55,810 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
Free energy determination of phase coexistence in model C60: A comprehensive Monte Carlo study
The free energy of the solid and fluid phases of the Girifalco C60 model are
determined through extensive Monte Carlo simulations. In this model the
molecules interact through a spherical pair potential, characterized by a
narrow and attractive well, adjacent to a harshly repulsive core. We have used
the Widom test particle method and a mapping from an Einstein crystal, in order
to estimate the absolute free energy in the fluid and solid phases,
respectively; we have then determined the free energy along several isotherms,
and the whole phase diagram, by means of standard thermodynamic integrations.
We highlight how the interplay between the liquid-vapor and the liquid-solid
coexistence conditions determines the existence of a narrow liquid pocket in
the phase diagram, whose stability is assessed and confirmed in agreement with
previous studies. In particular, the critical temperature follows closely an
extended corresponding-states rule recently outlined by Noro and Frenkel [J.
Chem. Phys. 113:2941 (2000)].
We discuss the emerging "energetic" properties of the system, which drive the
phase behavior in systems interacting through short-range forces [A. A. Louis,
Phil. Trans. R. Soc. A 359:939 (2001)], in order to explain the discrepancy
between the predictions of several structural indicators and the results of
full free energy calculations, to locate the fluid phase boundaries.
More generally, we aim to provide extended reference data for calculations of
the free energy of the C60 fullerite in the low temperature regime, as for the
determination of the phase diagram of higher order fullerenes and other
fullerene-related materials, whose description is based on the same model
adopted in this work.Comment: RevTeX, 11 pages, 9 figure
Cartoon planet: Micro-reflection through digital cartoons - a case study on teaching and learning with young people
The young learners of today tend to show little enthusiasm for formal schooling. This does not
necessarily mean pupils are not interested in learning or developing new skills and competences. In
fact, the opposite often happens in the informal settings they belong to. Finding ways of transferring
pupil’s informal learning to the school setting is therefore important. This paper gives a brief overview
on the development of informal learning activities to encourage young people’s active reflection on
their informally acquired competencies through the use of web technologies. The researchers also
explore the role of the teacher, and the need of a participatory learning environment in a less formal
classroom. Reflections on the experiences and recommendations are also provided
Texture Zeros and Weak Basis Transformations
We investigate the physical meaning of some of the "texture zeros" which
appear in most of the Ansatze on quark masses and mixings. It is shown that
starting from arbitrary quark mass matrices and making a suitable weak basis
transformation one can obtain some of these sets of zeros which therefore have
no physical content. We then analyse the physical implications of a
four-texture zero Ansatz which is in agreement with all present experimental
data.Comment: 11 pages, typeset using revte
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