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Ground states of a spin-boson model
ABSTRACTS
OF PAPERS
TO APPEAR
IN
FUTURE
475
ISSUES
defined limitations. For QED2, it is demonstrated that the known non-perturbative phenomena can be using the light-cone Coulomb gauge, the role of the gauge obtained on the light-cone. For QCDz, degrees of freedom for regularizing the infrared singularity of the gluon propagator is exhibited. The structure of the Hilbert space, the properties of the vacuum and of the elementary excitations are addressed. In the chiral limit (vanishing quark mass), analytical results for both SU(N) and Li(N) QCD, are presented. Relativistic many-body techniques are employed to solve the theory in the large N limit, and the quark condensate is evaluated on the light-cone. It is pointed out that the finite interval techniques allow taking advantage of the technical simplification usually attributed to light-cone quantization. even when using ordinary coordinates. This surprising result is intimately connected to Lorentz invariance.
Cla,wical
Theory
qf
Motion in the Large Amplitude, Small Velocity Regime. NIELS R. WALET Department of Physics. University of Pennsylvania, Philadelphia, Pennsylvania 19104-6396; AND G. Do DANG. Laboratoire de Physique Thtorique et Hautes Energies, Universite de Paris&d, 91405 Orsay, France. AND
ABRAHAM
Collective KLEIN.
A classical theory of collective motion is developed for the large amplitude, small velocity limit. i.e.. for a hamiltonian that is at most quadratic in the momenta, allowance being made for a mass tensor that is a general function of the coordinates. It is based on the identitication of decoupled motions that are confined to submanifolds of the full configuration space. Conditions for decoupling are derived and then transformed into several different sets of equivalent conditions, more useful for practical applications. Algorithms are given for constructing manifolds that are exactly decoupled if a given dynamical system admits such motions and that can be utilized as well when there is approximate decoupling. as evidenced by criteria that are established. Some examples are worked out. The connection to previous research on this problem is described.
Effects
qf Asymmefry in String Fragmentation. N. L. BALAZS. State Brook, Stony Brook, New York 11794; T. 06~~6, B. LUKACS, Institute for Physics, H-1525 Budapest 114, Pf. 49, Hungary.
University of New York AND J. ZIMANYI. Central
at Stony
Research
The general solution of the one flavour integral equation for string fragmentation is presented and is approximated by a finite sum. The N pion phase space distribution is calculated for the emission points; thence the hadronic fragmentation function, the number density, and the energy density vs rapidity are obtained. We discuss the effects of the left-right asymmetry embedded into the integral equation, and present numerical results based on the Lund fragmentation function.
Ground States of a Spin-Boson Model. CH-8092 Zurich, Switzerland.
ANTON
AWANN.
Laboratory
of Physical
Chemistry,
ETH-Zentrum,
Phase transitions with respect to ground states of a spin-boson Hamiltonian are investigated. The spin-boson model under discussion consists of one spin and infinitely many bosons with a dipole-type coupling. It is shown that the order parameter of the model vanishes with respect to arbitrary ground states if it vanishes with respect to ground states obtained as (biased) temperature to zero limits of thermic equilibrium states. The ground states of the latter special type have been investigated by H. Spohn. Spohn’s respective phase diagrams are therefore valid for arbitrary ground states. Furthermore, disjointness of ground states in the broken symmetry regime is examined.
OF PAPERS
TO APPEAR
IN
FUTURE
475
ISSUES
defined limitations. For QED2, it is demonstrated that the known non-perturbative phenomena can be using the light-cone Coulomb gauge, the role of the gauge obtained on the light-cone. For QCDz, degrees of freedom for regularizing the infrared singularity of the gluon propagator is exhibited. The structure of the Hilbert space, the properties of the vacuum and of the elementary excitations are addressed. In the chiral limit (vanishing quark mass), analytical results for both SU(N) and Li(N) QCD, are presented. Relativistic many-body techniques are employed to solve the theory in the large N limit, and the quark condensate is evaluated on the light-cone. It is pointed out that the finite interval techniques allow taking advantage of the technical simplification usually attributed to light-cone quantization. even when using ordinary coordinates. This surprising result is intimately connected to Lorentz invariance.
Cla,wical
Theory
qf
Motion in the Large Amplitude, Small Velocity Regime. NIELS R. WALET Department of Physics. University of Pennsylvania, Philadelphia, Pennsylvania 19104-6396; AND G. Do DANG. Laboratoire de Physique Thtorique et Hautes Energies, Universite de Paris&d, 91405 Orsay, France. AND
ABRAHAM
Collective KLEIN.
A classical theory of collective motion is developed for the large amplitude, small velocity limit. i.e.. for a hamiltonian that is at most quadratic in the momenta, allowance being made for a mass tensor that is a general function of the coordinates. It is based on the identitication of decoupled motions that are confined to submanifolds of the full configuration space. Conditions for decoupling are derived and then transformed into several different sets of equivalent conditions, more useful for practical applications. Algorithms are given for constructing manifolds that are exactly decoupled if a given dynamical system admits such motions and that can be utilized as well when there is approximate decoupling. as evidenced by criteria that are established. Some examples are worked out. The connection to previous research on this problem is described.
Effects
qf Asymmefry in String Fragmentation. N. L. BALAZS. State Brook, Stony Brook, New York 11794; T. 06~~6, B. LUKACS, Institute for Physics, H-1525 Budapest 114, Pf. 49, Hungary.
University of New York AND J. ZIMANYI. Central
at Stony
Research
The general solution of the one flavour integral equation for string fragmentation is presented and is approximated by a finite sum. The N pion phase space distribution is calculated for the emission points; thence the hadronic fragmentation function, the number density, and the energy density vs rapidity are obtained. We discuss the effects of the left-right asymmetry embedded into the integral equation, and present numerical results based on the Lund fragmentation function.
Ground States of a Spin-Boson Model. CH-8092 Zurich, Switzerland.
ANTON
AWANN.
Laboratory
of Physical
Chemistry,
ETH-Zentrum,
Phase transitions with respect to ground states of a spin-boson Hamiltonian are investigated. The spin-boson model under discussion consists of one spin and infinitely many bosons with a dipole-type coupling. It is shown that the order parameter of the model vanishes with respect to arbitrary ground states if it vanishes with respect to ground states obtained as (biased) temperature to zero limits of thermic equilibrium states. The ground states of the latter special type have been investigated by H. Spohn. Spohn’s respective phase diagrams are therefore valid for arbitrary ground states. Furthermore, disjointness of ground states in the broken symmetry regime is examined.