June 1993 arXiv papers — page 6

Xin-Nian Wang

Following my previous proposal that two-particle correlation functions can be used to resolve the minijet contribution to particle production in minimum biased events of high energy hadronic interactions, I study the $p_T$ and energy dependence of the correlation. Using HIJING Monte Carlo model, it is found that the correlation $c(ϕ_1,ϕ_2)$ in azimuthal angl

Nir Polonsky

The status of coupling constant unification (with and without a unification of Yukawa couplings) is discussed. Uncertainties associated with the input coupling constants, $m_{b}$ and $m_{t}$, threshold corrections at the low and high scale, and possible nonrenormalizable operators are described and a discrepancy between effective and physical scales is point

S. Bludman, N. Hata, P. Langacker

We consider the most general solar model, using the neutrino fluxes as free parameters constrained only by the solar luminosity, and show that the combined solar neutrino data exclude any astrophysical solution at 98\% C.L.\ Our best fit to the $^7$Be and $^8$B fluxes is respectively $<$7\% and 37$\pm$4\% of the standard solar model prediction, but only with

V. L. Eletsky, J. I. Kapusta, R. Venugopalan

We calculate the electric screening mass in hot hadronic matter using two different approaches, chiral perturbation theory and the relativistic virial expansion with empirical phase shifts, and compare the results to each other and to a gas of free pions and $ρ$ mesons. We also compute the electric screening mass for noninteracting, charged bosons with mass

F. Guerin

The general relationship between a Retarded-Advanced Green function of the Real Time formalism and analytical continuations of the Imaginary Time Amplitude is obtained via perturbation theory. A 4-point R-A function is, at most, a linear combination of three analytical continuations, and a 5-point R-A function of seven continuations. The R-A functions are wr

Biswajoy Brahmachari, Anjan S. Joshipura, Saurabh D. Rindani, D. P. Roy

In the Majoron models the $SU(2)$ doublet Higgs can decay invisibly into a Majoron pair via its mixing with a singlet. An analysis of the LEP data shows the invisible decay mode to be more visible than the SM decay. For these models, the dominantly doublet Higgs $H$ is shown to have a mass limit within $\pm 6$ GeV of the SM limit irrespective of the model pa

F. R. Klinkhamer

Our goal is to discover possible new 4-dimensional euclidean solutions (instantons) in fundamental SU(2) Yang-Mills-Higgs theory, with a constraint added to prevent collapse of the scale. We show that, most likely, there exists one particular new constrained instanton (\Istar) with vanishing Pontryagin index. This is based on a topological argument that invo

Howard E. Haber

Low-energy supersymmetry is a theoretical extension of the Standard Model of particle physics in which supersymmetry is invoked to explain the origin of the electroweak scale. In this approach, the energy scale of supersymmetry breaking can be no larger than about 1 TeV. In these lectures, a pedagogical account of softly broken supersymmetric gauge theories

Mirjam Cvetič, Stephen Griffies, Harald H. Soleng

Local and global gravitational effects induced by eternal vacuum domain walls are studied. We concentrate on thin walls between non-equal and non-positive cosmological constants on each side of the wall. These vacuum domain walls fall in three classes depending on the value of their energy density $σ$: (1)\ extreme walls with $σ= σ_{\text{ext}}$ are planar,

A. Sokol, D. Pines

We propose a unified magnetic phase diagram of cuprate superconductors. A new feature of this phase diagram is a broad intermediate doping region of quantum-critical, $z=1$, behavior, characterized by temperature independent $T_1T/T_{\rm 2G}$ and linear $T_1T$, where the spin waves are not completely absorbed by the electron-hole continuum. The spin gap in t

S. J. B. Einchcomb, A. J. McKane

Path integral techniques are used to understand the behaviour of a particle moving in a bistable potential well and acted upon by quasi-monochromatic external noise. In the limit of small diffusion coefficient, a steepest descent evaluation of the path integral enables mean first passage times and the transition times from one well to the other to be compute

M. Dobroliubov, E. Langmann, P. C. E. Stamp

We consider the experimental properties of superconductors with a gap which is an odd function of energy $\bepsk=\epsk - μ$, i.e.\ , a gap which vanishes everywhere on the Fermi surface; this is done within a in a BCS framework. Apart from the standard phenomenology (density of states, penetration depth, NMR, $C_V(T)$, $B_{c2}(T)$), we also look at the stabi

Biman B. Nath, Peter L. Biermann

We investigate the role of cosmic rays from young galaxies in heating and ionizing the intergalactic medium (IGM) at high redshift. Using the IRAS observations at $60 μm$, we estimate the cosmic ray luminosity density at the present epoch. We consider various forms of luminosity evolution in redshift and calculate (a) the thresholds corresponding to the uppe

Alexis Kouvidakis

We calculate the Picard group, over the integers, of the Hilbert scheme of smooth, irreducible, non-degenerate curves of degree $d$and genus $g \geq 4$ in ${\Bbb P}^r$, in the case when $d \geq 2g+1 $ and $r \leq d-g$. We express the classes of the generators in terms of some ``natural&#39;&#39; divisor classes.

Alexis Kouvidakis, Tony Pantev

Let ${\cal S}{\cal U}(r, L_0)$ denote the moduli space of semi stable vector bundles of rank $r$ and fixed determinant $L_0$ of degree $d$ on a smooth curve $C$ of genus $g \geq 3$. In this paper we describe the group of automorphisms of $ {\cal S}{\cal U}(r, L_0) $. The analogue of this result is carried out for the space ${\cal U}(r,d) $ of semi stable vec

Russell W. Anderson

Neural network models offer a theoretical testbed for the study of learning at the cellular level. The only experimentally verified learning rule, Hebb&#39;s rule, is extremely limited in its ability to train networks to perform complex tasks. An identified cellular mechanism responsible for Hebbian-type long-term potentiation, the NMDA receptor, is highly v

A. H. Castro Neto, A. O. Caldeira

We study the quantum tunnelling of a very complex object of which only part is coupled to an external potential ( the potential barrier ). We treat this problem as the tunnelling of a particle (part of the system affected by the potential) coupled to a ``heat bath&#34; ( all of the remaining degrees of freedom ) from the point of view of the wavefunction of

Sergey Fomin, Anatol N. Kirillov

New development of the theory of Grothendieck polynomials, based on an exponential solution of the Yang-Baxter equation in the algebra of projectors are given.

J. W. Moffat

The NGT field equations with sources are expanded first about a flat Minkowski background and then about a GR background to first-order in the antisymmetric part of the fundamental tensor, $g_{μν}$. From the general, static spherically symmetric solution of the field equation in empty space, we establish that there are two conserved charges $m$ and $\ell^2$

D. Senechal

This work studies the appearance of a Haldane gap in quasi one-dimensional antiferromagnets in the long wavelength limit, via the nonlinear $σ$-model. The mapping from the three-dimensional, integer spin Heisenberg model to the nonlinear $σ$-model is explained, taking into account two antiferromagnetic couplings: one along the chain axis ($J$) and one along

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

We calculate the free energy of SU(N) gauge theories on the lattice, to three loops. Our result, combined with Monte Carlo data for the average plaquette, gives a more precise estimate of the gluonic condensate.

I. Ya. Aref&#39;eva

Different aspects of the Verlinde and Verlinde relation between high-energy effective scattering in QCD and a two-dimensional sigma-model are discussed. Starting from a lattice version of the truncated 4-dimensional Yang-Mills action we derive an effective theory with non-trivial longitudinal dynamics which has a form of the lattice two-dimensional chiral fi

Stephen L. Adler

We propose a generalization of Heisenberg picture quantum mechanics in which a Lagrangian and Hamiltonian dynamics is formulated directly for dynamical systems on a manifold with non--commuting coordinates, which act as operators on an underlying Hilbert space. This is accomplished by defining the Lagrangian and Hamiltonian as the real part of a graded total

K. Haller, E. Lim-Lombridas

We discuss gauge transformations in QED coupled to a charged spinor field, and examine whether we can gauge-transform the entire formulation of the theory from one gauge to another, so that not only the gauge and spinor fields, but also the forms of the operator-valued Hamiltonians are transformed. The discussion includes the covariant gauge, in which the ga

A. H. Castro Neto, A. O. Caldeira

We calculate in this article the transport coefficients which characterize the dynamics of solitons in quantum field theory using the methods of dissipative quantum systems. We show how the damping and diffusion coefficients of soliton-like excitations can be calculated using the integral functional formalism. The model obtained in this article has new featu

Hoi-Kwong Lo, John Preskill

We study the interactions of non-abelian vortices in two spatial dimensions. These interactions have novel features, because the Aharonov-Bohm effect enables a pair of vortices to exchange quantum numbers. The cross section for vortex-vortex scattering is typically a multi-valued function of the scattering angle. There can be an exchange contribution to the

Ansar Fayyazuddin

We study bosons interacting with an abelian Chern-Simons field on Riemann surfaces of genus $g>0$. It is shown that a singular gauge transformation brings the hamiltonian to free form. The transformed wave functions furnish a multi-component representation of the braid group studied by Imbo and March-Russell. The construction constitutes a proof of the equiv

A. L. Larsen

We consider a pair of coupled non-linear partial differential equations describing a biochemical model system. The Weiss-algorithm for the Painleé test, that has been succesfully used in mathematical physics for the KdV-equation, Burgers equation, the sine-Gordon equation etc., is applied, and we find that the system possesses only the &#34;conditional&#34;

Tadashi Okai

Integral and differential mass formulae of 4-dimensional stationary and axisymmetric Einstein-Maxwell-dilaton systems are derived. The total mass (energy) of these systems are expressed in terms of other physical quantities such as electric charge of the black hole suitably modified due to the existence of the dilaton field. It is shown that when we vary sli

K. -I. Kondo

We investigate the critical behavior of the gauged NJL model (QED plus 4-fermion interaction) and the gauged Yukawa model by use of the inversion method. By calculating the gauge-invariant chiral condensate in the inversion method to the lowest order, we derive the critical line which separates the spontaneous chiral-symmetry breaking phase from the chiral s

Paul Langacker, Nir Polonsky

Grand unified theories often predict unification of Yukawa couplings (e.g., $h_{b} = h_τ$), and thus certain relations among fermion masses. The latter can distinguish these from models that predict only coupling constant unification. The implications of Yukawa couplings of the heavy-family in the supersymmetric extension of the standard model (when embedded

R. Michael Barnett, John F. Gunion, Howard E. Haber

Supersymmetry may be discovered at hadron colliders by searching for events similar to the top quark signal of two isolated leptons. In the case of gluino production, the most distinguishing feature is that in half the events the two leading leptons have the same sign. We demonstrate the remarkable sensitivity of this gluino signature at both the Fermilab Te

Tao Han, Stephen Parke

We present the results of a detailed study of the effects of $b$-tagging on the heavy top-quark signal and backgrounds for the modes of the di-lepton plus two high transverse energy jets at the Fermilab Tevatron. The general characteristics of the heavy top-quark signal events are also discussed so that a comparison can be made between $b$-tagging and imposi

Alexander Kyatkin

We have shown an example of semiclassical transition in ϕ^4 model with positive coupling constant. This process describes a semiclassical transition between two coherent states with much smaller average number of particles in the initial state than in the final state. This transition is technically analogous to the one-instanton transition in the electroweak

R. L. Jaffe, L. Randall

We present a QCD based interpretation of heavy quark fragmentation which utilizes the heavy quark mass expansion. By distinguishing between perturbative and non-perturbative QCD effects, we show how to reliably extract mass independent parameters characterizing the fragmentation function. Because these parameters are quark mass independent, this procedure sh

M. -C. Chu, J. M. Grandy, S. Huang, J. W. Negele

Point-to-point vacuum correlation functions for spatially separated hadron currents are calculated in quenched lattice QCD on a $16^3\times 24$ lattice with $6/g^2=5.7$. The lattice data are analyzed in terms of dispersion relations, which enable us to extract physical information from small distances where asymptotic freedom is apparent to large distances w

Luis J. Garay

Wormhole boundary conditions for the Wheeler--DeWitt equation can be derived from the path integral formulation. It is proposed that the wormhole wave function must be square integrable in the maximal analytic extension of minisuperspace. Quantum wormholes can be invested with a Hilbert space structure, the inner product being naturally induced by the minisu

Yu. A. Kubyshin, J. I. Perez Cadenas

We study ten-dimensional Einstein-Yang-Mills model with the space of extra dimensions being a non-symmetric homogeneous space with the invariant metric parametrized by two scales. Dimensional reduction of the model is carried out and the scalar potential of the reduced theory is calculated. In a cosmological setting minima of the potential in the radiation-d

E. S. Sorensen, S. Eggert, I. Affleck

Recent renormalization group studies of impurities in spin-1/2 chains appear to be inconsistent with Bethe ansatz results for a special integrable model. We study this system in more detail around the integrable point in parameter space and argue that this integrable impurity model corresponds to a non-generic multi-critical point. Using previous results on