Slepton mass splittings and cLFV in the SUSY seesaw in the light of recent experimental results

Following recent experimental developments, in this study we re-evaluate if the interplay of high- and low-energy lepton flavour violating observables remains a viable probe to test the high-scale type-I supersymmetric seesaw. Our analysis shows that fully constrained supersymmetric scenarios no longer allow to explore this interplay, since recent LHC data precludes the possibility of having sizeable slepton mass differences for a slepton spectrum sufficiently light to be produced, and in association to BR(mu -> e gamma) within experimental reach. However, relaxing the strict universality of supersymmetric soft-breaking terms, and fully exploring heavy neutrino dynamics, still allows to have slepton mass splittings O(few %), for slepton masses accessible at the LHC, with associated mu -> e gamma rates within future sensitivity. For these scenarios, we illustrate how the correlation between high- and low-energy lepton flavour violating observables allows to probe the high-scale supersymmetric seesaw.Comment: 19 pages, 12 eps figures. References updated; matches version accepted by JHE

Linear Invariant Systems Theory for Signal Enhancement

This paper discusses a linear time invariant (LTI) systems approach to signal enhancement via projective subspace techniques. It provides closed form expressions for the frequency response of data adaptive finite impulse response eigenfilters. An illustrative example using speech enhancement is also presented.Este artigo apresenta a aplicação da teoria de sistemas lineares invariantes no tempo (LTI) na análise de técnicas de sub-espaço. A resposta em frequência dos filtros resultantes da decomposição em valores singulares é obtida aplicando as propriedades dos sistemas LTI

Lepton flavour violation: physics potential of a Linear Collider

We revisit the potential of a Linear Collider concerning the study of lepton flavour violation, in view of new LHC bounds and of the (very) recent developments in lepton physics. Working in the framework of a type I supersymmetric seesaw, we evaluate the prospects of observing seesaw-induced lepton flavour violating final states of the type e \mu + missing energy, arising from e+ e- and e- e- collisions. In both cases we address the potential background from standard model and supersymmetric charged currents. We also explore the possibility of electron and positron beam polarisation. The statistical significance of the signal, even in the absence of kinematical and/or detector cuts, renders the observation of such flavour violating events feasible over large regions of the parameter space. We further consider the \mu-\mu- + E^T_miss final state in the e- e- beam option finding that, due to a very suppressed background, this process turns out to be a truly clear probe of a supersymmetric seesaw, assuming the latter to be the unique source of lepton flavour violation.Comment: 30 pages, 48 figure

Potential of a Linear Collider for Lepton Flavour Violation studies in the SUSY seesaw

We study the potential of an e+- e- Linear Collider for charged lepton flavour violation studies in a supersymmetric framework where neutrino masses and mixings are explained by a type-I seesaw. Focusing on e-mu flavour transitions, we evaluate the background from standard model and supersymmetric charged currents to the e mu + missing E_T signal. We study the energy dependence of both signal and background, and the effect of beam polarisation in increasing the signal over background significance. Finally, we consider the mu- mu- + missing E_T final state in e- e- collisions that, despite being signal suppressed by requiring two e-mu flavour transitions, is found to be a clear signature of charged lepton flavour violation due to a very reduced standard model background.Comment: 8 pages, 5 figures. To appear in the proceedings of "DISCRETE 2012 - 3rd Symposium on Prospects in the Physics of Discrete Symmetries", Lisbon, Portugal, 3-7 December 201

Phenomenology of LFV at low-energies and at the LHC: strategies to probe the SUSY seesaw

We study the impact of a type-I SUSY seesaw concerning lepton flavour violation (LFV) at low-energies and at the LHC. At the LHC, $\chi_2^0\to \tilde \ell \,\ell \to \ell \,\ell\,\chi_1^0$ decays, in combination with other observables, render feasible the reconstruction of the masses of the intermediate sleptons, and hence the study of $\ell_i - \ell_j$ mass differences. If interpreted as being due to the violation of lepton flavour, high-energy observables, such as large slepton mass splittings and flavour violating neutralino and slepton decays, are expected to be accompanied by low-energy manifestations of LFV such as radiative and three-body lepton decays. We discuss how to devise strategies based in the interplay of slepton mass splittings as might be observed at the LHC and low-energy LFV observables to derive important information on the underlying mechanism of LFV.Comment: 6 pages, 4 figures. To appear in the proceedings of the 11th International Workshop on Tau Lepton Physics (TAU2010), Manchester, UK, 13-17 September 201

F-threshold functions: syzygy gap fractals and the two-variable homogeneous case

In this article we study F-pure thresholds (and, more generally, F-thresholds) of homogeneous polynomials in two variables over a field of characteristic p>0. Passing to a field extension, we factor such a polynomial into a product of powers of pairwise prime linear forms, and to this collection of linear forms we associate a special type of function called a syzygy gap fractal. We use this syzygy gap fractal to study, at once, the collection of all F-pure thresholds of all polynomials constructed with the same fixed linear forms. This allows us to describe the structure of the denominator of such an F-pure threshold, showing in particular that whenever the F-pure threshold differs from its expected value its denominator is a multiple of p. This answers a question of Schwede in the two-variable homogeneous case. In addition, our methods give an algorithm to compute F-pure thresholds of homogenous polynomials in two variables.Comment: 42 pages; 6 figures. Section 6 was mostly rewritten; a new appendix was included; other smaller changes throughout. Comments welcom