January 1993 arXiv papers — page 2

M. Yu. Lashkevich

It is shown that zero ghost conformal blocks of coset theory G/H are determined uniquely by those of G and H theories. G/G theories are considered as an example, their structure constants and correlation functions on sphere are calculated.

M. Yu. Lashkevich

We consider a coset construction of minimal models. We define it rigorously and prove that it gives superconformal minimal models. This construction allows to build all primary fields of superconformal models and to calculate their three-point correlation functions.

Darwin Chang, Wai-Yee Keung, Ivan Phillips

We investigate possible CP violating effects in $e^+e^-$ annihilation into top quark pairs. One of the interesting observable effects is the difference in production rates between the two CP conjugate polarized states $t_L\bar t_L$ and $t_R\bar t_R$. The result is an asymmetry in the energy spectra of the lepton and the anti-lepton from the heavy quark decay

Boguslaw Broda

% A new, formal, non-combinatorial approach to invariants of % three-dimensional manifolds of Reshetikhin, Turaev and % Witten in the framework of non-perturbative topological % quantum Chern-Simons theory, corresponding to an arbitrary % compact simple Lie group, is presented. A direct % implementation of surgery instructions in the context of % quantum fie

Kanehisa Takasaki

Previous results on quasi-classical limit of the KP and Toda hierarchies are now extended to the BKP hierarchy. Basic tools such as the Lax representation, the Baker-Akhiezer function and the tau function are reformulated so as to fit into the analysis of quasi-classical limit. Two subalgebras $\WB_{1+\infty}$ and $\wB_{1+\infty}$ of the W-infinity algebras

W. Melnitchouk, A. W. Thomas

We calculate nuclear shadowing in lepton-deuteron deep inelastic scattering, which arises from the double scattering of the virtual photon from both nucleons in the deuteron. The total correction to the deuteron structure function is found to be less than about 1\% at small Bjorken-x, but dependent on the model deuteron wavefunction. The resulting increase i

Daniel Boyanovsky

We study the process of spinodal decomposition in a scalar quantum field theory that is quenched from an equilibrium disordered initial state at $T_i > T_f$ to a final state at $T_f \approx 0$. The process of formation and growth of correlated domains is studied in a Hartree approximation. We find an approximate scaling law for the size of the domains $ξ_D(t

B. Jurco

Star products on the classical double group of a simple Lie group and on corresponding symplectic grupoids are given so that the quantum double and the "quantized tangent bundle" are obtained in the deformation description. "Complex" quantum groups and bicovariant quantum Lie algebras are discused from this point of view. Further we discuss t

Doron Gepner

Recently, string theory on Calabi--Yau manifolds was constructed and was shown to be a fully consistent, space--time supersymmetric string theory. The physically interesting case is the case of three generations. Intriguingly, it appears at the present that there is a unique manifold which gives rise to three generations. We describe in this paper a full fle

N. P. Warner

These lectures review some of the basic properties of $N=2$ superconformal field theories and the corresponding topological field theories. One of my basic aims is to show how the techniques of topological field theory can be used to compute effective \LG potentials for perturbed $N=2$ superconformal field theories. In particular, I will briefly discuss the

Palash B. Pal

In the grand-unified models based on SU(15) and SU(16) in which the quarks and leptons are un-unified at the intermediate stages, we show that ${\rm BR}\; (K_L \to μe) \leq 10^{-14}$ and ${\rm BR}\; (K^+ \to π^+μe) \leq 10^{-14}$ despite the presence of leptoquark gauge bosons. Thus, the observation of these processes in the ongoing or upcoming experiments w

V. A. Naumov, S. I. Sinegovsky, E. V. Bugaev

An effective analytical method for calculating energy spectra of cosmic-ray muons at large depths of homogeneous media is developed. The method allows to include an arbitrary (decreasing) muon spectrum at the medium boundary and the energy dependence of both discrete (radiative and photonuclear) and continuous (ionization) muon energy losses, with resonable

S. Kumano

Gluon distributions in the carbon and tin nuclei are investigated by using a $Q^2$ rescaling model with parton recombination effects. We obtain strong shadowings in the small $x$ region due to the recombinations. The ratio $G_A(x)/G_N(x)$ in the medium $x$ region is typically 0.9 for medium size nuclei. At large $x$, the ratio becomes large due to gluon fusi

Alon E. Faraggi, Edi Halyo

We examine the problem of generation mixing in realistic superstring derived standard--like models, constructed in the free fermionic formulation. We study the possible sources of family mixing in these models . In a specific model we estimate the Cabibbo angle. We argue that a Cabibbo angle of the correct order of magnitude can be obtained in these models.

S. F. Novaes, D. Spehler

A possible way of producing gravitons in the laboratory is investigated. We evaluate the cross section electron + photon $\rightarrow$ electron + graviton in the framework of linearized gravitation, and analyse this reaction considering the photon coming either from a laser beam or from a Compton back-scattering process.

Donald N. Petcher

Summary talk presented at the Conference on Lattice Field Theory, Amsterdam, September, 1992. Abstract: The status of several proposals for defining a theory of chiral fermions on the lattice is reviewed and some new estimates for the upper bound on the Higgs mass are presented.

A. Mailhot, M. L. Plumer

We argue that the analysis of Reimers {\it et al.} [ Phys. Rev. B {\bf 45}, 7295 (1992)] of their Monte Carlo data on the Heisenberg pyrochlore antiferromagnet, which suggests a new universality class, is not conclusive. By re-analysis of their data, we demonstrate asymptotic volume dependence in some thermodynamic quantities, which suggests the possibility

M. L. Plumer, A. Mailhot, R. Ducharme, A. Caillé

Critical properties of the Ising model on a stacked triangular lattice, with antiferromagnetic first and second-neighbor in-plane interactions, are studied by extensive histogram Monte Carlo simulations. The results, in conjunction with the recently determined phase diagram, strongly suggest that the transition from the period-3 ordered state to the paramagn

J. Kellendonk, M. Rösgen, R. Varnhagen

Product forms of characters of Virasoro minimal models are obtained which factorize into $(2,\odd)\times(3,\even)$ characters. These are related by generalized Rogers-Ramanujan identities to sum forms allowing for a quasiparticle interpretation. The corresponding dilogarithm identities are given and the factorization is used to analyse the related path space

Joerg P. Rachen, Peter L. Biermann

We consider the hot spots in FR-II galaxies as sites of first order Fermi acceleration of protons to the highest energies observed in cosmic rays. We estimate the attainable maximum energy in the hot spot region allowed by the canonical physical conditions, which are found from radio-to-optical observations (Meisenheimer et al. 1989, A&A). We calculate obser

D. Bernard, M. Gaudin, F. D. M. Haldane, V. Pasquier

We consider the $ su(n) $ spin chains with long range interactions and the spin generalization of the Calogero-Sutherland models. We show that their properties derive from a transfer matrix obeying the Yang-Baxter equation. We obtain the expression of the conserved quantities and we diagonalize them.

B. Alles, M. Campostrini, A. Feo, H. Panagopoulos

We present a scheme for the analytic computation of renormalization functions on the lattice, using a symbolic manipulation computer language. Our first nontrivial application is a new three-loop result for the topological susceptibility.

A. Ono, H. Horiuchi, T. Maruyama, A. Ohnishi

Momentum distribution of fragments produced in 12C+12C reaction at 28.7 MeV/nucleon is analyzed with antisymmetrized version of molecular dynamics (AMD). Calculations are made for several cases of stochastic collisions and the projectile fragmentation peak in momentum distribution is reproduced by the incorporation of many-body nature in stochastic collision

N. Auerbach, D. C. Zheng, L. Zamick, B. A. Brown

Relations between the total beta+ Gamow-Teller (GT+) strength and the E2 strength are further examined. It is found that in shell-model calculations for N=Z nuclei, in which changes in deformation are induced by varying the single-particle energies, the total GT+ or GT- strength decreases monotonically with increasing values of the B(E2) from the ground stat

A. H. Bougourzi

Four apparently different bosonizations of the $U_q(su(2)_k)$ quantum current algebra for arbitrary level $k$ have recently been proposed in the literature. However, the relations among them have so far remained unclear except in one case. Assuming a special standard form for the $U_q(su(2)_k)$ quantum currents, we derive a set of general consistency equatio

Sudhakar Panda, Shibaji Roy

The Symmetry charges associated with the Lian-Zuckerman states for $d<2$ closed string theory are constructed. Unlike in the open string case, it is shown here that the symmetry charges commute among themselves and act trivially on all the physical states.

Stephen G. Naculich

Relations among fermion masses and mixing angles at the scale of grand unification are modified at lower energies by renormalization group running induced by gauge and Yukawa couplings. In supersymmetric theories, the $b$ quark and $τ$ lepton Yukawa couplings, as well as the $t$ quark coupling, may cause significant running if $\tan β$, the ratio of Higgs fi

V. M. Belyaev

We consider the QCD sum rules approach for Delta-isobar magnetic form factor in the infra-red region $0<Q^2<1GeV^2$. The QCD sum rules in external variable field are used. The obtained formfactor is in agreement with quark model predictions for the Delta-isobar magnetic moment.

M. C. Diamantini G. W. Semenoff P. Sodano

We examine the possibility of fermion mass generation in 2+1- dimensional gauge theory from the current algebra point of view.In our approach the critical behavior is governed by the fluctuations of pions which are the Goldstone bosons for chiral symmetry breaking. Our analysis supports the existence of an upper critical number of Fermion flavors and exhibit

Brian Hendee Smith

A diagrammatic technique is derived for calculating processes involving the production of large numbers of particles. As an example, the amplitude of three particles scattering into $n$ particles at the kinematical threshold in $λϕ^4$ theory is calculated. From the $3 \to n$ amplitude, it is seen that the one-loop amplitude for $2 \to n$ processes is suppres

P. Chiappetta, M. Greco, J. Ph. Guillet, S. Rolli

We perform a complete next to leading order evaluation of inclusive neutral pion production from hadronic colliders which is based on the knowledge of the pion fragmentation functions at next to leading order. This problem has been tackled for the first time using different approaches. Predictions at LHC are given with the estimate of the theoretical uncerta

F. E. Close, Nathan Isgur, S. Kumano

Existing predictions for the branching ratio for $ϕ\rightarrow K\bar{K}γ$ {\it via} $ϕ\rightarrow Sγ$ (where $S$ denotes one of the scalar mesons $f_0$(975) and $a_0$(980)) vary by several orders of magnitude. Given the importance of these processes for both hadron spectroscopy and CP-violation studies at $ϕ$ factories (where $ϕ\rightarrow K^0 \bar K^0 γ$ po

M. C. Diamantini E. Langmann G. W. Semenoff P. Sodano

We examine the strong coupling limit of both compact and non compact QED on a lattice with staggered fermions. We show that every SU(N) antiferromagnet with spins in a particular fundamental representation of the SU(N) Lie Algebra and with nearest neighbor couplings on a bipartite lattice is exactly equivalent to the infinite coupling limit of lattice QED wi

David J. E. Callaway

Magnetic flux penetration in superconductors involves a rich variety of subtle phenomena, much of which is still poorly understood. Here these complexities are studied by formulating the Ginzburg-Landau equations as a lattice gauge theory. Their solutions are compared and contrasted with the (heuristic) Landau model of type I superconductivity, and the (pert

Martin Grabenstein, Bernhard Mikeska

We study the dynamical critical behavior of multigrid Monte Carlo for the two dimensional Sine Gordon model on lattices up to 128 x 128. Using piecewise constant interpolation, we perform a W-cycle (gamma=2). We examine whether one can reduce critical slowing down caused by decreasing acceptance rates on large blocks by doing more work on coarser lattices. T

Kevin Cahill

Wilson loops have been measured at strong coupling, $β=0.5$, on a $12^4$ lattice in noncompact simulations of pure SU(2) without gauge fixing. There is no sign of quark confinement.

Andrey V. Chubukov, Subir Sachdev

We present the theory of two-dimensional, clean quantum antiferromagnets with a small, positive, zero temperature ($T$) stiffness $ρ_s$, but with the ratio $k_B T / ρ_s $ arbitrary. Universal scaling forms for the uniform susceptibility ($χ_u$), correlation length($ξ$), and NMR relaxation rate ($1/T_1$) are proposed and computed in a $1/N$ expansion and by M

Ned S. Wingreen, Antti-Pekka Jauho, Yigal Meir

We present a general formulation of the nonlinear, time-dependent current through a small interacting region, where electron energies are changed by time-dependent voltages. An exact solution is obtained for the non-interacting case when the elastic coupling to the leads is independent of energy. Temporal phase coherence in a double-barrier tunneling structu

A. Sanchez, F. Dominguez-Adame

We consider a one-dimensional continuous (Kronig-Penney) extension of the (tight-binding) Random Dimer model of Dunlap et al. [Phys. Rev. Lett. 65, 88 (1990)]. We predict that the continuous model has infinitely many resonances (zeroes of the reflection coefficient) giving rise to extended states instead of the one resonance arising in the discrete version.

Andrew H. Jaffe, Albert Stebbins, Joshua A. Frieman

Aside from primordial gravitational instability of the cosmological fluid, various mechanisms have been proposed to generate large-scale structure at relatively late times, including, e.g., ``late-time&#39;&#39; cosmological phase transitions. In these scenarios, it is envisioned that the universe is nearly homogeneous at the time of last scattering and that

David Bowser-Chao, Kingman Cheung

We consider the possibility of detecting a heavy Higgs boson ($m_H>2m_Z$) in proposed $γγ$ colliders through the semi-leptonic mode $γγ\rightarrow H \rightarrow ZZ \rightarrow q\bar q \ell^+\ell^-$. We show that due to the non-monochromatic nature of the photon beams produced by the laser-backscattering method, the resultant cross section for Higgs productio

D. C. Zheng, J. P. Vary, B. R. Barrett

We demonstrate with soluble models how to employ the effective Hamiltonian approach of Lee and Suzuki to obtain all the exact eigenvalues of the full Hamiltonian. We propose a new iteration scheme to obtain the effective Hamiltonian and demonstrate its convergence properties.

M. F. Jiang, R. Machleidt, T. T. S. Kuo

A relativistic extension of the particle-particle hole-hole ring-diagram many-body formalism is developed by using the Dirac equation for single-particle motion in the medium. Applying this new formalism, calculations are performed for nuclear matter. The results show that the saturation density is improved and the equation of state becomes softer as compare

Alan R. White, Ian G. Knowles, Kyungsik Kang

The $η_6$ is a ``heavy axion&#39;&#39; remnant of dynamical electroweak symmetry breaking by a color sextet quark condensate. Electroweak scale color instanton interactions allow it to be both very massive and yet be responsible for Strong CP conservation in the color triplet quark sector. It may have been seen at LEP via its two-photon decay mode and at TRI

Yue Shen

We show that at arbitrary value of the scalar self coupling and small Yukawa coupling $y$ the 2d Higgs-Yukawa model with Z(2) symmetry remains in the broken phase and the model is asymptotically free: $y \to 0$ as the cut-off $Λ\to \infty$. This is in agreement with a recent conjecture based on numerical simulation results.

John McCabe

We show how to quantize the anyon particle theory in the gauge $A_x=0$, where the statistical potential $\vec A(\vec x)$ is a Dirac string. In this gauge, anyons obey normal statistics.

A. E. Rana, S. M. Girvin

We present a `supersymmetric&#39; modification of the $d$-dimensional quantum rotor model whose ground state is exactly soluble. The model undergoes a vortex-binding transition from insulator to metal as the rotor coupling is varied. The Hamiltonian contains three-site terms which are relevant: they change the universality class of the transition from that o

A. Aure, W. Decker, K. Hulek, S. Popescu

In 1988 Serrano \cite{Ser}, using Reider&#39;s method, discovered a minimal bielliptic surface in $\PP^4$. Actually he showed that there is a unique family of such surfaces and that they have degree 10 and sectional genus 6. In this paper we describe, among other things, the geometry of the embedding of the minimal bielliptic surfaces. A consequence of this

Jun Liu

In the formulation of Banks, Peskin and Susskind, we show that one can construct evolution equations for the quantum mechanical density matrix $ρ$ with operators which do not commute with hamiltonian which evolve pure states into mixed states, preserve the normalization and positivity of $ρ$ and conserve energy. Furthermore, it seems to be different from a q

Alain Dasnieres de Veigy, Stephane Ouvry

We define a Chern- Simons Lagrangian for a system of planar particles topologically interacting at a distance. The anyon model appears as a particular case where all the particles are identical. We propose exact N-body eigenstates, set up a perturbative algorithm, discuss the case where some particles are fixed on a lattice, and also consider curved manifold

S. Mukhi, C. Vafa, E. Frenkel

We show that a special superconformal coset (with $\hat c =3$) is equivalent to $c=1$ matter coupled to two dimensional gravity. This identification allows a direct computation of the correlation functions of the $c=1$ non-critical string to all genus, and at nonzero cosmological constant, directly from the continuum approach. The results agree with those of

I. Ya. Aref&#39;eva

To study the behavior of the Kazakov-Migdal at large N the quenched momentum prescription with constraints for treating the large N limit of gauge theories is used. It is noted that it leads to a quartic dependence of an action on unitary matrix instead of a quadratic dependence discussed in previous considerations. Therefore the model is not exactly solvabl

P. Dargis, P. Mathieu

The \nl \cls for the N=1 supersymmetric KdV equation are shown to be related in a simple way to powers of the fourth root of its Lax operator. This provides a direct link between the supersymmetry invariance and the existence of \nl conservation laws. It is also shown that nonlocal conservation laws exist for the two integrable N=2 supersymmetric KdV equatio

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

The moduli dependent Yukawa couplings between twisted sectors of ${\bf Z}_M\times {\bf Z}_N$ Coxeter orbifolds are studied.

C. M. Yung, Roland C. Warner

We construct the $N=2$ super $W_4$ algebra as a certain reduction of the second Gel&#39;fand-Dikii bracket on the dual of the Lie superalgebra of $N=1$ super pseudo-differential operators. The algebra is put in manifestly $N=2$ supersymmetric form in terms of three $N=2$ superfields $Φ_i(X)$, with $Φ_1$ being the $N=2$ energy momentum tensor and $Φ_2$ and $Φ

Eric D&#39;Hoker, Pierre Sikivie

We consider a string with uniform energy density and tension and with a number of pointlike masses attached at fixed interdistances. We evaluate the effective interaction forces between these masses induced by the quantum fluctuations of the string. For interdistances large compared to the thickness of the string and small compared to the total length, these

Sumantra Chakravarty, Sun Myong Kim, Pyungwon Ko

Assuming the QCD multipole expansion is applicable to hadronic transitions of Upsilon(3S) into lower level bottomonia, we consider the possibility that Upsilon(3S) has a D-wave component. This assumption leads to a natural explanation of the pi-pi spectrum in Upsilon(3S) -> Upsilon(1S) pi-pi. Consequences of this assumption on other hadronic and radiative tr

Gerard Jungman

Yukawa coupling constant unification together with the known fermion masses is used to constrain SO(10) models. We consider the case of one (heavy) generation, with the tree-level relation $m_b=m_τ$, calculating the limits on the intermediate symmetry breaking scales. This analysis extends previous analyses which addressed only the simplest symmetry breaking

Kai T. Hansen

The singular bifurcations in a dispersive billiard are discussed in terms of symbolic dynamics and is compared to an example of a bifurcation tree in a smooth potential. Possible generalizations to other smooth potentials are discussed.

Kai T. Hansen

We construct a well ordered symbolic dynamics plane for the stadium billiard. In this symbolic plane the forbidden and the allowed orbits are separated by a monotone pruning front, and allowed orbits can be systematically generated by sequences of approximate finite grammars.

Kai T. Hansen

Orbits in different dispersive billiard systems, e.g. the 3 disk system, are mapped into a topological well ordered symbol plane and it is showed that forbidden and allowed orbits are separated by a monotone pruning front. The pruning front can be approximated by a sequence of finite symbolic dynamics grammars.

J. David Brown, James W. York

The authors have introduced recently a ``microcanonical functional integral&#34; which yields directly the density of states as a function of energy. The phase of the functional integral is Jacobi&#39;s action, the extrema of which are classical solutions at a given energy. This approach is general but is especially well suited to gravitating systems because

J. Harnad

The Hamiltonian structure of the monodromy preserving deformation equations of Jimbo {\it et al } is explained in terms of parameter dependent pairs of moment maps from a symplectic vector space to the dual spaces of two different loop algebras. The nonautonomous Hamiltonian systems generating the deformations are obtained by pulling back spectral invariants

Kanehisa Takasaki, Takashi Takebe

Previous results on quasi-classical limit of the KP hierarchy and its W-infinity symmetries are extended to the Toda hierarchy. The Planck constant $\hbar$ now emerges as the spacing unit of difference operators in the Lax formalism. Basic notions, such as dressing operators, Baker-Akhiezer functions and tau function, are redefined. $W_{1+\infty}$ symmetries

L. Begin, Anatol N. Kirillov, P. Mathieu, M. A. Walton

We present a general scheme for describing su(N)_k fusion rules in terms of elementary couplings, using Berenstein-Zelevinsky triangles. A fusion coupling is characterized by its corresponding tensor product coupling (i.e. its Berenstein-Zelevinsky triangle) and the threshold level at which it first appears. We show that a closed expression for this threshol

Farhad Ardalan

\small The SL$(2,R)/U(1)$ coset model, with $U(1)$ an element of the third conjugacy class of $SL(2,R)$ subgroups, is considered. The resulting theory is seen to collapse to a one dimensional field theory of Liouville. Then the 2 dimensional black hole $SL(2,R)/U(1)$, with $U(1)$ a non-compact subgroup boosted by a Lorentz transformation, is considered. In t

J. L. Cortés, J. Gamboa, L. Velázquez

A new formulation for fermions on the lattice based on a discretization of a second order formalism is proposed. A comparison with the first order formalism in connection with the $U(1)$ anomaly and the doubling problem is presented. The new formulation allows to eliminate half of the degrees of freedom, which can be important in non-perturbative calculation

J. L. Cortés, J. Gamboa, L. Velázquez

A new formulation of fermions based on a second order action is proposed. An analysis of the $U(1)$ anomaly allows us to test the validity of the formalism at the quantum level. This formulation gives a new perpective to the introduction of parity non-invariant interactions.

Wei Chen, Yuri Makeenko, Gordon W Semenoff

We employ the conformal bootstrap to re-examine the problem of finding the critical behavior of four-Fermion theory at its strong coupling fixed point. Existence of a solution of the bootstrap equations indicates self-consistency of the assumption that, in space-time dimensions less than four, the renormalization group flow of the coupling constant of a four

David J. Gross, Washington Taylor

The partition function of two dimensional QCD on a Riemann surface of area $A$ is expanded as a power series in $1/N$ and $A$. It is shown that the coefficients of this expansion are precisely determined by a sum over maps from a two dimensional surface onto the two dimensional target space. Thus two dimensional QCD has a simple interpretation as a closed st

E. Kh. Akhmedov, S. T. Petcov, A. Yu. Smirnov

We show that a left-handed neutrino $ν_L$ can oscillate into its $CP$- conjugated state $\barν_R$ with maximal amplitude, in direct analogy with $K^0-\bar{K}^0$ oscillations. Peculiarities of such oscillations under different conditions are studied.

Harry J. Lipkin

Overwhelming experimental evidence for quarks as real physical constituents of hadrons along with the QCD analogs of the Balmer Formula, Bohr Atom and Schroedinger Equation already existed in 1966. A model of colored quarks interacting with a one-gluon-exchange potential explained the systematics of the meson and baryon spectrum and gave a hadron mass formul

Paolo Rossi, Ettore Vicari

Finite size effects in Euclidean ${\rm CP}^{N-1}$ models with periodic boundary conditions are investigated by means of the $1/N$ expansion and by Monte Carlo simulations. Analytic and numerical results for magnetic susceptibility and correlation length are compared and found to agree for small volumes. For large volumes a discrepancy is found and explained

S. W. Hawking, R. Laflamme, G. W. Lyons

It is argued that the observed Thermodynamic Arrow of Time must arise from the boundary conditions of the universe. We analyse the consequences of the no boundary proposal, the only reasonably complete set of boundary conditions that has been put forward. We study perturbations of a Friedmann model containing a massive scalar field but our results should be

I. Vattulainen, K. Kankaala, J. Saarinen, T. Ala-Nissila

We have carried out extensive statistical, bit level and visual tests of several random number generators used in the applications of physics. Two of the generators tested were recently included in a paper by Ferrenberg {\it et al.} (Phys. Rev. Lett. {\bf 68}, 3382 (1992)) who reported correlations in their Monte Carlo simulations. As a possible explanation

J. E. Howe, D. T. Jaffe, E. N. Grossman, W. F. Wall

We mapped quiescent 807 GHz CO(7-6) emission from Orion along a strip in RA extending from 0.7 pc west to 1.2 pc east of Ori theta 1C. The lines arise in warm gas with T > 40 K. The line brightness temperature is > 160 K in the di- rection of theta 1C, more than twice the dust temperature, and still exceeds 35 K more than a parsec east of theta 1C. The lines

Sherman Frankel, William Frati, Niels R. Walet

We study nuclear structure effects on the transparency in high transverse momentum $(p,2p)$ and $(e,e&#39;p)$ reactions. We show that in the DWIA-eikonal approximation, even when correlations are included, one can get a factorized expression for the transparency. This depends only on the average nucleon density $ρ(r)$ and a correlation function. We develop a

Michele Maggiore

We discuss a Gedanken experiment for the measurement of the area of the apparent horizon of a black hole in quantum gravity. Using rather general and model-independent considerations we find a generalized uncertainty principle which agrees with a similar result obtained in the framework of string theories. The result indicates that a minimum length of the or

Galen Sotkov, Marian Stanishkov

We find an infinite set of new noncommuting conserved charges in a specific class of perturbed CFT&#39;s and present a criterion for their existence.They appear to be higher momenta of the already known commuting conserved currents.The algebra they close consists of two noncommuting$W_\infty$ algebras.We find various Virasoro subalgebras of the full symmetry

Alexander Turbiner

A general classification of linear differential and finite-difference operators possessing a finite-dimensional invariant subspace with a polynomial basis (the generalized Bochner problem) is given. The main result is that any operator with the above property must have a representation as a polynomial element of the universal enveloping algebra of some algeb

I. Ya. Aref&#39;eva

A simple lattice model inducing a gauge theory is considered. The model describes an interaction of a gauge field to an $N\times N$ complex matrix scalar field transforming as a field in the fundamental representation. In contrast to the Kazakov-Migdal model the model contains only the linear interaction between scalar and gauge lattice fields. This model do

Ernest Ma, Daniel Ng

There is a good reason why the standard electroweak SU(2) X U(1) gauge model may be supplemented by two Higgs scalar doublets. They may be remnants of the spontaneous breaking of an SU(2) X SU(2) X U(1) gauge symmetry at a much higher energy scale. In one case, the two-doublet Higgs potential has a custodial SU(2) symmetry and implies an observable scalar tr

J. Stern, H. Sazdjian, N. H. Fuchs

We describe a rearrangement of the standard expansion of the symmetry breaking part of the QCD effective Lagrangian that includes into each order additional terms which in the standard chiral perturbation theory ($χ$PT) are relegated to higher orders. The new expansion represents a systematic and unambiguous generalization of the standard $χ$PT, and is more

Lee Brekke, Shane J. Hughes, Tom D. Imbo

We examine the various linkings in space-time of ``ball-like&#39;&#39; and ``ring-like&#39;&#39; topological solitons in certain nonlinear sigma models in 2+1 and 3+1 dimensions. By going to theories where soliton overlaps are forbidden, these linkings become homotopically nontrivial and can be studied by investigating the topology of the corresponding confi

A. J. Niemi, O. Tirkkonen

Some mistakes have been corrected

Lee Smolin

An error in the gauge fixed quantization of section 3 is corrected. The result is a much simpler treatment of the clock field, leading to a simplification of the gauge fixed quantum theory and the treatment of the semiclassical limit.

David Seibert

I discuss methods for identifying and quantifying phase transitions in particle collisions, concentrating on two techniques for use in ultra-relativistic nuclear collisions. The first technique is to use rapidity correlation measurements to determine the correlation length, while the second is to use the transverse mass distribution of dileptons in the rho-o

Michael C. Laskowski, Saharon Shelah

We give an example of a countable theory T such that for every cardinal lambda >= aleph_2 there is a fully indiscernible set A of power lambda such that the principal types are dense over A, yet there is no atomic model of T over A. In particular, T(A) is a theory of size lambda where the principal types are dense, yet T(A) has no atomic model.

Alain Louveau, Boban Veličković, Saharon Shelah

A theorem of Galvin asserts that if the unordered pairs of reals are partitioned into finitely many Borel classes then there is a perfect set P such that all pairs from P lie in the same class. The generalization to n-tuples for n >= 3 is false. Let us identify the reals with 2^omega ordered by the lexicographical ordering and define for distinct x,y in 2^om

John T. Baldwin, Michael C. Laskowski, Saharon Shelah

A forcing extension may create new isomorphisms between two models of a first order theory. Certain model theoretic constraints on the theory and other constraints on the forcing can prevent this pathology. A countable first order theory is classifiable if it is superstable and does not have either the dimensional order property or the omitting types order p

Paul C. Eklof, Saharon Shelah

A new construction is given of non-standard uniserial modules over certain valuation domains; the construction resembles that of a special Aronszajn tree in set theory. A consequence is the proof of a sufficient condition for the existence of non-standard uniserial modules; this is a theorem of ZFC which complements an earlier independence result.

Tomek Bartoszyński, Martin Goldstern, Haim Judah, Saharon Shelah

We show that it is consistent with ZFC that all filters which have the Baire property are Lebesgue measurable. We also show that the existence of a Sierpinski set implies that there exists a nonmeasurable filter which has the Baire property.

Saharon Shelah, Heikki Tuuri, Jouko Väänänen

Let s(A) denote the number of automorphisms of a model A of power omega_1. We derive a necessary and sufficient condition in terms of trees for the existence of an A with omega_1 < s(A) < 2^{omega_1}. We study the sufficiency of some conditions for s(A)=2^{omega_1}. These conditions are analogous to conditions studied by D.Kueker in connection with countable

Alan H. Mekler, Saharon Shelah

We show that if we enrich first order logic by allowing quantification over isomorphisms between definable ordered fields the resulting logic, L(Q_{Of}), is fully compact. In this logic, we can give standard compactness proofs of various results. Next, we attempt to get compactness results for some other logics without recourse to diamond, i.e., all our resu

Alan H. Mekler, Evelyn Nelson, Saharon Shelah

In the literature two notions of the word problem for a variety occur. A variety has a decidable word problem if every finitely presented algebra in the variety has a decidable word problem. It has a uniformly decidable word problem if there is an algorithm which given a finite presentation produces an algorithm for solving the word problem of the algebra so

C. M. Hull

The higher-spin geometries of $W_\infty$-gravity and $W_N$-gravity are analysed and used to derive the complete non-linear structure of the coupling to matter and its symmetries. The symmetry group is a subgroup of the symplectic diffeomorphisms of the cotangent bundle of the world-sheet, and the $W_N$ geometry is obtained from a non-linear truncation of the

John C. Baez

Given a principal G-bundle over a smooth manifold M, with G a compact Lie group, and given a finite-dimensional unitary representation of G, one may define an algebra of functions on the space of connections modulo gauge transformations, the ``holonomy Banach algebra&#39;&#39; H_b, by completing an algebra generated by regularized Wilson loops. Elements of t

Louis Crane, David N. Yetter

We construct a four dimensional topological Quantum Field Theory from a modular tensor category. We complete the proof in the case of SU(2)q at a root of unity. Our construction may be important in the physical interpretation of the Chern Simons state in the Ashtekar variables.

Louis Crane

I propose a new mathematical form for the quantum theory of gravity coupled to matter. The motivation is from the connection between CSW TQFT and the Ashtekar variables. I also connect the algebraic structure of TQFT with some thoughts about the interpretation of quantum mechanics in a general relativistic setting.

Amitabha Lahiri

If the Higgs particle is never found, one will need an alternative theory for vector boson masses. I propose such a theory involving an antisymmetric tensor potential coupled to a gauge field.