September 1997 arXiv papers — page 6

Jean-Michel Kantor

Among integral polytopes (vertices with integral coordinates), lattice-free polytopes - intersecting the lattice ONLY at their vertices- are of particular interestin combinatorics and geometry of numbers. A natural question is to measure their "width" (with respect to the integral lattice).There were no known examples of lattice-free polytopes with w

E. Cheu

We, the KAMI (Kaons at the Main Injector) collaboration, express our interest to continue the experimental program of rare kaon decay physics at Fermilab using the Main Injector. KAMI's primary physics goals shall be: 1. The first detection of the rare, direct CP violating decay K_L --> pi0 nu nu_bar and measurement of its branching ratio with an accurac

S. V. Kravchenko, D. Simonian, M. P. Sarachik, A. D. Kent

The suppression by a magnetic field of the anomalous H=0 conducting phase in high-mobility silicon MOSFETs is independent of the angle between the field and the plane of the 2D electron system. In the presence of a parallel field large enough to fully quench the anomalous conducting phase, the behavior is similar to that of disordered GaAs/AlGaAs heterostruc

M. V. Polyakov, C. Weiss

We review the description of nucleon structure functions in the instanton vacuum. This includes the calculation of the twist-2 parton distributions at a low normalization point as well as higher-twist matrix elements. The instanton vacuum with its inherent small parameter, the packing fraction of the instanton medium, $\barρ/ R$, provides a consistent pictur

Z. Maassarani

The one-dimensional Hubbard model is known to possess an extended su(2) symmetry and to be integrable. I introduce an integrable model with an extended su(n) symmetry. This model contains the usual su(2) Hubbard model and has a set of features that makes it the natural su(n) generalization of the Hubbard model. Complete integrability is shown by introducing

Daniel Schaerer

We discuss recent results on the ionizing fluxes of O stars obtained from our "combined stellar structure and atmosphere models" (CoStar) accounting for stellar winds, non-LTE effects and line blanketing. The implications on the ionization structure of HII regions are summarized, and observational constraints on the ionizing spectra and the total ionizing ph

Sumati Surya, Sachindeo Vaidya

In this note we study the structure of diffeomorphism anomalies in 3+1 canonical gravity coupled to a chiral massless fermion. We find that when the spatial manifold is S^3 or a Lens space L(p,q), the first homotopy group of the related diffeomorphism group can be nontrivial and hence the question of global anomalies becomes relevant. Here we show that for g

Victor T. Kim, Grigorii B. Pivovarov

A discrepancy between new data on inclusive single jet production at the Fermilab Tevatron and perturbative QCD is discussed. It is shown that the discrepancy may be accounted for by the BFKL Pomeron.

Alexei Ashikhmin, Simon Litsyn

Several upper bounds on the size of quantum codes are derived using the linear programming approach. These bounds are strengthened for the linear quantum codes.

A. Zabrodin

Local M-operators for the classical sine-Gordon model in discrete space-time are constructed by convolution of the quantum trigonometric 4$\times$4 R-matrix with certain vectors in its "quantum" space. Components of the vectors are identified with $τ$-functions of the model. This construction generalizes the known representation of M-operators in con

Steven Corley, Ted Jacobson

We study the Hawking process on lattices falling into static black holes. The motivation is to understand how the outgoing modes and Hawking radiation can arise in a setting with a strict short distance cutoff in the free-fall frame. We employ two-dimensional free scalar field theory. For a falling lattice with a discrete time-translation symmetry we use ana

Jamal Jalilian-Marian, Alex Kovner, Heribert Weigert

We derive the complete Wilson renormalization group equation which governs the evolution of the gluon distribution and other gluonic observables at low $x$ and arbitrary density.

M. Schechter, Y. Imry, Y. Levinson

The effect of the barrier on the proximity effect in normal-superconductor junction is analyzed. A general criterion for the barrier, though large, to be effectively transparent, is given. This criterion is applied to both the conductance of a disordered NS junction (reflectionless tunneling) and the density of states across it, showing that both phenomena s

D. C. Brody, L. P. Hughston

The phase space of quantum mechanics can be viewed as the complex projective space endowed with a Kaehlerian structure given by the Fubini-Study metric and an associated symplectic form. We can then interpret the Schrodinger equation as generating a Hamiltonian dynamics. Based upon the geometric structure of the quantum phase space we introduce the correspon

Domingos Alves, J. F. Fontanari

A simple analytical framework to study the molecular quasispecies evolution of finite populations is proposed, in which the population is assumed to be a random combination of the constiyuent molecules in each generation,i.e., linkage disequilibrium at the population level is neglected. In particular, for the single-sharp-peak replication landscape we invest

H. Kharraziha, L. Lonnblad

We present an implementation of the Linked Dipole Chain model for deeply inelastic ep scattering into the framework of the Ariadne event generator. Using this implementation we obtain results both for the inclusive structure function as well as for exclusive properties of the hadronic final state. (The original publication was based on results from an implem

Thomas Buchert, Alvaro Dominguez, Juan Perez-Mercader

We propose a phenomenological generalization of the models of large-scale structure formation in the Universe by gravitational instability in two ways: we include pressure forces to model multi-streaming, and noise to model fluctuations due to neglected short-scale physical processes. We show that pressure gives rise to a viscous-like force of the same chara

A. U. Klimyk

The main aim of this paper is to give classes of irreducible infinite dimensional representations and of irreducible $*$-representations of the q-deformed algebra $U'_q(so_{2,2})$ which is a real form of the non-standard deformation $U'_q(so_4)$ of the universal enveloping algebra $U(so(4,C))$. These representations are described by two complex param

Weiqiang Wang

We introduce a tensor category O_+ (resp. O_{-}) of certain modules of gl_{\infty} with non-negative (resp. non-positive) integral central charges with the usual tensor product. We also introduce a tensor category O_f consisting of certain modules over GL(N) for all N. We show that the tensor categories O_+, O_{-} and O_f are semisimple abelian and all equiv

A. Aguado, A. Ayuela, J. M. Lopez, J. A. Alonso

The structural and bonding properties of small neutral alkali-halide clusters (AX)n, with n less than or equal to 10, A=Li, Na, K, Rb and X=F, Cl, Br, I, are studied using the ab initio Perturbed Ion (aiPI) model and a restricted structural relaxation criterion. A trend of competition between rock-salt and hexagonal ring-like isomers is found and discussed i

Aric Hagberg, Ehud Meron

We present a new set of kinematic equations for front motion in bistable media. The equations extend earlier kinematic approaches by coupling the front curvature with the order parameter associated with a parity breaking front bifurcation. In addition to naturally describing the core region of rotating spiral waves the equations can be be used to study the n

D. Vretenar, W. Pöschl, G. A. Lalazissis, P. Ring

The Relativistic Hartree Bogoliubov model in coordinate space, with finite range pairing interaction, is applied to the description of $Λ$-hypernuclei with a large neutron excess. The addition of the $Λ$ hyperon to Ne isotopes with neutron halo can shift the neutron drip by stabilizing an otherwise unbound core nucleus. The additional binding of the halo neu

Azwinndini Muronga, Jean Cleymans

Strange particle enhancement in relativistic ion collisions is discussed with particular attention to the dependence on the size of the volume and/or the baryon number of the system.

Daniel T. Wise

Let $ϕ:G\rightarrow G$ be an endomorphism of a finitely generated residually finite group. R.~Hirshon asked if there exists~$n$ such that the restriction of $ϕ$ to $ϕ^n(G)$ is injective. We give an example to show that this is not always the case.

Ken D. Olum

We call a state ``vacuum bounded'' if every measurement performed outside a specified interior region gives the same result as in the vacuum. We compute the maximum entropy of a vacuum-bounded state with a given energy for a one-dimensional model, with the aid of numerical calculations on a lattice. For large energies we show that a vacuum-bounded sy

Alfredo T. Suzuki, Alexandre G. M. Schmidt

In this sequel calculation of the one-loop Feynman integral pertaining to a massive box diagram contributing to the photon-photon scattering amplitude in quantum electrodynamics, we present the six solutions as yet unknown in the literature. These six new solutions arise quite naturally in the context of negative dimensional integration approach, revealing a

Pierre Grangé, Peter Ullrich, Ernst Werner

A genuine continuum treatment of the massive ϕ^4_{1+1}-theory in light-cone quantization is proposed. Fields are treated as operator valued distributions thereby leading to a mathematically well defined handling of ultraviolet and light cone induced infrared divergences and of their renormalization. Although non-perturbative the continuum light cone approach

Glenn Barnich

In the first part the sh Lie structure of brackets in field theory, described in the jet bundle context along the lines suggested by Gel'fand, Dickey and Dorfman, is analyzed. In the second part, we discuss how this description allows us to find a natural relation between the Batalin-Vilkovisky antibracket and the Poisson bracket.

A N Theron, F G Scholtz, H B Geyer

We show how to bosonize two-dimensional non-abelian models using finite chiral determinants calculated from a Gauss decomposition. The calculation is quite straightforward and hardly more involved than for the abelian case. In particular, the counterterm $A\bar A$, which is normally motivated from gauge invariance and then added by hand, appears naturally in

Franco Ferrari, Jan T. Sobczyk

A new approach to analyze the properties of the energy-momentum tensor $T(z)$ of conformal field theories on generic Riemann surfaces (RS) is proposed. $T(z)$ is decomposed into $N$ components with different monodromy properties, where $N$ is the number of branches in the realization of RS as branch covering over the complex sphere. This decomposition gives

S. Moretti, K. Odagiri

The production of top quarks in single mode at future ep colliders is studied, the attention being mainly focused to the case of the proposed LEPXLHC collider. We are motivated to reanalyse such a process following the discovery of the top quark at Fermilab. Thanks to the measurement of its mass one is now able to establish more accurately the relevance of s

Y. N. Srivastava, A. Widom, J. Swain

The thermodynamic equations of state for Majorana and Dirac fermions are quite different even in the limit of zero mass. The corresponding equations are derived from general principles, and then applied to neutrinos. The nature of the approach to equilibrium is explored, along with the subtleties of low or zero mass neutrinos interacting via purely left-hand

Ambar Ghosal, Anirban Kundu, Biswarup Mukhopadhyaya

We show the usefulness of an $e^-γ$ collider with backscattered laser photons in unveiling the signatures of Gauge-Mediated Supersymmetry Breaking models, with a right selectron as the next LSP. We also show how the signal can be distinguished from the Standard Model background as well as from signals of minimal supersymmetry.

Eduardo de Rafael

Invited talk given at the conference QCD97, Montpellier, France. I report on rec ent work done in collaboration with Laurent Lellouch and Josep Taron concerning the derivation of rigorous lower bounds for the combination of light quark massese s m_s + m_u and m_d + m_u.

W. J. Stirling

The strong coupling alpha_s is a fundamental parameter of the Standard Model. In comparison to parameters like alpha_em and M_Z it is relatively poorly known. However the precision of alpha_s measurements has improved dramatically in recent years. More than twenty different types of process, from lattice QCD studies to the highest energy colliders, can be us

N. N. Scoccola

We study the parity violating hyperon non-leptonic weak decays in the three flavor Skyrme model. We follow the approach in which the symmetry breaking terms in the action are diagonalized exactly within the collective coordinate approximation. We show that although this method introduces some configuration mixing, the $ΔI =1/2$ rule is numerically well satis

G. Ridolfi

I discuss some aspects of the comparison between QCD predictions and experimental data in charm and bottom production.

Peter Kroll

The present status of the diquark model for exclusive reactions at moderately large momentum transfer is reviewed. That model is a variant of the Brodsky-Lepage approach in which diquarks are considered as quasi-elementary constituents of baryons. Recent applications of the diquark model, relevant to high energy physics with electromagnetic probes, are discu

H. Jung

The concept of resolved virtual photons in addition to direct deep inelastic $ep$ scattering is used to simulate the 2+1 jet - rate and the forward jet cross section, which cannot be described by direct LO/NLO processes. With standard DGLAP evolution of the parton densities of the virtual photon and the proton the HERA data can be described, provided a suffi

J. S. Rozowsky

We show how Feynman diagrams may be evaluated to take advantage of recent developments in the application of Cutkosky rules to the calculation of one-loop amplitudes. A sample calculation of gg->gH, previously calculated by Ellis et al., is presented illustrating this equivalence. This example demonstrates the use of cutting rules for massive amplitudes.

J. J. Godina, Y. Meurice, M. B. Oktay, S. Niermann

The goal of this article is to provide a practical method to calculate, in a scalar theory, accurate numerical values of the renormalized quantities which could be used to test any kind of approximate calculation. We use finite truncations of the Fourier transform of the recursion formula for Dyson's hierarchical model in the symmetric phase to perform h

Stefan Sint, Peter Weisz

Using the Schrödinger functional we have computed a variety of renormalized on-shell correlation functions to one-loop order of perturbation theory. By studying their approach to the continuum limit we have determined the O($a$) counterterms needed to improve the quark mass and a number of isovector quark bilinear operators.

Thomas DeGrand, Anna Hasenfratz, Tamas G. Kovacs

We study the topological content of the vacuum of SU(2) pure gauge theory using lattice simulations. We use a smoothing process based on the renormalization group equation. This removes short distance fluctuations but preserves long distance structure. The action of the smoothed configurations is dominated by instantons, but they still show an area law for W

Alex Travesset

We start by discussing some theoretical issues of renormalization group transformations and Monte Carlo renormalization group technique. A method to compute the anomalous dimension is proposed and investigated. As an application, we find excellent values for critical exponents in $λϕ^4_3$. Some technical questions regarding the hybrid algorithm and strong co

Vicente Azcoiti, Giuseppe Di Carlo, Eduardo Follana

We introduce a U(1) lattice gauge theory which incorporates explicit frustration in $d>2$. We show, by identifying an appropiate order parameter and through computer simulations, the existence of a frustrated region in the phase diagram of the model. We study this phase diagram and the nature of the transition lines.

S. Kato, M. N. Chernodub, S. Kitahara, N. Nakamura

We study various representations of the infrared effective theory of SU(2) gluodynamics starting from the monopole action derived recently. We determine the coupling constants in the abelian-Higgs model directly from lattice QCD and evaluate the type of the QCD vacuum. The string action is derived using the BKT transformation on the lattice. At the classical

G. Koutsoumbas, I. Montvay, A. Pap, K. Spanderen

We report on a numerical investigation of the SU(2) gauge theory with gluinos. The low-lying spectrum in bosonic and fermionic channels is determined. Improvements of the multi-bosonic algorithm are discussed.

G. Colangelo, E. Pallante

The divergences of the generating functional of quenched Chiral Perturbation theory (qCHPT) to one loop are computed in closed form. We show how the quenched chiral logarithms can be reabsorbed in the renormalization of the $B_0$ parameter of the leading order Lagrangian. Finally, we do the chiral power counting for the quenched case and show that also finit

M. Caselle, M. Hasenbusch

We present a high precision Monte Carlo study of various universal amplitude ratios of the three dimensional Ising spin model. Using state of the art simulation techniques we studied the model close to criticality in both phases. Great care was taken to control systematic errors due to finite size effects and correction to scaling terms. We obtain $C_+/C_-=4

M. Guagnelli, R. Sommer

We discuss non-perturbative improvement of the vector current, using the Schroedinger Functional formalism. By considering a suitable Ward identity, we compute the improvement coefficient which gives the O(a) mixing of the tensor current with the vector one.

M. Caselle, M. Hasenbusch, P. Provero

We present a high precision Monte Carlo study of the spectrum of the Ising gauge theory in three dimensions in the confining phase. Using state of the art Monte Carlo techniques we are able to accurately determine up to three masses in a single channel. We compare our results with the SU(2) spectrum and with the prediction of the Isgur-Paton model. Our data

The OPAL Collaboration, K. Ackerstaff et al

We have searched for unstable neutral and charged heavy leptons, N and L^+/-, and for excited states of neutral and charged leptons, nu*, e*, mu* and tau*, in e^+e^- collisions at centre-of-mass energies of 170 and 172 GeV using the OPAL detector at LEP. No evidence for their existence was found. From the analysis of charged-current decays of pair-produced u

Juliet Lee-Franzini

We present a brief history and a summary of the physics results of CUSB at CESR.

A. Kirk, the WA102 Collaboration

A study of central meson production as a function of the difference in transverse momentum dPT of the exchanged particles shows that undisputed qqbar mesons are suppressed at small dPT whereas the glueball candidates are enhanced.

The OPAL Collaboration, K. Ackerstaff et al

We present measurements of triple gauge boson coupling parameters using data recorded by the OPAL detector at LEP2 at a centre-of-mass energy of 172 GeV. A total of 120 W-pair candidates has been selected in the q q(bar) q q(bar), q q(bar) l nu(bar)_l, and l nu(bar)_l l(bar)' nu_l' decay channels, for an integrated luminosity of 10.4 pb^-1. We use th

Kirill Krasnov

The formula for the area eigenvalues that was obtained by many authors within the approach known as loop quantum gravity states that each edge of a spin network contributes an area proportional to sqrt{j(j+1)} times Planck length squared to any surface it transversely intersects. However, some confusion exists in the literature as to a value of the proportio

Z. G. Yu, A. Saxena, A. R. Bishop

An exciton theory for quasi-one dimensional organic materials is developed in the framework of the Su-Schrieffer-Heeger Hamiltonian augmented by short range extended Hubbard interactions. Within a strong electron-electron correlation approximation, the exciton properties are extensively studied. Using scattering theory, we analytically obtain the exciton ene

Z. G. Yu, M. W. Wu, X. S. Rao, X. Sun

We have studied the exciton states in two coupled conjugated polymer chains which are modeled individually by the Su-Schrieffer-Heeger Hamiltonian and coupled by an interchain electron-transfer term. Both the intra- and inter-chain long range Coulomb interactions are taken into account. The properties of the lowest symmetric and antisymmetric exciton states

Wojciech Florek

Projective irreps of (Z_N)^2 can be labelled by divisors n of N. A product of two irreps, labelled by n and n', can be decomposed into projective irreps labelled by M, where M strongly depends on the arithmetic structure of N, n, n' and their relations (gcd, lcm etc.). Such decompostion describes two important physical effects: (i) changes of a magne

Weiqun Peng, Horacio E. Castillo, Paul M. Goldbart, Annette Zippelius

Systems undergoing an equilibrium phase transition from a liquid state to an amorphous solid state exhibit certain universal characteristics. Chief among these are the fraction of particles that are randomly localized and the scaling functions that describe the order parameter and (equivalently) the statistical distribution of localization lengths for these

Z. Yusof, J. F. Zasadzinski, L. Coffey

A theoretical model for tunneling spectroscopy employing tight-binding band structure, d-wave gap symmetry, group velocity, and tunneling directionality can exhibit a wide range of characteristics similar to the ones found in tunneling experiments on high-Tc superconductors. Using a band structure obtained for optimally-doped Bi_2Sr_2CaCu_2O_8, the model tun

Antoni Planes, Eduard Obrado, Alfons Gonzalez-Comas, Lluis Manosa

We show that the magnetoelastic coupling between the magnetization and the amplitude of a short wavelength phonon enables the existence of a first order premartensitic transition from a bcc to a micromodulated phase in $Ni_{2}MnGa$. Such a magnetoelastic coupling has been experimentally evidenced by AC susceptibility and ultrasonic measurements under applied

G. Mussardo

Exact calculations of some universal quantities of two-dimensional statistical models in the vicinity of their fixed points are illustrated.

Shuly Wintner

This work describes the design and implementation of an abstract machine, Amalia, for the linguistic formalism ALE, which is based on typed feature structures. This formalism is one of the most widely accepted in computational linguistics and has been used for designing grammars in various linguistic theories, most notably HPSG. Amalia is composed of data st

Caroline Lyon, Ray Frank

A natural language parser which has been successfully implemented is described. This is a hybrid system, in which neural networks operate within a rule based framework. It can be accessed via telnet for users to try on their own text. (For details, contact the author.) Tested on technical manuals, the parser finds the subject and head of the subject in over

Shuly Wintner, Nissim Francez

Typed feature structures are used extensively for the specification of linguistic information in many formalisms. The subsumption relation orders TFSs by their information content. We prove that subsumption of acyclic TFSs is well-founded, whereas in the presence of cycles general TFS subsumption is not well-founded. We show an application of this result for

Udo Hahn, Peter Neuhaus, Norbert Broeker

We argue for a performance-based design of natural language grammars and their associated parsers in order to meet the constraints imposed by real-world NLP. Our approach incorporates declarative and procedural knowledge about language and language use within an object-oriented specification framework. We discuss several message-passing protocols for parsing

Nickolay Y. Gnedin

I demonstrate by means of high resolution cosmological simulations, which include modelling of a two-phase interstellar medium, that the dominant mechanism for transporting heavy elements from the proto-galaxies into the IGM is the merger mechanism as discovered by Gnedin & Ostriker. Direct ejection of the interstellar gas by supernovae plays only a minor ro

RICE Collaboration, C. Allen, A. Bean, D. Besson

RICE is designed to detect ultrahigh energy (>100 TeV) neutrinos from astrophysical sources. It will consist of an array of compact radio (100 to 1000 MHz) receivers buried in ice at the South Pole. During the 1995-96 and 1996-97 austral summers, several receivers transmitters were deployed in bore holes drilled for the AMANDA project, at depths of 141 to 26

Ulf Torkelsson, G. Christopher Boynton

We present an one-dimensional numerical study of Alfven waves propagating along a radial magnetic field. Neglecting losses, any spherical Alfven wave, no matter how small its initial amplitude is, becomes nonlinear at sufficiently large radii. From previous simulations of Alfven waves in plane parallel atmospheres we did expect the waves to steepen and produ

P. P. Avelino, J. P. M. de Carvalho

We compute the linear power spectrum of cosmic string sedeed fluctuations in the context of neutrinos with a strong self-interaction and show that it is very similar to that obtained in the context of `normal' neutrinos. We compare our results with observational data and show that for any value of the cosmological parameters $h$ and $Ω_0$ the interacting

Lawrence M. Widrow, John Dubinski

We conduct gravitational microlensing experiments in a galaxy taken from a cosmological N-body simulation. Hypothetical observers measure the optical depth and event rate toward hypothetical LMCs and compare their results with model predictions. Since we control the accuracy and sophistication of the model, we can determine how good it has to be for statisti

M. Montuori, F. Sylos Labini, L. Pietronero

The properties of spatial distribution of luminous matter are investigated analysing all the available three dimensional catalogues of galaxies. In standard view, galaxies are believed to have a fractal distribution at small scale with a crossover to an homogeneous one at large scale. However up to now, the quantitative determination of this presumed homogen

Mareki Honma, Yoshiaki Sofue

We propose a criterion for examining whether or not the uncertainty of the outer rotation curves is sufficiently small to distinguish a Keplerian rotation curve from flat ones. We have applied this criterion to both Keplerian and non-Keplerian rotation curves so far obtained, and investigated their relative fraction. We also studied the minimum extent of the

Alexander Beilinson, Victor Ginzburg

We study Translation functors and Wall-Crossing functors on infinite dimensional representations of a complex semisimple Lie algebra using D-modules. This functorial machinery is then used to prove the Endomorphism-theorem and the Structure-theorem, two important results established earlier by W. Soergel in a totally different way. Other applications to the

The OPAL Collaboration, K. Ackerstaff et al

A search for the resonant production of high mass photon pairs associated with a leptonic or hadronic system has been performed using a total data sample of 25.7 pb^-1 taken at centre-of-mass energies between 130 GeV and 172 GeV with the OPAL detector at LEP. The observed number of events is consistent with the expected number from Standard Model processes.

Christoph Sorger

Let $G$ be a simple and simply connected complex Lie group, ${\goth{g}}$ its Lie algebra. I remove the restriction ``$G$ is of classical type or $G_2$'' made on $G$ in the papers of Beauville, Laszlo and myself [L-S] and [B-L-S] on the moduli of principal G-bundles over a curve. As I will just "patch" the missing technical points, this note s

Maxim Vavilov, Vinay Ambegaokar

We point out that even at the absolute zero of temperature environmental decoherence limits the destructive interference between time-reversed paths for an electron in a disordered metal, and thus causes the leading (`weak localization') quantum correction to the conductivity to saturate at T=0. Our calculation, which is intended to be illustrative rathe

Dung-Hai Lee

We present a particle-hole symmetric theory for a two-dimensional electron gas at filling factor one half. In this theory, elementary excitations are dipole-like fermions floating on top of the $ν=1/2$ boson quantum Hall liquid. In the absence of disorder these dipoles can form a Fermi-liquid. Disorder can break them apart and drive the ground state into a q

Shaisultanov R

The low-energy two neutrino-two photon interactions in the presence of homogeneous magnetic field are studied. The cross sections in external magnetic field are shown to be larger than in vacuum by factor $\sim (m_W /m_e) ^4(B/B_c) ^2$. The energy-loss rate due to the process $γγ\to ν\barν$ in magnetic field is obtained.

V. V. Kabachenko, Yu. F. Pirogov

In the context of the future high energy - high luminosity electron and muon colliders, all the relevant four-lepton processes with the lepton family violation (LFV) are systematically classified. The most general LFV effective lagrangians are found, and the helicity differential cross sections for the LFV processes are calculated. The six- and eight-lepton

Jens O. Andersen

The effective field theory approach to high temperature field theory can be used to study the phase transition in theories with spontaneously broken symmetry. I construct a sequence of two effective three--dimensional field theories which are valid on successively longer distance scales for a specific model: $N$ charged scalars coupled to a U(1) gauge field.

ZEUS Collaboration

This paper presents the first analysis of diffractive photon dissociation events in deep inelastic positron-proton scattering at HERA in which the proton in the final state is detected and its momentum measured. The events are selected by requiring a scattered proton in the ZEUS leading proton spectrometer (LPS) with $\xl>0.97$, where $\xl$ is the fraction o

M. Y. Simmons, A. R. Hamilton, M. Pepper, E. H. Linfield

We report the observation of a metal insulator transition at B=0 in a high mobility two dimensional hole gas in a GaAs-AlGaAs heterostructure. A clear critical point separates the insulating phase from the metallic phase, demonstrating the existence of a well defined minimum metallic conductivity sigma(min)=2e/h. The sigma(T) data either side of the transiti

Gunnar S. Bali, Nora Brambilla, Antonio Vairo

We study field strength correlators in presence of a static quark-antiquark pair by use of lattice methods. The lattice data have been acquired recently in the context of a determination of relativistic corrections to the static interquark potential. We extract independent estimates of the form factors of two point correlation functions and investigate the e

Bruce A. Bassett, Stefano Liberati

Inflationary reheating via resonant production of non-minimally coupled scalar particles with only gravitational coupling is shown to be extremely strong, exhibiting a negative coupling instability for $ξ< 0$ and a wide resonance decay for $ξ\gg 1$. Since non-minimal fields are generic after renormalisation in curved spacetime, this offers a new paradigm in

J. E. Avron, J. Berger

The Longuet-Higgins-Berry&#39;s phase has remarkable consequences for charge transport in molecular rings. For generic (conical) crossing, where the phase is $π$, a vanishing cause can lead to a diverging response in the amount of charge transport. Away from level crossings, when the phase is 0, a vanishing cause leads to a vanishing response. The divergence

F. Buccella, G. Mangano, O. Pisanti, L. Rosa

We review the status of a class of gauge unified models based on SO(10) group. After a pedagogical introduction to SO(10) gauge theories, we discuss the main phenomenological implications of these models. The upper limit on proton lifetime are obtained and the prediction for neutrino masses are compared with the astrophysical and cosmological constraints com

Adan Cabello, Guillermo Garcia-Alcaine

For a two-particle two-state system, sets of compatible propositions exist for which quantum mechanics and noncontextual hidden-variable theories make conflicting predictions for every individual system whatever its quantum state. This permits a simple all-or-nothing state-independent experimental verification of the Bell-Kochen-Specker theorem.

D. Saakian

We introduce a layered random spin model, equivalent to the Generalized Random Energy Model (GREM). In analogy with diluted spin systems, a diluted GREM (DGREM) is introduced.It can be applied to calculate approximately thermodynamic properties of spin glass models in low dimensions. For Edwards -Anderson model it gives correct critical dimension and 5% accu

Jeong-Young Ji, Hyun-Hee Jung, Kwang-Sup Soh

We study the photon production in a 1D cavity whose left and right walls oscillate with the frequency $Ω_{L} $ and $Ω_{R} $, respectively. For $Ω_{L} \neq Ω_{R}, $ the number of generated photons by the parametric resonance is the sum of the photon numbers produced when the left and the right wall oscillates separately. But for $Ω_{L} = Ω_{R} $, the interfer

K. Saito, K. Tsushima, A. W. Thomas

Using the quark-meson coupling (QMC) model, we study the density dependence of the quark and gluon condensates in nuclear matter. We show that the change of the quark condensate is mainly driven by the scalar field in the medium and that the reduction of the quark condensate is suppressed at high density, even in the mean-field approximation. The gluon conde

Masahito Ueda

A quantum measurement is logically reversible if the premeasurement density operator of the measured system can be calculated from the postmeasurement density operator and from the outcome of the measurement. This paper analyzes why many quantum measurements are logically irreversible, shows how to make them logically reversible, and discusses reversing meas

Richard E. Borcherds

These are the notes of an informal talk in Bonn describing how to define an analogue of vertex algebras in higher dimensions.

A. Gardestig, G. Faldt, C. Wilkin

The dd -> alpha X reaction is studied in a model where each pair of nucleons in the projectile and target deuterons undergoes pion production through the NN -> d pi reaction. The condition that the two deuterons fuse to form an alpha-particle then leads to peaks at small missing masses, the well-known ABC enhancement, but also a broad structure around the ma

H. Hofmann, Fedor A. Ivanyuk, Alexander G. Magner

We study large scale collective dynamics of isoscalar type and examine the influence of interactions residual to independent particle motion. It is argued that for excitations which commonly are present in experimental situations such interactions must not be neglected. They even help to justify better the assumption of locality, both in time as well as in p

N. Auerbach, O. K. Vorov

Isospin violation effects in nuclei are investigated within a microscopic approach which takes into account the influence of the residual strong interaction on the Coulomb interaction. The renormalization of the off-diagonal Coulomb field acting within a nucleus, by the residual strong interaction is calculated analytically in a simplified RPA. From the expr

Thomas R. Hemmert

I discuss recent results regarding the influence of pion-nucleon and and nucleon-resonance physics on the (spin-) polarizabilities of the nucleon as measured in (polarized) Compton scattering.

F. O. Durães, F. S. Navarra, G. Wilk

We have applied the Interacting Gluon Model (IGM) to calculate diffractive mass spectra measured recently in e-p collisions at HERA. We show that it is possible to treat them in terms of gluon-gluon collisions in the same way as was done before for hadronic collisions. Analysis of available data is performed.

Matthias Burkardt

In the first part of my lectures, I will use the example of deep-inelastic scattering to explain why light-front coordinates play a distinguished role in many high energy scattering experiments. After a brief introduction into the concept of light-front quantization, I will show that the vacuum for any light-front Hamiltonian is trivial, i.e. the same as for