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.
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.
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.
119165559
Oscillating instanton solutions in curved space
We investigate oscillating instanton solutions of a self-gravitating scalar field between degenerate vacua. We show that there exist O(4)-symmetric oscillating solutions in a de Sitter background. The geometry of this solution is finite and preserves the $Z_{2}$ symmetry. The nontrivial solution corresponding to tunneling is possible only if the effect of gravity is taken into account. We present numerical solutions of this instanton, including the phase diagram of solutions in terms of the parameters of the present work and the variation of energy densities. Our solutions can be interpreted as solutions describing an instanton-induced domain wall or braneworld-like object rather than a kink-induced domain wall or braneworld. The oscillating instanton solutions have a thick wall and the solutions can be interpreted as a mechanism providing nucleation of the thick wall for topological inflation. We remark that $Z_{2}$ invariant solutions also exist in a flat and anti-de Sitter background, though the physical significance is not clear.
119839635
Baryogenesis and EDMs: Constraining CP Violation Beyond the Standard Model
New sources of CPviolation 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. In this talk, I focus on the calculation of the sources and relaxation rates in the transport equations for particle densities in the closed time path formalism of quantum field theory, suitable for the finite temperature and out-of-equilbrium conditions present at the electroweak phase transition. 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
15776482
Charges and Magnetic Fields of the Slowly-rotating Neutron Stars
In association with the Goldreich-Julian's magnetic braking mechanism to explain the luminosity of radio pulsars as a result of their spin-down, it is of some interest to explore how much of magnetic flux can actually penetrate the surface of the rotating neutron stars at least in idealized situations. In order to address this issue, one needs to figure out the amount of charge on and the structure of magnetic field around a rotating neutron star. In the present work, based on the solution-generating method given by Wald, the magnetic fields around both the uncharged and (slightly) charged neutron star have been obtained. Particularly for the charged neutron star, it has been demonstrated following again the argument by Wald that the neutron star will gradually accrete the charge until it reaches the equilibrium value $\tilde{Q}=2B_{0}J$. Then next, the magnetic flux through one half of the surface of the rotating neutron star has been computed as well. With the nonvanishing accretion charge having value in the range $0 < \tilde{Q} \leq 2B_{0}J$, the total magnetic flux through the neutron star has been shown to be greater than that without the accretion charge.
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.