Cecilia Lunardini

Physics at a future Neutrino Factory and super-beam facility

The conclusions of the Physics Working Group of the International Scoping Study of a future Neutrino Factory and super-beam facility (the ISS) are presented. The ISS was carried out by the international community between NuFact05, (the 7th International Workshop on Neutrino Factories and Super-beams, Laboratori Nazionali di Frascati, Rome, 21–26 June 2005) and NuFact06 (Ivine, CA, 24–30 August 2006). The physics case for an extensive experimental programme to understand the properties of the neutrino is presented and the role of high-precision measurements of neutrino oscillations within this programme is discussed in detail. The performance of second-generation super-beam experiments, beta-beam facilities and the Neutrino Factory are evaluated and a quantitative comparison of the discovery potential of the three classes of facility is presented. High-precision studies of the properties of the muon are complementary to the study of neutrino oscillations. The Neutrino Factory has the potential to provide extremely intense muon beams and the physics potential of such beams is discussed in the final section of the report.The conclusions of the Physics Working Group of the International Scoping Study of a future Neutrino Factory and super-beam facility (the ISS) are presented. The ISS was carried out by the international community between NuFact05, (the 7th International Workshop on Neutrino Factories and Superbeams, Laboratori Nazionali di Frascati, Rome, June 21-26, 2005) and NuFact06 (Irvine, California, 2430 August 2006). The physics case for an extensive experimental programme to understand the properties of the neutrino is presented and the role of high-precision measurements of neutrino oscillations within this programme is discussed in detail. The performance of second generation super-beam experiments, beta-beam facilities, and the Neutrino Factory are evaluated and a quantitative comparison of the discovery potential of the three classes of facility is presented. High-precision studies of the properties of the muon are complementary to the study of neutrino oscillations. The Neutrino Factory has the potential to provide extremely intense muon beams and the physics potential of such beams is discussed in the final section of the report. The ISS Physics Working Group Editors: S.F. King1, K. Long2, Y. Nagashima3, B.L. Roberts4, and O. Yasuda5.

Cosmological and Astrophysical Neutrino Mass Measurements

Cosmological and astrophysical measurements provide powerful constraints on neutrino masses complementary to those from accelerators and reactors. Here we provide a guide to these different probes, for each explaining its physical basis, underlying assumptions, current and future reach.

Probing the neutrino mass hierarchy and the 13-mixing with supernovae

We consider in details the effects of the 13-mixing (sin^2 theta_{13}) and of the type of mass hierarchy/ordering (sign[ Delta m^2_{13}]) on neutrino signals from the gravitational collapses of stars. The observables (characteristics of the energy spectra of nu_e and antinu_e events) sensitive to sin^2 theta_{13} and sign[Delta m^2_{13}] have been calculated. They include the ratio of average energies of the spectra, r_E =/<\bar E>, the ratio of widths of the energy distributions, r_Gamma, the ratios of total numbers of nu_e and antinu_e events at low energies, S, and in the high energy tails, R_{tail}. We construct and analyze scatter plots which show the predictions for the observables for different intervals of sin^2 theta_{13} and signs of Delta m^2_{13}, taking into account uncertainties in the original neutrino spectra, the star density profile, etc.. Regions in the space of observables r_E, r_Gamma, S, R_{tail} exist in which certain mass hierarchy and intervals of sin^2 theta_{13} can be identified or discriminated. We elaborate on the method of the high energy tails in the spectra of events. The conditions are formulated for which sin^2 theta_{13} can be (i) measured, (ii) restricted from below, (iii) restricted from above. We comment on the possibility to determine sin^2 theta_{13} using the time dependence of the signals due to the propagation of the shock wave through the resonance layers of the star. We show that the appearance of the delayed Earth matter effect in one of the channels (nu_e or antinu_e) in combination with the undelayed effect in the other channel will allow to identify the shock wave appeareance and determine the mass hierarchy.We consider in detail the effects of the 13-mixing (sin2?13) and of the type of mass hierarchy/ordering (sign[?m213]) on neutrino signals from the gravitational collapses of stars. The observables (characteristics of the energy spectra of ?e and e events) sensitive to sin2?13 and sign[?m213] have been calculated. They include the ratio of average energies of the spectra, rE?E/?, the ratio of widths of the energy distributions, r???/, the ratios of total numbers of ?e and e events at low energies, S, and in the high energy tails, Rtail. We construct and analyse scatter plots which show the predictions for the observables for different intervals of sin2?13 and signs of ?m213, taking into account uncertainties in the original neutrino spectra, the star density profile, etc. Regions in the space of observables rE, r?, S, Rtail exist in which certain mass hierarchy and intervals of sin2?13 can be identified or discriminated. We elaborate on the method of the high energy tails in the spectra of events. The conditions are formulated for which sin2?13 can be (i) measured, (ii) restricted from below, (iii) restricted from above. We comment on the possibility to determine sin2?13 using the time dependence of the signals due to the propagation of the shock wave through the resonance layers of the star. We show that the appearance of the delayed Earth matter effect in one of the channels (?e or e) in combination with the undelayed effect in the other channel will allow us to identify the shock wave appeareance and determine the mass hierarchy.

Supernova neutrinos: Earth matter effects and neutrino mass spectrum

We perform a detailed study of the Earth matter effects on supernova neutrinos. The dependences of these effects on the properties of the original neutrino fluxes, on the trajectory of the neutrinos inside the Earth and on the oscillation parameters are described. We show that, for a large fraction (60 %) of the possible arrival times of the signal, the neutrino flux crosses a substantial amount of the matter of the Earth at least for one of the existing detectors. For oscillation parameters from the LMA solution of the solar neutrino problem the Earth matter effect consists in an oscillatory modulation of the

Atmospheric neutrinos as probes of neutrino-matter interactions

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Large-angle Bhabha scattering and luminosity at flavour factories

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High-energy neutrino conversion and the lepton asymmetry in the universe

\nu_e

Neutrino events at IceCube and the Fermi bubbles

energy spectra. The relative deviation with respect to the undistorted spectra can be as large as 20-30 % for E>20 MeV and 70-100 % for E>40 MeV. For parameters from the SMA and LOW solutions the effect is localized at low energies (E<10 MeV) and is not larger than 10 %. The Earth matter effects can be revealed (i) by the observation of oscillatory distortions of the energy spectra in a single experiment and (ii) by the comparison between the spectra at different detectors. For a supernova at distance D=10 Kpc, comparing the results of SuperKamiokande (SK), SNO and LVD experiments one can establish the effect at (2-3) \sigma level, whereas larger statistical significance ((4-5) \sigma) is obtained if two experiments of SK-size or larger are available. Studies of the Earth matter effect will select or confirm the solution of the solar neutrino problem, probe the mixing U_{e 3} and identify the hierarchy of the neutrino mass spectrum.We perform a detailed study of the Earth matter effects on supernova neutrinos. The dependences of these effects on the properties of the original neutrino fluxes, on the trajectory of the neutrinos inside the Earth and on the oscillation parameters are described. We show that, for a large fraction (60 %) of the possible arrival times of the signal, the neutrino flux crosses a substantial amount of the matter of the Earth at least for one of the existing detectors. For oscillation parameters from the LMA solution of the solar neutrino problem the Earth matter effect consists in an oscillatory modulation of the

Fast time variations of supernova neutrino fluxes and their detectability

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Two modes of searching for new neutrino interactions at MINOS

and/or