Regular Series

Vol. 45 (2014), No. 1, pp. 1 – 116


Black-hole Solution Without Curvature Singularity and Closed Timelike Curves

Acta Phys. Pol. B 45, 5 (2014)

DOI: 10.5506/APhysPolB.45.5

article page: 5 (contains 10 pages) •

abstract

With a prescribed Coulomb-type energy-momentum tensor, an exact solution of the Einstein field equations over a nonsimply-connected manifold is presented. This spherically symmetric solution has neither curvature singularities nor closed timelike curves. It can be considered to be a regularization of the singular Reissner–Nordström solution over a simply-connected manifold.


Exactly Solvable Extended Potentials in Arbitrary Dimensions

Acta Phys. Pol. B 45, 15 (2014)

DOI: 10.5506/APhysPolB.45.15

article page: 15 (contains 14 pages) •

abstract

We apply a simple transformation method to construct a set of new exactly solvable potentials (ESP) which gives rise to bound state solution of the \(D\)-dimensional Schrödinger equation. The important property of such exactly solvable quantum systems is that their normalized eigenfunctions can be written in terms of recently introduced exceptional orthogonal polynomials (EOP).


The Role of the Potential of a New Bistable System on Stochastic Resonance

Acta Phys. Pol. B 45, 29 (2014)

DOI: 10.5506/APhysPolB.45.29

article page: 29 (contains 13 pages) •

abstract

The phenomenon of stochastic resonance (SR) in a new bistable system is investigated in the presence of periodic force and additive noise. The exact expression of signal-to-noise ratio (SNR) of the new bistable system is obtained. Theoretical analysis and numerical simulation results show that the output SNR is a non-monotonic function of the noise intensity. The influence of parameters of system on SR is studied, moreover, the relationship between the barrier height of potential and the performance of SR is discussed. The target of this work is to explore the influence of the shape of potential function on SR and give a tool when dealing with particle diffusion, SR control and information processing.


Cost-benefit Analysis of Epidemics Spreading on Clustered Random Networks

Acta Phys. Pol. B 45, 43 (2014)

DOI: 10.5506/APhysPolB.45.43

article page: 43 (contains 18 pages) •

abstract

We study, control of infectious disease epidemics spreading on random networks with different levels of clustering. We use Gleeson’s et al. , Phys. Rev. E80, 036107 (2009) algorithm to create clustered networks in which a proportion of individuals is located in fully-connected cliques of certain size. A SIR model is extended to include delayed and imperfect detection of infectious individuals. We also include a combination of responsive (palliative) and preventive (vaccination) treatments and design cost-effective disease control strategies. Cost-benefit analysis is used in combination with epidemiological simulations to identify an optimal radius for a treatment centred upon the symptomatic individual. Three general control strategies occur depending on the relative cost of treatment and prevention. Network topology and, in particular, clustering also affects the applicability of the control strategy. The average path length appears to be more important; the range for the control strategy is wider with the length, but the optimal radius of control also extends. As the proportion of individuals in cliques and therefore the coefficient of clustering is higher, the range of the costs for which control scenario is optimal is greater. This results have important consequences for designing disease control strategies that also satisfy economic optimality criteria.


Constraints on Neutrino Mass Ordering and Degeneracy from Planck and Neutrino-less Double Beta Decay

Acta Phys. Pol. B 45, 61 (2014)

DOI: 10.5506/APhysPolB.45.61

article page: 61 (contains 9 pages) •

abstract

We investigate constraints on neutrino mass ordering and degeneracy by considering the first cosmological result based on the Planck measurements of the cosmic microwave background. It is shown that the result at 95% C.L. rejects a neutrino mass degeneracy larger than 85% (82.5%) for the normal (inverted) hierarchical case. We can also find some regions where the neutrino mass ordering will be able to be distinguished by combining a value of sum of the neutrino masses with an effective neutrino mass determined by neutrino-less double beta decay experiments. The results are obtained from the latest data of neutrino oscillation, cosmic microwave background, and the neutrino-less double beta decay experiments. These have significance in the discrimination of the neutrino mass ordering.


The LHC Excess of Four-lepton Events Interpreted as Higgs-boson Signal: Background from Double Drell–Yan Process?

Acta Phys. Pol. B 45, 71 (2014)

DOI: 10.5506/APhysPolB.45.71

article page: 71 (contains 17 pages) •

abstract

We construct a simple model of the Double Drell–Yan Process (DDYP) for proton–proton collisions and investigate its possible contribution to the background for the Higgs-boson searches at the LHC. We demonstrate that under the assumption of the predominance of short range, \({\cal O}(0.1)\) fm, transverse-plane correlations of quark–antiquark pairs within the proton, this contribution becomes important and may even explain the observed excess of the four-lepton events at the LHC — the events interpreted as originating from the Higgs-boson decays: \(H\rightarrow ZZ^{*} \rightarrow 4l\) and \(H\rightarrow WW^{*}\rightarrow 2l 2\nu \).


Initial State Characteristics of Proton–Nucleus and Nucleus–Nucleus Collisions from Glauber Monte Carlo

Acta Phys. Pol. B 45, 89 (2014)

DOI: 10.5506/APhysPolB.45.89

article page: 89 (contains 28 pages) •

abstract

Fluctuations in physics observables in heavy-ion collisions have been a topic of particular interest in recent years as they may provide important signals regarding the formation of quark-gluon plasma and the existence of a critical point. We provide predictions for basic initial state characteristics of proton–nucleus and nucleus–nucleus collisions from Glauber Monte Carlo models. The following systems were simulated and analysed: \(p+^{12}\)C, \(p+^{14}\)N, \(p+^{63}\)Cu, \(p+^{208}\)Pb, \(^7\)Be\(+^9\)Be, \(^{40}\)Ar\(+^{40}\)Ca, \(^{40}\)Ar\(+^{45}\)Sc, \(^{63}\)Cu\(+^{63}\)Cu, \(^{129}\)Xe\(+^{139}\)La and \(^{208}\)Pb\(+^{208}\)Pb at wide energy range. We apply GLISSANDO accordingly fitted to tasks defined in this paper.


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