13652721
Irreducible Killing Tensors from Conformal Killing Vectors
Koutras has proposed some methods to construct reducible proper conformal Killing tensorsand Killing tensors (which are, in general, irreducible) when a pair of orthogonal conformalKilling vectors exist in a given space. We give the completely general result demonstratingthat this severe restriction of orthogonality is unnecessary. In addition we correct andextend some results concerning Killing tensors constructed from a single conformal Killingvector. We give as an example a Kimura metric and demonstrate how it is possible toconstructalargerclassofreducibleproperconformalKillingtensorsandKillingtensorsthanpermitted by the Koutras algorithms. In addition, from our new result that all conformalKilling tensors are reducible in conformally ﬂat spaces, we have a method of constructingall conformal Killing tensors and hence all the Killing tensors (which will in general beirreducible) of conformally ﬂat spaces using their conformal Killing vectors.
119366478
On the symmetries of the Edgar?Ludwig metric
The conformal Killing equations for the most general (non-plane wave) conformally flat pure radiation field are solved to find the conformal Killing vectors. As expected 15 independent conformal Killing vectors exist, but in general the metric admits no Killing or homothetic vectors. However for certain special cases a one-dimensional group of homotheties or motions may exist and in one very special case, overlooked by previous investigators, a two-dimensional homethety group exists. No higher dimensional groups of motions or homotheties are admitted by these metrics.
118984350
Comment on"Conformally flat stationary axisymmetric metrics"
Garcia and Campuzano claim to have found a previously overlooked family of stationary and axisymmetric conformally flat spacetimes, contradicting an old theorem of Collinson. In both these papers it is tacitly assumed that the isometry group is orthogonally transitive. Under the same assumption, we point out here that Collinson's result still holds if one demands the existence of an axis of symmetry on which the axial Killing vector vanishes. On the other hand if the assumption of orthogonal transitivity is dropped, a wider class of metrics is allowed and it is possible to find explicit counterexamples to Collinson's result.
122426348
Pion Charge Exchange Scattering at High-Energies
We report on a study of pion charge-exchange scattering carried out at Fermilab in the energy range 20 to 200 GeV. The results can be described remarkably well by a simple Regge-pole model. The charge-exchange cross sections in the forward direction lead to a prediction for the difference in total cross sections of ..pi../sup -/p and ..pi../sup +/p which is in satisfactory agreement with direct measurements of this difference in another experiment at Fermilab. (AIP)