Massless Wigner particles in conformal field theory are free

We show that in a four dimensional conformal Haag-Kastler net, its massless particle spectrum is generated by a free field subnet. If the massless particle spectrum is scalar, then the free field subnet decouples as a tensor product component.Comment: 25 pages, 3 Tikz figures. The final version is available under Open Acces

Lunar radar measurements of the diurnal exchange of ionization between the ionosphere and the magnetosphere Scientific report no. 14

Diurnal exchange of ionization between ionosphere and magnetospher

High quality Fe3-deltaO4/InAs hybrid structure for electrical spin injection

Single Crystalline Fe3-deltaO4 (0<=delta<=0.33) films have been epitaxially grown on InAs (001) substrates by molecular beam epitaxy using O2 as source of active oxygen. Under optimum growth conditions in-situ real time reflection high-energy electron diffraction patterns along with ex-situ atomic force microscopy indicated the (001) Fe3-deltaO4 to be grown under step-flow-growth mode with a characteristic surface reconstruction. X-ray photoelectron spectroscopy demonstrate the possibility to obtain iron oxides with compositions ranging from Fe3O4 to gamma-Fe2O3. Superconducting quantum interference device magnetometer at 300K shows well behaved magnetic properties giving therefore credibility to the promise of iron based oxides for spintronic applications.Comment: 3 pages, 4 figures appeared in Virtual Journal of Nanoscale Science and Technology, Vol:15, issue12, March 26, 200

Conformal covariance and the split property

We show that for a conformal local net of observables on the circle, the split property is automatic. Both full conformal covariance (i.e. diffeomorphism covariance) and the circle-setting play essential roles in this fact, while by previously constructed examples it was already known that even on the circle, M\"obius covariance does not imply the split property. On the other hand, here we also provide an example of a local conformal net living on the two-dimensional Minkowski space, which - although being diffeomorphism covariant - does not have the split property.Comment: 34 pages, 3 tikz figure

Solitons and nonsmooth diffeomorphisms in conformal nets

We show that any solitonic representation of a conformal (diffeomorphism covariant) net on S^1 has positive energy and construct an uncountable family of mutually inequivalent solitonic representations of any conformal net, using nonsmooth diffeomorphisms. On the loop group nets, we show that these representations induce representations of the subgroup of loops compactly supported in S^1 \ {-1} which do not extend to the whole loop group. In the case of the U(1)-current net, we extend the diffeomorphism covariance to the Sobolev diffeomorphisms D^s(S^1), s > 2, and show that the positive-energy vacuum representations of Diff_+(S^1) with integer central charges extend to D^s(S^1). The solitonic representations constructed above for the U(1)-current net and for Virasoro nets with integral central charge are continuously covariant with respect to the stabilizer subgroup of Diff_+(S^1) of -1 of the circle.Comment: 33 pages, 3 TikZ figure

Positive energy representations of Sobolev diffeomorphism groups of the circle

We show that any positive energy projective representation of Diff(S^1) extends to a strongly continuous projective unitary representation of the fractional Sobolev diffeomorphisms D^s(S^1) with s>3, and in particular to C^k-diffeomorphisms Diff^k(S^1) with k >= 4. A similar result holds for the universal covering groups provided that the representation is assumed to be a direct sum of irreducibles. As an application we show that a conformal net of von Neumann algebras on S^1 is covariant with respect to D^s(S^1), s > 3. Moreover every direct sum of irreducible representations of a conformal net is also D^s(S^1)-covariant.Comment: 30 pages, 1 TikZ figur