English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

The dynamics of a spherically symmetric thin shell with arbitrary rest massand surface tension interacting with a central black hole is studied. A carefulinvestigation of all classical solutions reveals that the value of the radiusof the shell and of the radial velocity as an initial datum does not determinethe motion of the shell; another configuration space must, therefore, be found.A different problem is that the shell Hamiltonians used in literature arecomplicated functions of momenta (non-local) and they are gauge dependent. Tosolve these problems, the existence is proved of a gauge invariantsuper-Hamiltonian that is quadratic in momenta and that generates the shellequations of motion. The true Hamiltonians are shown to follow from thesuper-Hamiltonian by a reduction procedure including a choice of gauge andsolution of constraint; one important step in the proof is a lemma stating thatthe true Hamiltonians are uniquely determined (up to a canonicaltransformation) by the equations of motion of the shell, the value of the totalenergy of the system, and the choice of time coordinate along the shell. As anexample, the Kraus-Wilczek Hamiltonian is rederived from the super-Hamiltonian.The super-Hamiltonian coincides with that of a fictitious particle moving in afixed two-dimensional Kruskal spacetime under the influence of two effectivepotentials. The pair consisting of a point of this spacetime and a unittimelike vector at the point, considered as an initial datum, determines aunique motion of the shell.Comment: Some remarks on the singularity of the vector potantial are added and  some minor corrections done. Definitive version accepted in Phys. Re

Gauge-invariant Hamiltonian formalism for spherically symmetric gravitating shells