Lightest sterile neutrino abundance within the nuMSM

We determine the abundance of the lightest (dark matter) sterile neutrinos created in the Early Universe due to active-sterile neutrino transitions from the thermal plasma. Our starting point is the field-theoretic formula for the sterile neutrino production rate, derived in our previous work [JHEP 06(2006)053], which allows to systematically incorporate all relevant effects, and also to analyse various hadronic uncertainties. Our numerical results differ moderately from previous computations in the literature, and lead to an absolute upper bound on the mixing angles of the dark matter sterile neutrino. Comparing this bound with existing astrophysical X-ray constraints, we find that the Dodelson-Widrow scenario, which proposes sterile neutrinos generated by active-sterile neutrino transitions to be the sole source of dark matter, is only possible for sterile neutrino masses lighter than 3.5 keV (6 keV if all hadronic uncertainties are pushed in one direction and the most stringent X-ray bounds are relaxed by a factor of two). This upper bound may conflict with a lower bound from structure formation, but a definitive conclusion necessitates numerical simulations with the non-equilibrium momentum distribution function that we derive. If other production mechanisms are also operative, no upper bound on the sterile neutrino mass can be established.Comment: 34 pages. v2: clarifications and a reference added; published version. v3: erratum appende

Plantas palustres e aquáticas que se comportam como invasoras, no Estado de Minas Gerais

Foram cadastradas as espécies palustres e aquáticas com comportamento de plantas invasoras, quando da obstrução de canais de irrigação e drenagem de lagos, represas, ou ainda como competidoras em culturas irrigadas. As plantas cadastradas no presente trabalho somam um total de 113 espécies, englobando 64 gêneros e 40 famílias.<br>Are listed the boggy and aquatic plants that behave as weeds in the obstruction of drainage and irrigation canals, lakes, dams or irrigated crops, totalling 113 species, involving 64 genera and 40 families