1,727 research outputs found
BPS surface observables in six-dimensional (2,0) theory
The supergroup OSp(8*|4), which is the superconformal group of (2,0) theory
in six dimensions, is broken to the subgroup OSp(4|2)xOSp(4|2) by demanding the
invariance of a certain product in a superspace with eight bosonic and four
fermionic dimensions. We show that this is consistent with the symmetry
breaking induced by the presence of a flat two-dimensional BPS surface in the
usual (2,0) superspace, which has six bosonic and sixteen fermionic dimensions.Comment: 9 pages, LaTeX. v2: reference adde
Supersymmetric coupling of a self-dual string to a (2,0) tensor multiplet background
We construct an interaction between a (2,0) tensor multiplet in six
dimensions and a self-dual string. The interaction is a sum of a Nambu-Goto
term, with the tension of the string given by the modulus of the scalar fields
of the tensor multiplet, and a non-local Wess-Zumino term, that encodes the
electromagnetic coupling of the string to the two-form gauge field of the
tensor multiplet. The interaction is invariant under global (2,0)
supersymmetry, modulo the equations of motion of a free tensor multiplet. It is
also invariant under a local fermionic kappa-symmetry, as required by the
BPS-property of the string.Comment: 12 pages, LaTe
Comparison of methods for determining the fatty acid composition of photosynthetic tissues
The fatty acid (FA) composition of photosynthetic tissue differs from that in other plant or animal tissues. In leaves, the lipid fraction constitutes less than 10% of the dry weight and is mostly located in the chloroplasts. An extraction solvent should dissolve polar lipids readily, but should also overcome interactions between the lipids and the tissue matrix. A mixture of chloroform/methanol (C/M) is commonly used. However, less toxic alternative methods such as hexane/isopropanol (H/I) and ethanol (E) have been suggested. In this preliminary study we compared the effectiveness of these three methods which are used as standard extraction protocols for FA analysis of plant material at three different European Universities. C/M extraction gave the highest total FA content and H/I the lowest, suggesting that C/M is indeed the best general-purpose lipid extraction solvent. Significant differences were also observed for FA composition including the ratio of saturated to unsaturated FA indicating selectivity of the various solvents in extracting different individual FA. Further and more detailed investigations are required to confirm this hypothesi
Conformal anomaly of Wilson surface observables - a field theoretical computation
We make an exact field theoretical computation of the conformal anomaly for
two-dimensional submanifold observables. By including a scalar field in the
definition for the Wilson surface, as appropriate for a spontaneously broken
A_1 theory, we get a conformal anomaly which is such that N times it is equal
to the anomaly that was computed in hep-th/9901021 in the large N limit and
which relied on the AdS-CFT correspondence. We also show how the spherical
surface observable can be expressed as a conformal anomaly.Comment: 18 pages, V3: an `i' dropped in the Wilson surface, overall
normalization and misprints corrected, V4: overall normalization factor
corrected, references adde
Near- to mid-infrared picosecond optical parametric oscillator based on periodically poled RbTiOAsO4
We describe a Ti:sapphire-pumped picosecond optical parametric oscillator based on periodically poled RbTiOAsO4 that is broadly tunable in the near to mid infrared. A 4.5-mm single-grating crystal at room temperature in combination with pump wavelength tuning provided access to a continuous-tuning range from 3.35 to 5 mu m, and a pump power threshold of 90 mW was measured. Average mid-infrared output powers in excess of 100 mW and total output powers of 400 mW in similar to 1-ps pulses were obtained at 33% extraction efficiency. (C) 1998 Optical Society of America.</p
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