December 1995 arXiv papers — page 2

Sheldon Goldstein

This is a review-essay on ``Speakable and Unspeakable in Quantum Mechanics'' by John Bell and ``The Undivided Universe: An Ontological Interpretation of Quantum Mechanics'' by David Bohm and Basil Hiley. The views of these authors concerning the character of quantum theory and quantum reality---and, in particular, their approaches to the issu

Orfeu Bertolami, Juan García-Bellido

We investigate the astrophysical and cosmological implications of the recently proposed idea of a running gravitational coupling on macroscopic scales. We find that when applied to the rotation curves of galaxies, their flatness requires still the presence of dark matter. Bounds on the variation of the gravitational coupling from primordial nucleosynthesis,

Robert Shrock

We discuss some implications of anomaly cancellation in the standard model with (i) the color group extended to $SU(N_c)$, and (ii) the leptonic sector extended to allow right-handed components for neutrinos.

I. Gogoladze, A. Kobakhidze, Z. Tavartkiladze

In a $SU(6)$ gauge theory we found the irreducible representation (175-plet) which does not contain the Higgs doublet. Using this representation we construct two SUSY $SU(6)$ models in which the doublet-triplet splitting occurs naturally, without fine tuning. The crucial role is played by the ``custodial" global $SU(2)_H$ in combination with discrete or

Kaoru Hagiwara

There are two aspects to the 1995 summer update of the combined preliminary electroweak data from LEP and SLC. On the one hand, agreement between experiments and the Standard Model (SM) has improved for the line-shape and the asymmetry data. The $τ$ widths and asymmetries are now consistent with $e$--$μ$--$τ$ universality, and all the asymmetry data includin

Ashok Goyal, Sukanta Dutta

We consider right handed neutrino emission from charged and neutral pion condensate matter likely to be present in the supernova core associated with SN 1987 A. This is used to constrain the strength of right handed interaction and we get excluded range of values for the right handed $W$ boson and extra neutral $Z'$ boson masses. For vanishing $W_L-W_R$

S. R. Choudhury, Mamta, Sukanta Dutta

We study the implication of triviality on Higgs sector in next to minimal supersymmetric model (NMSSM) using variational field theory. It is shown that mass of the lightest Higgs boson in NMSSM has an upper bound $\sim 10\, M_W$ which is of the same order as that in standard model.

Arkady Vainshtein

A few topics on the expansion in heavy quark mass are discussed. The theoretical framework is the Wilson Operator Product Expansion rather than the Heavy Quark Effective Theory.

E. S. Cheb-Terrab, H. P. de Oliveira

A set of Maplev R.3 software routines, for plotting 2D/3D projections of Poincaré surfaces-of-section of Hamiltonian dynamical systems, is presented. The package consists of a plotting-command plus a set of facility-commands for a quick setup of the Hamilton equations of motion, initial conditions for numerical experiments, and for the zooming of plots.

Alejandro Gangui

I present recent work aimed at showing how currently competing theories of the early universe leave their imprint on the temperature anisotropies of the CMB radiation. We consider the 3-point correlation function, as well as the inherent theoretical uncertainties associated with it, for which we derive explicit analytic formulae. We apply them in the study o

Alexander Goncharov

I compute explicitly the regulator map on $K_4(X)$ for an arbitrary curve $X$ over a number field. Using this and Beilinson's theorem about regulators for modular curves ([B2]) I prove a formula expressing the value of the $L$-function $L(E,s)$ of a modular elliptic curve $E$ over $\Bbb Q$ at $s=3$ by the double Eisenstein-Kronecker series.

M. N. Chernodub, M. I. Polikarpov, A. I. Veselov

We present the results of the numerical calculation of the probability distribution of the value of the monopole creation operator in $SU(2)$ lattice gluodynamics. We work in the maximal abelian projection. It occurs that at the low temperature, below the deconfinement phase transition the maximum of the distribution is shifted from zero, which means that th

S. M. Troshin, N. E. Tyurin

On the basis of the mechanism proposed for one-spin asymmetries in inclusive hadron production we specify an $x$--dependence of asymmetries in inclusive processes of pion production. The main role in generation of this asymmetry belongs to the orbital angular momentum ofquark-antiquark cloud in internal structure of constituent quarks. The $x$--dependence of

Naoyuki Haba, Masahisa Matsuda, Morimitsu Tanimoto

We study the possibility of spontaneous CP violation in the next-to-minimal supersymmetric standard model (NMSSM). It is shown that the spontaneous CP violation is induced by the radiative effects of top, stop, bottom and sbottom superfields. The available regions of parameters, which are obtained by imposing the constraints from experiments, are rather narr

Hidetoshi Nishimori, Michiko Yamana

The microscopic probability distribution function of the Sherrington-Kirkpatrick (SK) model of spin glasses is calculated explicitly as a function of time by a high-temperature expansion. The resulting formula to the third order of the inverse temperature shows that an assumption made by Coolen, Laughton and Sherrington in their recent theory of dynamics is

Tomo Munehisa, Yasuko Munehisa

We present a new method to study the ground state of quantum spin systems using the Monte Carlo techniques together with restructured intermediate states which we proposed previously. Our basic idea is to obtain coefficients in the expansion of the ground state from measurements of the normalized frequencies of each state on the boundary in the Trotter direc

Andrei G. Bytsko

The definitions and some properties (e.g. the Wigner-Eckart theorem, the fusion procedure) of covariant and contravariant q-tensor operators for quasitriangular quantum Lie algebras are formulated in the R-matrix language. The case of U_q(sl(n)) (in particular, for n=2) is discussed in more detail.

Koji Hasegawa

For Belavin's elliptic quantum R-matrix, we construct an L-operator as a set of difference operators acting on functions on the type A weight space. According to the fundamental relation $RLL=LLR$, the trace of the L-operator gives a commuting difference operators. We show that for the above mentioned L-operator this approach gives Macdonald type operato

S. Majid

We collect here some less well-known results and formulae about the bosonisation construction which turns braided groups into quantum groups. We clarify the relation with biproduct Hopf algebras (the constructions are not the same), the response to twisting of braided groups and the abstract characterisation via automorphisms of the forgetful functor for the

S. Hirenzaki, E. Oset, P. Fernández de Córdoba

Recent experiments at Saturne at $4$ $GeV$ showed that the $(α,α')$ reaction on the proton shows two distinctive peaks, which were associated to $Δ$ projectile excitation and Roper target excitation. A subsequent theoretical analysis has shown that this picture is qualitatively correct but there are important interference effects between the two mechanis

Liu Chao

This report is consisted of six independent chapters, each chapter (except chapter 1) is a paper carried out in colabouration with others, who's names are indicated in chapter1. The topics included are (1)Overview of general properties of Toda-like systems (chapter1) (2)Free field representations of some particular example of entended Toda like system vi

Ken-ichi Hiraizumi, Yoshihisa Ohshima, Hiroshi Suzuki

The order dependent mapping method, its convergence has recently been proven for the energy eigenvalue of the anharmonic oscillator, is applied to re-sum the standard perturbation series for Stark effect of the hydrogen atom. We perform a numerical experiment up to the fiftieth order of the perturbation expansion. A simple mapping suggested by the analytic s

K. V. L. Sarma

The 1995 Nobel Prize in Physics is shared equally by the American physicists Frederick J. Reines and Martin L. Perl for their pioneering experimental contributions to lepton physics. Following is a brief account of their discoveries.

Darwin Chang, Shih-Chang Lee, Alexei Soumarokov

We propose to observe the top spin correlation effect at Tevatron through the measurement of the correlated asymmetries of the charged lepton momenta using the dilepton decay events of top and anti-top quark pairs. The possibility of reconstructing the events and observing the asymmetries at 3$σ$ level with projected luminosity of the Tevatron for Run II is

Ryoji Enomoto

We have observed highly virtual ($Q^2>1.05 GeV^2$) photon-photon collisions to hadronic final states at $\sqrt{s_{e^+e^-}}=58 GeV$. The integrated luminosity of the data sample was 241pb$^{-1}$. Both scattered beam-electrons and scattered beam-positrons were detected using low-angle calorimeters (i.e., both photons were highly virtual, "double-tag");

J. I. Katz, L. M. Canel

We report evidence from the 3B Catalogue that long ($T_{90} > 10$ s) and short ($T_{90} < 10$ s) gamma-ray bursts represent distinct source populations. Their spatial distributions are significantly different, with long bursts having $\langle V/V_{max} \rangle = 0.282 \pm 0.014$ but short bursts having $\langle V/V_{max} \rangle = 0.385 \pm 0.019$, differing

Keshav Dasgupta, Sunil Mukhi

We study Z2-orbifolds of 11-dimensional M-theory on tori of various dimensions. The most interesting model (besides the known S1/Z2 case) corresponds to T5/Z2, for which we argue that the resulting six-dimensional theory is equivalent to the type IIB string compactified on K3. Gravitational anomaly cancellation plays a crucial role in determining what states

Misha Verbitsky

We prove the Mirror Conjecture for Calabi-Yau manifolds equipped with a holomorphic symplectic form. Such manifolda are also known as complex manifolds of hyperkaehler type. We obtain that a complex manifold of hyperkaehler type is Mirror dual to itself. The Mirror Conjecture is stated (following Kontsevich, ICM talk) as the equivalence of certain algebraic

B. Stech

To know and understand form factors of hadronic currents is of decisive importance for analysing exclusive weak decays. The ratios of different form factors of a given process depend on the relativistic spin structure of initial and final particles. It is shown --- assuming simple properties of the spectator particle --- that these ratios can entirely be exp

Atsushi Nakayashiki, Yasuhiko Yamada

The relation between the charge of Lascoux-Schuzenberger and the energy function in solvable lattice models is clarified. As an application, A.N.Kirillov&#39;s conjecture on the expression of the branching coefficient of ${\widehat {sl_n}}/{sl_n}$ as a limit of Kostka polynomials is proved.

Luca Salasnich, Fabio Sattin

A Classical Trajectory Monte Carlo (CTMC) simulation has been made of processes of charge exchange and ionization between an hydrogen atom and fully stripped ions embedded in very strong static electric fields ($O(10^{10}$ V/m$)$), which are thought to exist in cosmic and laser--produced plasmas. Calculations show that the presence of the field affects absol

Pran Nath, R. Arnowitt

A review of supersymmetric dark matter in minimal supergravity unification with R-parity invariance and with radiative breaking of the electro-weak symmetry is given. The analysis shows the lightest neutralino is the LSP over most of the parameter space of the supergravity model. The event rates in neutralino- nucleus scattering in dark matter detectors are

Pran Nath

It is proposed that supergravity unified models contain in addition to the hidden and the visible sectors, a third sector which contains exotic matter with couplings to the fields of both the visible and the hidden sectors. After spontaneous breaking of supersymmetry exotic matter becomes superheavy and its elimination leads to quark-lepton textures at the G

David Lidsky

Tunneling of electrons between two $ν= 1/2$ quantum Hall parallel planes is studied. In order to calculate the physical electron Green&#39;s function, the Chern-Simons gauge field formalism is used, both in a perturbative many-body calculation and in a semiclassical calculation. In contrast to recent experiments, no gap in the physical electron density of st

Darwin Chang, Shih-Chang Lee, Wen-Jer Tzeng

Using the transfer matrix method, we give the exact solution of a deterministic sandpile model for arbitrary $N$, where $N$ is the size of a single toppling. The one- and two-point functions are given in term of the eigenvalues of an $N \times N$ transfer matrix. All the n-point functions can be found in the same way. Application of this method to a more gen

Darwin Chang, Chen-Shan Chin, Shih-Chang Lee

We present a transfer matrix method which is particularly useful for solving some classes of sandpile models. The method is then used to solve the deterministic nonabelian sandpile models for N=2 and N=3. The possibility of generalization to arbitrary N is discussed briefly.

L. S. Littenberg, G. Valencia

We study the reactions $K \rightarrow ππν\overlineν$ within the minimal standard model. We use isospin symmetry to relate the matrix elements to the form factors measured in $K_{\ell 4}$. We argue that these modes are short distance dominated and can be used for precise determinations of the CKM parameters $ρ$ and $η$. Depending on the value of the CKM angle

T. C. Lubensky, Randall D. Kamien, Holger Stark

Chiral molecules form a number of non-chiral structures, the simplest being an isotropic fluid phase. In a mesophase of achiral molecules the fluctuations will on average be achiral as well: left-handed twists and right-handed twists will occur with the same probability. In a system composed of chiral molecules, however, the fluctuations will be biased in on

V. Ostrik

Given a finite type root datum and a primitive root of unity $q=\sqrt[l]{1}$, G.~Lusztig has defined in [Lu] a remarkable finite dimensional Hopf algebra $\fu$ over the cyclotomic field ${\Bbb Q}(\sqrt[l]{1})$. In this note we study the adjoint representation $\ad$ of $\fu$ in the simplest case of the root datum $sl_2$. The semisimple part of this representa

A. T. Banin, N. G. Pletnev

New types &#34;extended&#34; (super)conformal algebras $G^{(\frac n2)}$ are presented. (Su\-per)twistor spaces $T$ are subspaces in cosets $G^{(\frac n2)}/H$. The (super)twistor correspondence has a cleary defined geometrical meaning.

H. -P. Pavel, D. Blaschke, G. Roepke, V. N. Pervushin

Generalizing the Bogoliubov model of a weakly non-ideal Bose gas to massless $λφ^4$ theory we show that spontaneous breaking of symmetry occurs due to condensation in a coherent vacuum % which is energetically favoured compared to the perturbative one. and leads to a vacuum energy density which is lower than that obtained by Coleman and Weinberg using the on

Riccardo D&#39;Auria

We discuss R-symmetry in locally supersymmetric $N=2$ gauge theories coupled to hypermultiplets, which can be viewed as effective theories of heterotic string models. In this type of supergravities a suitable R-symmetry exists and can be used to topologically twist the theory. The vector multiplet of the dilaton-axion field has a different R-charge assignmen

Keyan Yang

For strong enough Yukawa coupling the electroweak standard model fermion finds it energetically advantageous to transform itself into a bound state in the hedgehog background of Higgs field in semiclassical approximation. By considering the bound states give the masses for lepton and quark, we found that all the strongly Yukawa coupling constants tend to an

A. Di Clemente, E. Giallongo, G. Natali, D. Trevese

The variability of 30 PG quasars has been observed in the red band during three years. A rest-frame structure function analysis shows an increase of variability with the time interval up to 0.2 mag r.m.s. after two years. A comparison with the IUE data available for PG quasars shows that the variability increases with the rest-frame frequency at each time in

A. Yahil

The pixon-based image reconstruction of Puetter and Piña has achieved significant improvements over other methods in higher spatial resolution, greater sensitivity to faint sources, and immunity to the production of spurious artifacts and signal-correlated residuals. The same technique may be used for those problems of large-scale structure which allow for v

Bharat Ratra, Naoshi Sugiyama

We compute the cosmic microwave background (CMB) anisotropy in a low-density, flat, cosmological constant, cold dark matter model which is normalized to the two-year COBE DMR sky map. Although conclusions regarding model viability must remain tentative until systematic effects are better understood, there are mild indications that these models have more inte

Norman A. Grogin, Ramesh Narayan

We present a simple mass model for the lensing galaxy in the gravitationally lensed quasar 0957+561. The model is a generalization of the singular isothermal sphere and includes a core radius, $r_c$, and a power-law index, $η$, defined such that mass increases as $r^η$ at large radius. We approximate the galaxy cluster surrounding the lensing galaxy with a q

Dan Abramovich

The Lang map, namely the universal dominant rational map to a variety of general type, is constructed and briefly discussed in relation with arithmetic conjectures of Harris, Lang and Manin. Existence of the Lang map follows from the additivity of Kodaira dimension, but the fine structure depends on conjectures on birational classification of algebraic varie

Heinz König

I present a detailed and complete calculation of the gluino and neutralino contribution to the direct CP violating parameter $ε&#39;$\ within the MSSM. I include the complete mixing matrices of the neutralinos and of the scalar partners of the left and right handed down quarks. I find that the neutralino contribution is generally small but can be larger than

Zeljko Ivezic, Moshe Elitzur

Infrared imaging properties of dusty winds around late-type stars are investigated in detail, employing a self-consistent model that couples the equations of motion and radiative transfer. Because of general scaling properties, the angular profiles of surface brightness are self-similar. In any given star, the profile shape is determined essentially by overa

Zeljko Ivezic, Moshe Elitzur

Infrared emission from the dust shell around IRC+10216 is analysed in detail, employing a self-consistent model for radiatively driven winds around late-type stars that couples the equations of motion and radiative transfer in the dust. The resulting model provides agreement with the wealth of available data, including the spectral energy distribution in the

Jacob S. Sagi

A comprehensive theory of nuclear magnetic relaxation is developed for Haldane Gap materials using nonlinear sigma, boson and fermion models. We include a thorough discussion of of the effects of interchain couplings, nearest neighbour hyperfine couplings and crystal structure. We also introduce a new theory of impurities corresponding to broken chain ends w

Stefano Moretti

We study at LEP II and Next Linear Collider energies Higgs production via the bremsstrahlung channel $e^+e^-\ar ZH$, with $Z\ar μ^+μ^-$ and $H\ar b\bar b$, and the corresponding irreducible background, in presence of hard photon radiation, both from the initial and the final state. We carry out an analysis that includes the computation of all the relevant co

John W. Barrett

This paper relates skein spaces based on the Kauffman bracket and spin structures. A spin structure on an oriented 3-manifold provides an isomorphism between the skein space for parameter A and the skein space for parameter -A. There is an application to Penrose&#39;s binor calculus, which is related to the tensor calculus of representations of SU(2). The pe

Yu. L. Dokshitzer, N. G. Uraltsev

We study the origin of non-analyticity in α_s of a short-distance QCD observable to demonstrate that the infrared renormalons, the same-sign factorial growth of the perturbative expansion, is a universal phenomenon that originates entirely from the small coupling domain. In particular, both the position and the nature of the singularity of the Borel transfor

Kwan-Leung Chan, Mirjam Cvetic

Within a four-dimensional, toroidally compactified heterotic string, we identify (quantized) charge vectors of electrically charged BPS-saturated states (along with the tower of SL(2,Z) related dyonic states), which preserve 1/2 of N=4 supersymmetry and become massless along the hyper-surfaces of enhanced gauge symmetry of the two-torus moduli sub-space. In

Randall D. Kamien, Gary S. Grest

We present a Monte Carlo simulation of a polymer nematic for varying volume fractions, concentrating on the structure function of the sample. We achieve nematic ordering with stiff polymers made of spherical monomers that would otherwise not form a nematic state. Our results are in good qualitative agreement with theoretical and experimental predictions, mos

A. V. Belitsky

We calculate the spin dependent structure function of the polarized virtual photon $g_1^γ(x,Q^2,p^2)$, especially its hadronic part, using the OPE in the inverse powers of the target photon virtuality. Some model is accepted to achieve a correct analytical behaviour in the photon squared mass. This enables extrapolation to the case of a real photon.

Javier Mas, Marcos Seco

In this paper we continue with the program to explore the topography of the space of W-type algebras. In the present case, the starting point is the work of Khesin, Lyubashenko and Roger on the algebra of q-deformed pseudodifferential symbols and their associated integrable hierarchies. The analysis goes on by studying the associated hamiltonian structures f

M. Knecht, B. Moussallam, J. Stern, N. Fuchs

The chiral expansion of the $ππ$ amplitude to the order of two loops was expressed in terms of six independent parameters in a previous paper: four of these are shown here to satisfy sum rules. Their derivation, where crossing symmetry plays a key role, is explained. Their convergence properties are studied and their practical evaluation, in terms of the ava

Frank Wilczek

I briefly review the concept of d-density ordering, extend it to arbitrary dimensions, and speculate that it might describe Mott insulators. This ordering supports zero modes on domain walls, and quite plausibly dopants occupy such states. This phenomenon could induce quasi-one dimensional behavior in a two-dimensional electron system.

Oliver Rudolph

In this work a generalization of the consistent histories approach to quantum mechanics is presented. We first critically review the consistent histories approach to nonrelativistic quantum mechanics in a mathematically rigorous way and give some general comments about it. We investigate to what extent the consistent histories scheme is compatible with the r

L. Gerland, C. Spieles, M. Bleicher, P. Papazoglou

The extension of the Periodic System into hitherto unexplored domains - antimatter and hypermatter - is discussed. Starting from an analysis of hyperon and single hypernuclear properties we investigate the structure of multi-hyperon objects (MEMOs) using an extended relativistic meson field theory. These are contrasted with multi-strange quark states (strang

Kirill Ilinski, Alexander Moroz

Characteristics of the initial condensate in the recent experiment on Bose-Einstein condensation (BEC) of ${}^{87}$Rb atoms in an anisotropic magnetic trap is discussed. Given the aspect ratio $R$, the quality of BEC is estimated. A simple analytical Ansatz for the initial condensate wave function is proposed as a function of the aspect ratio which, in contr

Tsuyoshi Hondou, Yasuji Sawada

In the paper by J.Łuczka {\em et al.} ({\em Europhys. Lett.}, {\bf 31} (1995) 431), the authors reported by rigorous calculation that an additive Poissonian white shot noise can induce a macroscopic current of a dissipative particle in a periodic potential -- even {\em in the absence} of spatial asymmetry of the potential. We argue that their main result is

V. P. Frolov, D. V. Fursaev, A. I. Zelnikov

Different methods of calculation of quantum corrections to the thermodynamical characteristics of a black hole are discussed and compared. The relation between on-shell and off-shell approaches is established. The off-shell methods are used to explicitly demonstrate that the thermodynamical entropy $S^{TD}$ of a black hole, defined by the first thermodynamic

E. V. Tsiper, F. G. Pikus, A. L. Efros

We consider 2d gas of spinless fermions with the Coulomb interaction on a lattice at T=0 and at different values of the hopping amplitude J. At small J electrons form a periodic structure. At filling factor ν=1/6 this structure melts at J as low as 0.02--0.03 in units of the nearest-neighbor Coulomb energy. We argue that this transition is connected to the d

N. G. Deshpande, B. Dutta, E. Keith

In supersymmetric SO(10) grand unified models, we examine the lepton flavor violation process $μ\rightarrow eγ$ from having the SU(2)$_R\times $U(1)$_{B-L}$ gauge symmetry broken at an intermediate scale $M_I$ below the SO(10) grand unification scale $M_G$. Even in the case that supersymmetry is broken by universal soft terms introduced at the scale $M_G$, w

Andreas Zoupas

We analyse the evolution of a quantum oscillator in a finite temperature environment using the quantum state diffusion (QSD) picture. Following a treatment similar to that of reference [7] we identify stationary solutions of the corresponding Itô equation. We prove their global stability and compute typical time scales characterizing the localization process

Christopher A. Fuchs, Asher Peres

When an observer wants to identify a quantum state, which is known to be one of a given set of non-orthogonal states, the act of observation causes a disturbance to that state. We investigate the tradeoff between the information gain and that disturbance. This issue has important applications in quantum cryptography. The optimal detection method, for a given

Yi-Zhi Huang

We describe the construction of the genus-zero parts of conformal field theories in the sense of G. Segal from representations of vertex operator algebras satisfying certain conditions. The construction is divided into four steps and each step gives a mathematical structure of independent interest. These mathematical structures are intertwining operator alge

John R. de Bruyn

I have measured the early stages of the growth of branched metal aggregates formed by electrochemical deposition in very thin layers. The growth rate of spatial Fourier modes is described qualitatively by the results of a linear stability analysis [D.P. Barkey, R.H. Muller, and C.W. Tobias, J. Electrochem. Soc. {\bf 136}, 2207 (1989)]. The maximum growth rat

G. Carter, P. J. Ellis, S. Rudaz

We extend an effective Lagrangian embodying broken scale and chiral symmetry to include explicit chiral symmetry breaking and an additional chiral invariant term which allows for an axial coupling constant greater than unity. We also include a chiral Lagrangian for the isotriplet vector mesons which leads to a renormalization of the pion field. The propertie

Amy Y. Liu, Andrew A. Quong

An ab initio method for calculating electron-phonon coupling parameters is presented. The method is an extension of the plane-wave-based linear-response method for the calculation of lattice dynamics. Results for the mass enhancement parameter and the electron-phonon spectral function for Al, Pb and Li are presented. Comparisons are made to available experim

Vladimir Peller, Sergei Treil

We study the problem of finding a superoptimal solution to the four block problem. Given a bounded block matrix function $\left(\begin{array}{cc}Φ_{11} &Φ_{12}\\Φ_{21}&Φ_{22}\end{array}\right)$ on the unit circle the four block problem is to minimize the $L^\infty$ norm of $\left(\begin{array}{cc} Φ_{11}-F&Φ_{12}\\Φ_{21}&Φ_{22}\end{array}\right)$ over $F\in

R. G. Leigh

Recently, Witten has proposed a mechanism for symmetry enhancement in $SO(32)$ heterotic string theory, where the singularity obtained by shrinking an instanton to zero size is resolved by the appearance of an $Sp(1)$ gauge symmetry. In this short letter, we consider spacetime constraints from anomaly cancellation in six dimensions and D-flatness and demonst

G. Palma, L. Vergara

We present a novel way to compute the one-loop ring-improved effective potential numerically, which avoids the spurious appearence of complex expressions and at the same time is free from the renormalization ambiguities of the self-consistent approaches, based on the direct application of Schwinger-Dyson type equations to the masses.

Olaf Lechtenfeld

I present the moduli space of the (2+2)-dimensional critical closed fermionic string with two world-sheet supersymmetries. The integration of fermionic and Maxwell moduli in the presence of punctures yields the string measure for n-point amplitudes at arbitrary genus and instanton number. Generalized picture-changing and spectral-flow operators emerge, conne

J. Cruz, J. Navarro-Salas

Solvable theories of 2D dilaton gravity can be obtained from a Liouville theory by suitable field redefinitions. In this paper we propose a new framework to generate 2D dilaton gravity models which can also be exactly solved in the semiclassical approximation. Our approach is based on the recently introduced scheme to quantize massless scalar fields coupled

A. I. Alekseev

The equation for the gluon propagator in the approach of Baker-Ball-Zachariasen is considered. The possibility of non-integer power infrared behaviour is studied, $D(q) \sim (q^2)^{-c}$, $q^2 \rightarrow 0$. It is shown that the characteristic equation for the exponent has no solutions at $-1\leq c\leq 3$. The approximations made to obtain the closed integra

N. P. Warner

Quantum integrable models that possess $N=2$ supersymmetry are investigated on the half-space. Conformal perturbation theory is used to identify some $N=2$ supersymmetric boundary integrable models, and the effective boundary Landau-Ginzburg actions are constructed. It is found that $N=2$ supersymmetry largely determines the boundary action in terms of the b

A. V. Kotikov, G. Parente

We present a set of formulae to extract the gluon distribution function from the deep inelastic structure function F$_2$ and its derivative dF$_2$/dlnQ$^2$ at small x in the leading and next-to-leading order of perturbation theory. The detailed analysis is given for new HERA data. The values of the gluon distribution are found in the range $10^{-4} \leq x \l

M. Jezabek, R. Harlander, J. H. Kuehn, M. Peter

Recent calculations are presented of top quark polarization in $t\bar t$ pair production close to threshold. S-P-wave interference gives contributions to all components of the top quark polarization vector. Rescattering of the decay products is considered. Moments of the fourmomentum of the charged lepton in semileptonic top decays are calculated and shown t

T. Gehrmann, W. J. Stirling

The distribution of the spin of the nucleon among its constituents can be parametrized in the form of polarized parton distribution functions for quarks and gluons. Using all available data on the polarized structure function $g_1(x,Q^2)$, we determine these distributions both at leading and next-to-leading order in perturbation theory. We suggest three diff

M. Giffon, E. Predazzi, A. Samokhin

We provide a theorem to suggest that $t=0$ data may already be sufficient to detect possible asymptotic C-odd (Odderon) contributions. This can be done by comparing $\bar p p$ and $pp$ $t=0$ observables such as total cross sections, forward angular distributions and ratios of real to imaginary forward amplitudes for which well defined model independent corre

Daniele Dominici

An effective lagrangian describing a strong interacting electroweak sector is considered. It contains new vector and axial-vector resonances all degenerate in mass and mixed with $W$ and $Z$. The model, for large mass of these degenerate gauge bosons, becomes identical to the standard model in the limit of infinite Higgs mass. The limits on the parameter spa

A. Riotto, E. Roulet

It has been recently realized that within the Minimal Supersymmetric Standard Model, for certain patterns of superpartner masses, consistent with all the present experimental constraints, the scalar potential may develop at some scale $Q_0$ unbounded color/charge breaking directions involving the sfermion fields, and that these patterns are then excluded unl

Jisuke Kubo, Myriam Mondragon, George Zoupanos

Gauge-Yukawa Unification (GYU) is a renormalization group invariant functional relation among gauge and Yukawa couplings which holds beyond the unification point in Grand Unified Theories (GUTs). Here, GYU is obtained by requiring finiteness and reduction of couplings to all orders in perturbation theory. We examine the consequences of GYU in various supersy

Christopher D. Carone, Lawrence J. Hall, Hitoshi Murayama

We show how to incorporate the lepton sector in a supersymmetric theory of flavor based on the discrete flavor group $(S_3)^3$. Assuming that all possible nonrenormalizable operators are generated at the Planck scale, we show that the transformation properties of the leptons and of the flavor-symmetry breaking fields are uniquely determined. We then demonstr

Frithjof Karsch

During the first part of this review we will focus on the thermodynamics of $SU(N)$ gauge theories at finite temperature. We will present results from a calculation of electric and magnetic screening masses for the gluons, discuss calculations of the critical temperature in units of the string tension and bulk thermodynamic quantities like the energy density

Jun Nishimura

We argue that the definition of the partition function used recently to demonstrate the failure of Regge calculus is wrong. In fact, in the one-dimensional case, we show that there is a more natural definition, with which one can reproduce the correct results.

Mourad Daoudi, The SLD Collaboration

We present the first results on tau physics using polarized beams. These include measurements of the $τ$ Michel parameters $ξ$ and $ξδ$ and the $τ$ neutrino helicity $h_ν$. The measurements were performed using the SLD detector at the Stanford Linear Collider (SLC). (Invited talk at the 1995 International Europhysics Conference on High Energy Physics, Brusse

M. Arnaudon, S. Paycha

We introduce a class of regularisable infinite dimensional principal fibre bundles which includes fibre bundles arising in gauge field theories like Yang-Mills and string theory and which generalise finite dimensional Riemannian principal fibre bundles induced by an isometric action. We show that the orbits of regularisable bundles have well defined, both he

H. Rieger, A. P. Young

We study a model for a quantum Ising spin glass in two space dimensions by Monte Carlo simulations. In the disordered phase at $T=0$, we find power law distributions of the local susceptibility and local non-linear susceptibility, which are characterized by a smoothly varying dynamical exponent $z$. Over a range of the disordered phase near the quantum trans

T. Yanagisawa, Y. Shimoi

We examine the spin-reflection positivity of the ground state of the Kondo lattice model at half-filling with the antiferromagnetic and ferromagnetic exchange couplings $J\ne0$. For every positive $U>0$, where U is the Coulomb interaction between the conduction electrons, we can show that the ground state is unique.

A. Fabrocini, L. Vichi, F. Mazzanti, A. Polls

Correlated Basis Function perturbation theory is used to evaluate the zero temperature response $S(q,ω)$ of $^3$He-$^4$He mixtures for inelastic neutron scattering, at momentum transfers $q$ ranging from $1.1$ to $1.7 Å^{-1}$. We adopt a Jastrow correlated ground state and a basis of correlated particle-hole and phonon states. We insert correlated one partic

D. E. Feldman, A. V. Izyumov, Viktor Dotsenko

We study the critical properties of the weakly disordered two-dimensional Ising and Baxter models in terms of the renormalization group (RG) theory generalized to take into account the replica symmetry breaking (RSB) effects. Recently it has been shown that the traditional replica-symmetric RG flows in the dimensions $D = 4 - ε$ are unstable with respect to

E. Follana, F. Ritort

We study the relaxational dynamics of the one-spin facilitated Ising model introduced by Fredrickson and Andersen. We show the existence of a critical time which separates an initial regime in which the relaxation is exponentially fast and aging is absent from a regime in which relaxation becomes slow and aging effects are present. The presence of this fast

Georges Bouzerar, Didier Poilblanc

Persistent currents flowing through disordered mesoscopic rings threaded by a magnetic flux are investigated. Models of fermions with on-site interactions (Hubbard model) or models of spinless fermions with nearest neighbor interactions are considered on 2D cylinders with twisted boundary conditions in one direction to account for a magnetic flux. Self-consi

Karlo Penc, Karen Hallberg, Frederic Mila, Hiroyuki Shiba

We show that the factorized wave-function of Ogata and Shiba can be used to calculate the $k$ dependent spectral functions of the one-dimensional, infinite $U$ Hubbard model, and of some extensions to finite $U$. The resulting spectral function is remarkably rich: In addition to low energy features typical of Luttinger liquids, there is a well defined band,