Search results for "NAK"
showing 10 items of 469 documents
CP Violation in the SUSY Seesaw: Leptogenesis and Low Energy
2008
We suppose that the baryon asymmetry is produced by thermal leptogenesis (with flavour effects), at temperatures $\sim 10^{9} - 10^{10}$ GeV, in the supersymmetric seesaw with universal and real soft terms. The parameter space is restricted by assuming that $l_\alpha \to l_\beta \gamma$ processes will be seen in upcoming experiments. We study the sensitivity of the baryon asymmetry to the phases of the lepton mixing matrix, and find that leptogenesis can work for any value of the phases. We also estimate the contribution to the electric dipole moment of the electron, arising from the seesaw, and find that it is (just) beyond the sensitivity of next generation experiments ($\lsim 10^{-29} e$…
Lepton Flavor Violation and non-unitarity Lepton Mixing in Low-Scale Type-I Seesaw
2011
Within low-scale seesaw mechanisms, such as the inverse and linear seesaw, one expects (i) potentially large lepton flavor violation (LFV) and (ii) sizeable non-standard neutrino interactions (NSI). We consider the interplay between the magnitude of non-unitarity effects in the lepton mixing matrix, and the constraints that follow from LFV searches in the laboratory. We find that NSI parameters can be sizeable, up to percent level in some cases, while LFV rates, such as that for \mu -> e \gamma, lie within current limits, including the recent one set by the MEG collaboration. As a result the upcoming long baseline neutrino experiments offer a window of opportunity for complementary LFV and …
Neutrino mass hierarchy and Majorana CP phases within the Higgs triplet model at the LHC
2007
Neutrino masses may be generated by the VEV of an $SU(2)_L$ Higgs triplet. We assume that the doubly charged component of such a triplet has a mass in the range of several 100 GeV, such that it is accessible at LHC. Its decay into like-sign leptons provides a clean experimental signature, which allows for a direct test of the neutrino mass matrix. By exploring the branching ratios of this decay into leptons of various flavours, we show that within this model the type of the neutrino mass spectrum (normal, inverted or quasi-degenerate) might actually be resolved at the LHC. Furthermore, we show that within the Higgs triplet model for neutrino mass the decays of the doubly charged scalar into…
A large magnetic detector for the neutrino factory
2000
Abstract The physics opportunities of the neutrino factory have been the subject of a number of recent studies. It was shown that sensitive measurements of the angle θ 13 , of MSW effects, and of the sign of the atmospheric mass difference Δ m 23 2 are possible, and even CP violation in the neutrino mixing matrix may be within reach. The focus of interest is the oscillation ν e →ν μ , which leads in the well-defined neutrino beam of the neutrino factory to ‘wrong-sign’ muon events. In this paper, we show that a large magnetic detector will be capable of detecting with high efficiency and small backgrounds such wrong-sign muon events. We present a conceptual design of the apparatus and its p…
CP violation and neutrino oscillations
2007
We review the basic mechanisms of neutrino mass generation and the corresponding structure of the lepton mixing matrix. We summarize the status of three-neutrino oscillation parameters as determined from current observations, using state-of-the-art solar and atmospheric neutrino fluxes, as well as latest experimental data as of September 2007. We also comment on recent attempts to account for these results and to understand flavour from first principles. We discuss extensively the prospects for probing the strength of CP violation in two near term accelerator neutrino oscillation experiments, T2K and NOvA, as well as possible extensions such as T2KK and a second large off-axis detector near…
Symmetrical Parametrizations of the Lepton Mixing Matrix
2011
Advantages of the original symmetrical form of the parametrization of the lepton mixing matrix are discussed. It provides a conceptually more transparent description of neutrino oscillations and lepton number violating processes like neutrinoless double beta decay, clarifying the significance of Dirac and Majorana phases. It is also ideal for parametrizing scenarios with light sterile neutrinos.
On the description of non-unitary neutrino mixing
2015
28 pages.- 8 figures.- typos corrected.- modified bounds on non-unitarity parameters.- new figs 3 and 4
Neutrino oscillations from warped flavor symmetry: predictions for long baseline experiments T2K, NOvA and DUNE
2016
Here we study the pattern of neutrino oscillations emerging from a previously proposed warped model construction incorporating $\Delta(27)$ flavor symmetry. In addition to a complete description of fermion masses, the model predicts the lepton mixing matrix in terms of two parameters. The good measurement of $\theta_{13}$ makes these two parameters nearly proportional, leading to an approximate one-parameter description of neutrino oscillations. There is a sharp fourfold degenerate correlation between $\delta_{CP}$ and the atmospheric mixing angle $\theta_{23}$, so that maximal $\theta_{23}$ also implies maximal leptonic CP violation. The predicted electron neutrino and anti-neutrino appear…
Classifying CP transformations according to their texture zeros: theory and implications
2016
We provide a classification of generalized CP symmetries preserved by the neutrino mass matrix according to the number of zero entries in the associated transformation matrix. We determine the corresponding constrained form of the lepton mixing matrix, characterized by correlations between the mixing angles and the CP violating phases. We compare with the corresponding restrictions from current neutrino oscillation global fits and show that, in some cases, the Dirac CP phase characterizing oscillations is highly constrained. Implications for current and upcoming long baseline neutrino oscillation experiments T2K, NO$\nu$A and DUNE, as well as neutrinoless double beta decay experiments are d…
Search for heavy neutrinos in \(\pi ^{ + } \to \mu ^{ + }\nu \) decay and status of lepton universality test in the PIENU experiment
2019
International audience; In the present work of the PIENU experiment, heavy neutrinos were sought in pion decays \(\pi ^{ + } \to \mu ^{ + }\nu \). No evidence for extra peak was found in the muon kinetic energy spectrum and 90% confidence level upper limits were set on the neutrino mixing matrix \(|U_{\mu i}|^{2}\) in the mass range of 15.7 to 33.8 MeV/c^2, improving an order of magnitude over previous experiments. Current status of lepton universality test is also reported.