Axion Decay of a Photon in an External Electromagnetic Field

An interaction of a pseudoscalar particle with two photons induced by an external electromagnetic field is used to study the photon decay $\gamma \to \gamma a$ where a is a pseudoscalar particle associated with the Peccei-Quinn U(1) symmetry. The field-induced axion emission by photon is analyzed as a possible source of energy losses by astrophysical objects.Comment: 7 pages, latex, 1 PS figur

High Energy Hadron-Nucleus Cross Sections and Their Extrapolation to Cosmic Ray Energies

Old models of the scattering of composite systems based on the Glauber model of multiple diffraction are applied to hadron-nucleus scattering. We obtain an excellent fit with only two free parameters to the highest energy hadron-nucleus data available. Because of the quality of the fit and the simplicity of the model it is argued that it should continue to be reliable up to the highest cosmic ray energies. Logarithmic extrapolations of proton-proton and proton-antiproton data are used to calculate the proton-air cross sections at very high energy. Finally, it is observed that if the exponential behavior of the proton-antiproton diffraction peak continues into the few TeV energy range it will violate partial wave unitarity. We propose a simple modification that will guarantee unitarity throughout the cosmic ray energy region.Comment: 8 pages, 9 postscript figures. This manuscript replaces a partial manuscript incorrectly submitte

QCD axion and quintessential axion

The axion solution of the strong CP problem is reviewed together with the other strong CP solutions. We also point out the quintessential axion(quintaxion) whose potential can be extremely flat due to the tiny ratio of the hidden sector quark mass and the intermediate hidden sector scale. The quintaxion candidates are supposed to be the string theory axions, the model independent or the model dependent axions.Comment: 15 pages. Talk presented at Castle Ringberg, June 9-14, 200

Majorons and supernova cooling

We consider the role of Majoron emission in supernova cooling and its implications for the neutrino mass and lifetime in generic single Majoron models. It is found that, for ντ with mass m, if the lifetime for the decay ντ→Majoron+νe,μ is shorter than 10−7 (m/MeV) sec, then Majorons are so strongly trapped by the inverse process that the resulting Majoron luminosity is small enough not to destabilize the observed νe pulse from SN 1987A. For ντ with a longer lifetime, the Majoron luminosity can be large enough to destroy or significantly shorten the duration of the neutrino pulse. We then find the range of parameters, e.g., the ντ mass m and the B−L-breaking scale v, that is excluded by giving such a large Majoron luminosity. Our results imply that, for v between 1 GeV and 1 TeV, a wide range of m allowed by terrestrial experiments can be excluded in view of the observed νe, pulse from SN 1987A