Exploring New Physics from nu_tau events in OPERA

We analyze in details the impact of the $10$ $\nu_\tau$ events seen in the OPERA experiment in constraining the Non Standard Interaction parameter $\varepsilon_{\mu\tau}$ affecting neutrino propagation in matter and the allowed parameter space of models with one sterile neutrino of the $3+1$ type.Comment: 11 pages, 9 figures, paper accepted for publication in Physics Letters

GUT and flavor models for neutrino masses and mixing

In the recent years neutrino experiments have studied in detail the phenomenon of neutrino oscillations and most of the oscillation parameters have been measured with a good accuracy. However, in spite of many interesting ideas, the problem of flavor in the lepton sector remains an open issue. In this review, we discuss the state of the art of models for neutrino masses and mixings formulated in the context of flavor symmetries, with particular emphasis on the role played by grand unified gauge groups.Comment: Added new reference

TeV gravity at neutrino telescopes

Cosmogenic neutrinos reach the Earth with energies around 10^9 GeV, and their interactions with matter will be measured in upcoming experiments (Auger, IceCube). Models with extra dimensions and the fundamental scale at the TeV could imply signals in these experiments. In particular, the production of microscopic black holes by cosmogenic neutrinos has been extensively studied in the literature. Here we make a complete analysis of gravity-mediated interactions at larger distances, where they can be calculated in the eikonal approximation. In these processes a neutrino of energy E_\nu interacts elastically with a parton inside a nucleon, loses a small fraction y of its energy, and starts a hadronic shower of energy y E_\nu << E_\nu. We analyze the ultraviolet dependence and the relevance of graviton emission in these processes, and show that they are negligible. We also study the energy distribution of cosmogenic events in AMANDA and IceCube and the possibility of multiple-bang events. For any neutrino flux, the observation of an enhanced rate of neutral current events above 100 TeV in neutrino telescopes could be explained by TeV-gravity interactions. The values of the fundamental scale of gravity that IceCube could reach are comparable to those to be explored at the LHC.Comment: 10 pages, 7 figures; new section on air showers added, version to be publishe

Random Access in DVB-RCS2: Design and Dynamic Control for Congestion Avoidance

In the current DVB generation, satellite terminals are expected to be interactive and capable of transmission in the return channel with satisfying quality. Considering the bursty nature of their traffic and the long propagation delay, the use of a random access technique is a viable solution for such a Medium Access Control (MAC) scenario. In this paper, random access communication design in DVB-RCS2 is considered with particular regard to the recently introduced Contention Resolution Diversity Slotted Aloha (CRDSA) technique. This paper presents a model for design and tackles some issues on performance evaluation of the system by giving intuitive and effective tools. Moreover, dynamic control procedures that are able to avoid congestion at the gateway are introduced. Results show the advantages brought by CRDSA to DVB-RCS2 with regard to the previous state of the art.Comment: Accepted for publication: IEEE Transactions on Broadcasting; IEEE Transactions on Broadcasting, 201

Constraining new physics scenarios in neutrino oscillations from Daya Bay data

We perform for the first time a detailed fit to the $\bar \nu_e \to \bar \nu_e$ disappearance data of the Daya Bay experiment to constrain the parameter space of models where sterile neutrinos can propagate in a large compactified extra dimension (LED) and models where non-standard interactions affect the neutrino production and detection (NSI). We find that the compactification radius $R$ in LED scenarios can be constrained at the level of $0.57 \, \mu m$ for normal ordering and of $0.19\, \mu m$ for inverted ordering, at 2$\sigma$ confidence level. For the NSI model, reactor data put a strong upper bound on the parameter $\varepsilon_{ee}$ at the level of $\sim 10^{-3}$, whereas the main effect of $\varepsilon_{e\mu}$ and $\varepsilon_{e\tau}$ is a worsening of the determination of $\theta_{13}$.Comment: 5 pages, 2 figure

Physical Reach of a Neutrino Factory in the 2+2 and 3+1 Four-Family Scenario

We compare the physical reach of a Neutrino Factory in the 2+2 and 3+1 four-family models, with similar results in the two schemes; in both cases huge CP-violating effects can be observed with a near detector in the $\nu_\mu \to \nu_\tau$ channel. We also study the capability of long baseline experiments (optimized for the study of the three-family mixing parameter space) in distinguishing a three (active) neutrino model from a four-family scenario.Comment: 5 latex2e pages, 2 figures; talk given at NuFact '01, Tsukuba, 24-30 May 200

Neutrino flux ratios at neutrino telescopes: The role of uncertainties of neutrino mixing parameters and applications to neutrino decay

In this paper, we derive simple and general perturbative formulas for the flavor flux ratios $R_{\alpha\beta}=\phi_{\nu_\alpha}/\phi_{\nu_\beta}$ that could be measured at neutrino telescopes. We discuss in detail the role of the uncertainties of the neutrino mixing parameters showing that they have to be seriously taken into account in any realistic discussion about flavor measurements at neutrino telescopes. In addition, we analyze the impact of such uncertainties in telling the standard neutrino oscillation framework from scenarios involving, e.g., neutrino decay and we find that the ratio $R_{e\mu}$ is the most sensitive one to "new physics" effects beyond the Standard Model. We also compute the more realistic muon-to-shower ratio for a particular configuration of the IceCube experiment, observing that using this experimental quantity a clear separation between standard and non-standard neutrino physics cannot be obtained.Comment: 21 pages, 7 figures, LaTeX. Final version published in Phys. Rev.