1,091 research outputs found

### Dirac Variables and Zero Modes of Gauss Constraint in Finite-Volume Two-Dimensional QED

The finite-volume QED$_{1+1}$ is formulated in terms of Dirac variables by an
explicit solution of the Gauss constraint with possible nontrivial boundary
conditions taken into account. The intrinsic nontrivial topology of the gauge
group is thus revealed together with its zero-mode residual dynamics.
Topologically nontrivial gauge transformations generate collective excitations
of the gauge field above Coleman's ground state, that are completely decoupled
from local dynamics, the latter being equivalent to a free massive scalar field
theory.Comment: 13 pages, LaTe

### Laughlin type wave function for two-dimensional anyon fields in a KMS-state

The correlation functions of two-dimensional anyon fields in a KMS-state are
studied. For T=0 the $n$-particle wave functions of noncanonical fermions of
level $\alpha$, $\alpha$ odd, are shown to be of Laughlin type of order
$\alpha$. For $T>0$ they are given by a simple finite-temperature
generalization of Laughlin's wave function. This relates the first and second
quantized pictures of the fractional quantum Hall effect.Comment: 9 pages, LaTeX, comments and references added (version to appear in
Physics Letters B

### Do anyons solve Heisenberg's Urgleichung in one dimension

We construct solutions to the chiral Thirring model in the framework of
algebraic quantum field theory. We find that for all positive temperatures
there are fermionic solutions only if the coupling constant is $\lambda =
\sqrt{2(2n + 1)\pi}, n \in \bf N$.Comment: 19 pages LaTeX, to appear in Eur. Phys. J.

### A pair potential supporting a mixed mean-field / BCS- phase

We construct a Hamiltonian which in a scaling limit becomes equivalent to one
that can be diagonalized by a Bogoliubov transformation. There may appear
simultaneously a mean-field and a superconducting phase. They influence each
other in a complicated way. For instance, an attractive mean field may
stimulate the superconducting phase and a repulsive one may destroy it.Comment: 11 pages, 5 figures, LaTe

### Thermal correlators of anyons in two dimensions

The anyon fields have trivial $\alpha$-commutator for $\alpha$ not integer.
For integer $\alpha$ the commutators become temperature-dependent operator
valued distributions. The $n$-point functions do not factorize as for quasifree
states.Comment: 14 pages, LaTeX (misprints corrected, a reference added

### Determination of the beam-spin asymmetry of deuteron photodisintegration in the energy region E-gamma=1.1-2.3 GeV

The beam-spin asymmetry, Sigma, for the reaction gamma d -\u3e pn has been measured using the CEBAF Large Acceptance Spectrometer (CLAS) at the Thomas Jefferson National Accelerator Facility (JLab) for six photon-energy bins, between 1.1 and 2.3 GeV, and proton angles in the center-of-mass frame, theta(c.m.), between 25 degrees and 160 degrees. These are the first measurements of beam-spin asymmetries at theta(c.m.) = 90. for photon-beam energies above 1.6 GeV, and the first measurements for angles other than theta(c.m.) = 90 degrees. The angular and energy dependence of Sigma is expected to aid in the development of QCD-based models to understand the mechanisms of deuteron photodisintegration in the transition region between hadronic and partonic degrees of freedom, where both effective field theories and perturbative QCD cannot make reliable predictions

### Anyons and the Bose-Fermi duality in the finite-temperature Thirring model

Solutions to the Thirring model are constructed in the framework of algebraic
QFT. It is shown that for all positive temperatures there are fermionic
solutions only if the coupling constant is $\lambda=\sqrt{2(2n+1)\pi}, n\in
{\bf N}$. These fermions are inequivalent and only for $n=1$ they are canonical
fields. In the general case solutions are anyons. Different anyons (which are
uncountably many) live in orthogonal spaces and obey dynamical equations (of
the type of Heisenberg's "Urgleichung") characterized by the corresponding
values of the statistic parameter. Thus statistic parameter turns out to be
related to the coupling constant $\lambda$ and the whole Hilbert space becomes
non-separable with a different "Urgleichung" satisfied in each of its sectors.
This feature certainly cannot be seen by any power expansion in $\lambda$.
Moreover, since the latter is tied to the statistic parameter, it is clear that
such an expansion is doomed to failure and will never reveal the true structure
of the theory.
The correlation functions in the temperature state for the canonical dressed
fermions are shown by us to coincide with the ones for bare fields, that is in
agreement with the uniqueness of the $\tau$-KMS state over the CAR algebra
($\tau$ being the shift automorphism). Also the $\alpha$-anyon two-point
function is evaluated and for scalar field it reproduces the result that is
known from the literature.Comment: 25 pages, LaTe

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