733 research outputs found
SUSY radiative corrections on mu-tau neutrino refraction including possible R-parity breaking interactions
In this paper we investigate the one-loop radiative corrections to the
neutrino indices of refraction from supersymmetric models. We consider the
Next-to Minimal Supersymmetric extension of the Standard Model (NMSSM) which
happens to be a better supersymmetric candidate than the MSSM for both
theoretical and experimental reasons. We scan the relevant SUSY parameters and
identify regions in the parameter space which yield interesting values for
V_{mu tau}. If R-parity is broken there are significant differences between
MSSM and NMSSM contributions contrary to the R-parity conserved case. Finally,
for a non-zero CP-violating phase, we show analytically that the presence of
V_{mu tau} will explicitly imply CP-violation effects on the supernova electron
(anti-) neutrino fluxes.Comment: 23 pages, 15 figures; v2: typos and 5 figures correcte
Possible CP-Violation effects in core-collapse Supernovae
We study CP-violation effects when neutrinos are present in dense matter,
such as outside the proto-neutron star formed in a core-collapse supernova.
Using general arguments based on the Standard Model, we confirm that there are
no CP-violating effects at the tree level on the electron neutrino and
anti-neutrino fluxes in a core-collapse supernova. On the other hand
significant effects can be obtained for muon and tau neutrinos even at the tree
level. We show that CP violating effects can be present in the supernova
electron (anti)neutrino fluxes as well, if muon and tau neutrinos have
different fluxes at the neutrinosphere. Such differences could arise due to
physics beyond the Standard Model, such as the presence of flavor-changing
interactions.Comment: 11 pages, 18 figure
The K-process on a tree as a scaling limit of the GREM-like trap model
We introduce trap models on a finite volume -level tree as a class of
Markov jump processes with state space the leaves of that tree. They serve to
describe the GREM-like trap model of Sasaki and Nemoto. Under suitable
conditions on the parameters of the trap model, we establish its infinite
volume limit, given by what we call a -process in an infinite -level
tree. From this we deduce that the -process also is the scaling limit of the
GREM-like trap model on extreme time scales under a fine tuning assumption on
the volumes.Comment: Published in at http://dx.doi.org/10.1214/13-AAP937 the Annals of
Applied Probability (http://www.imstat.org/aap/) by the Institute of
Mathematical Statistics (http://www.imstat.org
Do we need a hybrid law of contract? Why Hugh Collins is wrong and why it matters
In Regulating Contracts Hugh Collins takes up the challenge presented by 40 years of empirical studies which show that business people make little use of contract law in settling disputes, preferring instead to rely on trust and various non-legal sanctions to organise their transactions. Indeed, business parties often actively avoid the use of law because of its expense, inconvenience and tendency to harm business relationships. These findings pose a challenge to traditional doctrinal scholars. If business parties do not make much use of contract law, one has to ask what role it does play and whether the attention that is paid to it by orthodox legal scholars is misplaced. Regulating Contracts takes on this challenge directly and is the most substantial attempt made so far to explain the role of contract law in light of the questions raised as to its usefulness.John Gava and Janey Green
Core-collapse supernova neutrinos and neutrino properties
Core-collapse supernovae are powerful neutrino sources. The observation of a
future (extra-)galactic supernova explosion or of the relic supernova neutrinos
might provide important information on the supernova dynamics, on the supernova
formation rate and on neutrino properties. One might learn more about unknown
neutrino properties either from indirect effects in the supernova (e.g. on the
explosion or on in the r-process) or from modifications of the neutrino time or
energy distributions in a detector on Earth. Here we will discuss in particular
possible effects of CP violation in the lepton sector. We will also mention the
interest of future neutrino-nucleus interaction measurements for the precise
knowledge of supernova neutrino detector response to electron neutrinos.Comment: 9 pages, 5 figures, Proceedings to "Three days of Strong Interactions
& Astrophysics HLPW08", 6-8 March 2008, SP
Influência da compactação do solo na produtividade da rebrota de eucalipto.
Normalmente, as áreas de rebrota sofrem a influência das operações de colheita, aplicação de herbicidas, adubos e resíduos, que concorrem para a compactação do solo. Em solos de texturas diferentes em áreas da Cia. Suzano de Papel e Celulose, nos municípios de Itatinga, SP, e São Miguel Arcanjo, SP, foram selecionadas 30 linhas de plantio para determinação da produtividade de eucalipto (Eucalyptus grandis Hill ex Maiden) aos sete anos de idade, bem como atributos físico-hídricos do solo a 50 cm da linha de plantio. Foram obtidas amostras indeformadas de solo em três profundidades: 0 a 10, 10 a 20 e 20 a 30 cm; a resistência do solo foi obtida com penetrômetro – SC 60 – até 60 cm de profundidade. As linhas de eucaliptos foram separadas, segundo a intensidade de movimentação das máquinas de colheita, em corte, galhada e tráfego. A redução da produtividade do eucalipto chegou até dois terços, comparando-se linhas de tráfego intenso das máquinas e sem tráfego. A camada superficial do solo (0 a 10 cm) recuperou parcialmente a estrutura durante os sete anos. A compactação foi máxima na camada de 10 a 20 cm, no solo argiloso e na camada de 20 a 30 cm, no solo arenoso. Houve correlação negativa (r² = 0,86) entre a densidade global, na profundidade de 10 a 20 cm, e o volume de madeira das linhas de eucalipto no solo arenoso. No solo argiloso, essa correlação (r² = 0,77) negativa ocorreu na profundidade de 20 a 30 cm
Closed String Tachyons on C/Z_N
We analyse the condensation of closed string tachyons on the
orbifold. We construct the potential for the tachyons upto the quartic
interaction term in the large limit. In this limit there are near marginal
tachyons. The quartic coupling for these tachyons is calculated by subtracting
from the string theory amplitude for the tachyons, the contributions from the
massless exchanges, computed from the effective field theory. We argue that
higher point interaction terms are are also of the same order in 1/N as the
quartic term and are necessary for existence of the minimum of the tachyon
potential that is consistent with earlier analysis.Comment: 19 pages, 1 figure; comments added about dependence of contact
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