In this brief note, we reconsider the problem of finding Euclidean wormhole solutions to maximal supergravity in d dimensions. We find that such solutions exists for all d ≤ 9. However, we argue that, in toroidally-compactified string theories, these saddle points never contribute to the path integral because of a tension with U-duality. Research supported by NSF Grants PHY-0505757, PHY-0555575...

For certain singularly perturbed two-component reaction-diffusion (RD) systems, the bifurcation diagram of steady-state spike solutions is characterized by a saddle-node behavior in terms of some parameter β in the system. For some such systems, such as the Gray-Scott model, a spike self-replication behavior is observed as a parameter varies across the saddle-node point. We demonstrate and anal...

Depending on the initial energies, a proton transfer may proceed either via a saddle-point in a potential energy surface or by crossing from the reactants' to the products' valley before the saddle-point is reached. In the second path the analogy to weak-overlap electron transfers is pointed out. The present study is intended to unify previously divergent viewpoints, by showing how they are spe...

The transition from fully synchronized behavior to two-cluster dynamics is investigated for a system of N globally coupled chaotic oscillators by means of a model of two coupled logistic maps. An uneven distribution of oscillators between the two clusters causes an asymmetry to arise in the coupling of the model system. While the transverse period-doubling bifurcation remains essentially unaffe...

In this paper we study the Lorentzian path-integral of Gauss-Bonnet gravity in mini-superspace approximation four spacetime dimensions and investigate transition amplitude from one configuration to another. Past studies motivate us on imposing Neumann boundary conditions initial as they lead stable behaviour fluctuations. The is computed exactly while incorporating non-trivial contribution comi...

A macro-continuum model of the traffic flow is derived from a micro-car-following that considers both upslope and downslope by using transformation relationship between macro- micro-variables. The perturbation propagation characteristics stability conditions macroscopic continuum equation are discussed. For uniform in initial equilibrium state, reveal as slope angle increased under action small...

We study counting statistics of number of transitions in a stochastic process. For mesoscopic systems, a path integral formulation for the counting statistics has already been derived. We here show that it is also possible to derive the similar path integral formulation without the assumption of mesoscopic systems. It has been clarified that the saddle point method for the path integral is not ...

In most attempts to compute the Hartle-Hawking “wave function of the universe” in Euclidean quantum gravity, two important approximations are made: the path integral is evaluated in a saddle point approximation, and only the leading (least action) extremum is taken into account. In (2+1)dimensional gravity with a negative cosmological constant, the second assumption is shown to lead to incorrec...