Papers by Isabella Masina
The European Physical Journal Plus
We consider light dark matter candidates originated from the evaporation of Schwarzschild primord... more We consider light dark matter candidates originated from the evaporation of Schwarzschild primordial black holes, with masses in the range $$10^{-5}$$ 10 - 5 –$$10^9$$ 10 9 g. These candidates are beyond standard model particles with negligible couplings to the other particles, so that they interact only gravitationally. Belonging to the category of warm dark matter, they nevertheless spoil structure formation, with a softer impact for increasing values of the candidate spin. Requiring such candidates to fully account for the observed dark matter, we find that the scenario of black hole domination is ruled out for all spin values up to 2. For the scenario of radiation domination, we derive upper limits on the parameter $$\beta $$ β (the primordial black hole energy density at formation over the radiation one), which are less stringent the higher the candidate spin is.
The European Physical Journal Plus
Physical Review D
We consider critical Higgs inflation, namely Higgs inflation with a rising inflection point at sm... more We consider critical Higgs inflation, namely Higgs inflation with a rising inflection point at smaller field values than those of the plateau induced by the non-minimal coupling to gravity. It has been proposed that such configuration is compatible with the present CMB observational constraints on inflation, and also with primordial black hole production accounting for the totality or a fraction of the observed dark matter. We study the model taking into account the NNLO corrections to the Higgs effective potential: such corrections are extremely important to reduce the theoretical error associated to the calculation. We find that, in the 3 σ window for the relevant low energy parameters, which are the strong coupling and the Higgs mass (the top mass follows by requiring an inflection point), the potential at the inflection point is so large (and so is the Hubble constant during inflation) that the present bound on the tensor-to-scalar ratio is violated. The model is viable only allowing the strong coupling to take its upper 3 − 4 σ value. In our opinion, this tension shows that the model of critical Higgs inflation is likely to be not viable: neither inflation nor black holes as dark matter can be originated in this version of the model.
We discuss the possibility of discriminating between different supersymmetric see-saw models by i... more We discuss the possibility of discriminating between different supersymmetric see-saw models by improving the experimental sensitivity to charged lepton flavour violating processes. Assuming a hierarchical neutrino mass spectrum, we classify realistic see-saw models according to how the hierarchy Delta m^2_{sun} << Delta m^2_{atm} is generated, and study the predictions of each class for the branching ratios of tau -> mu gamma and mu -> e gamma. The process tau -> mu gamma is found to be a particularly promising tool to probe the fundamental see-saw parameters, and especially to identify the origin of the large atmospheric mixing angle. Predictions for mu -> e gamma are more model-dependent. We point out that, even with an improvement of the experimental sensitivities by three orders of magnitude, both tau -> mu gamma and mu -> e gamma could escape detection in models where Delta m^2_{atm} is determined by one of the lightest right-handed neutrinos. Comment: ...
Towards New Milestones in Our Quest to Go Beyond the Standard Model, 2007
ABSTRACT After a brief summary about fermion masses and mixings, I will introduce the seesaw mech... more ABSTRACT After a brief summary about fermion masses and mixings, I will introduce the seesaw mechanism, digree on the difficulties found in constructing viable models of flavor, and conclude by addressing a couple of phenomenological aspects associated with the seesaw.
After a summary of the motivations for searching flavour violating decays and electric dipole mom... more After a summary of the motivations for searching flavour violating decays and electric dipole moments in the leptonic sector, I briefly sketch the present status of the limits on lepton-slepton misalignement and discuss the potentialities of the planned experimental improvements. Candidates for theories beyond the Standard Model have to satisfy all these experimental constraints; I will discuss in particular how the supersymmetric SM extended with the seesaw faces the flavour problem.
Physics Letters B, 2006
We point out an elegant mechanism to predict a maximal atmospheric angle, which is based on a max... more We point out an elegant mechanism to predict a maximal atmospheric angle, which is based on a maximal CP violating phase difference between second and third lepton families in the flavour symmetry basis. In this framework, a discussion of the general formulas for θ 12 , |U e3 |, δ and their possible correlations in some limiting cases is provided. We also present an explicit realisation in terms of an SO(3) flavour symmetry model.
Physical Review D, 2011
We introduce new sum rules allowing to determine universal properties of the unknown component of... more We introduce new sum rules allowing to determine universal properties of the unknown component of the cosmic rays and show how it can be used to predict the positron fraction at energies not yet explored by current experiments and to constrain specific models.
Nuclear Physics B - Proceedings Supplements, 2013
The measurements of the Higgs boson and top quark masses can be used to extrapolate the Standard ... more The measurements of the Higgs boson and top quark masses can be used to extrapolate the Standard Model Higgs potential at energies up to the Planck scale. Adopting a NNLO renormalization procedure, we: i) find that electroweak vacuum stability is at present allowed, discuss the associated theoretical and experimental errors and the prospects for its future tests; ii) determine the boundary conditions allowing for the existence of a shallow false minimum slightly below the Planck scale, which is a stable configuration that might have been relevant for primordial inflation; iii) derive a conservative upper bound on type I seesaw right-handed neutrino masses, following from the requirement of electroweak vacuum stability.
I introduce and sketch the main features of those see-saw models where a large atmospheric mixing... more I introduce and sketch the main features of those see-saw models where a large atmospheric mixing can be achieved starting from nearly diagonal matrices for charged leptons, Dirac neutrinos and Majorana right-handed neutrinos. It turns out that these models can be realized in Grand Unified Theories and they are well compatible with the related phenomenology of fermion masses and mixings.
Journal of Physics: Conference Series, 2011
We combine the data from PAMELA and FERMI-LAT cosmic ray experiments by introducing a simple sum ... more We combine the data from PAMELA and FERMI-LAT cosmic ray experiments by introducing a simple sum rule. This allows to investigate whether the lepton excess observed by these experiments is charge symmetric or not. We also show how the data can be used to predict the positron fraction at energies yet to be explored by the AMS-02 experiment.
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Papers by Isabella Masina