48 research outputs found
Flavoured soft leptogenesis and natural values of the B term
We revisit flavour effects in soft leptogenesis relaxing the assumption of
universality for the soft supersymmetry breaking terms. We find that with
respect to the case in which the heavy sneutrinos decay with equal rates and
equal CP asymmetries for all lepton flavours, hierarchical flavour
configurations can enhance the efficiency by more than two orders of magnitude.
This translates in more than three order of magnitude with respect to the
one-flavour approximation. We verify that lepton flavour equilibration effects
related to off-diagonal soft slepton masses are ineffective for damping these
large enhancements. We show that soft leptogenesis can be successful for
unusual values of the relevant parameters, allowing for and for values of the washout parameter up to .Comment: 23 pages, 5 figures postscript, Minor changes to match the published
version in JHE
Dark Radiation and Dark Matter in Large Volume Compactifications
We argue that dark radiation is naturally generated from the decay of the
overall volume modulus in the LARGE volume scenario. We consider both
sequestered and non-sequestered cases, and find that the axionic superpartner
of the modulus is produced by the modulus decay and it can account for the dark
radiation suggested by observations, while the modulus decay through the
Giudice-Masiero term gives the dominant contribution to the total decay rate.
In the sequestered case, the lightest supersymmetric particles produced by the
modulus decay can naturally account for the observed dark matter density. In
the non-sequestered case, on the other hand, the supersymmetric particles are
not produced by the modulus decay, since the soft masses are of order the heavy
gravitino mass. The QCD axion will then be a plausible dark matter candidate.Comment: 27 pages, 4 figures; version 3: version published in JHE
Charged Lepton Flavour Violating Radiative Decays in See-Saw Models with Symmetry
The charged lepton flavour violating (LFV) radiative decays, , and are investigated in a
class of supersymmetric models with three heavy right-handed (RH)
Majorana neutrinos, in which the lepton (neutrino) mixing is predicted to
leading order (LO) to be tri-bimaximal. The light neutrino masses are generated
via the type I see-saw mechanism. The analysis is done within the framework of
the minimal supergravity (mSUGRA) scenario, which provides flavour universal
boundary conditions at the scale of grand unification GeV. Detailed predictions for the rates of the three LFV decays are
obtained in two explicit realisations of the models due to Altarelli and
Feruglio and Altarelli and Meloni, respectively.Comment: Results unchanged, minor improvements made; version accepted for
publication in JHE
The Herschel-SPIRE Legacy Survey (HSLS): the scientific goals of a shallow and wide submillimeter imaging survey with SPIRE
A large sub-mm survey with Herschel will enable many exciting science opportunities, especially in an era of wide-field optical and radio surveys and high resolution cosmic microwave background experiments. The Herschel-SPIRE Legacy Survey (HSLS), will lead to imaging data over 4000 sq. degrees at 250, 350, and 500 micron. Major Goals of HSLS are: (a) produce a catalog of 2.5 to 3 million galaxies down to 26, 27 and 33 mJy (50% completeness; 5 sigma confusion noise) at 250, 350 and 500 micron, respectively, in the southern hemisphere (3000 sq. degrees) and in an equatorial strip (1000 sq. degrees), areas which have extensive multi-wavelength coverage and are easily accessible from ALMA. Two thirds of the of the sources are expected to be at z > 1, one third at z > 2 and about a 1000 at z > 5. (b) Remove point source confusion in secondary anisotropy studies with Planck and ground-based CMB data. (c) Find at least 1200 strongly lensed bright sub-mm sources leading to a 2% test of general relativity. (d) Identify 200 proto-cluster regions at z of 2 and perform an unbiased study of the environmental dependence of star formation. (e) Perform an unbiased survey for star formation and dust at high Galactic latitude and make a census of debris disks and dust around AGB stars and white dwarfs
Intrinsic and extrinsic goals as moderators of stress and depressive symptoms in Chinese undergraduate students: A multi-wave longitudinal study
Ion homeostasis in the Chloroplast
peer reviewedThe chloroplast is an organelle of high demand for macro- and micro-nutrient ions, which are required for the maintenance of the photosynthetic process. To avoid deficiency while preventing excess, homeostasis mechanisms must be tightly regulated. Here, we describe the needs for nutrient ions in the chloroplast and briefly highlight their functions in the chloroplastidial metabolism. We further discuss the impact of nutrient deficiency on chloroplasts and the acclimation mechanisms that evolved to preserve the photosynthetic apparatus. We finally present what is known about import and export mechanisms for these ions. Whenever possible, a comparison between cyanobacteria, algae and plants is provided to add an evolutionary perspective to the description of ion homeostasis mechanisms in photosynthesis