100 research outputs found
The Quark-Hadron Phase Transition, QCD Lattice Calculations and Inhomogeneous Big-Bang Nucleosynthesis
We review recent lattice QCD results for the surface tension at the finite
temperature quark-hadron phase transition and discuss their implications on the
possible scale of inhomogeneities. In the quenched approximation the average
distance between nucleating centers is smaller than the diffusion length of a
protron, so that inhomogeneities are washed out by the time nucleosynthesis
sets in. Consequently the baryon density fluctuations formed by a QCD phase
transition in the early universe cannot significantly affect standard big-bang
nucleosynthesis calculations and certainly cannot allow baryons to close the
universe. At present lattice results are inconclusive when dynamical fermions
are included.Comment: 8 pages, LaTe
Deep inelastic scattering of baryons in a modified soft wall model
We calculate the structure functions for unpolarized deep inelastic
scattering of baryons using an AdS/QCD soft wall model that considers a dressed
mass for the bulk fermionic fields. Considering the regime of large Bjorken
parameter x, we compare the results for the proton structure function
with experimental results.Comment: We improved the comparison with experimental data and included more
references, version to appear in EPJ
Colonization by benthic macroinvertebrates in two artificial substrate types of a Riparian Forest
Macroinvertebrados bentĂŽnicos como indicadores do impacto ambiental promovido pelos efluentes de ĂĄreas orizĂcolas e pelos de origem urbana/industrial
A critical look at 50 years particle theory from the perspective of the crossing property
The crossing property is perhaps the most subtle aspect of the particle-field
relation. Although it is not difficult to state its content in terms of certain
analytic properties relating different matrixelements of the S-matrix or
formfactors, its relation to the localization- and positive energy spectral
principles requires a level of insight into the inner workings of QFT which
goes beyond anything which can be found in typical textbooks on QFT. This paper
presents a recent account based on new ideas derived from "modular
localization" including a mathematic appendix on this subject. Its main novel
achievement is the proof of the crossing property of formfactors from a
two-algebra generalization of the KMS condition. The main content of this
article is the presentation of the derailments of particle theory during more
than 4 decades: the S-matrix bootstrap, the dual model and its string theoretic
extension. Rather than being related to crossing, string theory is the (only
known) realization of a dynamic infinite component one-particle wave function
space and its associated infinite component field. Here "dynamic" means that,
unlike a mere collection of infinitely many irreducible unitary Poincar\'e
group representation or free fields, the formalism contains also operators
which communicate between the different irreducible Poincar\'e represenations
(the levels of the "infinite tower") and set the mass/spin spectrum. Wheras in
pre-string times there were unsuccessful attempts to achieve this in analogy to
the O(4,2) hydrogen spectrum by the use of higher noncompact groups, the
superstring in d=9+1, which uses instead (bosonic/fermionic) oscillators
obtained from multicomponent chiral currents is the only known unitary positive
energy solution of the dynamical infinite component pointlike localized field
project.Comment: 66 pages, addition of new results, addition of references, will
appear in this form in Foundations of Physic
Should science educators deal with the science/religion issue?
I begin by examining the natures of science and religion before looking at the ways in which they relate to one another. I then look at a number of case studies that centre on the relationships between science and religion, including attempts to find mechanisms for divine action in quantum theory and chaos theory, creationism, genetic engineering and the writings of Richard Dawkins. Finally, I consider some of the pedagogical issues that would need to be considered if the science/religion issue is to be addressed in the classroom. I conclude that there are increasing arguments in favour of science educators teaching about the science/religion issue. The principal reason for this is to help students better to learn science. However, such teaching makes greater demands on science educators than has generally been the case. Certain of these demands are identified and some specific suggestions are made as to how a science educator might deal with the science/religion issue. © 2008 Taylor & Francis
Concomitant infection of Neospora caninum and Bovine Herpesvirus type 5 in spontaneous bovine abortions
Impactos do agrupamento do bambu Actinocladum verticillatum (Nees) McClure ex Soderstr. (POACEAE) sobre a vegetação lenhosa de duas fitofisionomias de Cerrado na transição Cerrado-Floresta AmazÎnica
ComparaçÔes florĂsticas e estruturais entre comunidades de palmeiras em fragmentos de floresta primĂĄria e secundĂĄria da Ărea de Proteção Ambiental Raimundo Irineu Serra - Rio Branco, Acre, Brasil
Floristic composition and structure of an upper montane cloud forest in the Serra da Mantiqueira Mountain Range of Brazil
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