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.
118626590
Instanton solutions mediating tunneling between the degenerate vacua in curved space
We investigate the instanton solution between the degenerate vacua in curved space. We show that there exist $O(4)$-symmetric solutions not only in de Sitter but also in both flat and anti\char21{}de Sitter space. The geometry of the new type of solutions is finite and preserves the ${Z}_{2}$ symmetry. The nontrivial solution corresponding to the tunneling is possible only if gravity is taken into account. The numerical solutions as well as the analytic computations using the thin-wall approximation are presented. We expect that these solutions do not have any negative mode as in the instanton solution.
14331342
Znajek-Damour horizon boundary conditions with Born-Infeld electrodynamics
In this work, the interaction of electromagnetic fields with a rotating (Kerr) black hole is explored in the context of the Born-Infeld (BI) theory of electromagnetism instead of standard Maxwell theory and particularly BI theory versions of the four horizon boundary conditions of Znajek and Damour are derived. Naturally, an issue to be addressed is then whether they would change from the ones given in the Maxwell theory context and if they do, how. Interestingly enough, as long as one employs the same local null tetrad frame as the one adopted in the works of Damour and of Znajek to read out physical values of electromagnetic fields and a fictitious surface charge and currents on the horizon, it turns out that one ends up with exactly the same four horizon boundary conditions despite the shift of the electrodynamics theory from a linear Maxwell one to a highly nonlinear BI one. Close inspection reveals that this curious and unexpected result can be attributed to the fact that the concrete structure of BI equations happens to be such that it is indistinguishable at the horizon to a local observer, say, in Damour's local tetrad frame from that of standard Maxwell theory.
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.
37989090
Static solution of the general relativistic nonlinear sigma -model equation.
The nonlinear [sigma] model is considered to be useful in describing hadrons (Skyrmions) in low energy hadron physics and the approximate behavior of the global texture. Here we investigate the properties of the static solution of the nonlinear [sigma]-model equation coupled with gravity. As in the case where gravity is ignored, there is still no scale parameter that determines the size of the static solution and the winding number of the solution is 1/2. The geometry of the spatial hyperspace in the asymptotic region of large [ital r] is explicitly shown to be that of a flat space with some missing solid angle.
15692757
Magnetic alignment process: a new mechanism for extracting energy from rotating black holes
The magnetic alignment process is proposed as a complementary or companion process to the Blandford–Znajek mechanism for the rotational energy extraction from a Kerr black hole, to serve as a viable model for the central engine of quasars, AGN, and even GRB. In contrast to the environment assumed in the Blandford–Znajek mechanism, in which the rotating hole's spin axis and the asymptotic direction of the magnetic field are aligned, this new process operates when they are generally misaligned, which obviously is the more natural situation likely to happen. The time scales over which these two processes take place and the total radiated powers released at the horizon by them have been estimated and found to be nearly comparable. This may imply that in a random, non-axisymmetric configuration, the magnetic alignment process would operate first, during which some of the hole's rotational energy is released, and then upon completion of the alignment, the Blandford–Znajek mechanism may follow and the rest of the hole's rotational energy, if any left, would be further released.
119244769
Solutions in IR Modified Horava-Lifshitz Gravity
In order to allow the asymptotically flat, we consider Ho\v{r}ava-Lifshitz gravity theory with a soft violation of the detailed balance condition and obtain various solutions. In particular, we find that such theory coupled to a global monopole leads to a solution representing a space with deficit solid angle, which is well matched with genuine feature of GR.
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.
12245422
Momentum broadening in weakly coupled quark-gluon plasma
We calculate the probability distribution P(k⊥) for the momentum perpendicular to its original direction of motion that an energetic quark or gluon picks up as it propagates through weakly coupled quark-gluon plasma in thermal equilibrium.
17888703
Resonant Flavor Oscillations in Electroweak Baryogenesis
Electroweak baryogenesis (EWBG) in extensions of the Standard Model will be tested quantitatively in upcoming nuclear and particle physics experiments, but only to the extent that theoretical computations are robust. Currently there exist orders-of-magnitude discrepancies between treatments of charge transport dynamics during EWBG performed by different groups, each relying on different sets of approximations. In this work, we introduce a consistent power counting scheme (in ratios of length scales) for treating systematically the dynamics of EWBG: CP-asymmetric flavor oscillations, collisions, and diffusion. Within the context of a simplified model of EWBG, we derive the relevant Boltzmann equations using non-equilibrium field theory, and solve them exactly without ansatz for the functional form of the density matrices. We demonstrate the existence of a resonant enhancement in charge production when the flavor oscillation length is comparable to the wall thickness. We compare our results with the existing treatment of EWBG by Konstandin, Prokopec, Schmidt, and Seco (KPSS) who previously identified the importance of flavor oscillations in EWBG. We conclude: (i) the power counting of KPSS breaks down in the resonant regime, and (ii) this leads to substantial underestimation of the charge generated in the unbroken phase, and potentially of the final baryon asymmetry.
119216120
Speculative Physics: the Ontology of Theory and Experiment in High Energy Particle Physics and Science Fiction
The dissertation brings together approaches across the fields of physics, critical theory, literary studies, philosophy of physics, sociology of science, and history of science to synthesize a hybrid approach for instigating more rigorous and intense cross-disciplinary interrogations between the sciences and the humanities. There are two levels of conversations going on in the dissertation; at the first level, the discussion is centered on a critical historiography and philosophical implications of the discovery Higgs boson in relation to its position at the intersection of old (current) and the potential for new possibilities in quantum physics; I then position my findings on the Higgs boson in connection to the double-slit experiment that represents foundational inquiries into quantum physics, to demonstrate the bridge between fundamental physics and high energy particle physics. The conceptualization of the variants of the double-slit experiment informs the aforementioned critical comparisons. At the second level of the conversation, theories are produced from a close study of the physics objects as speculative engine for new knowledge generation that are then reconceptualized and re-articulated for extrapolation into the speculative ontology of hard science fiction, particularly the hard science fiction written with the double intent of speaking to the science while producing imaginative and socially conscious science through the literary affordances of science fiction. The works of science fiction examined here demonstrate the tension between the internal values of physics in the practice of theory and experiment and questions on ethics, culture, and morality.