Regular Series


Vol. 46 (2015), No. 2, pp. 217 – 327


Neutrino-assisted Fermion–Boson Transitions

abstract

We study fermion–boson transitions. Our approach is based on the \(3\times 3\) subequations of Dirac and Duffin–Kemmer–Petiau equations, which link these equations. We demonstrate that free Dirac equation can be invertibly converted to spin-\(0\) Duffin–Kemmer–Petiau equation in the presence of a neutrino field. We also show that in special external fields, upon assuming again existence of a neutrino (Weyl) spinor, the Dirac equation can be transformed reversibly to spin-\(0\) Duffin–Kemmer–Petiau equation. We argue that such boson–fermions transitions are consistent with the main channel of pion decay.


Nonlocal Random Motions and the Trapping Problem

abstract

Lévy stable (jump-type) processes are examples of intrinsically nonlocal random motions. This property becomes a serious obstacle if one attempts to model conditions under which a particular Lévy process may be subject to physically implementable manipulations, whose ultimate goal is to confine the random motion in a spatially finite, possibly mesoscopic trap. We analyze this issue for an exemplary case of the Cauchy process in a finite interval. Qualitatively, our observations extend to general jump-type processes that are driven by non-Gaussian noises, classified by the integral part of the Lévy–Khintchine formula. For clarity of arguments, we discuss, as a reference model, the classic case of the Brownian motion in the interval.


Wilson Loops with Arbitrary Charges

abstract

We discuss how to implement, in lattice gauge theories, external charges which are not commensurate with an elementary gauge coupling. It is shown that an arbitrary, real power of a standard Wilson loop (or Polyakov line) can be defined and consistently computed in lattice formulation of Abelian, two dimensional gauge theories. However, such an observable can excite quantum states with integer fluxes only. Since the non-integer fluxes are not in the spectrum of the theory, they cannot be created, no matter which observable is chosen. Also the continuum limit of above averages does not exist unless the powers in question are, in fact, integer. On the other hand, a new continuum limit exists, which is rather intuitive, and where above observables make perfect sense and lead to the string tension proportional to the square of arbitrary (non-necessary commensurate with gauge coupling) charge.

Version corrected according to Erratum Acta Phys. Pol. B 46, 905 (2015)


all authors

M. Battaglieri, B.J. Briscoe, A. Celentano, S.-U. Chung, A. D'Angelo, R. De Vita, M. Döring, J.J. Dudek, S. Eidelman, S. Fegan, J. Ferretti, A. Filippi, G. Fox, G. Galata, H. García-Tecocoatzi, D.I. Glazier, B. Grube, C. Hanhart, M. Hoferichter, S.M. Hughes, D.G. Ireland, B. Ketzer, F.J. Klein, B. Kubis, B. Liu, P. Masjuan, V. Mathieu, B. McKinnon, R. Mitchel, F. Nerling, S. Paul, J.R. Peláez, J. Rademacker, A. Rizzo, C. Salgado, E. Santopinto, A.V. Sarantsev, T. Sato, T. Schlüter, M.L.L. da Silva, I. Stankovic, I. Strakovsky, A. Szczepaniak, A. Vassallo, N.K. Walford, D.P. Watts, L. Zana

Analysis Tools for Next-Generation Hadron Spectroscopy Experiments

abstract

The series of workshops on New Partial-Wave Analysis Tools for Next-Generation Hadron Spectroscopy Experiments was initiated with the ATHOS 2012 meeting, which took place in Camogli, Italy, June 20–22, 2012. It was followed by ATHOS 2013 in Kloster Seeon near Munich, Germany, May 21–24, 2013. The third, ATHOS3, meeting is planned for April 13–17, 2015 at The George Washington University Virginia Science and Technology Campus, USA. The workshops focus on the development of amplitude analysis tools for meson and baryon spectroscopy, and complement other programs in hadron spectroscopy organized in the recent past including the INT-JLab Workshop on Hadron Spectroscopy in Seattle in 2009, the International Workshop on Amplitude Analysis in Hadron Spectroscopy at the ECT*-Trento in 2011, the School on Amplitude Analysis in Modern Physics in Bad Honnef in 2011, the Jefferson Lab Advanced Study Institute Summer School in 2012, and the School on Concepts of Modern Amplitude Analysis Techniques in Flecken-Zechlin near Berlin in September 2013. The aim of this document is to summarize the discussions that took place at the ATHOS 2012 and ATHOS 2013 meetings. We do not attempt a comprehensive review of the field of amplitude analysis, but offer a collection of thoughts that we hope may lay the ground for such a document. The material presented in the article was edited by the following Editorial Board: Marco Battaglieri, Bill J. Briscoe, Su-Urk Chung, Michael Döring, JĂłzef Dudek, Geoffrey Fox, Christoph Hanhart, Martin Hoferichter, David G. Ireland, Bernhard Ketzer, Bastian Kubis, Vincent Mathieu, Ryan Mitchell, José R. Peláez, Elena Santopinto, Adam Szczepaniak.


Impact of Structural Centrality Based Attacks in Complex Networks

abstract

In this paper, we study a new strategy to find the influential nodes in the complex networks. This strategy is based on Structural Centrality (SC) of the node in the network. In this strategy, by using graph spectral analysis of the network, we find the hierarchy of the influential nodes in the form of central nodes in the network. The structural centrality of each node is ranked in the topology of complex networks which are modeled as the scale free networks. We have explored the structural centrality based targeted attack and compared our result with the degree based targeted attack. The robustness of the real world complex network has been measured efficiently against the degree, structural centrality based targeted attack and compared with the random attack and compared it. In the social networks, the mechanism to suppress the harmful rumors is of great importance. A rumor spreading model has been defined using the susceptible-infected-refractory (SIR) model to characterize the rumor propagation in the social networks. Inoculation strategy based on the structural centrality has been applied on the rumor spreading model for the heterogeneous networks. It is compared with the random and degree based targeted inoculations. The nodes with higher structural centrality are chosen for the inoculation in the proposed strategy. The structural centrality based targeted inoculation strategy is found to be more efficient in comparison to the random and degree based targeted inoculation strategies. One of the bottlenecks of this approach is the high complexity in computing the structural centrality of the nodes in the complex networks with very large number of nodes. Further, appearance of giant component has been studied in the network with random attacks, and degree and structural centrality based attacks. The proposed hypothesis has been verified using simulation results for e-mail network data and also for the generated scale free networks.


ERRATUM for Acta Phys. Pol. B 46, 133 (2015)

Luminosity Determination for the Deutron–Deutron Reactions Using Free and Quasi-free Reactions with WASA-at-COSY Detector


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