arXiv subjects

Enrique Fernandez-Martinez

Publications and source records attributed to Enrique Fernandez-Martinez.

42 records · Page 3Linked to original sources

arXiv2009

Probing non-unitary mixing and CP-violation at a Neutrino Factory

A low energy non-unitary leptonic mixing matrix is a generic feature of many extensions of the Standard Model. In such a case, the task of future precision neutrino oscillation experiments is more ambitious than measuring the three mixing angles and the leptonic (Dirac) CP-phase, i.e., the accessible parameters of a unitary leptonic mixing matrix. A non-unitary mixing matrix has 13 parameters that affect neutrino oscillations, out of which four are CP-violating. In the scheme of Minimal Unitarity Violation (MUV) we analyse the potential of a Neutrino Factory for determining or constraining the parameters of the non-unitary leptonic mixing matrix, thereby testing the origin of CP-violation in the lepton sector.

hep-ph↗

arXiv2009

Loop bounds on non-standard neutrino interactions

We reconsider the bounds on non-standard neutrino interactions with matter which can be derived by constraining the four-charged-lepton operators induced at the loop level. We find that these bounds are model dependent. Naturalness arguments can lead to much stronger constraints than those presented in previous studies, while no completely model-independent bounds can be derived. We will illustrate how large loop-contributions to four-charged-lepton operators are induced within a particular model that realizes gauge invariant non-standard interactions and discuss conditions to avoid these bounds. These considerations mainly affect the $\mathcal O(10^{-4})$ constraint on the non-standard coupling strength $\eps_{eμ}$, which is lost. The only model-independent constraints that can be derived are $\mathcal O(10^{-1})$. However, significant cancellations are required in order to saturate this bound.

hep-ph↗

arXiv2008

Non-Standard Neutrino Interactions with Matter from Physics Beyond the Standard Model

We investigate how non-standard neutrino interactions (NSIs) with matter can be generated by new physics beyond the Standard Model (SM) and analyse the constraints on the NSIs in these SM extensions. We focus on tree-level realisations of lepton number conserving dimension 6 and 8 operators which do not induce new interactions of four charged fermions (since these are already quite constrained) and discard the possibility of cancellations between diagrams with different messenger particles to circumvent experimental constraints. The cases studied include classes of dimension 8 operators which are often referred to as examples for ways to generate large NSIs with matter. We find that, in the considered scenarios, the NSIs with matter are considerably more constrained than often assumed in phenomenological studies, at least ${\cal O}(10^{-2})$. The constraints on the flavour-conserving NSIs turn out to be even stronger than the ones for operators which also produce interactions of four charged fermions at the same level. Furthermore, we find that in all studied cases the generation of NSIs with matter also gives rise to NSIs at the source and/or detector of a possible future Neutrino Factory.

hep-ph↗

arXiv2008

Prospects in Constraining the Dark Energy Potential

We generalize to non-flat geometries the formalism of Simon et al. (2005) to reconstruct the dark energy potential. This formalism makes use of quantities similar to the Horizon-flow parameters in inflation, can, in principle, be made non-parametric and is general enough to be applied outside the simple, single scalar field quintessence. Since presently available and forthcoming data do not allow a non-parametric and exact reconstruction of the potential, we consider a general parametric description in term of Chebyshev polynomials. We then consider present and future measurements of H(z), Baryon Acoustic Oscillations surveys and Supernovae type 1A surveys, and investigate their constraints on the dark energy potential. We find that, relaxing the flatness assumption increases the errors on the reconstructed dark energy evolution but does not open up significant degeneracies, provided that a modest prior on geometry is imposed. Direct measurements of H(z), such as those provided by BAO surveys, are crucially important to constrain the evolution of the dark energy potential and the dark energy equation of state, especially for non-trivial deviations from the standard LambdaCDM model.

astro-ph↗

arXiv2008

$θ_{13}$, $δ$ and the neutrino mass hierarchy at a $γ=350$ double baseline Li/B $β$-Beam

We consider a $β$-Beam facility where $^8$Li and $^8$B ions are accelerated at $γ= 350$, accumulated in a 10 Km storage ring and let decay, so as to produce intense $\bar ν_e$ and $ν_e$ beams. These beams illuminate two iron detectors located at $L \simeq 2000$ Km and $L \simeq 7000$ Km, respectively. The physics potential of this setup is analysed in full detail as a function of the flux. We find that, for the highest flux ($10 \times 10^{18}$ ion decays per year per baseline), the sensitivity to $θ_{13}$ reaches $\sin^2 2 θ_{13} \geq 2 \times10^{-4}$; the sign of the atmospheric mass difference can be identified, regardless of the true hierarchy, for $\sin^2 2 θ_{13} \geq 4\times10^{-4}$; and, CP-violation can be discovered in 70% of the $δ$-parameter space for $\sin^2 2 θ_{13} \geq 10^{-3}$, having some sensitivity to CP-violation down to $\sin^2 2 θ_{13} \geq 10^{-4}$ for $|δ| \sim 90^\circ$.

hep-ph↗

arXiv2003

New encoding schemes for quantum authentication

We study the potential of general quantum operations, Trace-Preserving Completely-Positive Maps (TPCPs), as encoding and decoding mechanisms in quantum authentication protocols. The study shows that these general operations do not offer significant advantage over unitary encodings. We also propose a practical authentication protocol based on the use of two successive unitary encodings.

quant-ph↗