Both electromagnetic and strong interactions contribute to make, in magnetic fields of the order of B > 1014 T, the neutron stable against beta decay and for somewhat larger fields the proton becomes unstable to a decay into a neutron via β emission. Changes in chiral condensates due to such fields and an unexpectedly large field dependence of hadronic magnetic moments would modify these arguments. Fields of such magnitude may exist in colliding neutron stars and in the vicinity of cosmic strings. Possible astrophysical consequences are discussed. © 1993.

We study the annihilation of free electrons and positrons in intense magnetic fields. In the case both the electron and the positron are in the lowest energy state the resulting gamma rays emerge predominantly transverse to the field direction; in the situation where one of the particles is in an excited spin state the radiation is predominantly along the field direction. We propose that this could be an explanation of a recently observed 545 keV line from the Crab Nebula. © 1993.

Composite hadronic states exhibit interesting properties in the presence of very intense magnetic fields, such as those conjectured to exist in the vicinity of certain astropysical objects. We discuss three scenarios. (i) The presence of vector particles with anomalous magnetic moment couplings to scalar particles, induces an instability of the vacuum. (ii) A delicate interplay between the anomalous magnetic moments of the proton and neutron makes, in magnetic fields B ≥ 2 × 1014 T, the neutron stable and for fields B ≥ 5 × 1014 T the proton becomes unstable to a decay into a neutron via β emission. (iii) In the unbroken chiral σ model magnetic fields would be screened out as in a superconductor. It is the explicit breaking of chiral invariance that restores standard electrodynamics. Astrophysical consequences of all these phenomena are discussed. © 1993.

Expected atmospheric ν̄e fluxes will result in a significant number of resonantly produced low mass hadronic vector states, as the ρ, in large volume neutrino telescopes. The existence of sources of higher energy neutrinos will result in the production of higher mass states, as the Ds* and the (t̄b)J=1. We calculate the rates of production of these states and discuss their signals. Independent of theoretical flux determinations, the detection of these states will be a tool for experimentally determining these fluxes. © 1995 The American Physical Society.

We present a new mechanism that will limit very high magnetic fields which have been conjectured to exist in connection with some astrophysical phenomena. Low lying strongly interacting particles and resonances mixing with each other via magnetic dipole QED couplings force a vacuum instability for large external magnetic fields. These mixings limit fields to a few GeV2. © 1992.

In very intense magnetic fields, B>1.5×1014T, the breaking of the strong interaction SU (2) × SU (2) symmetry arranges itself so that instead of the neutral σ field acquiring a vacuum expectation value it is the charged π field that does and the magnetic field is screened. Details are presented for a magnetic field generated by a current in a wire; we show that the magnetic field is screened out to a distance ρ{variant}0∼I f{hook}πmπ from the wire. © 1992.