February 1993 arXiv papers — page 2

C. G. Torre, I. M. Anderson

Generalized symmetries of the Einstein equations are infinitesimal transformations of the spacetime metric that formally map solutions of the Einstein equations to other solutions. The infinitesimal generators of these symmetries are assumed to be local, \ie at a given spacetime point they are functions of the metric and an arbitrary but finite number of der

D. Coffey, K. S. Bedell

We calculate the entropy of a two-dimensional Fermi Liquid(FL) using a model with a contact interaction between fermions. We find that there are $T^2$ contributions to the entropy from interactions separate from those due to the collective modes. These $T^2$ contributions arise from non-analytic corrections to the real part of the self-energy which may be ca

F. W. J. Hekking, Yu. V. Nazarov

The subgap conductivity of a normal-superconductor (NS) tunnel junction is thought to be due to tunneling of two electrons. There is a strong interference between these two electrons, originating from the spatial phase coherence in the normal metal at a mesoscopic length scale and the intrinsic coherence of the superconductor. We evaluated the interference e

F. W. J. Hekking, Yu. V. Nazarov

At low temperatures, the transport through a superconducting-normal tunnel interface is due to tunneling of electrons in pairs. The probability for this process is shown to depend on the layout of the electrodes near the tunnel junction, rather than on properties of the tunnel barrier. This dependence is due to interference of the electron waves on a space s

Nicholas B. Tufillaro

An exact solution is presented for a swinging Atwood's machine. This teardrop-heart orbit is constructed using Hamilton-Jacobi theory. The example nicely illustrates the utility of the Hamilton-Jacobi method for finding solutions to nonlinear mechanical systems when more elementary techniques fail.

George G. Szpiro

When a series of measurements is performed with increasingly coarse (or increasingly fine) precision, consecutive observations seem to be erratically distributed at first, and then organize themselves into cycles and patterns. The patterns, which arise because of roundoff errors, are related to a notion in number theory, the so- called Farey sequence. Key wo

M. S. Turner

The amplitude and spectrum of the scalar and tensor perturbations depend upon the shape of the inflationary potential in the small interval where the scalar field responsible for inflation was between about 46 and 54 e-folds before the end of inflation. By expanding the inflationary potential in a Taylor series in this interval we show that the amplitude of

L. Moscardini, S. Borgani, P. Coles, F. Lucchin

We generate artificial Lick maps using $N$--body simulations and compare the angular correlation function, $w(\vartheta)$, measured from the simulations with the APM correlation. For the Gaussian CDM model, neither the standard biassed model nor a more evolved model (as suggested by the COBE data), reproduce the correlations on large angular scales. We come

Claude LeBrun, Michael Singer

Let M be a compact complex surface which admits a Kaehler metric whose scalar curvature has integral zero; and suppose the fundamental group of M does not contain an Abelian subgroup of finite index. Then if M is blown up at sufficiently many points, the resulting surface M' admits scalar-flat Kaehler metrics.

Claude LeBrun

We study the topology and geometry of those compact Riemannian (4n)-manifolds (M,g), n > 1, with positive scalar curvature and holonomy in Sp(n)Sp(1). Up to homothety, we show that there are only finitely many such manifolds of any dimension 4n.

Wei-Min Zhang, Avaroth Harindranth

Understanding the nontrivial features of light-front QCD is a central goal in current investigations of nonperturbative light-front field theory. We find that, with the choice of light-front gauge with antisymmetric boundary conditions for the field variables, the residual gauge freedom is fixed and the light-front QCD vacuum is trivial. The nontrivial struc

Kenneth J. Dykema

This revised version corrects some substancial errors in the proofs. The old proofs were only valid for (finite dimensional) * (finite dimensional). The scope of the results remains the same, however for type I_\infty algebras, the results of the original version were incorrect.

Herman Verlinde, Erik Verlinde

Previous studies of high-energy scattering in QCD have shown a remarkable correspondence with two-dimensional field theory. In this paper we formulate a simple effective model in which this two-dimensional nature of the interactions is manifest. Starting from the (3+1)-dimensional Yang-Mills action, we implement the high energy limit $s\! >\! > \! t$ via a s

V. Pleitez

We consider generalizations of the standard model (SM) which are based on the gauge symmetry $SU(n)_c\otimes SU(m)_L\otimes U(1)_N$. Although the most interesting possibilities occur when $n=3$, we will consider also the cases $n=4,5$ both with $m=3,4$. Models with left-right symmetry, horizontal symmetries and the possible embedding in a larger group (grand

Zbigniew Jaskolski, Krzysztof A. Meissner

Using the Polyakov string ansatz for the rectangular Wilson loop we calculate the static potential in the semiclassical approximation. Our results lead to a well defined sum over surfaces in the range $1<d<25$.

Ramzi R. Khuri

We discuss three classes of solitonic solutions in string theory: instantons, monopoles and string-like solitons. Instantons may provide a nonperturbative understanding of the vacuum structure of string theory, while monopoles may appear in string predictions for grand unification. The particular monopole solution shown has finite action as the result of the

A. Jevicki

We describe some recent progress in understanding and formulating string theory which is based on extensive studies of strings in lower (D=2) dimension. At the center is a large $W_{\infty}$ symmetry that appears most simply in the matrix model picture. In turn the symmetry defines the dynamics giving Ward identities and the complete S-matrix. The integrabil

Jeffrey M. Rabin

A detailed study is made of super elliptic curves, namely super Riemann surfaces of genus one considered as algebraic varieties, particularly their relation with their Picard groups. This is the simplest setting in which to study the geometric consequences of the fact that certain cohomology groups of super Riemann surfaces are not freely generated modules.

M. Bershadsky, S. Cecotti, H. Ooguri, C. Vafa

We study the stringy genus one partition function of $N=2$ SCFT&#39;s. It is shown how to compute this using an anomaly in decoupling of BRST trivial states from the partition function. A particular limit of this partition function yields the partition function of topological theory coupled to topological gravity. As an application we compute the number of h

M. Nazarov, Vitaly Tarasov

We establish a relationship between the modern theory of Yangians and the classical construction of the Gelfand-Zetlin bases for the complex Lie algebra $\gn$. Our approach allows us to produce the $q$-analogues of the Gelfand-Zetlin formulae in a straightforward way.

Ken-ji Hamada, Asato Tsuchiya

The quantum theory of the spherically symmetric gravity in 3+1 dimensions is investigated. The functional measures are explicitly evaluated and the physical state conditions are derived by using the technique developed in two dimensional quantum gravity. Then the new features which are not seen in ADM formalism come out. If $κ_s > 0 $, where $κ_s =(N-27)/12π

Augusto Sagnotti

In models of oriented closed strings, anomaly cancellations are deeply linked to the {\it modular invariance} of the torus amplitude. If open and/or unoriented strings are allowed, there are no non-trivial modular transformations in the additional genus-one amplitudes (Klein bottle, annulus and Möbius strip). As originally recognized by Green and Schwarz, in

Christopher D. Carone

We consider the possibility that neutrinoless double beta decay may occur in models with unbroken lepton number via the emission of a massive gauge boson with electron lepton number $-2$. We determine the shape of the $β\,β$ sum energy spectrum as a function of the gauge coupling, independent of model-specific details. We discuss our results in light of the

David A. Kosower

In gauge theories with slowly-running coupling constants, it may be possible for four-fermion operators to be nearly marginal. Such operators can possess asymptotically weak couplings, and can plausibly give rise to light composite vector mesons.

Giuseppe Degrassi

The $O(αm_t^2/m_w^2)$ and $O(αα_s m_t^2/m_w^2)$ corrections to the partial decay width $Γ(Z \rightarrow b + \bar{b})$ are computed using the current algebra formulation of radiative corrections. This framework allows one to easily enforce the relevant Ward identity that greatly simplifies the calculations. As a result, the one-loop $O(αm_t^2/m_w^2)$ contribu

R. Decker, M. Finkemeier

We have calculated the decay $τ\rightarrow νπ(K) γ$. We present the photon energy spectrum, the meson-photon invariant mass spectrum and the integrated rate as a function of a photon energy cut or an invariant mass cut. Both the internal bremsstrahlung and the structure dependent radiation have been taken into account. To this aim we have parametrized the fo

K. Hagiwara, S. Matsumoto, M. Tanaka

If high mass di-gamma events observed at LEP are due to the production of a di-gamma resonance via its leptonic coupling, its consequences can be observed at TRISTAN. We find that a predicted $Z$ decay branching rate is too small to account for the observed events if the resonance spin is zero, due to a strong cancellation in the decay amplitudes. Such a can

J. W. Moffat

The problem of information loss in black hole formation and the associated violations of basic laws of physics, such as conservation of energy, causality and unitarity, are avoided in the nonsymmetric gravitational theory, if the NGT charge of a black hole and its mass satisfy an inequality that does not violate any known experimental data and allows the exi

B. L. Hu

We show how the concept of quantum open system and the methods in non-equilibrium statistical mechanics can be usefully applied to studies of quantum statistical processes in the early universe. We first sketch how noise, fluctuation, dissipation and decoherence processes arise in a wide range of cosmological problems. We then focus on the origin and nature

B. L. Hu

Methods and concepts for the study of phase transitions mediated by a time-dependent order-parameter field in curved spacetimes are discussed. A practical example is the derivation of an effective (quasi-)potential for the description of `slow-roll&#39; inflation in the early universe. We first summarize our early results on viewing the symmetry behavior of

B. L. Hu, Yuhong Zhang

We scrutize the commonly used criteria for classicality and examine their underlying issues. The two major issues we address here are that of decoherence and fluctuations. We borrow the insights gained in the study of the semiclassical limit of quantum cosmology to discuss the three criteria of classicality for a quantum closed system: adiabaticity, correlat

L. Diosi, B. Lukacs

By simple arguments, we have shown that Karolyhazy&#39;s model overestimates the quantum uncertainty of the space-time geometry and leads to absurd physical consequences. The given model can thus not account for gradual violation of quantum coherence and can not predict tiny experimental effects either.

Ken Dykema, Alexandru Nica

The q-commutation relations in the title are those that have recently received much attention, and that for -1<q<1 provide an interpolation between Bosonic and Fermionic statistics, passing through free statistics at q=0. We look at the C*-algebra R^q generated by the representation of these relations on the twisted Fock space of Bozejko-Speicher, and we fin

Oleg Mokhov

In this paper the explicit form of the operator of transformation of the vacuum states for the general two-mode Bogolubov transformation is found

Abhay Ashtekar, Ranjeet S. Tate, Claes Uggla

A canonical transformation is performed on the phase space of a number of homogeneous cosmologies to simplify the form of the scalar (or, Hamiltonian) constraint. Using the new canonical coordinates, it is then easy to obtain explicit expressions of Dirac observables, i.e.\ phase space functions which commute weakly with the constraint. This, in turn, enable

Abhay Ashtekar, Ranjeet S. Tate, Claes Uggla

In several of the class A Bianchi models, minisuperspaces admit symmetries. It is pointed out that they can be used effectively to complete the Dirac quantization program. The resulting quantum theory provides a useful platform to investigate a number of conceptual and technical problems of quantum gravity.

Christian Grosche

In this lecture a short introduction is given into the theory of the Feynman path integral in quantum mechanics. The general formulation in Riemann spaces will be given based on the Weyl- ordering prescription, respectively product ordering prescription, in the quantum Hamiltonian. Also, the theory of space-time transformations and separation of variables wi

O. J. P. Eboli, M. C. Gonzalez-Garcia, F. Halzen, D. Zeppenfeld

Observing the production of the Higgs particle in the $γ$-$γ$ mode of a linear $e^+e^-$ collider allows for the measurement of the $Hγγ$ coupling. We point out that for the intermediate Higgs mass range this measurement is considerably more challenging than previously believed. The $b \bar b$ signature receives a large background from the production of heavy

M. C. Gonzalez-Garcia, F. Halzen, R. A. Vazquez, E Zas

To cosmic rays incident near the horizon the Earth&#39;s atmosphere represents a beam dump with a slant depth reaching 36000~g~cm$^{-2}$ at $90^\circ$. The prompt decay of a heavy quark produced by very high energy cosmic ray showers will leave an unmistakable signature in this dump. We translate the failure of experiments to detect such a signal into an upp

P. Nielaba, V. Privman, J. -S. Wang

Random sequential adsorption (RSA) models have been studied due to their relevance to deposition processes on surfaces. The depositing particles are represented by hard-core extended objects; they are not allowed to overlap. Numerical Monte Carlo studies and analytical considerations are reported for 1D and 2D models of multilayer adsorption processes. Depos

R. A. Jalabert, J. -L. Pichard, C. W. J. Beenakker

We consider the energy level statistics of non-interacting electrons which diffuse in a $ d $-dimensional disordered metallic conductor of characteristic Thouless energy $ E_c. $ We assume that the level distribution can be written as the Gibbs distribution of a classical one-dimensional gas of fictitious particles with a pairwise additive interaction potent

Nathan Poliatzky

Levinson&#39;s theorem for the Dirac equation is known in the form of a sum of positive and negative energy phase shifts at zero momentum related to the total number of bound states. In this letter we prove a stronger version of Levinson&#39;s theorem valid for positive and negative energy phase shifts separately. The surprising result is, that in general th

B. Broda

A new topological invariant of closed connected orientable four-dimensional manifolds is proposed. The invariant, constructed via surgery on a special link, is a four-dimensional counterpart of the celebrated SU(2) three-manifold invariant of Reshetikhin, Turaev and Witten.

R. Cuerno, C. Gomez, E. Lopez, G. Sierra

We prove in this paper that the elliptic $R$--matrix of the eight vertex free fermion model is the intertwiner $R$--matrix of a quantum deformed Clifford--Hopf algebra. This algebra is constructed by affinization of a quantum Hopf deformation of the Clifford algebra.

A. P. Isaev, Z. Popowicz

The algebraic formulation of the quantum group gauge models in the framework of the $R$-matrix approach to the theory of quantum groups is given. We consider gauge groups taking values in the quantum groups and noncommutative gauge fields transformed as comodules under the coaction of the gauge quantum group $ G_{q}$. Using this approach we construct the qua

Frank Wilczek

Following Hawking, it is usual to mimic the effect of collapse space-time geometry on quantum fields in a semi-classical approximation by imposing suitable boundary conditions at the origin of coordinates, which effectively becomes a moving mirror. Suitable mirror trajectories induces a close analogue to the radiance of black holes, including a flux of outgo

Paul Martin, Hubert Saleur

We determine the structure of the partition algebra $P_n(Q)$ (a generalized Temperley-Lieb algebra) for specific values of $Q \in \C$, focusing on the quotient which gives rise to the partition function of $n$ site $Q$-state Potts models (in the continuous $Q$ formulation) in arbitrarily high lattice dimensions (the mean field case). The algebra is non-semi-

Paul Martin, Hubert Saleur

We determine the structure of two variations on the Temperley-Lieb algebra, both used for dealing with special kinds of boundary conditions in statistical mechanics models. The first is a new algebra, the `blob&#39; algebra (the reason for the name will become obvious shortly!). We determine both the generic and all the exceptional structures for this two pa

S. V. Ketov

The $N=2$ fermionic string theory is revisited in light of its recently proposed equivalence to the non-compact $N=4$ fermionic string model. The issues of space-time Lorentz covariance and supersymmetry for the BRST quantized $N=2$ strings living in uncompactified $2 + 2$ dimensions are discussed. The equivalent local quantum supersymmetric field theory app

Daniel Arnaudon, Vladimir Rittenberg

We consider two-state (q^2=-1) and three-state (q^3=1) one-dimensional quantum spin chains with U_q(SL(2)) symmetry. Taking unrestricted representations (periodic, semi-periodic and nilpotent), we show which are the necessary conditions to obtain a Hermitian Hamiltonian.

Dan Radu Grigore

It is shown that the quantum position operator of Newton and Wigner for non-zero mass systems is uniquely determined if one imposes a quantum &#39;&#39;manifest covariance&#39;&#39; condition of the same type as the similar condition of Currie, Jordan and Sudarshan in the the framework of the Hamiltonian formalism.

P. Bouwknegt, J. McCarthy, K. Pilch

We generalize some of the standard homological techniques to $\cW$-algebras, and compute the semi-infinite cohomology of the $\cW_3$ algebra on a variety of modules. These computations provide physical states in $\cW_3$ gravity coupled to $\cW_3$ minimal models and to two free scalar fields.

Robert Garisto, Gordy Kane

It is well known that if phases and masses in the Minimal Supersymmetric Standard Model (MSSM) are allowed to have general values, the resulting neutron EDM ($d_n$) exceeds the experimental upper limit by about $10^3$. We assume that the needed suppression is not due to a fine-tuning of phases or masses, and ask what natural size of $CP$ violation (CPV) resu

K. Melnikov, O. Yakovlev

QCD radiative correction to Higgs $\rightarrow$ two photons decay rate is calculated. Below the threshold we found negligible correction, thus supporting results obtained earlier by Djouadi et all [7]. Above the threshold radiative correction appears to be large for both real and imaginary part of H $γγ$ vertex. This leads to radiative correction for $Γ$(H $

Z. Bern, L. Dixon, D. A. Kosower

We present the one-loop helicity amplitudes with five external gluons. The computation employs string-based methods, new techniques for performing tensor integrals, and improvements in the spinor helicity method.

Michelangelo MANGANO

We analise the implications of the measurement of $B$ and $J/ψ$ inclusive \pt\ distributions performed in $p\bar p$ collisions by the UA1 and CDF experiments.

Alick L. Macpherson, Bruce A. Campbell

Recently it has been suggested that top quarks, or very massive fourth generation quarks, might surround themselves with a Higgs &#34;bag&#34; of deformation of the Higgs expectation value from its vacuum magnitude. In this paper we address the question of whether such nonlinear Higgs-top interaction effects are subject to experimental test. We first note th

The RTN Collaboration, Garcia Perez, Gonzalez-Arroyo, Martinez

We study $SU(2)$ lattice gauge theory in small volumes and with twist $\vec{m}=(1,1,1)$. We investigate the presence of the periodic instantons of $Q=\frac{1}{2}$ and determine their free energy and their contribution to the splitting of energy flux sectors \mbox{$E(\vec{e}=(1,1,1))-E(\vec{e}=(0,0,0)) $.}

Victor V. Matveev

Numerical minimization of the Euclidean action of the two-dimensional Abelian Higgs model is used to construct periodic instantons, the euclidean field configurations with two turning points describing transitions between the vicinities of topologically distinct vacua. Periodic instantons are found at any energy ( up to the sphaleron energy $E_{sph}$ ) and f

F. Karsch, M. L. Laursen, T. Neuhaus, B. Plache

Using a geometric definition for the lattice Chern-Simons term in even dimensions, we have studied the distribution of Chern-Simons numbers for the 2d-U(1) and the 4d-SU(2) lattice Higgs models. The periodic structure of the distributions is preserved in our lattice formulation and has been examined in detail. In both cases the finite size effects visible in

B. L. Hu, Juan Pablo Paz, Sukanya Sinha

We trace the development of ideas on dissipative processes in chaotic cosmology and on minisuperspace quantum cosmology from the time Misner proposed them to current research. We show 1) how the effect of quantum processes like particle creation in the early universe can address the issues of the isotropy and homogeneity of the observed universe, 2) how view

Abhay Ashtekar

The purpose of these lectures is to discuss in some detail a new, non-perturbative approach to quantum gravity. I would like to present the basic ideas, outline the key results that have been obtained so far and indicate where we are headed and what the hopes are. The audience at this summer school had a diverse background; many came from high energy physics

Niall Ó Murchadha

Brill waves are the simplest (non-trivial) solutions to the vacuum constraints of general relativity. They are also rich enough in structure to allow us believe that they capture, at least in part, the generic properties of solutions of the Einstein equations. As such, they deserve the closest attention. This article illustrates this point by showing how Bri

J. M. Mourão

Symmetric gauge fields and invariant metrics in homogeneous spaces are found. Their use for finding exact solutions of the Einstein-Yang-Mills (EYM) equations is discussed.

Myung-Hoon Chung

A many-particle Hamiltonian is proposed in order to explain the fractional quantum Hall effect (FQHE) for fractional filling factors $ν< 1$. The solutions of the corresponding Hartree-Fock equations make it possible to discuss the FQHE from the point of view of the single quasi-particle energy spectrum. It is shown how the specific couplings in the many-part

K. Schönhammer, V. Meden

The one electron spectral functions for the Luttinger model are discussed for large but finite systems. The methods presented allow a simple interpretation of the results. For finite range interactions interesting nonunivesal spectral features emerge for momenta which differ from the Fermi points by the order of the inverse interaction range or more. For a s

Peter Kopietz

We calculate the average persistent current in a mesoscopic metal ring threaded by a magnetic flux in the diffusive regime. It is shown that the classical electromagnetic energy leads to a {\it{universal}} average current of the order of $ αe c / C_{0}$, where $α$ is the fine structure constant, $-e$ is the charge of the electron, $c$ is the velocity of ligh

E. Hernandez-Garcia, Jorge Vinals, Raul Toral, M. San Miguel

We study the effect of fluctuations in the vicinity of an Eckhaus instability. The classical stability limit, which is defined in the absence of fluctuations, is smeared out into a region in which fluctuations and nonlinearities dominate the decay of unstable states. The width of this region is shown to grow as $ D^{1/2} $, where $D$ is the intensity of the

C. C. Dudley, C. G. Wynn-Williams

Arp 299C is a $5 \times 10^{10}$ \Lsun infrared source in the merging galaxy system Arp 299. It is the most luminous object known that is not obviously associated with a galaxy nucleus. Our data show that the 8--13 \mum spectrum of Arp 299C has a strong \NeII emission line and emission features like those of polycyclic aromatic hydrocarbon molecules. These e

A. A. Tseytlin

We develop a field-theoretical approach to determination of the background target space fields corresponding to general $G/H$ coset conformal theories described by gauged WZW models. The basic idea is to identify the effective action of a gauged WZW theory with the effective action of a sigma model. The derivation of the quantum effective action in the gauge

Ernest Ma

In the minimal supersymmetric standard model, the Higgs sector has two unknown parameters, usually taken to be $\tan β\equiv v_2/v_1$ and $m_A$, the mass of its one physical pseudoscalar particle. By minimizing the minimum of the Higgs potential along a certain direction in parameter space, it is shown that $m_A = M_Z$ + radiative correction, and if one furt

L. V. Avdeev, D. I. Kazakov, I. N. Kondrashuk

We investigate the possibility of generalizing differential renormalization of D.Z.Freedman, K.Johnson and J.I.Latorre in an invariant fashion to theories with infrared divergencies via an infrared $\tilde{R}$ operation. Two-dimensional $σ$ models and the four-dimensional $ϕ^4$ theory diagrams with exceptional momenta are used as examples, while dimensional

W. van Dijk, M. W. Kermode, D-C Zheng

We consider the $P$- and $Q$-shape parameters in the eigenphase and `bar&#39; phase shift representations for the two Reid potentials and the more recent Moscow potential. The values of these parameters were obtained from integrals of the zero-energy wave function in a similar manner to that for the effective range. Such expressions for the shape parameters

Gilles Pisier

This paper is mainly devoted to the following question:\ Let $M,N$ be von~Neumann algebras with $M\subset N$, if there is a completely bounded projection $P\colon \ N\to M$, is there automatically a contractive projection $\widetilde P\colon \ N\to M$? We give an affirmative answer with the only restriction that $M$ is assumed semi-finite.

U. Haagerup, Gilles Pisier

Let $u:A\to B$ be a bounded linear operator between two $C^*$-algebras $A,B$. The following result was proved by the second author. Theorem 0.1. There is a numerical constant $K_1$ such that for all finite sequences $x_1,\ldots, x_n$ in $A$ we have $$\leqalignno{&\max\left\{\left\|\left(\sum u(x_i)^* u(x_i)\right)^{1/2}\right\|_B, \left\|\left(\sum u(x_i) u(

Sergey Piunikhin

The most general R-matrix type state sum model for link invariants is constructed. It contains in itself all R-matrix invariants and is a generating function for &#34;universal&#34; Vassiliev link invariants. This expression is more simple than Kontsevich&#39;s expression for the same quantity, because it is defined combinatorially and does not contain any i

Branko Urosevic

In this paper we develop the covariant string field theory approach to open 2d strings. Upon constructing the vertices, we apply the formalism to calculate the lowest order contributions to the 4- and 5- point tachyon--tachyon tree amplitudes. Our results are shown to match the `bulk&#39; amplitude calculations of Bershadsky and Kutasov. In the present appro

Aharon Davidson, Uzi Paz

We extend Dirac&#39;s `extensible model of the electron&#39; to include spin and family. $U(1)_{e.m.}$ charge conservation on the bubble is translated into a secondary $U(1)_{g}$ world-manifold gauge principle. Reflecting the secondary magnetic monopole configuration on spatial $S^2$, the harmonic excitations may furnish half integer $SU(2)_{spin}\otimes U(1

Zhijian Tao

Charged scalar particles introduced in some extensions of the standard model can induce $τ$ leptonic decay at tree level. We find that with some charged SU(2)-singlet scalar particles, like ones introduced in Zee-type models, $τ$ leptonic decay width is always smaller than what is predicted by the standard model, therefore they may offer a natural solution t

A. Ballestrero, E. Maina, S. Moretti

The production of photon pairs in $e^+e^-\rightarrow f \bar f γγ$ processes is studied using exact helicity amplitudes at tree level. Total cross sections, including initial state radiation effects, are given. They are presented in the case of quarks as a function of $y_{\rm cut}$ in the JADE algorithm. In the case of leptons we use cuts similar to the ones

Hyun Kyu Lee, Mannque Rho

In this article, we show -- using a reasoning applicable to both the excitation spectrum in the chiral bag model and the hyperfine structure of diatomic molecules -- that the generic form of a non- abelian Berry potential appears in heavy-quark effective theory (HQET) and that the Berry potential vanishes for the soliton- heavy meson bound state in the heavy

C. Q. Geng, K. Whisnant, B. -L. Young

We explore the possibility of having new physics which could account for the $l^+l^-γγ$ events with $M_{γγ}\simeq 60\ $GeV recently reported by LEP. We consider models which contain an extra neutral gauge boson ($Z&#39;$) that couples only to right-handed fermions. The models naturally require at least three quark and lepton families from anomaly cancellatio

John F. Gunion, Howard E. Haber, Gordon L. Kane, Sally Dawson

Errata are given for &#34;The Higgs Hunter&#39;s Guide&#34;. These errata should be applied to the second printing of the book, dated 1991. The second printing has already corrected numerous errors and misprints contained in the originally published 1990 edition.

Bartomeu Alles, Massimo Campostrini, Adriano Di Giacomo, Yigit Gunduc

The renormalization functions involved in the determination of the topological susceptibility in the SU(2) lattice gauge theory are extracted by direct measurements, without relying on perturbation theory. The determination exploits the phenomenon of critical slowing down to allow the separation of perturbative and non-perturbative effects. The results are i

B. L. Hu

We discuss the appearance of time-asymmetric behavior in physical processes in cosmology and in the dynamics of the Universe itself. We begin with an analysis of the nature and origin of irreversibility in well-known physical processes such as dispersion, diffusion, dissipation and mixing, and make the distinction between processes whose irreversibility aris

R. Capovilla, J. Dell, T. Jacobson

The form of the initial value constraints in Ashtekar&#39;s hamiltonian formulation of general relativity is recalled, and the problem of solving them is compared with that in the traditional metric variables. It is shown how the general solution of the four diffeomorphism constraints can be obtained algebraically provided the curvature is non-degenerate, an

E. D. Stewart, D. H. Lyth

Formulae are derived for the spectra of scalar curvature perturbations and gravitational waves produced during inflation, special cases of which include power law inflation, natural inflation in the small angle approximation and inflation in the slow roll approximation.

Jayakumar Ramanathan, Pankaj Topiwala

The time-frequency content of a signal can be measured by the Gabor transform or windowed Fourier transform. This is a function defined on phase space that is computed by taking the Fourier transform of the product of the signal against a translate of a fixed window. The problem of finding signals with Gabor transform that are maximally concentrated within a

A. V. Balatsky, J. Bonca

An equal time version of odd-frequency pairing for a generalized $t-J$ model is introduced. It is shown that the composite operators describing binding of Cooper pairs with magnetization fluctuations naturally appear in this approach. The pairing correlations in both BCS and odd-frequency channels are investigated exactly in 1D systems with up to 16 sites. O

Ko Okumura

We study the U(M/N) supergroup keeping in mind its connection with electronic Hamiltonians. It is explicitly shown that the generators of the supergroup U(N/N) can be expressed by Clifford operators or Fermi operators. A multi-band supersymmetric electronic model is suggested.

Assa Auerbach

The Semiclassical Expansion of the t-J model. Lectures in the Jerusalem Winter School on Strongly Correlated Electrons, Dec. 1991, by Assa Auerbach, Physics Dept., Technion, Israel. LateX. Tech-102.

Maxim Raykin, Assa Auerbach

The staggered magnetization of the Heisenberg antiferromagnet in two dimensions can be systematically approximated by a 1/N expansion. Cancellation between self energy diagrams leads to a Luttinger-like theorem for the ground state. We prove (for a smooth enough self energy) that the long range order of mean field theory ($N$=$\infty$) survives corrections t

B. Bonnier, M. Hontebeyrie, C. Meyers

We compute the time-dependent coverage in the random sequential adsorption of aligned d-dimensional cubes in $R^d$ using time-series expansions. The seventh-order series in 2, 3 and 4 dimensions is resummed in order to predict the coverage at jamming. The result is in agreement with Monte-Carlo simulations. A simple argument, based on a property of the pertu

A R Liddle, D H Lyth

This paper is based on a talk given by A R Liddle at the PASCOS/TEXAS meeting in December 1992, and will appear in the proceedings. The central result is that all known models of inflation which end in a first order phase transition can be ruled out by combining galaxy surveys at a few tens of Mpc with the COBE data (including the effect of gravitational wav

James T. Liu, Daniel Ng

A global fit for experiments is included in this revised version.

I. Jack, J. Panvel

We construct a quantum Hamiltonian operator for the Wess-Zumino-Witten (WZW) model in terms of the Casimir operator. This facilitates the discussion of the reduction of the WZW model to Toda field theory at the quantum level and provides a very straightforward derivation of the quantum central charge for the Toda field theory.

S. Kalyana Rama

We present a static solution for $d = 2$ critical string theory including the tachyon $T$ but not its potential $V(T)$. This solution thus incorporates tachyon back reaction and, when $T = 0$, reduces to the black hole solution. When $T \neq 0$ one finds that (1) the Schwarzschild horizon of the above black hole splits into two, resembling Reissner-Nordstrom

Rafael D. Sorkin

It is shown that the attempt to extend the notion of ideal measurement to quantum field theory leads to a conflict with locality, because (for most observables) the state vector reduction associated with an ideal measurement acts to transmit information faster than light. Two examples of such information-transfer are given, first in the quantum mechanics of

T. Barnes, S. Capstick, M. D. Kovarik, E. S. Swanson

We derive nonstrange baryon-baryon scattering amplitudes in the nonrelativistic quark model using the ``quark Born diagram&#34; formalism. This approach describes the scattering as a single interaction, here the one-gluon-exchange (OGE) spin-spin term followed by constituent interchange, with external nonrelativistic baryon wavefunctions attached to the scat

A. Strominger, S. P. Trivedi

The low-energy scattering of charged fermions by extremal magnetic Reissner-Nordstrom black holes is analyzed in the large-$N$ and $S$-wave approximations. It is shown that (in these approximations) information is carried into a causally inaccessible region of spacetime, and thereby effectively lost. It is also shown that there is an infinite degeneracy of q