2,731 research outputs found
The Matsubara-Fradkin Thermodynamical Quantization of Podolsky Electrodynamics
In this work we apply the Matsubara-Fradkin formalism and the Nakanishi's
auxiliary field method to the quantization of the Podolsky electrodynamics in
thermodynamic equilibrium. This approach allows us to write consistently the
path integral representation for the partition function of gauge theories in a
simple manner. Furthermore, we find the Dyson-Schwinger-Fradkin equations and
the Ward-Fradkin-Takahashi identities for the Podolsky theory. We also write
the most general form for the polarization tensor in thermodynamic equilibrium.Comment: Submitted to Physical Review
Generating Functional for Gauge Invariant Actions: Examples of Nonrelativistic Gauge Theories
We propose a generating functional for nonrelativistic gauge invariant
actions. In particular, we consider actions without the usual magnetic term.
Like in the Born-Infeld theory, there is an upper bound to the electric field
strength in these gauge theories.Comment: 14 pages, 2 figures; v2: misprints correcte
High Temperature Superconductivity: Ineluctable Complexity
The discovery of charge-density-wave order in the high-temperature
superconductor YBaCuO places charge order centre stage with
superconductivity, suggesting they they are intertwined rather than competing.Comment: 3 pages, 1 figure, 19 references; News & Views article for Nature
Physic
Holst Actions for Supergravity Theories
Holst action containing Immirzi parameter for pure gravity is generalised to
the supergravity theories. Supergravity equations of motion are not modified by
such generalisations, thus preserving supersymmetry. Dependence on the Immirzi
parameter does not emerge in the classical equations of motion. This is in
contrast with the recent observation of Perez and Rovelli for gravity action
containing original Holst term and a minimally coupled Dirac fermion where the
classical equations of motion do develop a dependence on Immirzi parameter.Comment: 15 page
On bipartite Rokhsar-Kivelson points and Cantor deconfinement
Quantum dimer models on bipartite lattices exhibit Rokhsar-Kivelson (RK)
points with exactly known critical ground states and deconfined spinons. We
examine generic, weak, perturbations around these points. In d=2+1 we find a
first order transition between a ``plaquette'' valence bond crystal and a
region with a devil's staircase of commensurate and incommensurate valence bond
crystals. In the part of the phase diagram where the staircase is incomplete,
the incommensurate states exhibit a gapless photon and deconfined spinons on a
set of finite measure, almost but not quite a deconfined phase in a compact
U(1) gauge theory in d=2+1! In d=3+1 we find a continuous transition between
the U(1) resonating valence bond (RVB) phase and a deconfined staggered valence
bond crystal. In an appendix we comment on analogous phenomena in quantum
vertex models, most notably the existence of a continuous transition on the
triangular lattice in d=2+1.Comment: 9 pages; expanded version to appear in Phys. Rev. B; presentation
improve
Charge-Density-Wave and Superconductor Competition in Stripe Phases of High Temperature Superconductors
We discuss the problem of competition between a superconducting (SC) ordered
state with a charge density wave (CDW) state in stripe phases of high
superconductors. We consider an effective model for each stripe motivated by
studies of spin-gapped electronic ladder systems. We analyze the problem of
dimensional crossover arising from inter-stripe SC and CDW couplings using
non-Abelian bosonization and renormalization group (RG) arguments to derive an
effective -symmetric nonlinear -model in for the case of
when both inter-stripe couplings are of equal magnitude as well as equally RG
relevant. By studying the effects of various symmetry lowering perturbations,
we determine the structure of the phase diagram and show that, in general, it
has a broad regime in which both orders coexist. The quantum and thermal
critical behavior is discussed in detail, and the phase coexistence region is
found to end at associated as well as tetracritical points. The
possible role of hedgehog topological excitations of the theory is considered
and argued to be RG irrelevant at the spatially anisotropic higher dimensional
low-energy fixed point theory. Our results are also relevant to the case of
competing N\'eel and valence bond solid (VBS) orders in quantum magnets on 2D
isotropic square as well as rectangular lattices interacting via nearest
neighbor Heisenberg exchange interactions.Comment: 9 pages, 3 figures (one with 3 subfigures
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