120085942
Nucleation of vacuum bubbles of a self-gravitating scalar field
The case of a self-gravitating scalar field under-going the first-order phase transition is studied. Particularly the effects of self gravity on the nucleation of vacuum bubbles is investigated. We also investigate what modifications are induced by the introduction of nonminimal coupling of the scalar field. The possibility of nucleation of false vacuum bubbles within the true vacuum background in the case of a nonminimally coupled scalar field is discussed.
118417575
Cosmic Background Anisotropy due to Neutrino Oscillations Revisited
This paper has been withdrawn by the author due to a crucial error in several equations.
16162020
Boson Stars with Self-Interacting Quantum Scalar Fields
The Klein-Gordon-Einstein equations of classical real scalar fields have time-dependent solutions (periodic in time). We show that quantum real scalar fields can form non-oscillating (static) solitonic objects, which are quite similar to the solutions describing boson stars formed with classical and quantum complex scalar fields (the latter will be studied in this paper). We numerically analyze the difference between them concerning the mass of boson stars. On the other hand, we suggest an interesting test (a viable process that the boson star may undergo in the early universe) for the formation of boson stars. That is, it is questioned that after a second-order phase transition (a simple toy model will be considered here), what is the fate of the boson star composed of quantum real scalar field.
5695541
Nonvanishing magnetic flux through the slightly charged Kerr black hole
In association with the Blanford-Znajek mechanism for rotational energy extraction from Kerr black holes, it is of some interest to explore how much of magnetic flux can actually penetrate the horizon at least in idealized situations. For completely uncharged Kerr hole case, it has been known for some time that the magnetic flux gets entirely expelled when the hole is maximally-rotating. In the mean time, it is known that when the rotating hole is immersed in an originally uniform magnetic field surrounded by an ionized interstellar medium (plasma), which is a more realistic situation, the hole accretes certain amount of electric charge. In the present work, it is demonstrated that as a result of this accretion charge small enough not to disturb the geometry, the magnetic flux through this slightly charged Kerr hole depends not only on the hole's angular momentum but on the hole's charge as well such that it never vanishes for any value of the hole's angular momentum.
1893865
Black-string solutions with arbitrary tension
We consider 1+4 dimensional black-string solutions which are invariant under translation along the fifth direction. The solutions are characterized by the two parameters, mass and tension, of the source. The Gregory-Laflamme solution is shown to be characterized by the tension whose magnitude is one half of the mass per unit length of the source. A general class of black-string solutions with arbitrary tension is presented and the spacetime properties of the solutions are discussed.
2929156
Relativistic Electrodynamics of Spinning Compact Objects
A theoretical study of some electrodynamic features of a region close to a slowly-rotating magnetized relativistic star is performed. To be a little more specific, based on the solution-generating method given by Wald, the magnetic fields around both uncharged and (slightly) charged relativistic stars have been obtained. Particularly for a charged relativistic star, again following the argument by Wald, the star was shown to gradually accrete charge until it reached an equilibrium value Q = 2B0J . This value of the equilibrium charge seems to be generic as a rotating black hole is known to accrete exactly the same amount. Although these results are equally relevant to all species of slowly-rotating relativistic stars, we particularly have the rotating neutron star in mind. As such, it would be of some interest to attempt to make contact with a real pulsar case. Thus, we discuss how many of the theoretical results obtained in the present work can be carried over to a realistic, general relativistic description of a pulsar’s magnetosphere.
118378068
Resonantly Enhanced CP Violation and Relaxation in Electroweak Baryogenesis
New sources of CP violation beyond the Standard Model may help the scenario of electroweak baryogenesis (EWB) to account for the baryon asymmetry of the universe, and may be detectable in searches for permanent electric dipole moments of fundamental particles. Applying the methods of closed time‐path quantum field theory to derive transport equations relevant for EWB in the MSSM, we find regions of the parameter space where generation of the baryon asymmetry is resonantly enhanced, allowing successful baryogenesis with CP‐violating phases small enough to be consistent with experimental limits on electron and neutron EDMs.
118173758
Unstable D-branes and String Cosmology
Cosmological implication of rolling tachyons is reported in the context of effective field theory. With a brief review of rolling tachyons in both flat and curved spacetimes, we study the string cosmological model with both tachyon and dilaton. In the string frame, flat space solutions of both initial-stage and late-time are obtained in closed form. In the Einstein frame, every expanding solution is decelerating. When a Born-Infeld U(1) gauge field is coupled, enhancement of e-folding of scale factor is also discussed by numerical analysis.
16403765
3-dimensional holographic trace anomaly from AdS/CFT correspondence
We explicitly obtain energy-momentum tensor at the asymptotic 3-dimensional region of Schwarzschild AdS$_4$ and Taub-NUT-(A)dS$_4$ using the so-called `counter-term subtraction method' in Fefferman-Graham coordinate. The energy momentum tensor is presented in a closed form for the AdS$_4$ and for the special case of Taub-NUT-dS and in an asymptotic series for other cases. The result suggests that in light of AdS/CFT correspondence, the 3-dimensional trace anomaly can be expressed in terms of the 3-dimensional volume and Ricci scalar.
118636986
The holographic superconductors in higher-dimensional AdS soliton
We explore the behavior of the holographic superconductors at zero temperature for a charged scalar field coupled to a Maxwell field in higher-dimensional AdS soliton spacetime via analytical way. In the probe limit, we obtain the critical chemical potentials increase linearly as a total dimension d grows up. We find that the critical exponent for condensation operator is obtained as 1/2 independently of d, and the charge density is linearly related to the chemical potential near the critical point. Furthermore, we consider a slightly generalized setup the Einstein–Power–Maxwell field theory, and find that the critical exponent for condensation operator is given as 1/(4−2n) in terms of a power parameter n of the Power–Maxwell field, and the charge density is proportional to the chemical potential to the power of 1/(2−n).
2435715
Late time behaviors of an inhomogeneous rolling tachyon
We study an inhomogeneous decay of an unstable D-brane in the context of Dirac-Born-Infeld (DBI)-type effective action. We consider tachyon and electromagnetic fields with dependence of time and one spatial coordinate, and an exact solution is found under an exponentially decreasing tachyon potential, e{sup -|T|/{radical}}{sup (2)}, which is valid for the description of the late time behavior of an unstable D-brane. Though the obtained solution contains both time and spatial dependence, the corresponding momentum density vanishes over the entire spacetime region. The solution is governed by two parameters. One adjusts the distribution of energy density in the inhomogeneous direction, and the other interpolates between the homogeneous rolling tachyon and static configuration. As time evolves, the energy of the unstable D-brane is converted into the electric flux and tachyon matter.