Stationary closed strings in five-dimensional flat spacetime

Igata, Takahisa; Ishihara, Hideki; Nishiwaki, K

doi:10.1103/physrevd.86.104020

Cited by 5 publications

(10 citation statements)

References 49 publications

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“…Since the conservation law is based on symmetry, it has a universal role in physics. Furthermore, symmetry can also define symmetric configurations of test fields and extended objects [2][3][4][5][6][7][8].…”

Section: Introductionmentioning

confidence: 99%

Scale invariance and constants of motion

Igata

2018

Progress of Theoretical and Experimental Physics

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Scale invariance in the theory of classical mechanics can be induced from the scale invariance of background fields. In this paper we consider the relation between the scale invariance and the constants of particle motion in a self-similar spacetime, only in which the symmetry is well-defined and is generated by a homothetic vector. Relaxing the usual conservation condition by the Hamiltonian constraint in a particle system, we obtain a conservation law holding only on the constraint surface in the phase space. By the conservation law, we characterize constants of motion associated with the scale invariance not only for massless particles but for massive particles and classify the condition for the existence of the constants of motion. Furthermore, we find the explicit form of the constants of motion by solving the conservation equations.

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Section: Introductionmentioning

confidence: 99%

Scale invariance and constants of motion

Igata

2018

Progress of Theoretical and Experimental Physics

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“…• Well defined longitudinal speed of sound: If the longitudinal speed of sound is well defined then from (42) we must have F (n 2 ) = 0 and dp dρ ≥ 0. Of the three models above, only the first and the third satisfy this condition.…”

Section: The Choice Of Elastic Lawmentioning

confidence: 99%

Rotating elastic string loops in flat and black hole spacetimes: stability, cosmic censorship and the Penrose process

Natário¹,

Queimada²,

Vicente³

2018

Class. Quantum Grav.

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We rederive the equations of motion for relativistic strings, that is, one-dimensional elastic bodies whose internal energy depends only on their stretching, and use them to study circular string loops rotating in the equatorial plane of flat and black hole spacetimes. We start by obtaining the conditions for equilibrium, and find that: (i) if the string's longitudinal speed of sound does not exceed the speed of light then its radius when rotating in Minkowski's spacetime is always larger than its radius when at rest; (ii) in Minkowski's spacetime, equilibria are linearly stable for rotation speeds below a certain threshold, higher than the string's longitudinal speed of sound, and linearly unstable for some rotation speeds above it; (iii) equilibria are always linearly unstable in Schwarzschild's spacetime. Moreover, we study interactions of a rotating string loop with a Kerr black hole, namely in the context of the weak cosmic censorship conjecture and the Penrose process. We find that: (i) elastic string loops that satisfy the null energy condition cannot overspin extremal black holes; (ii) elastic string loops that satisfy the dominant energy condition cannot increase the maximum efficiency of the usual particle Penrose process; (iii) if the dominant energy condition (but not the weak energy condition) is violated then the efficiency can be increased. This last result hints at the interesting possibility that the dominant energy condition may underlie the well known upper bounds for the efficiencies of energy extraction processes (including, for example, superradiance).

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“…To calculate E 2 at the event horizon, we must obtain the values of g ab (∂ aS1 −e 1 A a )(∂ b S 2 − e 2 A b ) andΨ 1 Ψ 2 there. The former can be obtained only by asymptotic behaviors of the local solutions around the event horizon 13 . In sections 5.2 and 5.3, we calculate that in general situations.…”

Section: The Intensity Of Collision Of Two Scalar Field Excitationsmentioning

confidence: 99%

“…In [5], it was shown that nonrotating but extremely charged black holes also cause similar divergences of the collision energy for critically charged particles. Many authors have discussed the BSW effect in a variety of situations [6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31,32,33,34] and the possibilities of other processes of unboundedly high-energy collision, [35,36,37], and for a review see [38].…”

Section: Introductionmentioning

confidence: 99%

Several solutions of the Klein–Gordon equation in Kerr–Newman spacetime and the BSW effect

Yumisaki

2017

Progress of Theoretical and Experimental Physics

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We investigate the radial part of the charged massive Klein-Gordon equation in Kerr-Newman spacetime, and in several specific situations, obtain exact solutions by means of essentially hypergeometric functions or their confluent types. Using these global solutions and generally obtained local solutions, we calculate a sort of intensity of the collision of two field excitations, which is a slight generalization of the trace of the stress tensor. We find that when the black hole is nonextremal, the intensity of the collision of two ingoing modes is bounded. However, in the extremal limit, more precisely κ H → 0, the upper bound grows so that when the frequency of one of the two modes satisfies the critical relation, the intensity of the collision at the horizon becomes unboundedly large. Furthermore, the intensity of the collision of ingoing and outgoing modes is always unbounded, as well as in the classical particle theory. Our results suggest that the BSW effect is inherited by the quantum theory. *

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Stationary closed strings in five-dimensional flat spacetime

Cited by 5 publications

References 49 publications

Scale invariance and constants of motion

Scale invariance and constants of motion

Rotating elastic string loops in flat and black hole spacetimes: stability, cosmic censorship and the Penrose process

Several solutions of the Klein–Gordon equation in Kerr–Newman spacetime and the BSW effect

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