1,628 research outputs found
Coexistence of long-range order for two observables at finite temperatures
We give a criterion for the simultaneous existence or non existence of two
long-range orders for two observables, at finite temperatures, for quantum
lattice many body systems. Our analysis extends previous results of G.-S. Tian
limited to the ground state of similar models. The proof involves an inequality
of Dyson-Lieb-Simon which connects the Duhamel two-point function to the usual
correlation function. An application to the special case of the Holstein model
is discussed.Comment: 12 pages, accepted for publication in J. of Phys.
SU(m|n) supersymmetric Calogero-Sutherland model confined in harmonic potential
In this work, we study a continuous quantum system of a mixture of bosons and
fermions with the supersymmetry SU(m|n). The particles are confined in a
harmonic well and interact with each other through the 1/r2 interaction. The
ground state wavefunction is constructed explicitly for the most general
SU(m|n) case, with the ground state energy given explicitly. The full energy
spectrum of excitations in the SU(m|n) model is also equal spaced. In the
limiting case where there are no bosons in the system, our results reduce to
those obtained previously.Comment: 9 pages, preprint of ETH-Lausanne (August 1996
On Consistency Of Noncommutative Chern-Simons Theory
We consider the noncommutative extension of Chern-Simons theory. We show the
the theory can be fully expanded in power series of the noncommutative
parameter theta and that no non-analytical sector exists. The theory appears to
be unstable under radiative corrections, but we show that the infinite set of
instabilities, to all orders in \hbar and in theta, is confined to a BRS exact
cocycle. We show also that the theory is anomaly free. The quantum theory
cannot be written in terms of the Groenewald-Moyal star product, and hence
doubts arise on the interpretation of the noncommutative nature of the
underlying spacetime. Nonetheless, the deformed theory is well defined as a
quantum field theory, and the beta function of the Chern-Simons coupling
constant vanishes, as in the ordinary Chern-Simons theory.Comment: 17 page
Remarks on Existence of Proper Action for Reducible Gauge Theories
In the field-antifield formalism, we review existence and uniqueness proofs
for the proper action in the reducible case. We give two new existence proofs
based on two resolution degrees called "reduced antifield number" and "shifted
antifield number", respectively. In particular, we show that for every choice
of gauge generators and their higher stage counterparts, there exists a proper
action that implements them at the quadratic order in the auxiliary variables.Comment: 37 pages, LaTeX. v2,v3: Minor corrections. v4: Added reference. To
appear in IJMP
On 1+1 Dimensional Galilean Supersymmetry in Ultracold Quantum Gases
We discuss a 1+1 dimensional Galilean invariant model recently introduced in
connection with ultracold quantum gases. After showing its relation to a
nonrelativistic 2+1 Chern-Simons matter system, we identify the generators of
the supersymmetry and its relation with the existence of self-dual equationsComment: 12 page
Symmetry aspects of fermions coupled to torsion and electromagnetic fields
We study and explore the symmetry properties of fermions coupled to dynamical
torsion and electromagnetic fields. The stability of the theory upon radiative
corrections as well as the presence of anomalies are investigated.Comment: 9 pages, LaTe
Comments on the Equivalence between Chern-Simons Theory and Topological Massive Yang-Mills Theory in 3D
The classical formal equivalence upon a redefinition of the gauge connection
between Chern-Simons theory and topological massive Yang-Mills theory in
three-dimensional Euclidean space-time is analyzed at the quantum level within
the BRST formulation of the Equivalence Theorem. The parameter controlling the
change in the gauge connection is the inverse of the topological
mass. The BRST differential associated with the gauge connection redefinition
is derived and the corresponding Slavnov-Taylor (ST) identities are proven to
be anomaly-free. The Green functions of local operators constructed only from
the (-dependent) transformed gauge connection, as well as those of
BRST invariant operators, are shown to be independent of the parameter
, as a consequence of the validity of the ST identities. The relevance
of the antighost-ghost fields, needed to take into account at the quantum level
the Jacobian of the change in the gauge connection, is analyzed. Their role in
the identification of the physical states of the model within conventional
perturbative gauge theory is discussed.Comment: 19 pages, LATEX, to appear in Journal of High Energy Physic
- …