Escape of black holes from the brane

TeV-scale gravity theories allow the possibility of producing small black holes at energies that soon will be explored at the LHC or at the Auger observatory. One of the expected signatures is the detection of Hawking radiation, that might eventually terminate if the black hole, once perturbed, leaves the brane. Here, we study how the `black hole plus brane' system evolves once the black hole is given an initial velocity, that mimics, for instance, the recoil due to the emission of a graviton. The results of our dynamical analysis show that the brane bends around the black hole, suggesting that the black hole eventually escapes into the extra dimensions once two portions of the brane come in contact and reconnect. This gives a dynamical mechanism for the creation of baby branes.Comment: 4 pages, 6 figure

Phase Transitions with Discrete Symmetry Breaking in Antiferromagnetic Heisenberg Models on a Triangular Lattice

We study phase transition behavior of the Heisenberg model on a distorted triangular lattice with competing interactions. The ground-state phase diagram indicates that underlying symmetry can be changed by tuning parameters. We focus on two cases in which a phase transition with discrete symmetry breaking occurs. The first is that the order parameter space is SO(3)$\times C_3$. In this case, a first-order phase transition, with threefold symmetry breaking, occurs. The second has the order parameter space SO(3)$\times Z_2$. In this case, a second-order phase transition occurs with twofold symmetry breaking. To investigate finite-temperature properties of these phase transitions from a microscopic viewpoint, we introduce a method to make the connection between continuous frustrated spin systems and the Potts model with invisible states.Comment: 5 pages, 2 figure

Dilution effect in correlated electron system with orbital degeneracy

Theory of dilution effect in orbital ordered system is presented. The $e_g$ orbital model without spin degree of freedom and the spin-orbital coupled model in a three-dimensional simple-cubic lattice are analyzed by the Monte-Carlo simulation and the cluster expansion method. In the $e_g$ orbital model without spin degree of freedom, reduction of the orbital ordering temperature due to dilution is steeper than that in the dilute magnet. This is attributed to a modification of the orbital wave-function around vacant sites. In the spin-orbital coupled model, it is found that magnetic structure is changed from the A-type antiferromagnetic order into the ferromagnetic one. Orbital dependent exchange interaction and a sign change of this interaction around vacant sites bring about this novel phenomena. Present results explain the recent experiments in transition-metal compounds with orbital dilution.Comment: 12 pages, 16 figure

Bifurcation scenario to Nikolaevskii turbulence in small systems

We show that the chaos in Kuramoto-Sivashinsky equation occurs through period-doubling cascade (Feigenbaum scenario), in contrast, the chaos in Nikolaevskii equation occurs through torus-doubling bifurcation (Ruelle-Takens-Newhouse scenario).Comment: 8pages, 9figure

Theory of the tunneling spectroscopy of ferromagnetic superconductors

We study tunneling conductance in normal metal / insulator / ferromagnetic superconductor junctions. The tunneling spectra show a clear difference between spin-singlet s-wave pairing, spin-triplet opposite spin pairing and spin-triplet equal spin pairing: These pairings exhibit, respectively, gap struture, double peak structure and zero bias peak in the spectra. The obtained result may serve as a tool for determining the pairing symmetry of ferromagnetic superconductors.Comment: 4 pages, 2 figure

Evolution of Non-linear Fluctuations in Preheating after Inflation

We investigate the evolution of the non-linear long wavelength fluctuations during preheating after inflation. By using the separate universe approach, the temporal evolution of the power spectrum of the scalar fields and the curvature variable is obtained numerically. We found that the amplitude of the large scale fluctuations is suppressed after non-linear evolution during preheating.Comment: To be published in Class. Quantum Gra

Vibrationally resolved partial cross sections and asymmetry parameters for carbon K-shell photoionization of the CO_2 molecule

We have measured the vibrationally resolved partial cross sections \sigma_{v_1^{\prime}} and asymmetry parameters \beta_{v_1^{\prime}} for C K-shell photoionization of the CO2 molecule in the Σu shape resonance region above the C K-shell ionization threshold. The positions of both the maxima of \sigma_{v_1^{\prime}} and the minima of \beta_{v_1^{\prime}} move towards the C K-shell threshold with increasing symmetric stretching vibrational excitation v'1 in the C 1s single-hole state. Calculations employing the relaxed-core Hartree–Fock approach reproduce the observed vibrational effects

Branes and Black holes in Collision

We study the collision of a brane with a black hole. Our aim is to explore the topology changing process of perforation of a brane. The brane is described as a field theoretical domain wall in the context of an axion-like model consisting of a complex scalar effective field theory with approximate U(1) symmetry. We simulate numerically the dynamics of the collision and illustrate the transition from the configuration without a hole to the pierced one with the aid of a phase diagram. The process of perforation is found to depend on the collisional velocity, and, contrary to our expectation, we observe that above a critical value of the velocity, the black hole has no chance to perforate the wall. That is: high energy collisions do not assist piercing. We also show that, only when the model parameters are fine-tuned so that the energy scale of the string is very close to that of the domain wall, the collision of the wall with the black hole has a possibility to provide a mechanism to erase domain walls, if the hole expands. However, in such cases, domain walls will form with many holes edged by a string and therefore disappear eventually. Therefore this mechanism is unlikely to be a solution to the cosmological domain wall problem, although it may cause some minor effects on the evolution of a domain wall network.Comment: 14 pages; 9 figure