8,586 research outputs found
-Poincar\'e supersymmetry in
We consider the exact S-matrix governing the planar spectral problem for
strings on and super Yang-Mills, and we show
that it is invariant under a novel "boost" symmetry, which acts as a
differentiation with respect to the particle momentum. This generator leads us
also to reinterpret the usual centrally extended
symmetry, and to conclude that the S-matrix is invariant under a -Poincar\'e
supersymmetry algebra, where the deformation parameter is related to the 't
Hooft coupling. We determine the two-particle action (coproduct) that turns out
to be non-local, and study the property of the new symmetry under crossing
transformations. We look at both the strong-coupling (large tension in the
string theory) and weak-coupling (spin-chain description of the gauge theory)
limits; in the former regime we calculate the cobracket utilising the universal
classical r-matrix of Beisert and Spill. In the eventuality that the boost has
higher partners, we also construct a quantum affine version of 2D Poincar\'e
symmetry, by contraction of the quantum affine algebra
in Drinfeld's second realisation.Comment: 35 pages. Added discussion on antipode in the presence of the phase.
Published versio
Mitigation of GHGs Emission From Soils by a Catalyzed In-Situ Photo-Oxidative Polymerization of Soil Organic Matter
Agricultural lands under food and bio-energy crops, managed grass and permanent crops including agro-forestry, occupy about 40-50% of the Earth's land surface^1^. In 2005, agriculture accounted for an estimated emission of 5.1 to 6.1 GtCO2-eq/yr (10-12% of total global anthropogenic emissions of greenhouse gases (GHGs))^1^. However, measures to mitigate GHGs emission from agricultural soils are limited to improved cropland practices such as crop rotation, nutrient management, tillage/residue management, agroforestry, and return to natural vegetation^2^. These practices are not only far from substantially reducing GHGs emissions from soils or permanentlystabilizing soil organic matter^1-4^, but are also predicted to hardly match more than amaximum of 25% of the GHGs reductions required by the Kyoto Protocol within 2050^5^.Despite the knowledge that GHGs release from soil largely derives from biochemicaltransformations of plant litter and soil organic matter (SOM)^6-8^, no new and much wished biotechnological measures are adopted so far to augment mitigation^1^. Here we propose an innovative approach to mitigate GHGs emissions from soils based on the insitu photo-polymerization of SOM under biomimetic catalysis. Three Mediterranean soils of different physical and chemical properties were added with a synthetic watersolubleiron-porphyrin, irradiated by solar light, and subjected to 15, and 30 wetting and drying cycles. We found that the in situ catalysed photo-polymerization of SOM increased soil physical aggregation, shifted OC into larger soil aggregates, and reduced CO~2~ released by microbial respiration. Our findings suggest that "green" catalytic technologies can become viable soil management practices to enhance mitigation of GHGs emission from arable soils and contribute to match the expectations of the post-Kyoto Protocol in the agricultural sector
Test of different sensitizing dyes in dye-sensitized solar cells based on Nb2O5 photoanodes
High-performance dyes routinely employed in TiO2-based dye-sensitized solar
cells (DSSCs) were tested in cells assembled using Nb2O5 nanostructure-based photoanodes.
The sensitizers were chosen among both metal-complex (two Ru-based, N749 and C106, and one
Zn-based dye, DNF12) and metal-free organic dyes (DNF01, DNF11 and DNF15). Two different
sensitization processes were performed: the one commonly used for TiO2 photoanodes, and a new
process relying on high pressure by autoclavation. The assembled cells were characterized by current
density–voltage (J–V) curves under air mass (AM) 1.5 G illumination and in the dark, incident
photon-to-current efficiency (IPCE) measurements, and electrochemical impedance spectroscopy.
The tested cells show different proportional efficiencies of the dyes under investigation for Nb2O5-
and TiO2-based devices. Furthermore, the results were compared with those obtained in our previous
work using N719 anchored on Nb2O5. A remarkable efficiency value of 4.4% under 1 sun illumination
was achieved by coupling the C106 dye with a nonvolatile electrolyte. This value is higher than the
one attained under the same conditions by using N719
The quaternionic Gauss-Lucas Theorem
The classic Gauss-Lucas Theorem for complex polynomials of degree has
a natural reformulation over quaternions, obtained via rotation around the real
axis. We prove that such a reformulation is true only for . We present a
new quaternionic version of the Gauss-Lucas Theorem valid for all ,
together with some consequences.Comment: 7 pages, 1 figure. Remarks added in section 3. Proposition 14 added
with complete proo
Slice regular functions on real alternative algebras
In this paper we develop a theory of slice regular functions on a real alternative algebra . Our approach is based on a well-known Fueter's construction. Two recent function theories can be included in our general theory: the one of slice regular functions of a quaternionic or octonionic variable and the theory of slice monogenic functions of a Clifford variable. Our approach permits to extend the range of these function theories and to obtain new results. In particular, we get a strong form of the fundamental theorem of algebra for an ample class of polynomials with coefficients in and we prove a Cauchy integral formula for slice functions of class
What is the limit on the Higgs mass?
We obtain the bounds on all the gauge invariant, flavour symmetric, CP-even
operators of dimension 6 that can affect the electroweak precision tests. For
the preferred Higgs mass of about 100 GeV, their minimal scales range from 2 to
10 TeV. Depending on the individual operator, these limits are often
significantly stronger than those quoted in the literature, when they exist at
all. The impact, if any, of these bounds on the upper limit con the Higgs mass
itself is discussed.Comment: 5 pages, 3 fig.s. v2: ref.s added. v3: final version, one more re
Relating m_Higgs to m_SUSY by a loop factor
We assume that the scale of the soft supersymmetry breaking masses, m_SUSY,
sliding at tree level, is fixed by the minimization of the potential, but
without a significant contribution of the cosmological term. Under these
assumptions the electroweak breaking scale gets related to m_SUSY by a loop
factor. Applied to specific models of supersymmetry breaking, this mechanism
naturally gives sparticles slightly above all present accelerator bounds.Comment: 3 pages, 1 fi
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