Impact of sterile neutrinos on nuclear-assisted cLFV processes

We discuss charged lepton flavour violating processes occurring in the presence of muonic atoms, such as muon-electron conversion in nuclei $\text{CR}(\mu -e, \text{ N})$, the (Coulomb enhanced) decay of muonic atoms into a pair of electrons BR($\mu^- e^- \to e^- e^-$, N), as well as Muonium conversion and decay, $\text{Mu}-\bar{\text{Mu}}$ and $\text{Mu}\to e^+ e^-$. Any experimental signal of these observables calls for scenarios of physics beyond the Standard Model. In this work, we consider minimal extensions of the Standard Model via the addition of sterile fermions, providing the corresponding complete analytical expressions for all the considered observables. We first consider an "ad hoc" extension with a single sterile fermion state, and investigate its impact on the above observables. Two well motivated mechanisms of neutrino mass generation are then considered: the Inverse Seesaw embedded into the Standard Model, and the $\nu$MSM. Our study reveals that, depending on their mass range and on the active-sterile mixing angles, sterile neutrinos can give significant contributions to the above mentioned observables, some of them even lying within present and future sensitivity of dedicated cLFV experiments. We complete the analysis by confronting our results to other (direct and indirect) searches for sterile fermions.Comment: 32 pages, 11 figures. v2: minor revision, matches published version on JHE

Effect of steriles states on lepton magnetic moments and neutrinoless double beta decay

We address the impact of sterile fermion states on the anomalous magnetic moment of charged leptons, as well as their contribution to neutrinoless double beta decays. We illustrate our results in a minimal, effective extension of the Standard Model by one sterile fermion state, and in a well-motivated framework of neutrino mass generation, embedding the Inverse Seesaw into the Standard Model. The simple "3+1" effective case succeeds in alleviating the tension related to the muon anomalous magnetic moment, albeit only at the 3$\sigma$ level, and for light sterile states (corresponding to a }cosmologically disfavoured regime). Interestingly, our analysis shows that a future $0 \nu 2 \beta$ observation does not necessarily imply an inverted hierarchy for the active neutrinos in this simple extension. Although the Inverse Seesaw realisation here addressed could indeed ease the tension in $(g-2)_\mu$, bounds from lepton universality in kaon decays mostly preclude this from happening. However, these scenarios can also have a strong impact on the interpretation of a future $0 \nu 2 \beta$ signal regarding the hierarchy of the active neutrino mass spectrum.Comment: 25 pages, 19 figure

Theory of Nonequilibrium Spin Transport and Spin Transfer Torque in Superconducting-Ferromagnetic Nanostructures

Spin transport currents and the spin-transfer torques in voltage-biased superconducting-ferromagnetic nanopillars (SFNFS point contacts) are computed. We develop and implement an algorithm based on the Ricatti formulation of the quasiclassical theory of superconductivity to solve the time-dependent boundary conditions for the nonequilibrium Green's functions for spin transport through the ferromagnetic interfaces. A signature of the nonequilibrium torque is a component perpendicular to the plane spanned by the two ferromagnetic moments. The perpendicular component is absent in normal-metal-ferromagnetic nanopillars (NFNFN) contacts, but is shown to have the same order of magnitude as the in-plane torque for non-equilibrium SFNFS contacts. The out-of-plane torque is due to the rotation of quasiparticle spin by the exchange fields of the ferromagnetic layers. In the ballistic limit the equilibrium torque is related to the spectrum of spin-polarized Andreev bound states, while the {\sl ac} component, for small bias voltages, is determined by the nearly adiabatic dynamics of the Andreev bound states. The nonlinear voltage dependence of the non-equilibrium torque, including the subharmonic gap structure and the high-voltage asymptotics, is attributed to the interplay between multiple Andreev reflections, spin filtering and spin mixing. These properties of spin angular momentum transport may be exploited to control the state of nanomagnets.Comment: 15 pages, 14 figure

Broadcast Strategies with Probabilistic Delivery Guarantee in Multi-Channel Multi-Interface Wireless Mesh Networks

Multi-channel multi-interface Wireless Mesh Networks permit to spread the load across orthogonal channels to improve network capacity. Although broadcast is vital for many layer-3 protocols, proposals for taking advantage of multiple channels mostly focus on unicast transmissions. In this paper, we propose broadcast algorithms that fit any channel and interface assignment strategy. They guarantee that a broadcast packet is delivered with a minimum probability to all neighbors. Our simulations show that the proposed algorithms efficiently limit the overhead

Fold-Saddle Bifurcation in Non-Smooth Vector Fields on the Plane

This paper presents results concerning bifurcations of 2D piecewise-smooth dynamical systems governed by vector fields. Generic three parameter families of a class of Non-Smooth Vector Fields are studied and its bifurcation diagrams are exhibited. Our main result describes the unfolding of the so called Fold-Saddle singularity

Agricultural Credit Interest Rate Equalization Policy: A Growth Subsidy?

The Brazilian Interest Rate Equalization System (IRES) subsidizes farmers by providing them with credit at lower than market interest rates. The objective of this research is to evaluate the IRES by comparing its monetary cost with its benefits as measured by Brazilian GDP growth. Estimates are carried out using input-output matrix. The results suggest that each Brazilian real spent by IRES to assist Brazilian family farms increases Brazilian GDP by R$1.75 and that each real spent to assist commercial farms increases GDP by R$ 3.57. The IRES is a subsidy that generates economic growth greater than its cost to society.IRES subsidy, growth, input-output matrix, Agricultural Finance, Q18, C67, O40, H81,