QCD in the large N_C limit. The situation is demonstrated to be the two dimensional analogue of the problem in 3+1 QCD corresponding to the essentially nonlocal case of zero vacuum correlation length, which does not allow perturbative treatment. The modified Fock-Schwinger gauge condition

JLQCD collaboration, S. Aoki, M. Fukugita, S. Hashimoto

We present results of our quenched study of the B meson decay constant obtained with a parallel set of simulations with the Wilson and Clover actions at β=5.9, 6.1 and 6.3. Systematic errors associated with the large b-quark mass are analyzed within the Fermilab non-relativistic formalism. As our best estimate in the continuum limit we obtain $f_B=163 \pm 16

Xiang-Qian Luo, Shuo-Hong Guo, Helmut Kroeger, Dieter Schuette

Improvement of the Hamiltonian in lattice gauge theory is considered. We give explicit expressions for classical improvement and discuss also quantum corrections.

JLQCD collaboration, S. Aoki, M. Fukugita, S. Hashimoto

A lattice QCD calculation of the B meson decay constant is presented. In order to investigate the scaling violation associated with the heavy quark, parallel simulations are carried out employing both Wilson and the O(a)-improved clover actions for the heavy quark. The discretization errors due to the large $b$ quark mass are estimated in a systematic way wi

A. Cucchieri, M. Masetti, T. Mendes, R. Petronzio

We make a quenched lattice simulation of hadron spectroscopy at beta=6.2 with the Wilson action non-perturbatively improved. With respect to the unimproved case, the estimate of the lattice spacing is less influenced by the choice of input hadron masses. We study also the effects of using an improved quark mass in the fits to the dependence of hadron masses

C. Adloff

Quasi-elastic (z >0.95) photo-production of psi&#39; mesons has been observed at HERA for photon-proton centre-of-mass energies in the range 40 to 160 GeV. The psi&#39; mesons were identified through their decays to l+l- and to J/psi pi+ pi-, where the J/psi subsequently decays to l+l-, the lepton l being either a muon or an electron. The cross-section for q

CLEO Collaboration, J. Bartelt et al

We have observed a signal for the decay D*+ -> D+ gamma at a significance of 4 standard deviations. From the measured branching ratio B(D*+ -> D+ gamma)/B(D*+ -> D+ pi0)=0.055 +- 0.014 +- 0.010 we find B(D*+ -> D+ gamma)= 0.017 +- 0.004 +- 0.003, where the first uncertainty is statistical and the second is systematic. We also report the highest precision mea

Jelle Boersma

In this paper we discuss the effect of local inhomogeneities on the global expansion of nearly FLRW universes, in a perturbative setting. We derive a generic linearized averaging operation for metric perturbations from basic assumptions, and we explicify the issue of gauge invariance. We derive a gauge invariant expression for the back-reaction of density in

Abdelghani Zeghib

This is the first part of a series on non-compact groups acting isometrically on compact Lorentz manifolds. This subject was recently investigated by many authors. In the present part we investigate the dynamics of affine, and especially Lorentz transformations. In particular we show how this is related to geodesic foliations. The existence of geodesic folia

Miguel Abreu

Recently Guillemin gave an explicit combinatorial way of constructing &#34;toric&#34; Kahler metrics on (symplectic) toric varieties, using only data on the moment polytope. In this paper, differential geometric properties of these metrics are investigated using Guillemin&#39;s construction. In particular, a nice combinatorial formula for the scalar curvatur

A. L. Ferreira, W. Korneta

A two-dimensional fluid of hard spheres each having a spin $\pm 1$ and interacting via short-range Ising-like interaction is studied near the second order phase transition from the paramagnetic gas to the ferromagnetic gas phase. Monte Carlo simulation technique and the multiple histogram data analysis were used. By measuring the finite-size behaviour of sev

P. W. Anderson, G. Baskaran

This is a critique of cond-mat/9709195 . This paper is being submitted at this time for archiving purposes.

Song He, X. C. Xie

We argue that there is a new liquid phase in the two-dimensional electron system in Si MOSFETs at low enough electron densities. The recently observed metal-insulator transition results as a crossover from the percolation transition of the liquid phase through the disorder landscape in the system below the liquid-gas critical temperature. The consequences of

Baruch Horovitz, T. Ruth Goldin

Phase transitions of a flux lattice in layered superconductors with magnetic field perpendicular to the layers and in presence of disorder are studied. We find that the Josephson coupling between layers leads to a strongly pinned Josephson glass (JG) phase at low temperatures and fields. The JG phase undergoes either a decoupling transition with increasing f

Fausto Rossi, Elisa Molinari

We review recent results on the linear and non-linear optical response of realistic quantum-wire structures. Our theoretical approach is based on a set of generalized semiconductor Bloch equations, and allows a full three-dimensional multisubband description of Coulomb correlation for any shape of the confinement profile, thus permitting a direct comparison

Fausto Rossi

The theoretical analysis of the ultrafast energy relaxation and transport phenomena in semiconductor superlattices is reviewed. In particular, we discuss the two equivalent quantum-mechanical pictures of Bloch oscillations and Wannier-Stark localization. A review of simulated experiments and their comparison with available experimental investigations is also

Fausto Rossi

A review of coherent phenomena in photoexcited semiconductors is presented. In particular, two classes of phenomena are considered: On the one hand the role played by optically-induced phase coherence in the ultrafast spectroscopy of semiconductors; On the other hand the Coulomb-induced effects on the coherent optical response of low-dimensional structures.

Andrei Manolescu, Vidar Gudmundsson

We investigate the far-infrared (FIR) absorption of a two-dimensional electron gas in a periodically modulated quantizing magnetic field. The magnetic field varies along only one spatial direction and the external time-dependent electric field is linearly polarized along that axis. The mutual Coulomb interaction of the electrons is treated self-consistently

Jason K. Perry, Jamil Tahir-Kheli

We present the results of a new Hubbard model for optimally doped LaSrCuO. This model uses parameters derived from BLYP calculations on the cluster CuO6. It explicitly includes the Cu dx2-y2 and dz2 orbitals, the O psigma orbitals, and the apical O pz orbitals. When correlation is properly included in the Hubbard model, we find that there is a crossing of tw

Jamil Tahir-Kheli

A model for high temperature superconductors based on the idea of Cooper pairs comprised of electrons from different bands is studied. We propose that the two bands relevant for the cuprates are comprised of Cu dx2-y2, dz2, planar O psigma, and apical O pz orbitals. Along the diagonal, kx=ky in the Brillouin zone, the two band Fermi surfaces may cross. We as

Renate Henschel, John A. Bateman

The space and run-time requirements of broad coverage grammars appear for many applications unreasonably large in relation to the relative simplicity of the task at hand. On the other hand, handcrafted development of application-dependent grammars is in danger of duplicating work which is then difficult to re-use in other contexts of application. To overcome

Joerg P. Ueberla

In this paper a first attempt at deriving an improved performance measure for language models, the probability ratio measure (PRM) is described. In a proof of concept experiment, it is shown that PRM correlates better with recognition accuracy and can lead to better recognition results when used as the optimisation criterion of a clustering algorithm. Inspit

Morena Danieli

In this paper I describe how miscommunication problems are dealt with in the spoken language system DIALOGOS. The dialogue module of the system exploits dialogic expectations in a twofold way: to model what future user utterance might be about (predictions), and to account how the user&#39;s next utterance may be related to previous ones in the ongoing inter

Cosmin Popovici, Paolo Baggia

This paper is focused on the language modelling for task-oriented domains and presents an accurate analysis of the utterances acquired by the Dialogos spoken dialogue system. Dialogos allows access to the Italian Railways timetable by using the telephone over the public network. The language modelling aspects of specificity and behaviour to rare events are s

Paolo Baggia, Morena Danieli, Elisabetta Gerbino, Loreta M. Moisa

In this paper we explain how contextual expectations are generated and used in the task-oriented spoken language understanding system Dialogos. The hard task of recognizing spontaneous speech on the telephone may greatly benefit from the use of specific language models during the recognition of callers&#39; utterances. By &#39;specific language models&#39; w

John A. Bateman

Grammar development environments (GDE&#39;s) for analysis and for generation have not yet come together. Despite the fact that analysis-oriented GDE&#39;s (such as ALEP) may include some possibility of sentence generation, the development techniques and kinds of resources suggested are apparently not those required for practical, large-scale natural language

Anton M. Koekemoer, Geoffrey V. Bicknell

Results are presented from a programme of detailed longslit spectroscopic observations of the extended emission-line region (EELR) associated with the powerful radio galaxy PKS 2356-61. The observations have been used to construct spectroscopic datacubes, which yield detailed information on the spatial variations of emission-line ratios across the EELR, toge

D. L. Welch

The influence of new techniques on the discovery and characterization of pulsating variables has been enormous. In this paper, I will review the methods and results of a number of research programmes which have dramatically altered our ability to study variable stars and will likely bear fruit for many years into the future. Specifically, I will touch on res

R. C. Kraan-Korteweg, A. Schroeder, G. A. Mamon, S. Ruphy

About 25% of the optical extragalactic sky is obscured by the dust and stars of our Milky Way. Dynamically important structures might still lie hidden in this zone. Various approaches are presently being employed to uncover the galaxy distribution in the Zone of Avoidance (ZOA) but all suffer from (different) limitations and selection effects. We investigate

B. Femenia, R. Rebolo, C. M. Gutierrez, M. Limon

We present the results of a Cosmic Microwave Background (CMB) anisotropy ground-based millimetric experiment sensitive to fluctuations on angular scales of $\sim 2\degg$. Four independent bands centered at 3.3, 2.1, 1.3 and 1.1 mm collected $\sim 550$ hours of observation during the Summer of 1994. The instrument was located on the island of Tenerife at an a

Carl J. Grillmair

We discuss recent observational and numerical work on tidal tails in globular clusters. Evidence of tidal tails has now been found in 16 Galactic globulars and 4 globulars in M31. Simulations indicate that mapping of these tidal tails over most of a typical cluster&#39;s orbit may be quite feasible. A relatively modest effort in this regard would yield relia

Rudy Wijnands, Michiel van der Klis, Jan van Paradijs

In numerous low-mass X-ray binaries kHz quasi-periodic oscillations (kHz QPOs) are detected. We observed the atoll sources GX 9+1 and GX 9+9 with the RXTE satellite. Both sources were on the (upper) banana branch during our observations. No kHz QPOs were detected, with upper limits of 1.3-1.8 %. It is known from other atoll sources (e.g. 4U 1636-53 and 4U 18

Istvan Szapudi

In the near future a new generation of CCD based galaxy surveys will enable high precision determination of the N-point correlation functions. The resulting information will help to resolve the ambiguities associated with two-point correlation functions thus constraining theories of structure formation, biasing, and Gaussianity of initial conditions independ

Edward L. Wright

The Cosmic Microwave Background Radiation (CMBR) is the radiation left over from the hot Big Bang. Its blackbody spectrum and small anisotropy provide clues about the origin and early evolution of the Universe. In particular, the spectrum of the CMBR rules out many non-gravitational models of structure formation, and the anisotropy of the CMBR provides a mea

Rudy Wijnands, Jeroen Homan, Michiel van der Klis, Erik Kuulkers

During observations with RXTE we discovered two simultaneous kHz QPOs near 500 Hz and 860 Hz in the Z source Cyg X-2. In the X-ray color-color diagram and hardness-intensity diagram (HID) a clear Z track was traced out. A single kHz QPO peak was detected at the left end of the horizontal branch (HB) of the Z track, with a frequency of 731+/-20 Hz and an ampl

Matthew G. Baring, Alice K. Harding

Eleven bright gamma-ray bursts (GRBs) detected by BATSE have also been seen at much higher energies by EGRET, six at energies above 10 MeV. Such observations imply that these bursts are optically thin to photon-photon pair production at all observed energies. For bursts more than about 30pc away, internal transparency can be achieved only if the source is mo

M. Orlandini, D. Dal Fiume, F. Frontera, G. Cusumano

We report on the 20 ksec observation of Vela X-1 performed by BeppoSAX on 1996 July 14 during its Science Verification Phase. We observed the source in two intensity states, characterized by a change in luminosity of a factor ~ 2, and a change in absorption of a factor ~ 10. The single Narrow Field Instrument pulse-averaged spectra are well fit by a power la

Vladimir I. Pariev, Benjamin C. Bromley

The observed iron K-alpha fluorescence lines in Seyfert galaxies provide strong evidence for an accretion disk near a supermassive black hole as a source of the line emission. Previous studies of line emission have considered only geometrically thin disks, where the gas moves along geodesics in the equatorial plane of a black hole. Here we extend this work t

C. Terquem, J. C. B. Papaloizou, R. P. Nelson, D. N. C. Lin

We examine the effect of dynamical tides raised by a companion on a solar-type star. In these binaries, gravity or g mode oscillations are excited by the companion in the radiative region beneath the convective envelope of the star. They become evanescent in the convection zone. This is of particular interest in connection with the newly discovered planets,

Dave Bayer, Bernd Sturmfels

We construct a canonical free resolution for arbitrary monomial modules and lattice ideals. This includes monomial ideals and defining ideals of toric varieties, and it generalizes our joint results with Irena Peeva for generic ideals.

G. Laumon, M. Rapoport

We consider from a geometric point of view the conjectural fundamental lemma of Langlands and Shelstad for unitary groups over a local field of positive characteristic. We introduce projective algebraic varieties over the finite residue field $k$ and interpret the conjecture in this case as a remarkable identity between the number of $k$-rational points of t

F. Gonzalez-Rey, R. von Unge

Manifest N=2 supersymmetric hypermultiplet mass terms can be introduced in the projective N=2 superspace formalism. In the case of complex hypermultiplets, where the gauge covariantized spinor derivatives have an explicit representation in terms of gauge prepotentials, it is possible to interpret such masses as vacuum expectation values of an Abelian vector

Ocker C. de Jager, Matthew G. Baring

Due to observations made by the Compton Gamma-Ray Observatory over the last six years, it appears that a number of galactic supernova remnants may be candidates for sources of cosmic gamma-rays. These include shell-type remnants such as IC443 and $γ$ Cygni, which have no known parent pulsars, but have significant associations with unidentified EGRET sources,

G. Valencia

We revisit the calculation of the long distance contribution to $K_L \to μ^+ μ^-$. We discuss this process within the framework of chiral perturbation theory, and also using simple models for the $K_L γ^* γ^*$ vertex. We argue that it is unlikely that this mode can be used to extract information on short distance parameters. The process $K_L \to e^+ e^-$ is

A. V. Rozhkov

In this paper the entropy of the two-channel Kondo impurity is calculated. We demonstrate that the exactly solvable system of finite size can be described in terms of free fermions. None of these fermions is Majorana fermion. This allows us to find the impurity entropy $S(T, L)$ for arbitrary values of $T$ and $L$. As found before, $S(T=0, L=\infty)$ equals

J. W. F. Valle

I review the main options one has of introducing mass to neutrinos, including broken R-parity models, as well as the constraints on neutrino properties that follow from astrophysics, cosmology as well as laboratory observations.

J. M. Mourao, T. Thiemann, J. M. Velhinho

Well known methods of measure theory on infinite dimensional spaces are used to study physical properties of measures relevant to quantum field theory. The difference of typical configurations of free massive scalar field theories with different masses is studied. We apply the same methods to study the Ashtekar-Lewandowski (AL) measure on spaces of connectio

K. Sfetsos, K. Skenderis

We derive the Bekenstein-Hawking entropy formula for four and five dimensional non-supersymmetric black holes (which include the Schwarzchild ones) by counting microscopic states. This is achieved by first showing that these black holes are U-dual to the three-dimensional black hole of Banados-Teitelboim-Zanelli and then counting microscopic states of the la

J. E. Avron, P. G. Zograf

We study the forces that act on a point flux carrying an integral number of flux units in quantum Hall fluids. Forces due to external fields, Lorentz and Magnus type forces, and the forces due to mutual interaction of point fluxes are considered. The forces are related to the adiabatic curvature associated with families of Landau Hamiltonians. The problem di

P. Bozhilov

BRST quantization is carried out for a model of p-branes with second class constraints. After extension of the phase space the constraint algebra coincides with the one of null string when p=1. It is shown that in this case one can or can not obtain critical dimension for the null string, depending on the choice of the operator ordering and corresponding vac

NA22 Collaboration, N. M. Agababyan et al

The invariant spectra of pi- mesons produced in (pi+/K+)p interactions at 250 GeV/c are analysed in the framework of the hydrodynamical model of three-dimensionally expanding cylindrically symmetric finite systems. A satisfactory description of experimental data is achieved. The data favour the pattern according to which the hadron matter undergoes predomina

J. M. F. Labastida, Carlos Lozano

Mass perturbations of the twisted N=4 supersymmetric gauge theory considered by Vafa and Witten to test S-duality are studied for the case of Kahler four-manifolds. It is shown that the resulting mass-perturbed theory can be regarded as an equivariant extension associated to a U(1) symmetry of the twisted theory, which is only present for Kahler manifolds. I

C. Giunti, C. W. Kim

The temporal and spatial coherence widths of the microscopic process by which a neutrino is detected are incorporated in the quantum mechanical wave packet treatment of neutrino oscillations, confirming the observation of Kiers, Nussinov and Weiss that an accurate measurement of the energies of the particles participating in the detection process can increas

Ashoke Sen

Type IIB string theory admits a BPS configuration in which three strings (of different type) meet at a point. Using this three string configuration we construct a string network and study its properties. In particular we prove supersymmetry of this configuration. We also consider string lattices, which can be used to construct BPS states in toroidally compac

Juan Garcia-Bellido, Andrei Linde

We investigate the possibility of preheating in hybrid inflation. This scenario involves at least two scalar fields, the inflaton field $ϕ$, and the symmetry breaking field $σ$. We found that the behavior of these fields after inflation, as well as the possibility of preheating (particle production due to parametric resonance), depends crucially on the ratio

Myung Gyoon Lee, Eunhyeuk Kim, Doug Geisler

We present a comprehensive study of the luminosity function and spatial structure of the globular cluster system of NGC 4472, based on deep wide field Washington CT1 CCD images. The globular cluster luminosity function shows a peak at T1=23.3 +/- 0.1 mag, about 1.5 mags brighter than our 50% completeness limit. We estimate the true distance modulus to NGC 44

Vadim Ponomarenko, Naoto Nagaosa

Transport through a 1D Mott-Hubbard insulator of a finite length $L$ is studied beyond perturbative approach. At special value of the low energy constant of the interaction we have mapped the problem onto the exactly solvable models and found current vs. voltage $V$ at high temperature $T>max(m,T_L)$ and at low energy $T,V<T_L$ ($T_L=v_c/L$; $v_c:$ charge ve

Takanori Sugihara

An indication of spontaneous symmetry breaking is found in the two-dimensional $λϕ^4$ model, where attention is paid to the functional form of an effective action. An effective energy, which is an effective action for a static field, is obtained as a functional of the classical field from the ground state of the hamiltonian $H[J]$ interacting with a constant

Johann Rafelski, Jean Letessier, Ahmed Tounsi

We study quark-gluon plasma (QGP) and hadronic gas (HG) models of the central fireball presumed to be the source of abundantly produced strange (anti-)baryons in S -> W collisions at 200 GeV A. We consider how multi-strange (anti-)baryon multiplicities depend on strangeness conservation and compare the HG and QGP fireball scenarios. We argue that the total p

Edward Farhi, Sam Gutmann

An unstructured search for one item out of N can be performed quantum mechanically in time of order square root of N whereas classically this requires of order N steps. This raises the question of whether square root speedup persists in problems with more structure. In this note we focus on one example of a structured problem and find a quantum algorithm whi

A. M. Bychkov, L. A. Openov, I. A. Semenihin

A possibility to perform single-electron computing without dissipation in the array of tunnel-coupled quantum dots is studied theoretically, taking the spin gate NOT (inverter) as an example. It is shown that the logical operation can be realized at the stage of unitary evolution of electron subsystem, though complete switching of the inverter cannot be achi

N. Lütkenhaus, Stephen M. Barnett

In this article we deal with the security of the BB84 quantum cryptography protocol over noisy channels using generalized privacy amplification. For this we estimate the fraction of bits needed to be discarded during the privacy amplification step. This estimate is given for two scenarios, both of which assume the eavesdropper to access each of the signals i

R. Gambini, J. Griego, J. Pullin

We apply the ideas of Alvarez and Labastida to the invariant of spin networks defined by Witten and Martin based on Chern-Simons theory. We show that it is possible to define ambient invariants of spin networks that (for the case of SU(2)) can be considered as extensions to spin networks of the Jones polynomial. Expansions of the coefficients of the polynomi

Thorsten Emig

An electromagnetic truncated Gaussian pulse propagates through a waveguide with piecewise different dielectric constants. The waveguide contains a barrier, namely a region of a lower dielectric constant compared to the neighboring regions. This set-up yields a purely imaginary wave vector in the region of the barrier (&#39;electromagnetic tunneling&#39;). We

Lars Petter Endresen, Kevin Hall

We give an explicit formula for the membrane potential of cells in terms of the intracellular and extracellular ionic concentrations, and derive equations for the ionic currents that flow through channels, exchangers and electrogenic pumps based on simple energy considerations and conservation laws. We demonstrate that the work done by the pump is equal to t

Michael J. Coleman, Andy Ruina

We built a simple two-leg toy that can walk stably with no control system. It walks downhill powered only by gravity. It seems to be the first McGeer-like passive-dynamic walker that is statically unstable in all standing positions, yet is stable in motion. It is one of few known mechanical devices that are stable near a statically unstable configuration but

Gerald A. Miller

The consequences of the charge symmetry breaking effects of the mass difference between the up and down quarks and electromagnetic effects for searches for strangeness form factors in parity violating electron scattering from the proton are investigated. The formalism necessary to identify and compute the relevant observables is developed by separating the H

J. Caro, C. García-Recio, J. M. Nieves

The $Λ$-$Λ$ effective interaction, in the channel $L=S=0$, in the nuclear medium is fitted to the available binding energies, $B_{ΛΛ}$, of double $Λ$ hypernuclei: $^{6}_{ΛΛ}$He, $^{10}_{ΛΛ}$Be and $^{13}_{ΛΛ}$B. The mesonic decay of these hypernuclei is also investigated. Finally, this effective interaction is used to predict the binding energies and mesonic

V. I. Kukulin, V. N. Pomerantsev, S. G. Cooper, S. B. Dubovichenko

Improved potential solutions are presented for the inverse scattering problem for $d$+$^4$He data. The input for the inversions includes both the data of recent phase shift analyses and phase shifts from RGM coupled-channel calculations based on the NN Minnesota force. The combined calculations provide a more reliable estimate of the odd-even splitting of th

J. Diaz Alonso, L. Mornas

We investigate the screening effects on the nucleon-nucleon elastic cross section inside nuclear matter at zero and finite temperature. The N-N interaction is described phenomenologically via meson exchanges ($σ$, $π$ and $ω$) in the framework of a relativistic lagrangian model. The expressions for the in-medium meson propagators, which take into account the

S. A. Bass, M. Belkacem, M. Brandstetter, M. Bleicher

Ratios of hadronic abundances are analyzed for pp and nucleus-nucleus collisions at sqrt(s)=20 GeV using the microscopic transport model UrQMD. Secondary interactions significantly change the primordial hadronic cocktail of the system. A comparison to data shows a strong dependence on rapidity. Without assuming thermal and chemical equilibrium, predicted had

M. Hirata, K. Ochi, T. Takaki

A model for the two-pion photoproduction on the nucleon proposedearlier is modified to simultaneously explain the total cross sections and the invariant mass spectra. Using this model, we discuss the role of the $ρ$ meson in the $γN \to ππN$ reaction.

Fedor Nazarov, Sergei Treil, Alexander Volberg

We give necessary and sufficient conditions for two weight norm inequalities for Haar multipliers operators and for square functions. We also give sufficient conditions for two weight norm inequalities for the Hilbert transform.

Ram Brustein, Richard Madden

The graceful exit transition from a dilaton-driven inflationary phase to a decelerated Friedmann-Robertson-Walker era requires certain classical and quantum corrections to the string effective action. Classical corrections can stabilize a high curvature string phase while the evolution is still in the weakly coupled regime, and quantum corrections can induce

Alan Carey, Jouko Mickelsson, Michael Murray

This paper reviews recent work on a new geometric object called a bundle gerbe and discusses some new examples arising in quantum field theory. One application is to an Atiyah-Patodi-Singer index theory construction of the bundle of fermionic Fock spaces parametrized by vector potentials in odd space dimensions and a proof that this leads in a simple manner

Marcus T. Grisaru, Marcia E. Knutt-Wehlau, Warren Siegel

Using normal coordinate expansions we derive by purely superspace methods the density formula giving the component action corresponding to a superspace supergravity-matter action.

M. M. Block, E. M. Gregores, F. Halzen, G. Pancheri

Using vector meson dominance we calculate the $γγ$ total cross section from data on $pp$, $p\bar p$ and $γp$ total cross sections. Our result agrees with recent high energy measurements performed by the L3 experiment at the LEP collider, not with the conflicting preliminary data obtained by OPAL.

M. Svec

Model independent amplitude analyses of $π^- p_\uparrow \to π^- π^+ n$ on polarized target at 17.2 GeV/c reveal resonant structure of S-wave transversity amplitudes $|\bar S|^2Σ$ and $|S|^2Σ$ near 750 MeV. Simultaneous fit to $|\bar S|^2Σ$ and $|S|^2Σ$ with a single $σ$ pole yields $m_σ= 775 \pm 17$ MeV and $Γ_σ= 147 \pm 33$ MeV. Simultaneous fit with two co

Chi-Keung Chow

Three topics about the application of quenched chiral perturbation theory to matter fields are studied. It is proved that the hairpin axial current couplings in quenched chiral perturbation theories do not contribute to the quenched chiral singularities for one chiral loop renormalization of matter field properties. The modification of mass corrections in th

G. Radel, A. De Roeck, M. Maul

We present a possible direct measurement of the polarised gluon density $ΔG(x)$ in LO from di-jet production in polarised deep inelastic ep scattering, assuming the kinematics of the HERA collider. We show the sensitivity to the x-dependence of $ΔG(x)$ and to the first moment $\int ΔG(x) dx$ in the range $0.002< x <0.2$, assuming the electron and proton beam

B. R. Kim, G. Kreyerhoff, S. K. Oh

We analyze the possibility of detecting one of the three scalar Higgs bosons in the next-to-minimal supersymmetric model at the future $e^+e^-$ linear collider, by examining their productions via the Higgsstrahlung process. The production cross sections of the three scalar Higgs bosons in $e^+e^-$ collisions are evaluated for the proposed c.m. energies of th

A. D. Martin, M. G. Ryskin

We present a simple physical description of the off-diagonal gluon distribution g (x,x^\prime,Q^2) and splitting function P_{gg}(x,x^\prime) which enter the amplitude for diffractive vector meson production. We study the off-diagonal effects both on the evolution in Q^2 and on the input distribution. We predict the ratio $R$ of the off-diagonal to the diagon

A. S. Johnson, J. A. McNeil, J. R. Shepard

We present a nonperturbative renormalization group solution of the Gell-Mann--Levy $σ$-model which was originally proposed as a phenomenological description of the dynamics of nucleons and mesons. In our version of the model the fermions are interpreted as quarks which interact via the $σ$ and $π$ mesons. We derive and numerically solve renormalization group

M. Gluck, E. Reya, M. Stratmann

Using constituent quark model constraints we calculate the gluon and sea content of pions solely in terms of their valence density and the known sea and gluon densities of the nucleon. The resulting small-x predictions for g^{pi}(x,Q^2) and \bar{q}^{pi}(x,Q^2) are unique and parameter free, being entirely due to QCD dynamics. Similar ideas are applied for ca

K. Suzuki, W. Weise

We investigate the structure of constituent quarks and study implications for quark distribution functions of hadrons. Constituent quarks are constructed by dressing bare quarks with Goldstone bosons using the chiral quark model. We calculate resulting corrections to the twist-2 structure functions $f_1(x)$, $g_1(x)$ and $h_1(x)$. The Goldstone boson fluctua

N. V. Krasnikov, R. Rodenberg

We recalculate the hadronic contribution to the effective electromagnetic coupling constant $α(M^2_Z)$ using quasi-analytical approximations for the cross-section of $e^{+}e^{-} \to hadrons$ proposed earlier by one of the authors(N.V.K.,Mod.Phys.Lett.A9(1994)2825). We find that $α^{-1}(M^2_Z) = 128.98 \pm 0.06$.

E. Mirkes, S. Willfahrt, D. Zeppenfeld

Next-to-leading order QCD predictions for 1-jet and 2-jet cross sections in deep inelastic scattering with complete neutral current ($γ^*$ and $Z$) and charged current ($W^\pm$) exchange are presented.

Ulf-G. Meißner

These lectures give an introduction to baryon chiral perturbation theory. I show in detail how to construct the chiral effective pion-nucleon Lagrangian in the one loop approximation. Particular emphasis is put on the physics related to electromagnetic probes, as manifest in pion photo- and electroproduction, Compton scattering off nucleons and the electrowe

J. H. Kuehn, E. Mirkes

CP violating signals in semileptonic $τ$ decays induced by an exotic scalar exchange are studied in a completely model-independent way. These can be observed in decays of unpolarized single $τ$&#39;s even if their rest frame cannot be reconstructed. No beam polarization is required. The importance of the two-meson channel, in particular the $Kπ$ final state

D. Melikhov, N. Nikitin, S. Simula

We study long-distance effects in rare exclusive semileptonic decays B -> (K, K*) (l+ l-, nu bar{nu}) and analyze dilepton spectra and asymmetries within the framework of the Standard Model. The form factors, describing the meson transition amplitudes of the effective Hamiltonian are calculated within the lattice-constrained dispersion quark model: the form

Ulf-G. Meißner, Martin Sevior, A. Badertscher, B. Borasoy

This is the summary of the working group on $ππ$ and $π$N interactions of the Chiral Dynamics Workshop in Mainz, September 1-5, 1997. Each talk is represented by an extended one page abstract. Some additional remarks by the convenors are added

Reginald T. Cahill, Susan M. Gunner

The Global Colour Model of QCD is used in conjunction with a pure-gluon lattice correlator (by Marenzoni et al.) to extract from meson data a momentum-dependent quark-gluon coupling down to $s \approx 0.3 GeV^2$. This is compared with a lattice calculation (by Skullerud) of the quark-gluon coupling.

John Bahcall

The first lecture describes the conflicts between the combined standard model (minimal electroweak and solar) predictions and the results of solar neutrino experiments. The second lecture discusses the possibilities for detecting with solar neutrinos ``smoking gun&#39;&#39; indications of departures from minimal electroweak theory. Viewgraphs and related dat