2,240 research outputs found

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

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 ${\cal L_I}=m_\mu\>A_\nu {\tilde
F}^{\mu\nu}$. The four vector $m_\mu \simeq d_i \mu_i m_i^2
~{\partial_\mu}\>(ln T)$ is interpreted as a Chern- Simon type mass of photons,
which is determined by the electric (magnetic) dipole moments $d_i$ ($\mu_i$)
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 $T
\sim 100 MeV$) then the time lag between the two circularly polarised signals
of frequency $\omega$ will be $\Delta t(\omega) \simeq 10^{-6} /\omega$. 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

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 $\nu_{\mu}$ to $\bar{\nu_{\mu}}$ Ratio in a High Statistics Atmospheric Neutrino Experiment

By exploiting differences in muon lifetimes it is possible to distinguish
$\nu_{\mu}$ from $\bar{\nu_{\mu}}$ 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

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

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