574 research outputs found
On Hexagonal Structures in Higher Dimensional Theories
We analyze the geometrical background under which many Lie groups relevant to
particle physics are endowed with a (possibly multiple) hexagonal structure.
There are several groups appearing, either as special holonomy groups on the
compactification process from higher dimensions, or as dynamical string gauge
groups; this includes groups like SU(2),SU(3), G_2, Spin(7), SO(8) as well as
E_8 and SO(32). We emphasize also the relation of these hexagonal structures
with the octonion division algebra, as we expect as well eventually some role
for octonions in the interpretation of symmetries in High Energy Physics.Comment: 9 pages, Latex, 3 figures. Accepted for publication in International
Journal of Theoretical Physic
Biosorption: a solution to pollution?
To solve the water pollution problem by toxic heavy metal contamination resulting from humans technological activities has for long presented a challenge. Biosorption can be a part of the solution. Some types of biosorbents such as seaweeds, molds, yeasts, bacteria or crab shells are examples of biomass tested for metal biosorption with very encouraging results. The uptake of heavy metals by biomass can in some cases reach up to 50% of the biomass dry weight. New biosorbents can be manipulated for better efficiency and multiple re-use to increase their economic attractiveness
One-parameter Darboux-transformed quantum actions in Thermodynamics
We use nonrelativistic supersymmetry, mainly Darboux transformations of the
general (one-parameter) type, for the quantum oscillator thermodynamic actions.
Interesting Darboux generalizations of the fundamental Planck and pure vacuum
cases are discussed in some detail with relevant plots. It is shown that the
one-parameter Darboux-transformed Thermodynamics refers to superpositions of
boson and fermion excitations of positive and negative absolute temperature,
respectively. Recent results of Arnaud, Chusseau, and Philippe physics/0105048
regarding a single mode oscillator Carnot cycle are extended in the same
Darboux perspective. We also conjecture a Darboux generalization of the
fluctuation-dissipation theoremComment: 14 pages, 13 figures, correction of the formula in the text after Eq.
7, accepted at Physica Script
Composition algebras and the two faces of
We consider composition and division algebras over the real numbers: We note
two r\^oles for the group : as automorphism group of the octonions and
as the isotropy group of a generic 3-form in 7 dimensions. We show why they are
equivalent, by means of a regular metric. We express in some diagrams the
relation between some pertinent groups, most of them related to the octonions.
Some applications to physics are also discussed.Comment: 11 pages, 3 figure
Random walks of partons in SU(N_c) and classical representations of color charges in QCD at small x
The effective action for wee partons in large nuclei includes a sum over
static color sources distributed in a wide range of representations of the
SU(N_c) color group. The problem can be formulated as a random walk of partons
in the N_c-1 dimensional space spanned by the Casimirs of SU(N_c). For a large
number of sources, k >> 1, we show explicitly that the most likely
representation is a classical representation of order O(\sqrt{k}). The quantum
sum over representations is well approximated by a path integral over classical
sources with an exponential weight whose argument is the quadratic Casimir
operator of the group. The contributions of the higher N_c-2 Casimir operators
are suppressed by powers of k. Other applications of the techniques developed
here are discussed briefly.Comment: 51 pages, includes 3 eps file
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