93,590 research outputs found
The prompt lepton cookbook
We review the calculation of the prompt lepton flux, produced in the
atmosphere by the semileptonic decay of charmed particles. We describe side by
side the intermediary ingredients used by different authors, which include not
only the charm production model, but also other atmospheric particle showering
parameters. After evaluating separately the relevance of each single
ingredient, we analyze the effect of different combinations over the final
result. We highlight the impact of the prompt lepton flux calculation upon
high-energy neutrino telescopes.Comment: 21 pages, 10 figures; revised version, accepted for publication in
Astroparticle Physic
Growth-Driven Percolations: The Dynamics of Community Formation in Neuronal Systems
The quintessential property of neuronal systems is their intensive patterns
of selective synaptic connections. The current work describes a physics-based
approach to neuronal shape modeling and synthesis and its consideration for the
simulation of neuronal development and the formation of neuronal communities.
Starting from images of real neurons, geometrical measurements are obtained and
used to construct probabilistic models which can be subsequently sampled in
order to produce morphologically realistic neuronal cells. Such cells are
progressively grown while monitoring their connections along time, which are
analysed in terms of percolation concepts. However, unlike traditional
percolation, the critical point is verified along the growth stages, not the
density of cells, which remains constant throughout the neuronal growth
dynamics. It is shown, through simulations, that growing beta cells tend to
reach percolation sooner than the alpha counterparts with the same diameter.
Also, the percolation becomes more abrupt for higher densities of cells, being
markedly sharper for the beta cells.Comment: 8 pages, 10 figure
Atomic Radiative Transitions in Thermo Field Dynamics
In this work we rederive the Lamb-Retherford energy shift for an atomic
electron in the presence of a thermal radiation. Using the Dalibard, Dupont-Roc
and Cohen-Tannoudji (DDC) formalism, where physical observables are expressed
as convolutions of suitable statistical functions, we construct the
electromagnetic field propagator of Thermo Field Dynamics in the Coulomb gauge
in order to investigate finite temperature effects on the atomic energy levels.
In the same context, we also analyze the problem of the ground state stability.Comment: LaTex file, 13 pages, no figures, includes PACS numbers and minor
changes in the text where a new section has been adde
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