A Novel Kind of Neutrino Oscillation Experiment

A novel method to look for neutrino oscillations is proposed based on the elastic scattering process $\bar{\nu}_{i} e^{-}\rightarrow \bar{\nu}_{i} e^{-}$, taking advantage of the dynamical zero present in the differential cross section for $\bar{\nu}_{e} e^{-}\rightarrow \bar{\nu}_{e} e^{-}$. An effective tunable experiment between the "appearance" and "disappearance" limits is made possible. Prospects to exclude the allowed region for atmospheric neutrino oscillations are given.Comment: 11 pages (+3 figures, available upon request),Standard Latex, FTUV/94-3

Tau EDM at Low Energies

Low energy tau pair production, at B factories and on top of the $\Upsilon$ resonances, allows for a detailed investigation on the CP violation at the electromagnetic tau pair production vertex. High statistic available at low energies offers the opportunity for an independent analysis of CP-violation in the $\tau$ lepton physics. We show that stringent and independent bounds on the $\tau$ electric dipole moment, competitive with the high energy measurements, can be established in low energies experiments.Comment: Talk at the Seventh International Workshop on Tau Lepton Physics (TAU02), Santa Cruz, Ca, USA, Sept 2002, 5 pages, LaTeX, 1 eps figur

Electric polarizability of nuclei from a longitudinal sum rule

The nuclear electric polarizability is theoretically analyzed using a sum rule derived from the longitudinal part of the forward Compton amplitude. Beyond the leading dipole contribution, this approach leads to the presence of potential-dependent terms that do not show up in previous analyses. The significance of these new contributions is illustrated by performing an explicit calculation for a proton-neutron system interacting via a separable potential.Comment: 9 pages, revtex. Minor changes, two references added. To appear in Nucl. Phys.

Universality-Breaking Effects in Leptonic Z Decays

We analyze the possibility of universality violation in diagonal leptonic decays of the $Z$ boson, in the context of interfamily "see-saw" models. In a minimal extension of the Standard Model with right-handed neutrino fields, we find that universality-breaking effects increase quadratically with the heavy Majorana neutrino mass and may be observed in the running $LEP$ experiments.Comment: MZ-TH/93-04 #, LaTeX, 14 p. (2 Figs

WEAK DIPOLE MOMENTS AT e+e−{\bf e^+e^-} COLLIDERS

The weak dipole moments of leptons and quarks, \ie those related to their $Z$--coupling, are reviewed. Standard Model predictions and experimental results may result in a stringent test for both their pointlike structure and also for the Standard Model. Special attention is devoted to the anomalous weak--magnetic dipole moment and to the $CP$--violating weak--electric dipole moment.Comment: Latex file and 2 figures included in an uucoded compressed postscript file. To appear in the proceedings of the Ringberg Workshop on "Perspectives for electroweak interactions in $e^+e^-$ collisions" hosted by the Max Planck Institut, at the Ringberg Castle, M\"unich, February 5-8, 1995. Edited by B. Knieh

An XMM-Newton view of FeK{\alpha} in HMXBs

We present a comprehensive analysis of the whole sample of available XMM-Newton observations of High Mass X-ray Binaries (HMXBs) until August, 2013, focusing on the FeK{\alpha} emission line. This line is a key tool to better understand the physical properties of the material surrounding the X-ray source within a few stellar radii (the circumstellar medium). We have collected observations from 46 HMXBs, detecting FeK{\alpha} in 21 of them. We have used the standard classification of HMXBs to divide the sample in different groups. We find that: (1) FeK{\alpha} is centred at a mean value of 6.42 keV. Considering the instrumental and fits uncertainties, this value is compatible with ionization states lower than FeXVIII. (2) The flux of the continuum is well correlated with the flux of the line, as expected. Eclipse observations show that the Fe fluorescence emission comes from an extended region surrounding the X-ray source. (3) FeK{\alpha} is narrow (width lower than 0.15keV), reflecting that the reprocessing material does not move at high speeds. We attempt to explain the broadness of the line in terms of three possible broadening phenomena: line blending, Compton scattering and Doppler shifts (with velocities of the reprocessing material V=1000-2000 km/s). (4) The equivalent hydrogen column (NH) directly correlates with the EW of FeK{\alpha}, displaying clear similarities to numerical simulations. It highlights the strong link between the absorbing and the fluorescent matter. The obtained results clearly point to a very important contribution of the donors wind in the FeK{\alpha} emission and the absorption when the donor is a supergiant massive star.Comment: Accepted for publication in A&A. 13 pages, 16 figures + Appendice

Time Reversal Violation from the entangled B0-antiB0 system

We discuss the concepts and methodology to implement an experiment probing directly Time Reversal (T) non-invariance, without any experimental connection to CP violation, by the exchange of "in" and "out" states. The idea relies on the B0-antiB0 entanglement and decay time information available at B factories. The flavor or CP tag of the state of the still living neutral meson by the first decay of its orthogonal partner overcomes the problem of irreversibility for unstable systems, which prevents direct tests of T with incoherent particle states. T violation in the time evolution between the two decays means experimentally a difference between the intensities for the time-ordered (l^+ X, J/psi K_S) and (J/psi K_L, l^- X) decays, and three other independent asymmetries. The proposed strategy has been applied to simulated data samples of similar size and features to those currently available, from which we estimate the significance of the expected discovery to reach many standard deviations.Comment: 17 pages, 2 figures, 6 table