November 1995 arXiv papers — page 8

M. R. Frank, T. Meissner

A detailed investigation of the low-energy chiral expansion is presented within a model truncation of QCD. The truncation allows for a phenomenological description of the quark-quark interaction in a framework which maintains the global symmetries of QCD and permits a $1/N_c$ expansion. The model dependence of the chiral coefficients is tested for several fo

Rennan Bar-Kana

We study the effects of large-scale density fluctuations on strong gravitational lensing. Previous studies have focused mostly on weak lensing, since large-scale structure alone cannot produce multiple images. When a galaxy or cluster acts as a primary lens, however, we find that large-scale structure can produce asymmetric shear of the same order as the len

Cumrun Vafa

We test the prediction of a hagedorn density of BPS states which carry RR charge in type II compactifications. We find that in certain cases they correspond to the supersymmetric ground states for a gas of identical 0-branes.

A. Ballestrero, V. A. Khoze, E. Maina, S. Moretti

We examine the colour structure and charged particle yield for both the $t \bar t$ signal and the irreducible background processes contributing to \eebbww\ production close to the \ttb\ threshold. The charged particle multiplicity for the various components of the cross section is computed as a function of several kinematic variables. Our study may have impo

K. Melnikov

We present an analytical calculation of additional real or virtual radiation of the light fermion pair in the fermionic decay of the Higgs boson $ H \to f_1\bar f_1$ for arbitrary ratios of the Higgs boson mass to the $f_1$ fermion mass. This result gives us a value of the $O(N_f α_s^2)$ radiative correction to the inclusive decay rate $ H \to f_1\bar f_1$.

K. Kalna, M. Mosko, F. M. Peeters

Electron capture times in a separate confinement quantum well (QW) structure with finite electron density are calculated for electron-electron (e-e) and electron-polar optic phonon (e-pop) scattering. We find that the capture time oscillates as function of the QW width for both processes with the same period, but with very different amplitudes. For an electr

Andrew R Liddle, David H Lyth, R K Schaefer, Q Shafi

We present an extensive comparison of models of structure formation with observations, based on linear and quasi-linear theory. We assume a critical matter density, and study both cold dark matter models and cold plus hot dark matter models. We explore a wide range of parameters, by varying the fraction of hot dark matter $Ω_ν$, the Hubble parameter $h$ and

Kedar Damle, Satya Majumdar, Subir Sachdev

We study the approach to equilibrium of a Bose gas to a superfluid state. We point out that dynamic scaling, characteristic of far from equilibrium phase-ordering systems, should hold. We stress the importance of a non-dissipative Josephson precession term in driving the system to a new universality class. A model of coarsening in dimension $d=2$, involving

J. Maeder, W. Ruehl

The Greensite-Halpern method of stabilizing bottomless Euclidean actions is applied to zerodimensional O(N) sigma models with unstable $A_k$ singularities in the $N = \infty$ limit.

Gary W. Gibbons, Michael B. Green, Malcolm J. Perry

Instanton and seven-brane solutions of type IIB supergravity carrying charges in the Ramond-Ramond sector are constructed. The singular seven-brane has a quantized \RR \ \lq magnetic' charge whereas its dual is the instanton, which is non-singular in the string frame and has an associated {\it global} \lq electric' charge. The product of these charge

Arlen Anderson

Experimentally, certain degrees of freedom may appear classical because their quantum fluctuations are smaller than the experimental error associated with measuring them. An approximation to a fully quantum theory is described in which the self-interference of such ``quasiclassical'' variables is neglected so that they behave classically when not cou

Jung Kon Kim, Sang Pyo Kim

For a time-dependent harmonic oscillator with an inverse squared singular term, we find the generalized invariant using the Lie algebra of $SU(2)$ and construct the number-type eigenstates and the coherent states using the spectrum-generating Lie algebra of $SU(1,1)$. We obtain the evolution operator in both of the Lie algebras. The number-type eigenstates a

Leonid L. Vaksman

In the present paper the algebras of functions on quantum homogeneous spaces are studied. The author introduces the algebras of kernels of intertwining integral operators and constructs quantum analogues of the Poisson and Radon transforms for some quantum homogeneous spaces. Some applications and the relation to $q$-special functions are discussed.

A. P. Isaev

We consider the modified (or twisted) Yang-Baxter equations for the $SL_{q}(N)$ groups and $SL_{q}(N|M)$ supergroups. The general solutions for these equations are presented in the case of the linear quantum (super)groups. The introduction of spectral parameters in the twisted Yang-Baxter equation and its solutions are also discussed.

C. Sauermann, B. L. Friman, W. Nörenberg

An effective field theory with hadrons and photons is constructed, where the hadronic parameters are determined by fitting elastic $π$N scattering data. The predicted pion-induced $η$-production on the nucleon agrees well with the data. The hadronic model is then used to describe the final-state interaction in photoinduced processes. We present a consistent

Carroll Guillory

We give several examples of Douglas Algebras that do not have any maximal subalgebra. We find a condition on these algebras that guarantees that some do not have any minimal superalgebra. We also show that if $A$ is the only maximal subalgebra of a Douglas algebra $B$, then the algebra $A$ does not have any maximal subalgebra.

T. Y. Lam, K. H. Leung

Consider the $m$-th roots of unity in {\bf C}, where $m>0$ is an integer. We address the following question: For what values of $n$ can one find $n$ such $m$-th roots of unity (with repetitions allowed) adding up to zero? We prove that the answer is exactly the set of linear combinations with non-negative integer coefficients of the prime factors of $m$.

Ashok Das, Shibaji Roy

A particular dispersive generalization of long water wave equation in $1+1$ dimensions, which is important in the study of matrix models without scaling limit, known as two--Boson (TB) equation, as well as the associated hierarchy has been derived from the zero curvature condition on the gauge group $SL(2,R)\otimes U(1)$. The supersymmetric extension of the

T. Gannon, P. Ruelle, M. A. Walton

This is an elementary review of our recent work on the classification of the spectra of those two-dimensional rational conformal field theories (RCFTs) whose (maximal) chiral algebras are current algebras. We classified all possible partition functions for such theories when the defining finite-dimensional Lie algebra is simple. The concepts underlying this

D. A. Korotkin, J. A. H. Samtleben

The quantization of isomonodromic deformation of a meromorphic connection on the torus is shown to lead directly to the Knizhnik-Zamolodchikov-Bernard equations in the same way as the problem on the sphere leads to the system of Knizhnik-Zamolodchikov equations. The Poisson bracket required for a Hamiltonian formulation of isomonodromic deformations is natur

Fabio Zwirner

We review the construction of $N=1$ supergravity models where the Higgs and super-Higgs effects are simultaneously realized, with naturally vanishing classical vacuum energy and goldstino components along gauge-non-singlet directions: this situation is likely to occur in the effective theories of realistic string models. (Invited talk presented at SUSY--95,

A. Ghosh, P. Mitra, A. Kundu

q-oscillator models are considered in two and higher dimensions and their symmetries are explored. New symmetries are found for both isotropic and anisotropic cases. Applications to the spectra of triatomic molecules and superdeformed nuclei are discussed.

Robert J. Budzynski

A few observations concerning topological string theories at the string-tree level are presented: (1) The tree-level, large phase space solution of an arbitrary model is expressed in terms of a variational problem, with an ``action'' equal, at the solution, to the one-point function of the puncture operator, and found by solving equations of Gauss-Ma

Sang Pyo Kim

We elaborate further the functional Schrödinger-picture approach to the quantum field in curved spacetimes using the generalized invariant method and construct explicitly the Fock space, which we relate with the thermal field theory. We apply the method to a free massive scalar field in the de Sitter spacetime, and find the exact quantum states, construct th

A. Nersessian

The Weil algebra of a semisimple Lie group and an exterior algebra of a symplectic manifold possess antibrackets. They are applied to formulate the models of non--abelian equivariant cohomologies.

Rulin Xiu

We propose that gaugino condensation in the hidden sector may dynamically induce intermediate gauge symmetry breaking and specify the compactification scale. We also show that this scheme makes possible affine level one grand unified string models with gauge breaking scale $M_{\rm GUT} \sim 10^{16}$ GeV. $T$-duality plays a crucial role in making this scheme

R. Barbieri, A. Romanino, A. Strumia

If supersymmetric unification is true, we show how the combined effort of several experiments under way to try to measure an electric dipole moment of the electron or of the neutron has a significant chance not only of producing a positive signal but also of providing crucial information to understand the physical origin of the signal itself.

Jisuke Kubo, Myriam Mondragon, George Zoupanos

The idea of Gauge-Yukawa Unification (GYU) based on the principle of reduction of couplings is elucidated. We show how the observed top-bottom mass hierarchy can be explained in terms of supersymmetric GYU by considering an example of the minimal supersymmetric GUT.

I. M. Dremin

The solution of QCD equations for generating functions of {\it parton} multiplicity distributions reveals new peculiar features of cumulant moments oscillating as functions of their rank. It happens that experimental data on {\it hadron} multiplicity distributions in $e^{+}e^{-}, hh, AA$ collisions possess the similar features. However, the "more regular

M. Szczekowski, G. Wilk

It is demonstrated that universal mass dependence for meson and baryon inclusive cross-sections advocated recently in $e^+e^-$ annihilation and in hadronic reactions is consistent also with heavy ion collisions data and can therefore be used as a reference for quark-gluon plasma studies.

Keiichi Akama

We investigate the compositeness condition in four dimensions at the non-trivial order (next-to-leading order in $1/N$ with the number $N$ of the colors), taking the Nambu-Jona-Lasinio model as an example. In spite of its non-renormalizability, the compositeness condition can be successfully derived and solved in compact forms. The resultant problems are dis

Peter Weisz

A review of investigations of running couplings using lattice techniques is given. This includes i) studies of the running of particular non-perturbatively defined renormalized couplings in pure gauge theories over a range of energies, and ii) how estimates of $α_{\overline{MS}}(m_Z)$ in lattice QCD are presently obtained.

The SLD Collaboration

We report a measurement of the average $B$-hadron lifetime using data collected with the SLD detector at the SLC in 1993. An inclusive analysis selected three-dimensional vertices with $B$-hadron lifetime information in a sample of 50k $Z^{0}$ decays. A lifetime of $1.564\pm0.030\,(\rm stat)\pm 0.037\,(\rm syst)$~ps was extracted from the decay length distri

Z. Perjés, A. Komárik

A first-order perturbation approach to $k=0$ Friedmann cosmologies filled with dust and radiation is developed. Adopting the coordinate gauge comoving with the perturbed matter, and neglecting the vorticity of the radiation, a pair of coupled equations is obtained for the trace $h$ of the metric perturbations and for the velocity potential $v$. A power serie

Sang Pyo Kim

A new asymptotic expansion method is developed to separate the Wheeler-DeWitt equation into the time-dependent Schrödinger equation for a matter field and the Einstein-Hamilton-Jacobi equation for the gravitational field including the quantum back-reaction of the matter field. In particular, the nonadiabatic basis of the generalized invariant for the matter

Sang Pyo Kim

The condition for the unitarity of a quantum field is investigated in semiclassical gravity from the Wheeler-DeWitt equation. It is found that the quantum field preserves unitarity asymptotically in the Lorentzian universe, but does not preserve unitarity completely in the Euclidean universe. In particular we obtain a very simple matter field equation in the

Marcus Kollar, Rainer Strack, Dieter~Vollhardt

Nagaoka's theorem on ferromagnetism in the Hubbard model with one electron less than half filling is generalized to the case where all possible nearest-neighbor Coulomb interactions (the density-density interaction $V$, bond-charge interaction $X$, exchange interaction $F$, and hopping of double occupancies $F'$) are included. It is shown that for fe

P. Dalmas de Réotier, A. Huxley, A. Yaouanc, J. Flouquet

We present muon spin relaxation measurements performed on crystals of the heavy fermion superconductor UPt$_3$. In zero applied field, contrary to a previous report, we do not observe an increase of the internal magnetic field in the lower superconducting phase (the B phase). Our result gives an experimental upper bound of the magnetic field that could be as

T. Miyazaki, I. Nakamura, D. Yoshioka

A two-dimensional bi-layer, square lattice Heisenberg model with different intraplane($J_{\parallel}$) and interplane($J_{\perp}$) couplings is investigated. The model is first solved in the Schwinger boson mean-field approximation. %It is shown that order-disorder transition occurs as the interplane Coupling %is increased. The critical ratio is $J_{\perp/\p

K. Tsutsui, Y. Ohta, R. Eder, S. Maekawa

An exact-diagonalization technique on small clusters is used to study the dynamics of the one-dimensional symmetric Anderson lattice model. Our calculated excitation spectra reproduce key features expected for an infinite Kondo lattice such as nearly localized low-energy spin excitations and extended regions of `heavy-quasiparticle' bands. We show that,

Chris Brew

Describes an algorithm for the generation phase of a Shake-and-Bake Machine Translation system. Since the problem is NP-complete, it is unlikely that the algorithm will be efficient in all cases, but for the cases tested it offers an improvement over Whitelock's previously published algorithm. The work was carried out while the author was employed at Sha

R. Barbier, M. Kibler

A two-parameter deformation of the Lie algebra u$_2$ is used, in conjunction with the rotor system and the oscillator system, to generate a model for rotation-vibration spectroscopy of molecules and nuclei.

J. I. Collar

To appear in Phys. Rev. Lett. together with the author's Reply.

Frederic A. Rasio, Mario Livio

We discuss the formation of a common envelope system following dynamically unstable mass transfer in a close binary, and the subsequent dynamical evolution and final fate of the envelope. We base our discussion on new three-dimensional SPH calculations that we have performed for a close binary system containing a $4\,M_\odot$ red giant with a $0.7\,M_\odot$

V. Kolokotronis, M. Plionis, P. Coles, S. Borgani

We use numerical simulations to investigate the behaviour of the dipole moment of the spatial distribution of different kinds of mass tracers. We select density peaks of the simulated matter distribution with mean separations of 38 and 30 $h^{-1}$ Mpc to represent two samples of rich clusters of galaxies. We extract, from the same simulations, samples select

A. Mazure, P. Katgert, R. den Hartog, A. Biviano et al

Summary - By combining the 5634 redshifts from the ESO Nearby Abell Cluster Survey (the ENACS) with another 1000 redshifts from the literature we are able to study the distribution of velocity dispersions for a volume-limited sample of 128 $R_{\rm ACO} \geq 1$ clusters, out to a redshift $z=0.1$, in a solid angle of 2.55 sr centered on the South Galactic Pol

P. Katgert, A. Mazure, J. Perea, R. den Hartog

Summary - We describe the results of the ESO Key-programme on `Structure and Dynamics of Rich Galaxy Clusters' (or ENACS). The final database contains a total of 5634 galaxies in the directions of 107 clusters from the ACO catalogue with richness $R\ge 1$ and mean redshifts $z \le 0.1$. Of the 5634 redshifts, 4465 are based on absorption lines only, 583

A. Biviano, P. Katgert, A. Mazure, M. Moles

Summary - By using the data from the ESO Nearby Abell Cluster Survey (ENACS), we have studied the properties of emission-line galaxies (ELG) in clusters. The fraction of ELG in clusters is 16~\%; this fraction is slightly dependent on the cluster velocity dispersion, being larger for ``colder'' systems. ELG tend to occur more frequently than other cl

W. D. McGlinn, L. O'Raifeartaigh, S. Sen, R. D. Sorkin

The first and second homology groups are computed for configuration spaces of framed three-dimensional point particles with annihilation included, when up to two particles and an antiparticle are present.

Aharon Levy

Soft interactions are not easily disentangled from hard ones. In an operational definition of soft and hard processes one finds that at presently analyzed scales there is an interplay of soft and hard processes. As the scale increases, so does the amount of hard processes. So far, nothing is as soft nor as hard as we would like.

E. Bergshoeff, M. B. Green, G. Papadopoulos, P. K. Townsend

We present a version of ten-dimensional IIA supergravity containing a 9-form potential for which the field equations are equivalent to those of the standard, massless, IIA theory for vanishing 10-form field strength, $F_{10}$, and to those of the `massive' IIA theory for non-vanishing $F_{10}$. We exhibit a multi 8-brane solution of this theory which pre

Alexander Belopolsky, Barton Zwiebach

In general bosonic closed string backgrounds the ghost-dilaton is not the only state in the semi-relative BRST cohomology that can change the dimensionless string coupling. This fact is used to establish complete dilaton theorems in closed string field theory. The ghost-dilaton, however, is the crucial state: for backgrounds where it becomes BRST trivial we

E. Vinteler

The star-matrix models are difficult to solve due to the multiple powers of the Vandermonde determinants in the partition function. We apply to these models a modified Q-matrix approach and we get results consistent with those obtained by other methods.As examples we study the inhomogenous gaussian model on Bethe tree and matrix $q$-Potts-like model. For the

Mairi Sakellariadou

We investigate some classical aspects of fundamental strings via numerical experiments. In particular, we study the thermodynamics of a string network within a toroidal universe, as a function of string energy density and space dimensionality. We find that when the energy density of the system is low, the dominant part of the string is in the form of closed

V. V. Andreev, A. A. Pankov, N. Paver

We evaluate the constraints on anomalous trilinear gauge-boson couplings that can be obtained from the study of electron-positron annihilation into $W$ pairs at a facility with either the electron beam longitudinally polarized or both electron and positron beams transversely polarized. The energy ranges considered in the analysis are the ones relevant to the

N. I. Kochelev

The instanton contribution to the quark distribution functions in the nucleon is estimated. It is shown, that taking into account the instanton induced interaction between quarks allows to explain the anomalous violation of the Ellis-Jaffe and Gottfried sum rules. The spin-dependent structure functions $g_1^p(x)$, $g_1^n(x)$, $g_1^d(x)$ are calculated in the

L. B. Ioffe, A. J. Millis

We determine the properties and leading instabilities of a spin liquid with a Fermi surface passing near a van Hove singularity. Our study is motivated by recent photoemission experiments on high $T_c$ cuprates in which it is found that for the optimally doped material the experimental Fermi surface passes near a van Hove singularity, while for underdoped ma

Yu-Liang Liu

Using the spin-hole coherent state representation, and taking the long range antiferromagnetic Néel order as the background of the spin degree part, we have studied the magnetic behavior of the t-J model in the usual slave boson and slave fermion treatment of the single occupation constraint, and shown that we can qualitatively explain the anomalous magnetic

Devendra Ojha, Olivier Bienayme, Annie Robin, Michel Creze

We have carried out a sample survey in UBVR photometry and proper motions in different directions in the Galaxy, as part of an investigation of galactic structure and evolution. Three fields in the direction of galactic anticentre, centre and antirotation have been surveyed. Using our new data together with wide-area surveys in other fields available to date

R. Srianand, Pushpa Khare

We have compiled, from the literature, a sample of Ly $α$ forest lines in the spectra of 69 QSOs, all observed with a resolution between 60 to 100 km s$^{-1}$. The sample is studied for proximity effect. We have tried to account for the effect of blending which is inherent in the intermediate resolution sample, by calculating the column density distribution,

Albert-László Barabási

The connectivity of individual neurons of large neural networks determine both the steady state activity of the network and its answer to external stimulus. Highly diluted random networks have zero activity. We show that increasing the network connectivity the activity changes discontinuously from zero to a finite value as a critical value in the connectivit

Cetin Savkli, Frank Tabakin, Shin Nan Yang

A multipole analysis of vector meson photoproduction is formulated as a generalization of the pseudoscalar meson case. Expansion of spin observables in the multipole basis and behavior of these observables near threshold and resonances are examined.

Mladen Damjanovic, Zvonko Maric

In the framework of the Time Dependent Scattering Theory we discuss three forms of Cluster Separability as well as the conditions for the representation of the scattering system dynamics implied by their respective use.

M. Caselle, M. Hasenbusch

We present a high precision Monte Carlo study of the finite temperature $Z_2$ gauge theory in 2+1 dimensions. The duality with the 3D Ising spin model allows us to use powerful cluster algorithms for the simulations. For temporal extensions up to $N_t=16$ we obtain the inverse critical temperature with a statistical accuracy comparable with the most accurate

K. Kakazu, Y. S. Kim

We present a quantization procedure for the electromagnetic field in a circular cylindrical cavity with perfectly conducting walls, which is based on the decomposition of the field. A new decomposition procedure is proposed; all vector mode functions satisfying the boundary conditions are obtained with the help of this decomposition. After expanding the quan

V. N. Soshnikov

The theory of plasma waves and Landau damping in Maxwellian plasmas, Landau's ``rule of pass around poles'' include doubtful statements, particularly related to an artificial ``constructing'' of the dispersion equation, what should allow the possibility of its solution otherwise not existing at all, and the possibility of analytical conti

Subir Ghosh, S. Mukhopadhyay

A novel BRST quantization is described, which is applied in generalizing the Jackiw-Nair construction of anyon. We have explicitly shown that the matter states connected to an unconventional ("non-zero") BRST ghost sector are physical. They are identified to the Jackiw-Nair system in a particular gauge. Also for the first time an indepth analysis of

A. A. Likhoded, T. Han, G. Valencia

We consider the possibility of observing deviations from the Standard Model gauge-boson self-couplings at a future $500$~GeV $e^+ e^-$ linear collider. We concentrate on the case in which the electroweak symmetry breaking sector is strongly interacting and there are no new resonances within reach of the collider. We find a sensitivity to the anomalous coupli

J. A. Coarasa, A. Méndez, J. Solà

We consider the effect of complex Higgs triplets on purely leptonic processes and survey the experimental constraints on the mass and couplings of their single and double charge members. Present day experiments tolerate values of the Yukawa couplings of these scalars at the level of the standard electroweak gauge couplings. We show that the proposed measurem

A. Hart, M. Teper

We study the Abelian projection of SU(2) instantons in the Maximally Abelian gauge. We find that in this gauge an isolated instanton produces a closed monopole loop within its core and the size of this loop increases with the core size. We show that this result is robust against the introduction of small quantum fluctuations. We investigate the effects of ne

Jörg Frauendiener, George A. J. Sparling

We analyze a class of linear wave equations for odd half spin that have a well posed initial value problem. We demonstrate consistency of the equations in curved space-times. They generalize the Weyl neutrino equation. We show that there exists an associated invariant exact set of spinor fields indicating that the characteristic initial value problem on a nu

Flavio S. Nogueira, Enrique V. Anda

A toy model of strongly correlated fermions is studied using Green function and functional integration methods. The model exhibits a metal-insulator transition as the interaction is varied. In the case of unrestricted hopping is established the equivalence of the model with the Hubbard model with infinite range hopping. The generalization to the case with $N

V. S. Berezinsky, P. Blasi, B. I. Hnatyk

We propose a new mechanism for high energy gamma ray burst in Supernova type I (SNI) explosion. Presupernova is assumed to be a binary system comprised of a red giant and a white dwarf with a wind accretion. The accretion flow terminates by the accretion shock in the vicinity of the white dwarf at the distance of the order of the accretion radius. The gas in

Thomas G. Roos

For a large class of field theories there exist portions of parameter space for which the loop expansion predicts increased symmetry breaking at high temperature. Even though this behavior would clearly have far reaching implications for cosmology such theories have not been fully investigated in the literature. This is at least partially due to the counter

Julian Borrill

Lattice-based string formation algorithms can, at least in principle, be reduced to the study of the statistics of the corresponding aperiodic random walk. Since in three or more dimensions such walks are transient this approach necessarily generates a population of open strings. To investigate whether open strings are an artefact of the lattice we develop a

P. Daguier, S. Henaux, E. Bouchaud, F. Creuzet

The fracture surface of a Ti3Al-based alloy is studied using both an atomic force microscope and a standard scanning electron microscope. Results are shown to be quantitatively comparable. Two fracture regimes are observed. It is shown in particular that the roughness index characterizing the small lengthscales regime is equal to 0.5. Furthermore, the large

Mark Srednicki

We consider a quantum system with $N$ degrees of freedom which is classically chaotic. When $N$ is large, and both $\hbar$ and the quantum energy uncertainty $ΔE$ are small, quantum chaos theory can be used to demonstrate the following results: (1) given a generic observable $A$, the infinite time average $\overline A$ of the quantum expectation value $<A(t)

P. Kanti, N. E. Mavromatos, J. Rizos, K. Tamvakis

We give analytical arguments and demonstrate numerically the existence of black hole solutions of the $4D$ Effective Superstring Action in the presence of Gauss-Bonnet quadratic curvature terms. The solutions possess non-trivial dilaton hair. The hair, however, is of ``secondary" type", in the sense that the dilaton charge is expressed in terms of the black

Joao Magueijo, Andreas Albrecht, David Coulson, Pedro Ferreira

We examine how the qualitative structure of the Doppler peaks in the angular power spectrum of the cosmic microwave anisotropy depends on the fundamental nature of the perturbations which produced them. The formalism of Hu and Sugiyama is extended to treat models with cosmic defects. We discuss how perturbations can be ``active&#39;&#39; or ``passive&#39;&#3

A. Donini

We compute the one-loop radiative corrections to the masses of the top quark, the stop squarks and the gluino in the Minimal Supersymmetric Standard Model. We include the loops controlled by the strong coupling constant and the top Yukawa coupling, neglecting those controlled by the $SU(2) \times U(1)$ gauge couplings and by other Yukawa couplings. We find t

C. J. Burden, C. D. Roberts, M. J. Thomson

The charged and neutral kaon form factors are calculated as a phenomenological application of the QCD Dyson-Schwinger equations. The results are compared with the pion form factor calculated in the same framework and yield \mbox{$F_{K^\pm}(Q^2) > F_{\pi^\pm}(Q^2)$} on \mbox{$Q^2\in[0,3]$~GeV$^2$}; and a neutral kaon form factor that is similar in form and ma

Ricardo A. Jimenez, Joan Sola

The supersymmetric QCD corrections to the hadronic width of a heavy charged Higgs boson, basically dominated by the top-quark decay mode $H^{+}\rightarrow t \bar{b}$, are evaluated at ${\cal O}(α_s)$ within the MSSM and compared with the standard QCD corrections. The study of such quantum effects, which turn out to be rather large, is essential to understand

V. Frolov, S. Hendy, A. L. Larsen

The interaction of a cosmic string with a four-dimensional stationary black hole is considered. If a part of an infinitely long string passes close to a black hole it can be captured. The final stationary configurations of such captured strings are investigated. A uniqueness theorem is proved, namely it is shown that the minimal 2-D surface $Σ$ describing a

G. Grignani, M. Plyushchay, P. Sodano

A pseudoclassical model is proposed for the description of planar $P,T-$invariant massive fermions. The quantization of the model leads to the (2+1)-dimensional $P,T-$invariant fermion model used recently in $P,T-$conserving theories of high-T${}_c$ superconductors. The rich symmetry of the quantum model is elucidated through the analysis of the canonical st

M. E. Ferrero, G. Parisi

By studying the structure of infrared divergences in a toy propagator in the replica approach to the Ising spin glass below $T_c$, we suggest a possible cancellation mechanism which could decrease the degree of singularity in the loop expansion.

Alberto Blasi, Nicola Maggiore

We introduce an infrared regulator in Yang--Mills theories under the form of a mass term for the nonabelian fields. We show that the resulting action, built in a covariant linear gauge, is multiplicatively renormalizable by proving the validity at all orders of the Slavnov identity defining the theory.

T. M. Aliev, D. A. Demir, E. Iltan, N. K. Pak

The radiative decays $ B^{*} (D^{*})\rightarrow B(D) γ$ are investigated in the framework of light cone QCD sum rules. The transition amplitude and decay rates are estimated.It is shown that our results on branching ratios of D meson decays are in good agreement with the existing experimental data.

Ralf Hempfling

In minimal SUSY GUT models the $R$-parity breaking terms are severely constrained by SU(5) gauge invariance. We consider the particular case where the explicit $R$-parity breaking occurs only via dimension 2 terms of the superpotential. This model possesses only three R-parity breaking parameters. We have studied the predictions of this model for the neutrin

Sebastian Eggert, Henrik Johannesson, Ann Mattsson

The single electron Green's function of the one-dimensional Tomonaga-Luttinger model in the presence of open boundaries is calculated with bosonization methods. We show that the critical exponents of the local spectral density and of the momentum distribution change in the presence of a boundary. The well understood universal bulk behavior always crosses ove

M. Göckeler, R. Horsley, E. -M. Ilgenfritz, H. Oelrich

We report on recent results of a high statistics lattice calculation of the unpolarized and polarized structure functions of the nucleon.

S. Kanemura, H. -T. Sato

We discuss phase structure of chiral symmetry breaking of the $D$-dimensional ($2\leq D\leq3$) Gross-Neveu model at finite temperature, density and constant curvature. We evaluate the effective potential in a weak background approximation to thermalize the model as well as in the leading order of the $1/N$-expansion. A third order critical line is observed s

Anton Deitmar

The theory of geometric zeta functions for locally symmetric spaces as initialized by Selberg and continued by numerous mathematicians is generalized to the case of higher rank spaces. We show analytic continuation, describe the divisor in terms of tangential cohomology and in terms of group cohomology which generalizes the Patterson conjecture. We also exte

J. Alfaro, P. H. Damgaard

The $Δ$-operator of the Batalin-Vilkovisky formalism is the Hamiltonian BRST charge of Abelian shift transformations in the ghost momentum representation. We generalize this $Δ$-operator, and its associated hierarchy of antibrackets, to that of an arbitrary non-Abelian and possibly open algebra of any rank. We comment on the possible application of this form

B. Reznik

First order corrections to the Unruh effect are calculated from a model of an accelerated particle detector of finite mass. We show that quantum smearing of the trajectory and large recoil essentially do not modify the Unruh effect. Nevertheless, we find corrections to the thermal distribution and to the Unruh temperature. In a certain limit, when the distri

G. E. Romero, J. A. Combi, S. E. Perez Bergliaffa, L. A. Anchordoqui

The ultra--high energy cosmic rays recently detected by several air shower experiments could have an extragalactic origin. In this case, the nearest active galaxy Centaurus A might be the source of the most energetic particles ever detected on Earth. We have used recent radio observations in order to estimate the arrival energy of the protons accelerated by

S. M. Khoroshkin, A. A. Stolin, V. N. Tolstoy

A quantization of a non-standard rational solution of CYBE for $sl_2$ is given explicitly. We obtain the quantization with the help of a twisting of the usual Yangian $Y(sl_2$. This quantum object (deformed Yangian $Y_{η,ξ}(sl_2))$ is a two-parametric deformation of the universal enveloping algebra $U(sl_2[u])$ of the positive current algebra $sl_2[u]$. We c

E. V. Damaskinski, P. P. Kulish, V. V. Lyakhovsky, M. A. Sokolov

The Gauss decomposition of quantum groups and supergroups are considered. The main attention is paid to the R-matrix formulation of the Gauss decomposition and its properties as well as its relation to the contraction procedure. Duality aspects of the Gauss decomposition are also touched. For clarity of exposition a few simple examples are considered in some

A. Reuber, K. Holinde, H. -C. Kim, J. Speth

A dynamical model for correlated two-pion and two-kaon exchange in the baryon- baryon interaction is presented, both in the scalar-isoscalar ($σ$) and the vector-isovector ($ρ$) channel. The correlations between the two pseudoscalar mesons are taken into account by means of $ππ- K\bar K$ amplitudes derived from a meson-exchange model, which is in line with t

M. V. Stoitsov, S. S. Dimitrova, A. N. Antonov

An asymptotic restoration procedure is applied for analyzing bound--state overlap functions, separation energies and single--nucleon spectroscopic factors by means of a model one--body density matrix emerging from the Jastrow correlation method in its lowest order approximation for $^{16}O$ and $^{40}Ca$ nuclei . Comparison is made with available experimenta

F. Cardarelli, E. Pace, G. Salmè, S. Simula

We have evaluated nucleon and pion electromagnetic form factors using for the first time eigenfunctions of a light-front mass operator, reproducing a large set of energy levels, and constituent quark form factors in the one-body current. The comparison with the experimental data yields valuable information on the electromagnetic structure of light constituen