5,428 research outputs found
A new bridge between leptonic CP violation and leptogenesis
Flavor effects due to lepton interactions in the early Universe may have
played an important role in the generation of the cosmological baryon asymmetry
through leptogenesis. If the only source of high-energy CP violation comes from
the left-handed leptonic sector, then it is possible to establish a bridge
between flavored leptogenesis and low-energy leptonic CP violation. We explore
this connection taking into account our present knowledge about low-energy
neutrino parameters and the matter-antimatter asymmetry observed in the
Universe. In this framework, we find that leptogenesis favors a hierarchical
light neutrino mass spectrum, while for quasi-degenerate and inverted
hierarchical neutrino masses there is a very narrow allowed window. The
absolute neutrino mass scale turns out to be m < 0.1 eV.Comment: 10 pages, 3 figure
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
Spontaneous leptonic CP violation and nonzero
We consider a simple extension of the Standard Model by adding two Higgs
triplets and a complex scalar singlet to its particle content. In this
framework, the CP symmetry is spontaneously broken at high energies by the
complex vacuum expectation value of the scalar singlet. Such a breaking leads
to leptonic CP violation at low energies. The model also exhibits an flavour symmetry which, after being spontaneously broken at a high-energy
scale, yields a tribimaximal pattern in the lepton sector. We consider small
perturbations around the tribimaximal vacuum alignment condition in order to
generate nonzero values of , as required by the latest neutrino
oscillation data. It is shown that the value of recently measured
by the Daya Bay Reactor Neutrino Experiment can be accommodated in our
framework together with large Dirac-type CP violation. We also address the
viability of leptogenesis in our model through the out-of-equilibrium decays of
the Higgs triplets. In particular, the CP asymmetries in the triplet decays
into two leptons are computed and it is shown that the effective leptogenesis
and low-energy CP-violating phases are directly linked.Comment: 17 pages; 6 figures; references added and typos corrected. Final
version to appear in PR
Mass-radius relation for magnetized strange quark stars
We review the stability of magnetized strange quark matter (MSQM) within the
phenomenological MIT bag model, taking into account the variation of the
relevant input parameters, namely, the strange quark mass, baryon density,
magnetic field and bag parameter. A comparison with magnetized asymmetric quark
matter in -equilibrium as well as with strange quark matter (SQM) is
presented. We obtain that the energy per baryon for MSQM decreases as the
magnetic field increases, and its minimum value at vanishing pressure is lower
than the value found for SQM, which implies that MSQM is more stable than
non-magnetized SQM. The mass-radius relation for magnetized strange quark stars
is also obtained in this framework.Comment: 7 pages, 6 figures. To be published in the Proceedings of 4th
International Workshop on Relativistic Astrophysical and Astronomy IWARA0
One-loop conformal anomaly in an implicit momentum space regularization framework
In this paper we consider matter fields in a gravitational background in
order to compute the breaking of the conformal current at one-loop order.
Standard perturbative calculations of conformal symmetry breaking expressed by
the non-zero trace of the energy-momentum tensor have shown that some violating
terms are regularization dependent, which may suggest the existence of spurious
breaking terms in the anomaly. Therefore, we perform the calculation in a
momentum space regularization framework in which regularization dependent terms
are judiciously parametrized. We compare our results with those obtained in the
literature and conclude that there is an unavoidable arbitrariness in the
anomalous term .Comment: in European Physical Journal C, 201
Optimized Effective Potentials in Finite Basis Sets
The finite basis optimized effective potential (OEP) method within density
functional theory is examined as an ill-posed problem. It is shown that the
generation of nonphysical potentials is a controllable manifestation of the use
of unbalanced, and thus unsuitable, basis sets. A modified functional
incorporating a regularizing smoothness measure of the OEP is introduced. This
provides a condition on balanced basis sets for the potential, as well as a
method to determine the most appropriate OEP potential and energy from
calculations performed with any finite basis set.Comment: 23 pages, 28 figure
Análise lexical e discursiva em notícias da Internet
Anais e artigos do 28º Fórum Acadêmico de Letras, realizado nos dias 23 a 25 de agosto de 2017 na Universidade Federal da Integração Latino-Americana (Unila) e Universidade Estadual do Oeste do Paraná (Unioeste) com tema: A pesquisa nos cursos de letras em contexto de línguas e culturas em contato.No decorrer deste artigo, serão investigadas duas notícias veiculadas na internet com o
objetivo de analisar e comparar os elementos lexicais utilizados nos textos, dentre eles as palavras
utilizadas, seus significados e sentidos proporcionados ao interlocutor. As análises se respaldam na
Lexicologia e na Linguística Textual, demonstrando que o emprego de uma expressão ou de outra não
é casual, ao contrário, as expressões se destinam a uma função específica relacionada ao processo de
referenciação. A análise considerou o texto como um todo, a finalidade argumentativa do autor e o
contexto de produção que caracteriza o discurso, visto que o texto é marcado pela coerência,
encadeamento de ideias e pela progressão textual, sendo que sua principal característica é a
comunicabilidade que dependem da produção e da interpretaçã
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