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