Leptonic Invariants, Neutrino Mass-Ordering and the Octant of θ23\theta_{23}

We point out that leptonic weak-basis invariants are an important tool for the study of the properties of lepton flavour models. In particular, we show that appropriately chosen invariants can give a clear indication of whether a particular lepton flavour model favours normal or inverted hierarchy for neutrino masses and what is the octant of $\theta_{23}$. These invariants can be evaluated in any conveniently chosen weak-basis and can also be expressed in terms of neutrino masses, charged lepton masses, mixing angles and CP violation phases.Comment: 10 pages, no figure

Non-Factorizable Phases, Yukawa Textures and the Size of sin (2 beta)

We emphasize the crucial r\^ ole played by non-factorizable phases in the analysis of the Yukawa flavour structure performed in weak bases with Hermitian mass matrices and with vanishing $(1,1)$ entries. We show that non-factorizable phases are important in order to generate a sufficiently large $\sin 2 \beta$. A method is suggested to reconstruct the flavour structure of Yukawa couplings from input experimental data both in this Hermitian basis and in a non-Hermitian basis with a maximal number of texture zeros. The corresponding Froggatt--Nielsen patterns are presented in both cases.Comment: 15 pages, 3 figure

Flavour Changing Higgs Couplings in a Class of Two Higgs Doublet Models

We analyse various flavour changing processes like $t\to hu,hc$, $h\to \tau e,\tau\mu$ as well as hadronic decays $h\to bs,bd$, in the framework of a class of two Higgs doublet models where there are flavour changing neutral scalar currents at tree level. These models have the remarkable feature of having these flavour-violating couplings entirely determined by the CKM and PMNS matrices as well as $\tan\beta$. The flavour structure of these scalar currents results from a symmetry of the Lagrangian and therefore it is natural and stable under the renormalization group. We show that in some of the models the rates of the above flavour changing processes can reach the discovery level at the LHC at 13 TeV even taking into account the stringent bounds on low energy processes, in particular $\mu\to e\gamma$.Comment: 33 pages, 8 figures; matches version accepted for publicatio

What if the Masses of the First Two Quark Families are not Generated by the Standard Higgs?

We point out that, in the context of the SM, $|V^2_{13}| + | V^2_{23}|$ is expected to be large, of order one. The fact that $|V^2_{13}| + |V^2_{23}| \approx 1.6 \times 10^{-3}$ motivates the introduction of a symmetry S which leads to $V_{CKM} ={1\>\!\!\!\mathrm{I}}$, with only the third generation of quarks acquiring mass. We consider two scenarios for generating the mass of the first two quark generations and full quark mixing. One consists of the introduction of a second Higgs doublet which is neutral under S. The second scenario consists of assuming New Physics at a high energy scale , contributing to the masses of light quark generations, in an effective field theory approach. This last scenario leads to couplings of the Higgs particle to $s\overline s$ and $c \overline c$ which are significantly enhanced with respect to those of the SM. In both schemes, one has scalar-mediated flavour- changing neutral currents which are naturally suppressed. Flavour violating top decays are predicted in the second scenario at the level \mbox{Br} (t \rightarrow h c ) \geq 5\times 10^{-5}.Comment: 11 pages, 1 figur

Quasidegeneracy of Majorana Neutrinos and the Origin of Large Leptonic Mixing

We propose that the observed large leptonic mixing may just reflect a quasidegeneracy of three Majorana neutrinos. The limit of exact degeneracy of Majorana neutrinos is not trivial, as leptonic mixing and even CP violation may occur. We conjecture that the smallness of $|U_{13}|$, when compared to the other elements of $U_{PMNS}$, may just reflect the fact that, in the limit of exact mass degeneracy, the leptonic mixing matrix necessarily has a vanishing element. We show that the lifting of the mass degeneracy can lead to the measured value of $|U_{13}|$ while at the same time accommodating the observed solar and atmospheric mixing angles. In the scenario we consider for the breaking of the mass degeneracy there is only one CP violating phase, already present in the limit of exact degeneracy, which upon the lifting of the degeneracy generates both Majorana and Dirac-type CP violation in the leptonic sector. We analyse some of the correlations among physical observables and point out that in most of the cases considered, the implied strength of leptonic Dirac-type CP violation is large enough to be detected in the next round of experiments.Comment: 16 pages, 4 figures. Matches published version, references added, improved discussion, results unchange

Yukawa Textures, New Physics and Nondecoupling

We point out that New Physics can play an important r\^ ole in rescuing some of the Yukawa texture zero ans\" atze which would otherwise be eliminated by the recent, more precise measurements of $V_{CKM}$. As an example, a detailed analysis of a four texture zero ansatz is presented, showing how the presence of an isosinglet vector-like quark which mixes with standard quarks, can render viable this Yukawa texture. The crucial point is the nondecoupling of the effects of the isosinglet quark, even for arbitrary large values of its mass.Comment: 13 pages, no figure

Vector-like Quarks at the Origin of Light Quark Masses and Mixing

We show how a novel fine-tuning problem present in the Standard Model can be solved through the introduction of a single flavour symmetry G, together with three $Q = - 1/3$ quarks, three $Q = 2/3$ quarks, as well as a complex singlet scalar. The symmetry G is extended to the additional fields and it is an exact symmetry of the Lagrangian, only spontaneously broken by the vacuum. Specific examples are given and a phenomenological analysis of the main features of the model is presented. It is shown that even for vector-like quarks with masses accessible at the LHC, one can have realistic quark masses and mixing, while respecting the strict constraints on process arising from flavour changing neutral currents (FCNC). The vector-like quark decay channels are also described.Comment: 25 pages, no figure

SN contributions to GRB lightcurves

Several of the nearer GRB afterglows (up to z ∼ 1) show bumps in their lightcurves that have been interpreted as contributions from associated SNae. Thebumps arecustomarily modelled likethet ype-Ic SN 1998bw, but wein vestigate here, for several low-z GRBs, whether other SN types might offer alternatives. While several SN types are ruled out, or are unlikely, a type “II-bl” could also explain the observations

AVALIAÇÃO DO POTENCIAL NEUROPROTETOR DA N-ACETILCISTEÍNA SOBRE PARÂMETROS COMPORTAMENTAIS E DE ESTRESSE OXIDATIVO NO MODELO EXPERIMENTAL DE COCAÍNA SUBAGUDA EM RATOS.

O consumo de drogas de abuso é considerado um sério problema sócio-econômico de abrangência global. Dentre essas drogas destaca-se a cocaína, visto que pesquisas recentes têm apontado um aumento no consumo, principalmente, devido ao aumento de usuários na América do Sul. O consumo dessa droga tem sido associado a danos cognitivos, dentre esses o prejuízo na memória. Estudos tem buscado tratamentos medicamentos afim de reduzir/prevenir os danos sobre a memória, dentre esses medicamentos tem-se a N-acetilcisteína (NAC). Diante do exposto o presente trabalho teve como objetivo investigar os possíveis efeitos do pré-tratamento com NAC seguido do consumo de cocaína, sobre a memória de reconhecimento e estresse oxidativo proteíco cerebral. Para tanto, ratos Wistar machos foram submetidos ao protocolo do teste de reconhecimento de objetos (TRO) para avaliação da memória de curto prazo 1h 30 min após a seção treino e memória de longo prazo 24h após a seção treino. Ao final do protocolo comportamental os animais foram eutanasiados e as regiões cerebrais do córtex pré-frontal (CPF) e hipocampo (HPC) foram coletados para análise bioquímicas, como: concentração de glutationa reduzida (GSH), razão glutationa reduzida e glutationa oxidada (GSH/GSSG), produtos avançados de oxidação proteica (AOPP) e índice de carbonilação proteica por densitometria (Oxyblot). Nossos resultados mostraram que os animais que receberam cocaína (10mg/Kg) apresentaram um prejuízo na memória de curto prazo quando comparados aos animais controle (p=0,005). Os animais que receberam cocaína, porém foram previamente tratados com NAC apresentaram melhora na memória de longo prazo quando comparados com os animais que não foram previamente tratados com NAC (p=0,001). O grupo submetido ao pré-tratamento com NAC seguido do tratamento com cocaína não apresentou diferença significativa no dano oxidativo proteico no córtex pré-frontal (CPF) e hipocampo (HPC), quando comparados com o grupo previamente tratado com salina. As principais conclusões do presente trabalho apontam a NAC foi capaz de proteger a memória de reconhecimento