Null Strings in Schwarzschild Spacetime

• Published in: Physical Review D
• Main Authors: Dabrowski, M P, Larsen, A L
• Language: English
• Published: 1996
• Subjects: Particle Physics - Theory; North Pole; South Pole; South pole
• Online Access: https://doi.org/10.1103/PhysRevD.55.6409; http://cds.cern.ch/record/313985

The null string equations of motion and constraints in the Schwarzschild spacetime are given. The solutions are those of the null geodesics of General Relativity appended by a null string constraint in which the "constants of motion" depend on the world-sheet spatial coordinate. Because of the extended nature of a string, the physical interpretation of the solutions is completely different from the point particle case. In particular, a null string is generally not propagating in a plane through the origin, although each of its individual points is. Some special solutions are obtained and their physical interpretation is given. Especially, the solution for a null string with a constant radial coordinate $r$ moving vertically from the south pole to the north pole around the photon sphere, is presented. A general discussion of classical null/tensile strings as compared to massless/massive particles is given. For instance, tensile circular solutions with a constant radial coordinate $r$ do not exist at all. The results are discussed in relation to the previous literature on the subject.