117905421
The nucleation of false vacuum bubbles with compact geometries
We investigate and classify the possible types of false vacuum bubbles in Einstein gravity. The false vacuum bubbles can occur only if gravity is taken into account. We show that there exist solutions only with compact geometries. The analytic computations for the radius and nucleation rate of a vacuum bubble are evaluated using the thin-wall approximation. We discuss possible cosmological implications of our new solutions.
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.
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.
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.
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.
17669329
Infrared Safety in Factorized Hard Scattering Cross-Sections
Abstract The rules of soft-collinear effective theory can be used naively to write hard scattering cross-sections as convolutions of separate hard, jet, and soft functions. One condition required to guarantee the validity of such a factorization is the infrared safety of these functions in perturbation theory. Using e + e − angularity distributions as an example, we propose and illustrate an intuitive method to test this infrared safety at one loop. We look for regions of integration in the sum of Feynman diagrams contributing to the jet and soft functions where the integrals become infrared divergent. Our analysis is independent of an explicit infrared regulator, clarifies how to distinguish infrared and ultraviolet singularities in pure dimensional regularization, and demonstrates the necessity of taking zero-bins into account to obtain infrared-safe jet functions.
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.
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.
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.
119268364
Cardy-Verlinde formula in Taub-NUT/Bolt-(A)dS space
Abstract We consider a finite action for a higher dimensional Taub–NUT/Bolt–(A)dS space via the so-called counter term subtraction method. In the limit of high temperature, we show that the Cardy–Verlinde formula holds for the Taub–Bolt–AdS metric and for the specific dimensional Taub–NUT–(A)dS metric, except for the Taub–Bolt–dS metric.