8,306 research outputs found
Anisotropy in Inflation with Non-minimal Coupling
We study a new anisotropic inflation model, with an inflaton field
nonminimally coupled with the gravity and a vector field. We find that the
anisotropic attractor solution exists not only in the weak curvature coupling
limit, but more interestingly in the strong curvature coupling limit as well.
We show that in the strong curvature coupling limit, the contribution from the
anisotropy is greatly suppressed.Comment: V2, 12 pages, 3 figures, numerical analysis adde
Neutral Color Superconductivity Including Inhomogeneous Phases at Finite Temperature
We investigate neutral quark matter with homogeneous and inhomogeneous color
condensates at finite temperature in the frame of an extended NJL model. By
calculating the Meissner masses squared and gap susceptibility, the uniform
color superconductor is stable only in a temperature window close to the
critical temperature and becomes unstable against LOFF phase, mixed phase and
gluonic phase at low temperatures. The introduction of the inhomogeneous phases
leads to disappearance of the strange intermediate temperature 2SC/g2SC and
changes the phase diagram of neutral dense quark matter significantly.Comment: 12 pages, 7 figures. v2: references added, accepted for publication
in PRD. V3: Calculation of the neutral LOFF state clarified, typos corrected
Effect of Breaking on Chiral Phase Structure and Pion Superfluidity at Finite Isospin Chemical Potential
We investigate the isospin chemical potential effect in the frame of SU(2)
Nambu-Jona-Lasinio model. When the isospin chemical potential is less than the
vacuum pion mass, the phase structure with two chiral phase transition lines
does not happen due to breaking of QCD. When the isospin chemical
potential is larger than the vacuum pion mass, the ground state of the system
is a Bose-Einstein condensate of charged pions.Comment: Talk presented at Conference on Non-Perturbative Quantum Field
Theory: Lattice and Beyond, Guangzhou, China, Dec.16--18, 2004; v2: error
correcte
Exploration of the chemistry of alkynes and Selectfluor : search for cytotoxic agents from the Amazonian rainforest.
Vicinal dithioethers and alkenyl thioethers were synthesized under environmentally friendly conditions using alkyne and thiol in water. Alkynes were also used to develop a multibond-fonning reaction that fonned cyclic ketones or ketoesters through a goldcatalyzed intramolecular oxygen transfer isomerization of 2-alkynyl-l ,5-diketones or 2- alkyny 1-5 -ketoesters. The investigation of Selectfluor chemistry yielded a highly stereoselective synthesis of fluoroalky (E)-a,ß-unsaturated ketones from allenyl esters, through a gold-catalyzed rearrangement that produced an intennediate dienyl ester. When Selectfluor was combined with copper, it produced two oxidative systems, F-TEDA-BF4 and F-TEDAPF 6, both of which efficiently converted amides into imides at room temperature in short time, but whereas the fonner employed stoichiometric amounts of copper(I), the latter only needed catalytic amounts. The bioassay-directed fractionation of Physalis angulata L. afforded three new antiproliferative withanolides: physangulidines A, B and C. Each has shown significant cytotoxic activity (GI50 is less than 4µg/mL) on DUI45 and RWPE-I in vitro. In addition, compared to positive drug 5-fluorouracil, physangulidine A had significant cytotoxic activity on different cells. The bioassay-guided fractionation of Cremastosperma microcarpum led to the isolation and identification of dehydrodiisoeugenol as its main cytotoxic agent. Lastly, selected fractions of Hyptis lantanaefolia have shown promising cytotoxic activities; with one of semi purified chromatographic fraction (LHL 15) exhibiting very high bioactivity on various cell lines (IC50 is lower than 50 ng/mL)
Magnetic Stability Analysis for Abelian and Non-Abelian Superconductors
We investigate the origin of Abelian and non-Abelian type magnetic
instabilities induced by Fermi surface mismatch between the two pairing
fermions in a non-relativistic model. The Abelian type instability occurs only
in gapless state and the Meissner mass squared becomes divergent at the
gapless-gapped transition point, while the non-Abelian type instability happens
in both gapless and gapped states and the divergence vanishes. The non-Abelian
type instability can be cured in strong coupling region.Comment: 7 pages, 2 figures, more references added, accepted for publication
in PR
Continuous-variable controlled-Z gate using an atomic ensemble
The continuous-variable controlled-Z gate is a canonical two-mode gate for
universal continuous-variable quantum computation. It is considered as one of
the most fundamental continuous-variable quantum gates. Here we present a
scheme for realizing continuous-variable controlled-Z gate between two optical
beams using an atomic ensemble. The gate is performed by simply sending the two
beams propagating in two orthogonal directions twice through a spin-squeezed
atomic medium. Its fidelity can run up to one if the input atomic state is
infinitely squeezed. Considering the noise effects due to atomic decoherence
and light losses, we show that the observed fidelities of the scheme are still
quite high within presently available techniques.Comment: 7 pages, 3 figures, to appear in Physical Review
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