Probing the stability of superheavy dark matter particles with high-energy neutrinos

Two of the most fundamental properties of the dark matter particle, the mass and the lifetime, are only weakly constrained by the astronomical and cosmological evidence of dark matter. We derive in this paper lower limits on the lifetime of dark matter particles with masses in the range 10 TeV-10^15 TeV from the non-observation of ultrahigh energy neutrinos in the AMANDA, IceCube, Auger and ANITA experiments. For dark matter particles which produce neutrinos in a two body or a three body decay, we find that the dark matter lifetime must be longer than O(10^26-10^28) s for masses between 10 TeV and the Grand Unification scale. Finally, we also calculate, for concrete particle physics scenarios, the limits on the strength of the interactions that induce the dark matter decay.Comment: 17 pages, 6 figures; v2: references added, discussion improved, matches the version published at JCA

Solution Of Wheeler-De Witt Equation, Potential Well And Tunnel Effect

This paper uses the relation of the cosmic scale factor and scalar field to solve Wheeler-DeWitt equation, gives the tunnel effect of the cosmic scale factor a and quantum potential well of scalar field, and makes it fit with the physics of cosmic quantum birth. By solving Wheeler-DeWitt equation we achieve a general probability distribution of the cosmic birth, and give the analysis of cosmic quantum birth.Comment: 12 page

Fast and Compact Distributed Verification and Self-Stabilization of a DFS Tree

We present algorithms for distributed verification and silent-stabilization of a DFS(Depth First Search) spanning tree of a connected network. Computing and maintaining such a DFS tree is an important task, e.g., for constructing efficient routing schemes. Our algorithm improves upon previous work in various ways. Comparable previous work has space and time complexities of $O(n\log \Delta)$ bits per node and $O(nD)$ respectively, where $\Delta$ is the highest degree of a node, $n$ is the number of nodes and $D$ is the diameter of the network. In contrast, our algorithm has a space complexity of $O(\log n)$ bits per node, which is optimal for silent-stabilizing spanning trees and runs in $O(n)$ time. In addition, our solution is modular since it utilizes the distributed verification algorithm as an independent subtask of the overall solution. It is possible to use the verification algorithm as a stand alone task or as a subtask in another algorithm. To demonstrate the simplicity of constructing efficient DFS algorithms using the modular approach, We also present a (non-sielnt) self-stabilizing DFS token circulation algorithm for general networks based on our silent-stabilizing DFS tree. The complexities of this token circulation algorithm are comparable to the known ones

Regularization Independent Analysis of the Origin of Two Loop Contributions to N=1 Super Yang-Mills Beta Function

We present a both ultraviolet and infrared regularization independent analysis in a symmetry preserving framework for the N=1 Super Yang-Mills beta function to two loop order. We show explicitly that off-shell infrared divergences as well as the overall two loop ultraviolet divergence cancel out whilst the beta function receives contributions of infrared modes.Comment: 7 pages, 2 figures, typos correcte

Affleck-Dine baryogenesis with modulated reheating

Modulated reheating scenario is one of the most attractive models that predict possible detections of not only the primordial non-Gaussianity but also the tensor fluctuation through future CMB observations such as the Planck satellite, the PolarBeaR and the LiteBIRD satellite experiments. We study the baryonic-isocurvature fluctuations in the Affleck-Dine baryogenesis with the modulated reheating scenario. We show that the Affleck-Dine baryogenesis can be consistent with the modulated reheating scenario with respect to the current observational constraint on the baryonic-isocurvature fluctuations.Comment: 7 page

Remote Inflation: Hybrid-like inflation without hybrid-type potential

A new scenario of hybrid-like inflation is considered without using hybrid-type potential. Radiation raised continuously by a dissipating inflaton field keeps symmetry restoration in a remote sector, and the false-vacuum energy of the remote sector dominates the energy density during inflation. Remote inflation is terminated when the temperature reaches the critical temperature, or when the slow-roll condition is violated. Without introducing a complex form of couplings, inflaton field may either roll-in (like a standard hybrid inflation) or roll-out (like an inverted-hybrid model or quintessential inflation) on arbitrary inflaton potential. Significant signatures of remote inflation can be observed in the spectrum caused by (1) the inhomogeneous phase transition in the remote sector, or (2) a successive phase transition in the remote sector. Remote inflation can predict strong amplification or suppression of small-scale perturbations without introducing multiple inflation. Since the inflaton may have a run-away potential, it is also possible to identify the inflaton with quintessence, without introducing additional mechanisms. Even if the false-vacuum energy is not dominated by the remote sector, the phase transition in the remote sector is possible during warm inflation, which may cause significant amplification/suppression of the curvature perturbations.Comment: 28 pages, 1 figure, fixed references, accepted for publication in JCA

Backward pion-nucleon scattering

A global analysis of the world data on differential cross sections and polarization asymmetries of backward pion-nucleon scattering for invariant collision energies above 3 GeV is performed in a Regge model. Including the $N_\alpha$, $N_\gamma$, $\Delta_\delta$ and $\Delta_\beta$ trajectories, we reproduce both angular distributions and polarization data for small values of the Mandelstam variable $u$, in contrast to previous analyses. The model amplitude is used to obtain evidence for baryon resonances with mass below 3 GeV. Our analysis suggests a $G_{39}$ resonance with a mass of 2.83 GeV as member of the $\Delta_{\beta}$ trajectory from the corresponding Chew-Frautschi plot.Comment: 12 pages, 16 figure

Stability of Repulsive Bose-Einstein Condensates in a Periodic Potential

The cubic nonlinear Schr\"odinger equation with repulsive nonlinearity and an elliptic function potential models a quasi-one-dimensional repulsive dilute gas Bose-Einstein condensate trapped in a standing light wave. New families of stationary solutions are presented. Some of these solutions have neither an analog in the linear Schr\"odinger equation nor in the integrable nonlinear Schr\"odinger equation. Their stability is examined using analytic and numerical methods. All trivial-phase stable solutions are deformations of the ground state of the linear Schr\"odinger equation. Our results show that a large number of condensed atoms is sufficient to form a stable, periodic condensate. Physically, this implies stability of states near the Thomas-Fermi limit.Comment: 12 pages, 17 figure

Running-Mass Inflation Model and Primordial Black Holes

We revisit the question whether the running-mass inflation model allows the formation of Primordial Black Holes (PBHs) that are sufficiently long-lived to serve as candidates for Dark Matter. We incorporate recent cosmological data, including the WMAP 7-year results. Moreover, we include "the running of the running" of the spectral index of the power spectrum, as well as the renormalization group "running of the running" of the inflaton mass term. Our analysis indicates that formation of sufficiently heavy, and hence long-lived, PBHs still remains possible in this scenario. As a by-product, we show that the additional term in the inflaton potential still does not allow significant negative running of the spectral index.Comment: 22 pages, 6 figures, Refs. added, Published in JCA

Canadians Should Travel Randomly

We study online algorithms for the Canadian Traveller Problem (CTP) introduced by Papadimitriou and Yannakakis in 1991. In this problem, a traveller knows the entire road network in advance, and wishes to travel as quickly as possible from a source vertex s to a destination vertex t, but discovers online that some roads are blocked (e.g., by snow) once reaching them. It is PSPACE-complete to achieve a bounded competitive ratio for this problem. Furthermore, if at most k roads can be blocked, then the optimal competitive ratio for a deterministic online algorithm is 2k + 1, while the only randomized result known is a lower bound of k + 1. In this paper, we show for the first time that a polynomial time randomized algorithm can beat the best deterministic algorithms, surpassing the 2k + 1 lower bound by an o(1) factor. Moreover, we prove the randomized algorithm achieving a competitive ratio of (1 + [√2 over 2])k + 1 in pseudo-polynomial time. The proposed techniques can also be applied to implicitly represent multiple near-shortest s-t paths.NSC Grant 102-2221-E-007-075-MY3Japan Society for the Promotion of Science (KAKENHI 23240002