8/12/2023 0 Comments Black hole removal![]() Also, trials to fix the time taken before the collision are subjected to fine tuning process, this is because the parameters cannot be fixed by the dynamics of the theory but rather fixed by hand.įrom the trials explained above, we conclude that brane world models consisting of two or more D branes and antibranes with black holes are inherently unstable regardless of the potential added. ![]() It is obvious that the adjustable parameters could be selected to remove the black holes instability but not prevent the motion of the branes towards each other. However, an alternative instability connected to the moving system will show up. Where a i are adjustable coefficients, which can be used to mitigate or even remove the instability from the black hole. The later, case gives back the original RS I model where black holes are unstable, and the introduction of a potential is redundant.įor both cases taking the potential to be a general series (each case can be derived by adjusting the parameters in the series) This implies that the structures on the branes are unstable. The former case introduces another instability in the system from the fact that the branes will collide because the RR force and the gravitational force do not cancel. Where λ + is the positive tension of the first brane, λ − is the negative tension of the second brane, R 1, R 2 are the Ricci scalars of the first and second branes respectively, y is the coordinate normal to the branes, y 1 and y 2 refer to the positions of the first and second branes at a given time t, and V( y) is the introduced potential.ġ) V( y) is attractive to a certain value of y at which it is prevented the approach of the two branes towards each other.Ģ) V( y) should depend on the difference between the RR and gravitational force such that the total force vanishes everywhere. In the modification proposed we considered the model where the branes are moving with respect to each other, and there is an additional force between them induced by a potential depending on the separation of the branes. In the original RS I model, the two branes are static, thus, the gravitational force between them exactly cancels the force from the RR charge. The Modified Model and the Trial to Remove the Instability This matter seems to us rather paradoxical.Ģ. This arbitrariness is due to the too many parameters in the theory which cannot be fixed by the model’s dynamics and must be fine-tuned to get desirable results. It is shown that the removal of intrinsic black holes instability in the model is subjected to the appearance of arbitrariness in the model generated by the relative motion of the two branes. In this letter, we report on our trials to remove these types of instabilities by modifying the model and introducing an additional potential. In this model, black holes cannot be present in the universe, because it introduces instabilities to the system. ![]() One model is particularly interesting in terms of the resulting cosmology called the Randall Sundrum (RS) I model where the branes are located on an orbifold. Since then, there have been many developments and different models proposed in this field. The models propose that there are two 4-dimensional D-branes in a 5-dimensional world, our universe is situated on one of the branes, so called the visible brane, and the other brane is called the hidden brane. Brane world type cosmology was introduced by Turok to solve some problems in conventional cosmology.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |