October 1993 arXiv papers — page 4

F. Ferrari, J. Sobczyk, W. Urbanik

In this work, the following conjectures are proven in the case of a Riemann surface with abelian group of symmetry: a) The $b-c$ systems on a Riemann surface $M$ are equivalent to a multivalued field theory on the complex plane if $M$ is represented as an algebraic curve; b) the amplitudes of the $b-c$ systems on a Riemann surface $M$ with discrete group of

David London

B decays in and beyond the standard model are reviewed. I specifically discuss right-handed B decays, rare B decays, B_c decays, B_s-B_s(bar) mixing, and T violation. (Plenary talk given at the `Workshop on B Physics at Hadron Accelerators', Snowmass, Colorado, June 21-July 2, 1993.)

Q. Liu

We study dynamics of non-relativistic Chern-Simons solitons, both in the absence and in the presence of external fields. We find that a phase, related to the $1$-cocyle of the Galileo group, must be included to give the correct dynamical behavior. We show that interactions among Chern-Simons solitons are mediated by an effective Chern-Simons gauge field indu

B. S. Balakrishna, K. T. Mahanthappa

We present a generalization of the non-Abelian version of the $CP^{N-1}$ models (also known as Grassmannian models) that involve composite gauge fields to accommodate partial breaking of the non-Abelian gauge symmetry. For this to be possible, in most cases, the constituent fields need to belong to an anomaly free complex representation. Symmetry is broken d

F. W. Nijhoff

I present a $q$-analog of the discrete Painlevé I equation, and a special realization of it in terms of $q$-orthogonal polynomials.

Hermann Riecke, Mary Silber, Lorenz Kramer

We investigate the effect of resonant temporal forcing on an anisotropic system that exhibits a Hopf bifurcation to obliquely traveling waves in the absence of this forcing. We find that the forcing can excite various phase-locked standing-wave structures: rolls, rectangles and cross rolls. At onset, at most one of the two - rolls or rectangles - is stable.

K. J. Eskola, Xin-Nian Wang

To calculate dilepton rates in a Monte Carlo simulation of ultrarelativistic heavy ion collisions, one usually scales the number of similar QCD processes by a ratio of the corresponding differential probabilities. We derive the formula for such a ratio especially for dilepton bremsstrahlung processes. We also discuss the non-triviality of including higher or

K. J. Eskola, Xin-Nian Wang

Dilepton production associated with minijets is calculated in ultrarelativistic heavy ion collisions using the first order approximation of the dilepton fragmentation functions of quarks and gluons. The full QCD evolution of the fragmentation functions is also studied. We find that the dilepton pairs from the fragmentation of minijets are comparable to direc

J. K"onig, P. Ring

Relativistic Mean Field Theory in the rotating frame is used to describe superdeformed nuclei. Nuclear currents and the resulting spatial components of the vector meson fields are fully taken into account. Identical bands in neighboring Rare Earth nuclei are investigated and excellent agreement with recent experimental data is observed.

Haim Judah, Andrzej Rosłanowski, Saharon Shelah

We give a model where there is a ccc Souslin forcing which does not satisfy the Knaster condition. Next, we present a model where there is a sigma-linked not sigma-centered Souslin forcing such that all its small subsets are sigma-centered but Martin Axiom fails for this order. Furthermore, we construct a totally nonhomogeneous Souslin forcing and we build a

Leo P. Comerford, Charles C. Edmunds

A classification of the ways in which an element of a free group can be expressed as a product of commutators or as a product of squares is given. This is then applied to some particular classes of elements. Finally, a question about expressing a commutator as a product of squares is addressed.

Leo P. Comerford, Charles C. Edmunds, Gerhard Rosenberger

The ways in which a nontrivial commutator can be a proper power in a free product of groups are identified.

Chryssomalis Chryssomalakos, Peter Schupp, Paul Watts

We review the construction of the cross product algebra $\A\rtimes\U$ from two dually paired Hopf algebras $\U$ and $\A$. The canonical element in $\U \otimes \A$ is then introduced, and its properties examined. We find that it is useful for giving coactions on $\A\rtimes\U$, and it allows the construction of objects with specific invariance properties under

Steven S. Gubser, Igor R. Klebanov

We apply the recently proposed transfer matrix formalism to 2-dimensional quantum gravity coupled to $(2, 2k-1)$ minimal models. We find that the propagation of a parent universe in geodesic (Euclidean) time is accompanied by continual emission of baby universes and derive a distribution function describing their sizes. The $k\to \infty~ (c\to -\infty)$ limi

Mathias Pillin

Based on the representation theory of the $q$-deformed Lorentz and Poincaré symmeties $q$-deformed relativistic wave equation are constructed. The most important cases of the Dirac-, Proca-, Rarita-Schwinger- and Maxwell- equations are treated explicitly. The $q$-deformed wave operators look structurally like the undeformed ones but they consist of the gener

Alexios P. Polychronakos

The spectrum and partition function of a model consisting of SU(n) spins positioned at the equilibrium positions of a classical Calogero model and interacting through inverse-square exchange are derived. The energy levels are equidistant and have a high degree of degeneracy, with several SU(n) multiplets belonging to the same energy eigenspace. The partition

A. P. Demichev, Yu. A. Kubyshin, J. I. Pérez Cadenas

We analyze a possibility of experimental detection of the contribution of the Kaluza-Klein tower of heavy particles to scattering cross-section in a six-dimensional scalar model with two dimensions being compactified to the torus with the radii $R$. It is shown that there is a noticeable effect even for the energies of colliding particles below $R^{-1}$ whic

J. W. van Holten

The usual extensions of supersymmetry require the existence of a complex structure and the formulation of the theory on Kähler manifolds. It is shown, that by relaxing the constraints on the algebra of supercharges we can get new supersymmetries whenever a manifold possesses a structure admitting the existence of a Killing-Yano tensor field. Examples of such

R. Mochizuki

We study the stochastic quantization of the system with first class constraints in phase space. Though the Langevin equations of the canonical variables are defined without ordinary gauge fixing procedure, gauge fixing conditions are automatically selected and introduced by imposing stochastic consistency conditions upon the first class constraints. Then the

Makoto Idzumi

Vertex operators associated with level two $U_q(\widehat{sl}_2)$ modules are constructed explicitly using bosons and fermions. An integral formula is derived for the trace of products of vertex operators. These results are applied to give $n$-point spin correlation functions of an integrable $S=1$ quantum spin chain, extending an earlier work of Jimbo {\em e

J. Stern, N. H. Fuchs, M. Knecht

A method of indirect measurement of the light quark running mass $\hat{m} = (m_d + m_u)/2$ is elaborated in detail. It is based on measuring 1\%-level azimuthal angular asymmetries in the decay $τ\rightarrow ν_τ+ 3π$. The latter are then used in QCD sum rules to obtain experimental lower bounds for $\hat{m}$. For a sample of $2.5 \times 10^5$ $τ\rightarrow ν

H. Weigel

It is demonstrated how in the soliton approach to baryons a small but non-vanishing matrix element of the axial singlet current is obtained. Furthermore it is shown that these models also provide a mechanism to disentangle the ``matter" and ``glue" contributions to this matrix element. Numerical results indeed exhibit a cancellation between these two

Nir Polonsky

When realizing the Minimal Supersymmetric Standard Model (MSSM) within a (simple) Grand Unified Theory (GUT), the predicted ranges for the strong coupling and the ratio of two Higgs doublet expectation values are strongly correlated with the weak angle and the $t$-quark mass. (The latter are extracted from precision data.) We spell out those relations and po

H. Dreiner, Manoranjan Guchait, D. P. Roy

The isolated like sign dilepton signature for gluino production is investigated at the LHC energy for the $R$ conserving as well as the $L$ and $B$ violating SUSY models over a wide range of the parameter space. One gets viable signals for gluino masses of 300 and 600 GeV for both $R$ conserving and $L$ violating models, while it is less promising for the $B

G. Bimonte, E . Ercolessi, P. Teotonio-Sobrinho

The Laplace operator admits infinite self-adjoint extensions when considered on a segment of the real line. They have different domains of essential self-adjointness characterized by a suitable set of boundary conditions on the wave functions. In this paper we show how to recover these extensions by studying the continuum limit of certain discretized version

E. Adi, M. Hasenbusch, M. Marcu, E. Pazy

We describe a Monte Carlo procedure for the simulation of dynamically triangulate random surfaces with a boundary (topology of a disk). The algorithm keeps the total number of triangles fixed, while the length of the boundary is allowed to fluctuate. The algorithm works in the presence of matter fields. We here present results for the pure gravity case. The

R. Brout, Ph. Spindel

Using as dynamical variable the square of the radius of the Universe, we solve analytically the Einstein equations in the framework of Robertson-Walker models where a cosmological constant describing phenomenologically the vacuum energy decays into radiation. Emphasis is put on the computation of the entropy creation.

Huw Price

It is widely accepted that temporal asymmetry is largely a cosmological problem; the task of explaining temporal asymmetry reduces in the main to that of explaining an aspect of the condition of the early universe. However, cosmologists who discuss these issues often make mistakes similar to those that plagued nineteenth century discussions of the statistica

Bulbul Chakraborty

This paper presents a theoretical model for studying the dynamics of ordering in alloys which exhibit modulated phases. The model is different from the standard time-dependent Ginzburg-Landau description of the evolution of a non-conserved order parameter and resembles the Swift-Hohenberg model. The early-stage growth kinetics is analyzed and compared to the

Karin Dahmen, James P. Sethna

The hysteresis loop in the zero-temperature random-field Ising model exhibits a critical point as the width of the disorder increases. Above six dimensions, the critical exponents of this transition, where the "infinite avalanche" first disappears, are described by mean-field theory. We expand the critical exponents about mean-field theory, in 6-epsi

J. K. Jain, S. A. Kivelson, D. J. Thouless

We consider a channel of an incompressible fractional-quantum-Hall-effect (FQHE) liquid containing an island of another FQHE liquid. It is predicted that the resistance of this channel will be periodic in the flux through the island, with the period equal to an odd integer multiple of the fundamental flux quantum, $ϕ_{0}=hc/e$. The multiplicity depends on th

Michel Caffarel, Patrick Azaria, Bertrand Delamotte, Dominique Mouhanna

Using a collective-mode Monte Carlo method (the Wolff-Swendsen-Wang algorithm), we compute the spin-stiffness of the two-dimensional classical Heisenberg model. We show that it is the relevant physical quantity to investigate the behaviour of the model in the very low temperature range inaccessible to previous studies based on correlation length and suscepti

T. R. Kirkpatrick, D. Belitz

The effect of Cooperons on metal-insulator transitions (MIT) in disordered interacting electronic systems is studied. It is argued that previous results which concluded that Cooperons are qualitatively unimportant near the MIT might not be correct, and that the problem is much more complicated than had previously been realized. Although we do not completely

Martin A. Hendry, Mark A. O'Dell, Andrew Collier-Cameron

We present a new technique for estimating the distance to young open clusters. The method requires accurate measurement of the axial rotation period of late-type members of the cluster: rotation periods are first combined with projected rotation velocities and an estimate of the angular diameter for each star -- obtained using the Barnes-Evans relation betwe

Pavel Etingof, Alexander Kirillov

We consider correlation functions for the Wess-Zumino-Witten model on the torus with the insertion of a Cartan element; mathematically this means that we consider the function of the form $F=\Tr (Φ_1 (z_1)\ldots Φ_n (z_n)q^{-\d}e^{h})$ where $Φ_i$ are intertwiners between Verma modules and evaluation modules over an affine Lie algebra $\ghat$, $\d$ is the gr

Alexander MOROZ

Key words : The Maxwell equations, band structure calculations, Kohn-Korringa-Rostocker method, and multiple-scattering theory for photons. For those who are interested in how to prepare perfect mirror from a purely transparent material. Some recent results of ours are summarized and presented.

Oscar Diego

I construct the ground state, up to first nonperturbative order, of the stochastic stabilization of the zero dimensional matrix model which defines 2D Quantum Gravity. It is given by the linear combination of a perturbative wave function and a nonperturbative one. The nonperturbative behaviour which arise from the stabilized model and from the string equatio

P. Collet

We investigate the existence of a global semiflow for the complex Ginzburg-Landau equation on the space of bounded functions in unbounded domain. This semiflow is proven to exist in dimension 1 and 2 for any parameter values of the standard cubic Ginzburg-Landau equation. In dimension 3 we need some restrictions on the parameters but cover nevertheless some

Thomas B. Bright, Stephen R. Cotanch

The photonuclear reactions 16O(gamma,n)15O and 16O(gamma,p)15N are simultaneously described within a coupled channels framework based on a continuum shell model formulation. The inclusion of Delta(1232) isobar degrees of freedom improves the description of the available data, however, complete quantitative agreement is still lacking.

S. J. Wang, W. Cassing, M. H. Thoma

A constraint correlation dynamics up to 4-point Green's functions is proposed for SU(N) gauge theories which reduces the N-body quantum field problem to the two-body level. The resulting set of nonlinear coupled equations fulfills all conservation laws including baryon number, linear and angular momenta as well as the total energy. Apart from the conserv

P. Mohr, H. Abele, V. Kölle, G. Staudt

The $α$--$α$ differential cross sections are analyzed in the optical model using a double--folded potential. With the knowledge of this potential bound and resonance--state properties of $α$--cluster states in $^{8}$Be and $^{12}$C as well as astrophysical S--factors of $^{4}$He($α$,$γ$)$^{8}$Be and $^{8}$Be($α$,$γ$)$^{12}$C are calculated. $Γ_γ$--widths and

H. Oberhummer, H. Krauss, K. Grün, T. Rauscher

The astrophysical S--factor and reaction rates for the triple--alpha process are calculated in the direct--capture model. It is shown that the stellar carbon production is extremely sensitive to small variations in the N--N interaction.

A. Itabashi, K. Aizawa, M. Ichimura

We calculated response functions of the deuteron for charge exchange processes, including the final state interaction between two protons. Using them we evaluated the double differential cross section and polarization observables of $d(\vec{p},\vec{n})2p$ by means of plane wave impulse approximation with an optimal factorization. Calculation well reproduced

Amnon Rosenmann

The cogrowth of a subgroup is defined as the growth of a set of coset representatives which are of minimal length. A subgroup is essential if it intersects non-trivially every non-trivial subgroup. The main result of this paper is that every function $f:{\Bbb N}\cup \{0\}\rightarrow {\Bbb N}$ which is strictly increasing, but at most exponential, is equivale

Alexander A. Migdal

This is the extended version of the preprint \ct{Loop}, based on the lectures given in Cargese Summer School and Chernogolovka Summer School in 93. The incompressible fluid dynamics is reformulated as dynamics of closed loops $C$ in coordinate space. We derive explicit functional equation for the pdf of the circulation $P_C(Γ)$ which allows the scaling solut

M. Temple-Raston

We present a topological Lagrangian field theory that is geometrically similar to the Yang-Mills(-Higgs) Lagrangian, and study the Bogomol'nyi solitons contained within this theory. The topological field theory may provide an example of a dual field theory to Yang-Mills(-Higgs). The existence of a dual field theory to Yang-Mills(-Higgs) was conjectured b

Denjoe O'Connor, C. R. Stephens

Series for the Wilson functions of an ``environmentally friendly'' renormalization group are computed to two loops, for an $O(N)$ vector model, in terms of the ``floating coupling'', and resummed by the Padé method to yield crossover exponents for finite size and quantum systems. The resulting effective exponents obey all scaling laws, includ

I. Sachs, A. Wipf

The partition function and the order parameter for the chiral symmetry breaking are computed for a family of 2-dimensional interacting theories containing the gauged Thirring model. In particular we derive non-perturbative expressions for the dependence of the chiral condensate on the temperature and the curvature. Both, high temperature and high curvature s

M. A. Olshanetsky, V. -B. K. Rogov

We consider the quantum Lobachevsky space ${\bf L}_q^3$, which is defined as subalgebra of the Hopf algebra ${\cal A}_q(SL_2({\bf C}))$. The Iwasawa decomposition of ${\cal A}_q(SL_2({\bf C}))$ introduced by Podles and Woronowicz allows to consider the quantum analog of the horospheric coordinates on ${\bf L}_q^3$. The action of the Casimir element, which be

Eli J. Mlawer, Harold A. Riggs, Howard J. Schnitzer

The discovery of integrable $N=2$ supersymmetric Landau-Ginzburg theories whose chiral rings are fusion rings suggests a close connection between fusion rings, the related Landau-Ginzburg superpotentials, and $N=2$ quantum integrability. We examine this connection by finding the natural $SO(N)_K$ analogue of the construction that produced the superpotentials

Malte Henkel

The extension of strongly anisotropic or dynamical scaling to local scale invariance is investigated. For the special case of an anisotropy or dynamical exponent $θ=z=2$, the group of local scale transformation considered is the Schrödinger group, which can be obtained as the non-relativistic limit of the conformal group. The requirement of Schrödinger invar

F. Brandt

It is shown that generally the consistency equation for anomalies of quantum field theories has solutions which depend nontrivially on the sources of the (generalized) BRS-transformations of the fields. Explicit previously unknown examples of such solutions are given for Yang-Mills and super Yang-Mills theories.

Susumu Ariki, Tomohide Terasoma, Hirofumi Yamada

The purpose of this paper is to give a reciprocity between $U_q(h)$ and $\Cal H_{n,r}$, the Hecke algebra of $(\Bbb Z / r\Bbb Z)\wr \frak S_n$ introduced by Ariki and Koike. Let $K=\Bbb Q(q,u_1,\dots ,u_r)$ be the field of rational funcitons in variables $q,u_1,\dots ,u_r$. We adopt $K$ as the base field for both the quantized universal enveloping algebra $U

J. Sonnenschein, S. Yankielowicz

The topological coset model appraoch to non-critical string models is summarized. The action of a topological twisted ${G\over H}$ coset model ($rank\ H = rank\ G$) is written down. A ``topological coset algebra" is derived and compared with the algebraic structure of the $N=2$ twisted models. The cohomology on a free field Fock space as well as on the s

Katsushi Ito, Hiroaki Kanno

We study the hamiltonian reduction of affine Lie superalgebra $sl(2|1)^{(1)}$. Based on a scalar Lax operator formalism, we derive the free field realization of the classical topological topological algebra which appears in the $c\leq1$ non-critical strings. In the quantum case, we analyze the BRST cohomology to get the quantum free field expression of the a

John Bagnasco, Michael Dine, Scott Thomas

The technibaryon constitutes a possible dark matter candidate. Such a particle with electroweak quantum numbers is already nearly ruled out as the dominant component of the galactic dark matter by nuclear recoil experiments. Here, the scattering of singlet technibaryons, without electroweak quantum numbers, is considered. For scalar technibaryons the most im

David J. Summers

We review recent progress in techniques for searching for the Standard Model light `Intermediate Mass' Higgs Boson ($80 \GeV \lsim M_H \lsim 140\GeV$). We pay particular attention to associated production at the SSC and LHC where we search for the Higgs produced in association with either a $W$ boson or a $t$ quark. This production mode can be detected c

Sacha Davidson, Michael Peskin

The upper bound on the number of relativistic species present at nucleosynthesis has been used to constrain particles with electric charge $εe$ ($10^{-8} < ε<1$). We correct the bound previously calculated for milli-charged particles that interact with a shadow photon. We also discuss the additional constraints from the properties of red giants and of Supern

T. Barnes

In this review talk I summarize theoretical expectations for properties of hybrid mesons and baryons, and discuss the prospects for identifying these states experimentally. This is an expanded version of an Invited Contribution to the Conference on Exclusive Reactions at High Momentum Transfers, Marciana Marina, Elba, Italy, 24-26 June 1993.

B. Grzadkowski, W. -Y. Keung

The asymmetries ${\cal A}_k \equiv [Γ(\twddec) -Γ(\tbwddec)] /[Γ(\twddec) + Γ(\tbwddec)]$ in the partial widths of the top quark decays are discussed within the Standard Model (SM), the Two-Higgs-Doublet Model (2HDM) and supersymmetric extensions of the SM (SSM). The leading contributions to these asymmetries in the SM and in the 2HDM are induced by the up-t

I. I. Bigi, N. G. Uraltsev

A general relationship is formulated between the contributions of `Weak Annihilation&#39; (WA) to inclusive semileptonic decays of heavy flavour hadrons and the matrix elements of four fermion operators. We argue that nonperturbative contributions from low energy hadronic final states provide the dominant impact of WA on the semileptonic $b\ra u$ width of $B

J. Cleymans, V. V. Goloviznin, K. Redlich

An estimate is made of the Landau-Pomeranchuk effect on the production of dileptons in a hadronic gas and in a quark-gluon plasma. For low mass dilepton pairs this effect reduces the production rate for bremsstrahlung by an order of magnitude. For high invariant masses its influence is negligible. This behaviour is of importance for the theoretical analysis

Julian Schwinger

This is a lecture given July 14, 1993, at Nottingham.

S. Wiseman, E. Domany

A cluster Monte Carlo algorithm for the Ashkin-Teller (AT) model is constructed according to the guidelines of a general scheme for such algorithms. Its dynamical behaviour is tested for the square lattice AT model. We perform simulations on the line of critical points along which the exponents vary continuously, and find that critical slowing down is signif

A. Economou, C. O. Lousto

We point out that in general the Reissner-Nordström (RN) charged black holes of general relativity are not solutions of the four dimensional quadratic gravitational theories. They are, e.g., exact solutions of the $R+R^2$ quadratic theory but not of a theory where a $R_{ab}R^{ab}$ term is present in the gravitational Lagrangian. In the case where such a non

Norbert Schultka, Efstratios Manousakis

Using the $x-y$ model and a non-local updating scheme called cluster Monte Carlo, we calculate the superfluid density of a two dimensional superfluid on large-size square lattices $L \times L$ up to $400\times 400$. This technique allows us to approach temperatures close to the critical point, and by studying a wide range of $L$ values and applying finite-si

Dirk Jan Bukman, J. M. J. van Leeuwen

Crystals of $^4$He contain vacancies that move around by a quantum mechanical hopping process. The density and pressure of these vacancies can be experimentally studied. The accuracy of the experiments is high enough to detect the effect of the Bose statistics of the vacancies. In this paper we examine the effect of the hard-core repulsion between the vacanc

T. A. Costi, A. C. Hewson, V. Zlatic

The transport coefficients of the Anderson model are calculated by extending Wilson&#39;s NRG method to finite temperature Green&#39;s functions. Accurate results for the frequency and temperature dependence of the single--particle spectral densities and transport time $τ(ω,T)$ are obtained and used to extract the temperature dependence of the transport coef

K. Ziegler

The stability of the insulating regime of the Hubbard model on a $d$-dimensional lattice, which is characterized by an exponential decay of the Green&#39;s functions, is investigated in terms of a cluster expansion. This expansion for the Green&#39;s function is organized in terms of connected clustered transfer matrices. An upper bound for the expansion ter

Barbara Drossel, Siegfried Clar, Franz Schwabl

We present the analytic solution of the self-organized critical (SOC) forest-fire model in one dimension proving SOC in systems without conservation laws by analytic means. Under the condition that the system is in the steady state and very close to the critical point, we calculate the probability that a string of $n$ neighboring sites is occupied by a given

Giovanni Gallavotti, Guido Gentile

A selfcontained proof of the KAM theorem in the Thirring model is discussed, completely relaxing the ``strong diophantine property&#39;&#39; hypothesis used in previous papers. Keywords: \it KAM, invariant tori, classical mechanics, perturbation theory, chaos

S. Bardelli, E. Zucca, G. Vettolani, G. Zamorani

We report the first results of a spectroscopic survey of galaxies in the core of the Shapley Concentration, the richest nearby supercluster of clusters of galaxies. We have measured 311 new galaxy redshifts in an area of $\sim 4.5$ square degrees centered around the Abell cluster A3558. Considering also the data already available in the literature, the total

Mark A. O&#39;Dell, Martin A. Hendry, Andrew Collier Cameron

We apply the new distance measuring technique of Hendry, O&#39;Dell and Collier- Cameron, 1993, to the Pleiades and $α$ Persei clusters. The method relies on knowledge of the periods, rotation velocities and angular diameters of a sample of late-type stars within each cluster. The angular diameters were found by recalibrating the Barnes-Evans surface brightn

Gerard Jungman, Marc Kamionkowski

We estimate the flux of cosmic-ray antiprotons expected from the annihilation of neutralinos in the galactic halo. The antiproton signal may offer an important alternative detection scheme in the case that neutralino annihilation proceeds mainly to the two-gluon final state.

Philippe Fischer, Greg P. Kochanski

In this paper we describe weighting techniques used for the optimal coaddition of CCD frames with differing characteristics. Optimal means maximum signal-to-noise (s/n) for stellar objects. We derive formulae for four applications: 1) object detection via matched filter, 2) object detection identical to DAOFIND, 3) aperture photometry, and 4) ALLSTAR profile

F. Fusi Pecci, P. Battistini, O. Bendinelli, F. Bònoli

We present the initial results of a study of globular clusters in M31, using the Faint Object Camera (FOC) on the Hubble Space Telescope (HST). The sample of objects consists of 13 clusters spanning a range of properties. Three inde- pendent image deconvolution techniques were used in order to compensate for the optical problems of the HST, leading to mutual

Martin A. Hendry, John F. L. Simmons

The statistical properties of galaxy distance estimators are studied and a rigorous framework is developed for identifying and removing the effects of Malmquist bias due to obsevational selection. The prescription of Schechter (1980) for defining unbiased distance estimators is extended to more general -- and more realistic -- cases. The derivation of `optim

Martin A. Hendry, John F. L. Simmons, Andrew M. Newsam

In this paper we review the two main approaches to the problem of Malmquist bias which have been adopted in the cosmology literature, and show how these two formulations of the problem represent fundamentally different views of the nature of probability. We discuss the assumptions upon which both approaches are based and indicate some of their limitations. I

P. Mohr, H. Abele, V. Kölle, G. Staudt

The $α$--$α$ differential cross sections are analyzed in the optical model using a double--folded potential. With the knowledge of this potential bound and resonance--state properties of $α$--cluster states in $^{8}$Be and $^{12}$C as well as astrophysical S--factors of $^{4}$He($α$,$γ$)$^{8}$Be and $^{8}$Be($α$,$γ$)$^{12}$C are calculated. $Γ_γ$--widths and

H. Oberhummer, H. Krauss, K. Grün, T. Rauscher

The astrophysical S--factor and reaction rates for the triple--alpha process are calculated in the direct--capture model. It is shown that the stellar carbon production is extremely sensitive to small variations in the N--N interaction.

G. Moultaka

It is shown that quantum mechanical systems obtained from a heuristic path integral quantization of lagrangians of the form $ L= \sum_{n} \frac{1}{n!} f_n(q) \dot{q}^n $ violate in general the correspondence principle, unless $L$ is not more than quadratic in $\dot{q}$. The field theoretic counterpart of this result and its consequence on models of interacti

Xiao-Gang Wen, Yong-Shi Wu

In this paper we study the conditions under which an N-electron wave function for a fractional quantum Hall (FQH) state can be viewed as N-point correlation function in a conformal field theory (CFT). Several concrete examples are presented to illustrate, when these condition are satisfied, how to ``derive&#39;&#39; or ``uncover&#39;&#39; relevant operator a

Q. F. Zhong, S. Sorella, A. Parola

The one-hole spectral weight for two chains and two dimensional lattices is studied numerically using a new method of analysis of the spectral function within the Lanczos iteration scheme: the Lanczos spectra decoding method. This technique is applied to the $t-J_z$ model for $J_z \to 0$, directly in the infinite size lattice. By a careful investigation of t

K. S. Ahluwalia

We give a constructive account of the fundamental ingredients of Poisson Lie theory as the basis for a description of the classical double group $D$. The double of a group $G$ has a pointwise decomposition $D\sim G\times G^*$, where $G$ and $G^*$ are Lie subgroups generated by dual Lie algebras which form a Lie bialgebra. The double is an example of a factor

K. Kubodera, S. Nozawa

Neutrino-nucleus reactions as applied to astrophysics are reviewed.

Ellis, Engeland, Hjorth-Jensen, Holt

The convergence properties of two perturbative schemes to sum the so-called folded diagrams are critically reviewed, with an emphasis on the intruder state problem. The methods we study are the approaches of Kuo and co-workers and Lee and Suzuki. The suitability of the two schemes for shell-model calculations are discussed.

A. Bianconi, S. Boffi, D. E. Kharzeev

We suggest the measurement of the integrated asymmetry of teh missing momentum distribution in (e,e$&#39;$p)reactions to check color transparency effects at intermediate momentum transfers.

H. Müther, L. D. Skouras

The effects of correlations on the bulk properties of nuclei are investigated in large model spaces including up to 21 single-particle orbits. The evaluation of the single-particle Green function is made feasible by means of the BAGEL approximation. The spectral function for single-nucleon pick-up and removal is investigated for the nuclei $^{16}O$ and $^{40

E. Hsu, I. Klebanov

We review and extend the computation of scattering amplitudes of tachyons in the $c=1$ matrix model using a manifestly finite prescription for the collective field hamiltonian. We give further arguments for the exactness of the cubic hamiltonian by demonstrating the equality of the loop corrections in the collective field theory with those calculated in the

D. M. Gitman, Sh. M. Shvartsman

Representations of propagators by means of path integrals over velocities are discussed both in nonrelativistic and relativistic quantum mechanics. It is shown that all the propagators can only be expressed through bosonic path integrals over velocities of space-time coordinates. In the representations the integration over velocities is not restricted by any

F. Combes, H. J. de Vega, A. V. Mikhailov, N. Sánchez

{\bf Exact} solutions of the string equations of motion and constraints are {\bf systematically} constructed in de Sitter spacetime using the dressing method of soliton theory. The string dynamics in de Sitter spacetime is integrable due to the associated linear system. We start from an exact string solution $q_{(0)}$ and the associated solution of the linea

Ch. Devchand, V. Ogievetsky

In this talk we review the harmonic space formulation of the twistor transform for the supersymmetric self-dual Yang-Mills equations. The recently established harmonic-twistor correspondence for the N-extended supersymmetric gauge theories is described. It affords an explicit construction of solutions to these equations which displays a remarkable matreoshka

Ch. Devchand, V. Ogievetsky

We describe the harmonic superspace formulation of the Witten-Manin supertwistor correspondence for N=3 extended super Yang-Mills theories. The essence is that on being sufficiently supersymmetrised (up to the N=3 extension), the Yang-Mills equations of motion can be recast in the form of Cauchy-Riemann-like holomorphicity conditions for a pair of prepotenti

L. D. Faddeev, R. M. Kashaev

A quantum generalization of Rogers&#39; five term, or ``pentagon&#39;&#39; dilogarithm identity is suggested. It is shown that the classical limit gives usual Rogers&#39; identity. The case where the quantum identity is realized in finite dimensional space is also considered and the quantum dilogarithm is constructed as a function on Fermat curve, while the

Cumrun Vafa

We review aspects of spacetime singularities from the view point of string theory. Examples considered include cosmological, cosmic string and black-hole singularities. We also discuss the consistency of viewing black-holes as excited states of fundamental strings (based on talk presented at Salamfest, March 1993, Trieste).

B. de Wit, A. Van Proeyen

The moduli space of the Calabi-Yau three-folds, which play a role as superstring ground states, exhibits the same {\em special geometry} that is known from nonlinear sigma models in $N=2$ supergravity theories. We discuss the symmetry structure of special real, complex and quaternionic spaces. Maps between these spaces are implemented via dimensional reducti

S. Dawson, R. Kauffman

We compute analytic results for the QCD corrections to Higgs boson production via gluon fusion in hadronic collisions in the limit in which the top quark is much heavier than the Higgs boson. The first non-leading corrections of $Ø(α_s^3 \mh^2/m_t^2)$ are given and numerical results presented for both LHC and SSC energies. We confirm earlier numerical result

Ernest Ma

Given the conservation of baryon number as well as electron and muon numbers, all present data can be explained without the need of a conserved quantum number for the tau lepton and its neutrino. A supersymmetric extension of the standard model naturally allows for such a scenario. One consequence is that the tau neutrino becomes the lightest supersymmetric

Michael Sotiropoulos, George Sterman

We study the large-$t$ small angle behavior of quark-quark elastic scattering. We employ a factorization procedure previously developed for fixed angle scattering, which depends on the color structure of the factorized hard subprocess. We find an evolution in $t$ that (in leading logarithmic approximation) becomes diagonal in a singlet-octet basis in the $t$

Abdellatif Abada

The soliton breathing mode is investigated in the framework of linear response theory within a Skyrme model vector meson stabilized. The effective Lagrangian considered includes the $ρ$ (introduced following the standard prescription of nonlinear chiral symmetry) and the $ω$ mesons. The monopole response function is found to have a pronounced peak which is i