1,446 research outputs found
Quantum ether: photons and electrons from a rotor model
We give an example of a purely bosonic model -- a rotor model on the 3D cubic
lattice -- whose low energy excitations behave like massless U(1) gauge bosons
and massless Dirac fermions. This model can be viewed as a ``quantum ether'': a
medium that gives rise to both photons and electrons. It illustrates a general
mechanism for the emergence of gauge bosons and fermions known as ``string-net
condensation.'' Other, more complex, string-net condensed models can have
excitations that behave like gluons, quarks and other particles in the standard
model. This suggests that photons, electrons and other elementary particles may
have a unified origin: string-net condensation in our vacuum.Comment: 10 pages, 6 figures, RevTeX4. Home page http://dao.mit.edu/~we
An Abelian two-Higgs model of strongly correlated electrons: phase structure, strengthening of phase transition and QCD at finite density
We investigate non-perturbative features of a three-dimensional Abelian Higgs
model with singly- and doubly-charged scalar fields coupled to a single compact
Abelian gauge field. The model is pretending to describe various planar systems
of strongly correlated electrons such as high-Tc superconductivity in the
overdoped regime and exotic materials possessing excitations with
fractionalized quantum numbers. The complicated phase structure of the model is
studied thoroughly using numerical tools and analytical arguments. In the
three-dimensional space of coupling parameters we identify the Fermi liquid,
the spin gap, the superconductor and the strange metallic phases. The behavior
of three kinds of topological defects -- holon and spinon vortices and
monopoles - is explored in various phases. We also observe a new effect, the
strong enhancement of the phase transition strength reflected in a lower order
of the transition: at sufficiently strong gauge coupling the two second order
phase transitions -- corresponding to spinon-pair and holon condensation lines
- join partially in the phase diagram and become a first order phase transition
in that region. The last observation may have an analogue in Quantum
Chromodynamics at non-zero temperature and finite baryon density. We argue that
at sufficiently large baryon density the finite-temperature transition between
the (3-flavor paired) color superconducting phase and the quark-gluon plasma
phases should be much stronger compared with the transition between 2-flavor
paired and 3-flavor paired superconducting phases.Comment: 21 pages, 40 figures, RevTeX 4.
Phase structure of an Abelian two-Higgs model and high temperature superconductors
We study the phase structure of a three dimensional Abelian Higgs model with
singly- and doubly-charged scalar fields coupled to a compact Abelian gauge
field. The model is pretending to describe systems of strongly correlated
electrons such as high-Tc superconductivity in overdoped regime and exotic
phases supporting excitations with fractionalized quantum numbers. We identify
the Fermi liquid, the spin gap, the superconductor and the strange metallic
phases in which densities and properties of holon and spinon vortices and
monopoles are explored. The phase diagram in the 3D coupling space is
predicted. We show that at sufficiently strong gauge coupling the spinon-pair
and holon condensation transitions merge together and become, unexpectedly,
first order.Comment: 5 pages, 9 figures, RevTeX
Effect of Plant Growth Regulators on Corm Production in Gladiolus
Experiments (spraying and dipping) were carried out to study the effect of different plant growth regulators with two methods of application on gladiolus cv. Pusa Jyotsna for various parameters of corm production. Spraying TIBA at 500 ppm produced maximum number of corms. Maximum number of cormels was produced by dipping corms in kinetin at 500 ppm concentration. Corm weight was maximum by dipping with 200 ppm of GA3. Spraying GA3 at 500 ppm resulted in maximum weight of cormels per plant and maximum diameter of corms. Dipping in 500 ppm of GA3 produced maximum volume of corms. Propagation co-efficient was maximum in BA at 100 ppm as spray treatment, whereas it was minimum in the case of TIBA at 1500 ppm. This may be due to growth retardation
Effective action of magnetic monopole in three-dimensional electrodynamics with massless matter and gauge theories of superconductivity
We compute one-loop effective action of magnetic monopole in
three-dimensional electrodynamics of massless bosons and fermions and find that
it contains an infrared logarithm. So, when the number of massless matter
species is sufficiently large, monopoles are suppressed and in the weak
coupling limit charged particles are unconfined. This result provides some
support to gauge theories of high-temperature superconductors. It also provides
a mechanism by which interlayer tunneling of excitations with one unit of the
ordinary electric charge can be suppressed while that of a doubly charged
object is allowed.Comment: 8 pages, LATEX, UCLA/93/TEP/41 (the last sentence of the paragraph
concerning applications at the end of the paper has been deleted; mailing
problems have been corrected
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