scholarly journals Dyonic black holes in effective string theory

1995 ◽  
Vol 51 (2) ◽  
pp. 934-937 ◽  
Author(s):  
S. Mignemi

1993 ◽  
Vol 47 (12) ◽  
pp. 5259-5269 ◽  
Author(s):  
S. Mignemi ◽  
N. R. Stewart


1998 ◽  
Vol 07 (01) ◽  
pp. 73-80
Author(s):  
S. DEMELIO ◽  
S. MIGNEMI

The effective four-dimensional action for string theory contains non-minimal couplings of the dilaton and the moduli arising from the compactification of higher dimensions. We show that the resulting field equations admit multi-black hole solutions. The Euclidean continuation of these solutions can be interpreted as an instanton mediating the splitting and recombination of the throat of extremal magnetically charged black holes.



2007 ◽  
Vol 22 (32) ◽  
pp. 6089-6131 ◽  
Author(s):  
M. RAMÓN MEDRANO ◽  
N. G. SÁNCHEZ

An effective string theory in physically relevant cosmological and black hole space–times is reviewed. Explicit computations of the quantum string entropy, partition function and quantum string emission by black holes (Schwarzschild, rotating, charged, asymptotically flat, de Sitter dS and anti-de Sitter AdS space–times) in the framework of effective string theory in curved backgrounds provide an amount of new quantum gravity results as: (i) gravitational phase transitions appear with a distinctive universal feature: a square-root branch point singularity in any space–time dimensions. This is of the type of the de Vega–Sánchez transition for the thermal self-gravitating gas of point particles. (ii) There are no phase transitions in AdS alone. (iii) For dS background, upper bounds of the Hubble constant H are found, dictated by the quantum string phase transition. (iv) The Hawking temperature and the Hagedorn temperature are the same concept but in different (semiclassical and quantum) gravity regimes respectively. (v) The last stage of black hole evaporation is a microscopic string state with a finite string critical temperature which decays as usual quantum strings do in nonthermal pure quantum radiation (no information loss). (vi) New lower string bounds are given for the Kerr–Newman black hole angular momentum and charge, which are entirely different from the upper classical bounds. (vii) Semiclassical gravity states undergo a phase transition into quantum string states of the same system, these states are duals of each other in the precise sense of the usual classical–quantum (wave–particle) duality, which is universal irrespective of any symmetry or isommetry of the space–time and of the number or the kind of space–time dimensions.



2021 ◽  
Vol 812 ◽  
pp. 136025
Author(s):  
A. Belhaj ◽  
H. Belmahi ◽  
M. Benali ◽  
W. El Hadri ◽  
H. El Moumni ◽  
...  
Keyword(s):  


2020 ◽  
Vol 2020 (7) ◽  
Author(s):  
Chris Hull ◽  
Eric Marcus ◽  
Koen Stemerdink ◽  
Stefan Vandoren
Keyword(s):  


2005 ◽  
Vol 14 (12) ◽  
pp. 2347-2353 ◽  
Author(s):  
CHRIS CLARKSON ◽  
ROY MAARTENS

If string theory is correct, then our observable universe may be a three-dimensional "brane" embedded in a higher-dimensional spacetime. This theoretical scenario should be tested via the state-of-the-art in gravitational experiments — the current and upcoming gravity-wave detectors. Indeed, the existence of extra dimensions leads to oscillations that leave a spectroscopic signature in the gravity-wave signal from black holes. The detectors that have been designed to confirm Einstein's prediction of gravity waves, can in principle also provide tests and constraints on string theory.



Author(s):  
Iosif Bena ◽  
Sheer El-Showk ◽  
Bert Vercnocke
Keyword(s):  


2021 ◽  
Author(s):  
Andrey Chernov

Abstract In this study, a new concept is introduced into physics - gravitational cells. The gravitational cell hypothesis was organically integrated into string theory. As a result, using the Schwarzschild radius formula and the Coulomb formula, a gravitational formula in the region of black holes was obtained on the basis of two fundamental constants, and its exact value was determined. The value of the "usual" gravitational constant was also confirmed and the mass of the gravitational cell was obtained. The introduction of the hypothesis of gravitational cells into string theory made it possible to apply Planck's formula to gravitational interaction. As a result, a formula for the energy of a gravitational quantum and a formula for the vibrational velocity of a gravitational string were obtained. On this basis, the formula for the mass of the electron was obtained and its value was calculated, which coincided with the experimental mass of the electron. The exact minimum distance of the gravitational interaction was determined by the formula for the vibrational velocity of the gravitational string. This calculated minimum distance completely coincided with the known experimental data obtained when determining the Casimir effect (force).





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