11,667 research outputs found
A Coherent State Path Integral for Anyons
We derive an coherent state path integral formula for a system of
two one-dimensional anyons in a harmonic potential. By a change of variables we
transform this integral into a coherent states path integral for a harmonic
oscillator with a shifted energy. The shift is the same as the one obtained for
anyons by other methods. We justify the procedure by showing that the change of
variables corresponds to a version of the Holstein-Primakoff
transformation.Comment: Latex 6 pages, USITP-94-1
The QCD Trace Anomaly as a Vacuum Effect (The vacuum is a medium is the message!)
We use arguments taken from the electrodynamics of media to deduce the QCD
trace anomaly from the expression for the vacuum energy in the presence of an
external color magnetic field.Comment: 18 pages, USITP 94-1
TeV Neutrinos in a dense medium
The dispersion relation of energetic (few TeV) neutrinos traversing a medium
is studied. We use the real time formalism of thermal field theory and we
include the effects from the propagator of the W gauge boson. We consider then
the MSW oscillations for cosmic neutrinos traversing the Earth, adopting for
the neutrino parameters values suggested by the LSND results. It is found that
the flux, for neutrinos passing through the center of the Earth, will
appear reduced by 15% for energies around 10 TeV.Comment: 12 pages, latex, 2 figure
Higgs Pain? Take a Preon!
The Higgs mechanism is the favourite cure for the main problem with
electroweak unification, namely how to reconcile a gauge theory with the need
for massive gauge bosons. This problem does not exist in preon models for quark
and lepton substructure with composite and s, which, consequently,
also avoid all other theoretical complications and paradoxes with the Higgs
mechanism. We present a new, minimal preon model, which explains the family
structure, and predicts several new, heavy quarks, leptons and vector bosons.
Our preons obey a phenomenological supersymmetry, but without so-called squarks
and sleptons, since this SUSY is effective only on the composite scale.Comment: The preon contents of some quarks and leptons have been changed in
order to achieve a more consistent scheme. A few new comments have been
added. 13 pages, LaTeX, no figures. To be published in Proc. of the Meeting
on 'The Fundamental Structure of Matter' and 'Tests of the Electroweak
Symmetry Breaking', Ouranoupolis, Greece, May 199
Preon Trinity
We present a new minimal model for the substructure of all known quarks,
leptons and weak gauge bosons, based on only three fundamental and stable
spin-1/2 preons. As a consequence, we predict three new quarks, three new
leptons, and six new vector bosons. One of the new quarks has charge .
The model explains the apparent conservation of three lepton numbers, as well
as the so-called Cabibbo-mixing of the and quarks, and predicts
electromagnetic decays or oscillations between the neutrinos
() and (). Other neutrino oscillations, as well
as rarer quark mixings and CP violation can come about due to a small
quantum-mechanical mixing of two of the preons in the quark and lepton wave
functions.Comment: 5 pages, Latex, no figure
Dynamical two electron states in a Hubbard-Davydov model
We study a model in which a Hubbard Hamiltonian is coupled to the dispersive
phonons in a classical nonlinear lattice. Our calculations are restricted to
the case where we have only two quasi-particles of opposite spins, and we
investigate the dynamics when the second quasi-particle is added to a state
corresponding to a minimal energy single quasi-particle state. Depending on the
parameter values, we find a number of interesting regimes. In many of these,
discrete breathers (DBs) play a prominent role with a localized lattice mode
coupled to the quasiparticles. Simulations with a purely harmonic lattice show
much weaker localization effects. Our results support the possibility that DBs
are important in HTSC.Comment: 14 pages, 12 fig
Spin Measurements in lp -> hX Deep Inelastic Scattering
The production of hadrons in polarized lepton-nucleon deep inelastic
scattering is discussed. The helicity density matrix of the hadron is computed
within the QCD hard scattering formalism and its elements are shown to yield
information on the spin structure of the nucleon and the spin dependence of the
quark fragmentation process. The case of vector mesons is considered in
more detail and estimates are given.Comment: 3 pages, LaTeX, no figures. Talk delivered by J. Hansson at the XII
International Symposium on High Energy Spin Physics, Amsterdam, Sept. 10-14,
1996. To be published in the proceeding
- …