2,240 research outputs found

    Chern-simon type photon mass from fermion electric dipole moments at finite temperature in 3+1 dimensions

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    We study the low energy effective field theory of fermions with electric and magnetic dipole moments at finite temperature. We find that at one loop there is an interaction term of the Chern-Simon form LI=mμAνF~μν{\cal L_I}=m_\mu\>A_\nu {\tilde F}^{\mu\nu}. The four vector mμdiμimi2 μ(lnT)m_\mu \simeq d_i \mu_i m_i^2 ~{\partial_\mu}\>(ln T) is interpreted as a Chern- Simon type mass of photons, which is determined by the electric (magnetic) dipole moments did_i (μi\mu_i) of the fermions in the vacuum polarisation loop diagram. The physical consequence of such a photon mass is that, photons of opposite circular polarisations, propagating through a hot medium, have different group velocities. We estimate that the time lag between the arrival times of the left and right circularly polarised light signals from pulsars. If the light propagates through a hot plasma (where the temperature in some regions is T100MeVT \sim 100 MeV) then the time lag between the two circularly polarised signals of frequency ω\omega will be Δt(ω)106/ω\Delta t(\omega) \simeq 10^{-6} /\omega. It may be possible to observe this effect in pulsar signals which propagate through nebula at high temperatures.Comment: plain TeX, 9 page

    Imperfect Detectors in Linear Optical Quantum Computers

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    We discuss the effects of imperfect photon detectors suffering from loss and noise on the reliability of linear optical quantum computers. We show that for a given detector efficiency, there is a maximum achievable success probability, and that increasing the number of ancillary photons and detectors used for one controlled sign flip gate beyond a critical point will decrease the probability that the computer will function correctly. We have also performed simulations of some small logic gates and estimate the efficiency and noise levels required for the linear optical quantum computer to function properly.Comment: 13 pages, 5 figure

    Measuring the νμ\nu_{\mu} to νμˉ\bar{\nu_{\mu}} Ratio in a High Statistics Atmospheric Neutrino Experiment

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    By exploiting differences in muon lifetimes it is possible to distinguish νμ\nu_{\mu} from νμˉ\bar{\nu_{\mu}} charged current interactions in underground neutrino detectors. Such observations would be a useful tool in understanding the source of the atmospheric neutrino anomaly.Comment: 6 pages no figure

    A study of atmospheric neutrinos with the IMB detector

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    A sample of 401 contained neutrino interactions collected in the 3300 metric ton fiducial mass IMB detector was used to study neutrino oscillations, geomagnetic modulation of the flux and to search for point sources. The majority of these events are attributed to neutrino interactions. For the most part, these neutrinos are believed to originate as tertiary products of cosmic ray interactions in the atmosphere. The neutrinos are a mixture of v sub e and v sub micron