18835111
Chern-Simons-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-Simons form ${\mathcal{L}}_{\mathcal{I}}={M}_{\ensuremath{\mu}}{A}_{\ensuremath{\nu}}{\stackrel{\ifmmode \tilde{}\else \~{}\fi{}}{F}}^{\ensuremath{\mu}\ensuremath{\nu}}$. The four-vector ${M}_{\ensuremath{\mu}}\ensuremath{\simeq}{d}_{i}{\ensuremath{\mu}}_{i}{m}_{i}^{2}{\ensuremath{\partial}}_{\ensuremath{\mu}}(\mathrm{ln}T)$ is interpreted as a Chern-Simons-type mass of photons, which is determined by the electric (magnetic) dipole moments ${d}_{i}({\ensuremath{\mu}}_{i})$ of the fermions in the vacuum polarization loop diagram. The physical consequence of such a photon mass is that photons of opposite circular polarizations, propagating through a hot medium, have different group velocities. We estimate the time lag between the arrival times of the left and right circularly polarized light signals from pulsars. If the light propagates through a hot plasma (where the temperature in some regions is $T\ensuremath{\sim}100$ MeV) then the time lag between the two circularly polarized signals of frequency $\ensuremath{\omega}$ will be $\ensuremath{\Delta}t(\ensuremath{\omega})\ensuremath{\simeq}\frac{{10}^{\ensuremath{-}6}}{\ensuremath{\omega}}$. It may be possible to observe this effect in pulsar signals which propagate through nebulas at high temperatures.
118059039
Determination of the age of the earth from Kamland measurement of geo-neutrinos
The low energy component of the antineutrino spectrum observed in the recent Kamland experiment has significant contribution from the radioactive decay of $^{238}U$ and $^{232}Th$ in the crust and mantle of the earth. By taking the ratio of the antineutrino events obeserved in two different energy ranges we can determine the present value $[Th/U]$ independent of the U,Th distribution in the earth. Comparing with the r-process initial value of $[Th/U]_0$ we determine the age of the earth as a function of $\Delta m^2$ and $Sin^2 2 \theta$. We find that the age of the earth determined from KamLAND data matches the age of solar system ($4.5 Gyrs$ from meteorites) for the LMA-I solution. For the LMA-II solution the age of the earth does not match the solar system age at 90 % C.L.
11918846
Neutrino and astroparticle physics: Working group report
The contributions made to the Working Group activities on neutrinos and astrophysics are summarized in this article. The topics discussed were inflationary models in Raman-Sundrum scenarios, ultra high energy cosmic rays and neutrino oscillations in 4 flavour and decaying neutrino models.
117886121
Field-theoretical treatment of neutrino oscillations
We discuss the field-theoretical approach to neutrino oscillations. This approach includes the neutrino source and detector processes and allows to obtain the neutrino transition or survival probabilities as cross sections derived from the Feynman diagram of the combined source -- detection process. In this context, the neutrinos which are supposed to oscillate appear as propagators of the neutrino mass eigenfields, connecting the source and detection processes.
121168530
Quantum cosmology of the superstring universe
Abstract We study the quantum cosmology of the string universe obtained by embedding the Robertson-Walker metric in the non-linear model of Antoniadis, Bachas, Ellis and Nanopoulos (ABEN). We find that the quantum model has some unusual features not seen in the classical model. Initially, the universe exists in a series of metastable bound states with scale factor taking discrete values. Then the universe tunnels through a barrier and comes out in an inflationary state. This tunneling (or evolution in imaginary time) also has the effect of heating up the matter field so that we have the conditions of chaotic inflation. Our asymptotic solutions agree with those obtained from the classical Einstein equations by ABEN.
15412351
Production process dependence of neutrino flavor conversion
We perform a covariant wave-packet analysis of neutrino oscillations taking into account the lifetime of the neutrino production process . We find that flavor oscillations in space are washed out when the neutrinos are produced from long lived resonances - and what may be observed in appearance/disappearance experiments is a uniform conversion probability independent of distance. The lifetime of the resonance which produces the neutrinos acts as the the effective baseline of the experiment. 
For this reason the LSND experiment where neutrinos are produced from muon decay has two orders of magnitude more sensitivity to neutrino mass square difference than other experiments where the neutrinos are produced from pion or kaon decays.
11125240
Experimental determination of energy-dependent barriers for fusion.
Experimental fusion excitation functions have been fitted for several systems using an energy-dependent barrier-penetration model as suggested in our earlier work where the barrier height is written as a function of the radial kinetic energy {var epsilon} at the interaction barrier. This form of the energy dependence of the fusion barrier leads also to an implied {ital l} dependence of the barrier. It is shown that the enhancement of {l angle}{ital l}{r angle} over {l angle}{ital l}{r angle}{sub {ital o}{ital d}} predicted by a simple energy-independent barrier-penetration model is maximum around the Coulomb barrier. A correlation has also been oberved between this maximum enhancement factor and the product of the charges of the colliding nuclei.