188 research outputs found
SO(10) GUTs with gauge mediated supersymmetry breaking
We explore the phenomenology of supersymmetric SO(10) grand unified theories
with gauge mediated supersymmetry breaking. We show that if SO(10) breaking
proceeds through intermediate left-right symmetric gauge groups which are
broken at the supersymmetry breaking scale, then perturbative unification
allows the existence of only a few consistent models with very similar
phenomenological consequences. We list and discuss some distinctive signatures
of these theories. The most remarkable feature of the class of theories
introduced here is that, unlike in models with simpler symmetry breaking
chains, the allowed messenger spectrum is practically unique.Comment: 5 pages, no figures, uses REVTeX (replaced to match the version to be
published in PLB: some typos corrected and a reference updated, a minor
clarifying modification to the text
Quantum Critical Behavior in Gauged Yukawa Matrix Field Theories with Quenched Disorder
We use the Wilson-Fisher expansion to study quantum critical
behavior in gauged Yukawa matrix field theories with weak quenched disorder. We
find that the resulting quantum critical behavior is in the universality class
of the pure system. As in the pure system, the phase transition is typically
first order, except for a limited range of parameters where it can be second
order with computable critical exponents. Our results apply to the study of
two-dimensional quantum antiferromagnets with weak quenched disorder and
provide an example for fluctuation-induced first order phase transitions in
circumstances where naively none is expected.Comment: 8 pages, LaTeX, 1 eps figur
Synthesis of novel azo compounds containing 5(4H)-oxazolone ring as potent tyrosinase inhibitors
Six new azo dyes containing of 5(4H)-oxazolone ring were prepared by diazotization of 4-aminohippuric acid and coupling with N,N-dimethylaniline, 1-naphthol and 2-naphthol and condensation with 4-fluoro benzaldehyde or 4-trifluoromethoxy benzaldehyde. The new compounds were fully characterized by spectroscopic techniques. All synthesized compounds exhibited high tyrosinase inhibitory behavior. The results of mushroom tyrosinase inhibition assays indicate that the 4-trifluoromethoxy derivatives have high degrees of inhibition and N,N-dimethylaniline derivatives are better for tyrosinase inhibition than 1-naphthol and 2-naphthol derivatives. All synthesized azo compounds (4a-4f) showed the most potent mushroom tyrosinase inhibition, comparable to that of Kojic acid and l-mimosine, as reference standard inhibitors. © 2013 Elsevier Ltd. All rights reserved
Tween 80 coated alumina: An alternative support for solid phase extraction of copper, nickel, cobalt and cadmium prior to flame atomic absorption spectrometric determination
AbstractThe potential of coated alumina as a sorbent for the simultaneous separation and preconcentration of copper, nickel, cobalt and cadmium ions has been investigated. Copper, nickel, cobalt and cadmium were adsorbed quantitatively on coated alumina in the pH of 6. The main factors such as pH, amount sorbent, sample and eluent flow rate, type and volume of elution solution and interfering ions on the sorption of metal ions have been investigated in detail. Under the optimum experimental conditions, the detection limits (3Sb) of this method for Cu(II), Ni(II), Co(II) and Cd(II) ions were 0.4, 1.0, 1.2 and 0.2ngmL−1 in the original solution, respectively. Seven replicate determinations of a mixture of 5.0μg of Cu(II), Ni(II), Co(II) and 1.0μg of Cd(II) ions in the original solution gave a mean absorbance of 0.093, 0.071, 0.066 and 0.049 with relative standard deviations 1.9%, 2.3%, 2.6% and 2.1%, respectively. The method has been applied for the determination of trace amounts of Cu(II), Ni(II), Co(II) and Cd(II) ions in tobacco, brewed tea and water samples with satisfactory results
Commensurate period Charge Density Modulations throughout the Pseudogap Regime
Theories based upon strong real space (r-space) electron electron
interactions have long predicted that unidirectional charge density modulations
(CDM) with four unit cell (4) periodicity should occur in the hole doped
cuprate Mott insulator (MI). Experimentally, however, increasing the hole
density p is reported to cause the conventionally defined wavevector of
the CDM to evolve continuously as if driven primarily by momentum space
(k-space) effects. Here we introduce phase resolved electronic structure
visualization for determination of the cuprate CDM wavevector. Remarkably, this
new technique reveals a virtually doping independent locking of the local CDM
wavevector at throughout the underdoped phase diagram of the
canonical cuprate . These observations have significant
fundamental consequences because they are orthogonal to a k-space (Fermi
surface) based picture of the cuprate CDM but are consistent with strong
coupling r-space based theories. Our findings imply that it is the latter that
provide the intrinsic organizational principle for the cuprate CDM state
Deformation of a renormalization-group equation applied to infinite-order phase transitions
By adding a linear term to a renormalization-group equation in a system
exhibiting infinite-order phase transitions, asymptotic behavior of running
coupling constants is derived in an algebraic manner. A benefit of this method
is presented explicitly using several examples.Comment: 6 pages, 5 figures, revtex4, typo corrected, references adde
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