131 research outputs found
La filosofía del derecho y sus temas. Sobre la no necesidad de la "teoría del derecho" como sucedáneo
Double Pion Photoproduction on the Nucleon: Study of the Isospin Channels
A model for the gamma p ----> pion+ pion- p reaction developed earlier is
extended to account for all isospin channels. The model includes N,
Delta(1232), N^*(1440) and N^*(1520) as intermediate baryonic states and the
rho-meson as an intermediate two pion resonance. Although many terms contribute
to the cross section, some channels exhibit particular sensitivity to certain
mechanisms of resonance excitation or decay and the reactions provide novel
information on such mechanisms. In particular the gamma N ----> N^*(1520) ---->
Delta(1232) pion process affects all the channels and is a key ingredient in
the interpretation of the data. Comparison is made with all available data and
the agreement is good in some channels. The remaining discrepancies in some
other channels are discussed.Comment: 23 pages, 13 figures. TeX, Version 3.141 [PD VMS 3.4/CERN 1.0
From QFT to DCC
A quantum field theoretical model for the dynamics of the disoriented chiral
condensate is presented. A unified approach to relate the quantum field theory
directly to the formation, decay and signals of the DCC and its evolution is
taken. We use a background field analysis of the O(4) sigma model keeping
one-loop quantum corrections (quadratic order in the fluctuations). An
evolution of the quantum fluctuations in an external, expanding metric which
simulates the expansion of the plasma, is carried out. We examine, in detail,
the amplification of the low momentum pion modes with two competing effects,
the expansion rate of the plasma and the transition rate of the vacuum
configuration from a metastable state into a stable state.We show the effect of
DCC formation on the multiplicity distributions and the Bose-Einstein
correlations.Comment: 34 pages, 10 figure
Water vapour detection in hot Jupiters with the CARMENES NIR channel
Stars and planetary system
Qualidade do solo em sistemas de manejo avaliada pela dinâmica da matéria orgânica e atributos relacionados
Inter-relation between soybean yield and soil compaction under degraded pasture in Brazilian Savannah
Global CO2 emissions from dry inland waters share common drivers across ecosystems
Many inland waters exhibit complete or partial desiccation, or have vanished due to global change, exposing sediments to the atmosphere. Yet, data on carbon dioxide (CO2) emissions from these sediments are too scarce to upscale emissions for global estimates or to understand their fundamental drivers. Here, we present the results of a global survey covering 196 dry inland waters across diverse ecosystem types and climate zones. We show that their CO2 emissions share fundamental drivers and constitute a substantial fraction of the carbon cycled by inland waters. CO2 emissions were consistent across ecosystem types and climate zones, with local characteristics explaining much of the variability. Accounting for such emissions increases global estimates of carbon emissions from inland waters by 6% (~0.12 Pg C y−1). Our results indicate that emissions from dry inland waters represent a significant and likely increasing component of the inland waters carbon cycle
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