3,111 research outputs found
Invariant approach to CP in family symmetry models
We propose the use of basis invariants, valid for any choice of CP
transformation, as a powerful approach to studying specific models of CP
violation in the presence of discrete family symmetries. We illustrate the
virtues of this approach for examples based on and family
symmetries. For , we show how to elegantly obtain several known results in
the literature. In we use the invariant approach to identify how
explicit (rather than spontaneous) CP violation arises, which is geometrical in
nature, i.e. persisting for arbitrary couplings in the Lagrangian.Comment: 4 pages plus references. v2: to be published in PR
Invariant approach to CP in unbroken
The invariant approach is a powerful method for studying CP violation for
specific Lagrangians. The method is particularly useful for dealing with
discrete family symmetries. We focus on the CP properties of unbroken
invariant Lagrangians with Yukawa-like terms, which proves to be a
rich framework, with distinct aspects of CP, making it an ideal group to
investigate with the invariant approach. We classify Lagrangians depending on
the number of fields transforming as irreducible triplet representations of
. For each case, we construct CP-odd weak basis invariants and use
them to discuss the respective CP properties. We find that CP violation is
sensitive to the number and type of representations.Comment: 24 pages, 1 figure. v2: to be published in NP
On the link between rotation, chromospheric activity and Li abundance in subgiant stars
The connection rotation-CaII emission flux-lithium abundance is analyzed for
a sample of bona fide subgiant stars, with evolutionary status determined from
HIPPARCOS trigonometric parallax measurements and from the Toulouse-Geneva
code.Comment: 9 pages, 8 figure
Efeito do substrato e da temperatura na germinação de sementes de Escallonia montevidensis (Cham. & Schl.) DC. (Saxifragaceae).
Organizado por Patricia PĂłvoa de Mattos, Celso Garcia Auer, Rejane Stumpf Sberze, Katia Regina Pichelli e Paulo CĂ©sar Botosso
Efeito de diferentes embalagens no armazenamento de sementes de vacum (Allophylus edulis) - Sapindaceae.
Resumo
Does rotation of B stars depend on metallicity? preliminary results from GIRAFFE spectra
We show the vsini distribution of main sequence B stars in sites of various
metallicities, in the absolute magnitude range -3.34 < Mv < -2.17. These
include Galactic stars in the field measured by Abt et al. (2002), members of
the h & chi Per open clusters measured by North et al. (2004), and five fields
in the SMC and LMC measured at ESO Paranal with the FLAMES-GIRAFFE
spectrograph, within the Geneva-Lausanne guaranteed time. Following the
suggestion by Maeder et al. (1999), we do find a higher rate of rapid rotators
in the Magellanic Clouds than in the Galaxy, but the vsini distribution is the
same in the LMC and in the SMC in spite of their very different metallicities.Comment: 2 pages, 1 figure, poster presented at the ESO/Arcetri Workshop on
"Chemical abundances and mixing in stars in the Milky Way and its
satellites", 13-17 Sept. 200
Caracterização de genótipos de pinhão manso do banco ativo de germoplasma da embrapa algodão.
On the nature of Lithium-rich giant stars: constraints from Beryllium abundances
We have derived beryllium abundances for 7 Li-rich giant (A(Li) > 1.5) stars
and 10 other Li-normal giants, with the aim of investigating the origin of the
Lithium in the Li-rich giants. In particular, we test the predictions of the
engulfment scenario proposed by Siess & Livio (1999), where the engulfment of a
brown dwarf or one or more giant planets would lead to a simultaneous
enrichment of 7Li and 9Be. We show that regardless their nature, none of the
stars studied in this paper were found to have detectable beryllium. Using
simple dilution arguments we show that the engulfment of an external object as
the sole source of Li enrichment is ruled out by the Li and Be abundance data.
The present results favor the idea that Li has been produced in the interior of
the stars by a Cameron-Fowler process and brought up to the surface by an extra
mixing mechanism.Comment: Accepted in A&
Efeito do substrato e da temperatura na germinação de sementes de Maytenus ilicifolia, Mart. ex Reiss (espinheira santa).
Resumo
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