On unusual narrow transmission bands for a multi-layered periodic structure containing left-handed materials

A multi-layered structure consisting of alternate right-handed material (RHM) and left-handed material (LHM)is considered and the unusual narrow transmission bands are explained as the competitive results of the Bragg condition and the transparent condition. These unusual narrow transmission bands may exist regardless whether the optical length of the LHM layer cancels the optical length of the RHM layer or not. This unusual transmission property may disappear when the reflection coefficient for each interface is small and the optical length of the LHM layer does not cancel the optical length of the RHM layer. An non-ideal model when the LHM is dispersive and lossy is also employed to confirm the unusual transmission phenomenon.Comment: 9 pages, 4 figure

Diethyl 4-acetyl-5-(2-nitro­phen­yl)pyrrolidine-2,2-dicarboxyl­ate

The title compound, C18H22N2O7, was synthesized by the 1,3-dipolar cyclo­addition reaction of but-3-en-2-one, diethyl 2-amino­malonate and 2-nitro­benzaldehyde. In the mol­ecule, the pyrrolidine ring possesses an envelope conformation. Inter­molecular N—H⋯O and C—H⋯O hydrogen bonds are present in the crystal structure

Constraints on Unparticle Interactions from Invisible Decays of Z, Quarkonia and Neutrinos

Unparticles (\U) interact weakly with particles. The direct signature of unparticles will be in the form of missing energy. We study constraints on unparticle interactions using totally invisible decay modes of $Z$, vector quarkonia $V$ and neutrinos. The constraints on the unparticle interaction scale \Lambda_\U are very sensitive to the dimension d_\U of the unparticles. From invisible $Z$ and $V$ decays, we find that with d_\U close to 1 for vector \U, the unparticle scale \Lambda_\U can be more than $10^4$ TeV, and for d_\U around 2, the scale can be lower than one TeV. From invisible neutrino decays, we find that if d_\U is close to 3/2, the scale can be more than the Planck mass, but with d_\U around 2 the scale can be as low as a few hundred GeV. We also study the possibility of using V (Z)\to \gamma + \U to constrain unparticle interactions, and find that present data give weak constraints.Comment: 12 pages, 4 figures, version to appear in JHEP