Regular Series


Vol. 40 (2009), No. 6, pp. 1551 – 1763


Tilted Cylindrically Symmetric Self-Similar Solutions

abstract

This paper is devoted to explore tilted kinematic self-similar solutions of the the general cylindrical symmetric spacetimes. These solutions are of the first, zeroth, second and infinite kinds for the perfect fluid and dust cases. Three different equations of state are used to obtain these solutions. We obtain a total of five independent solutions. The correspondence of these solutions with those already available in the literature is also given.


Probing the Schwarzschild Horizon Temperature

abstract

In this paper using a Gedanken experiment we have measured the black hole horizon temperature. In this process, the total thermal uncertainty is calculated.


Conical Thin Shell Wormhole from Global Monopole: A Theoretical Construction

abstract

By applying ‘Darmois–Israel formalism’, we establish a new class of thin shell wormhole in the context of global monopole resulting from the breaking of a global O(3) symmetry. Since global monopole is asymptotically conical (no longer asymptotically flat), we call it as conical thin shell wormhole. Different characteristics of this conical thin shell wormhole, namely, time evolution of the throat, stability, total amount of exotic matter have been discussed.


Explicit Example of Local Differential Calculus over Fedosov Algebra

abstract

In this paper example of local differential calculus over Fedosov algebra is constructed. The trivialization isomorphism for Fedosov \(*\)-algebra is used. The explicit formulas for deformed derivations are given up to power 2 of formal parameter. The resulting calculus can be considered as a building block for the theory of Seiberg–Witten map with Fedosov type of noncommutativity.


Group Actions as Stroboscopic Maps of Ordinary Differential Equations

abstract

Discrete-time dynamical systems can be derived from group actions. In the present work possibility of application of this method to systems of ordinary differential equations is studied. Invertible group actions are considered as possible candidates for stroboscopic maps of ordinary differential equations. It is shown that flow of the Bloch equation is a unique suspension of an invertible map on the SU(2) group.


Late-Time Evolution of the Gravitating Skyrmion

abstract

We study the dynamics of spherically symmetric solutions in the Einstein–Skyrme model. We focus our attention on generic long-time evolution of initial data resulting in the formation of the \(B=1\) soliton, which plays the role of an attractor. We demonstrate that similarly to the case of flat space evolution, the relaxation to the regular soliton (which we will call Skyrmion) is universal and may be treated as a superposition of two effects — quasinormal oscillations responsible for intermediate asymptotics and a power-law tail describing the behavior of the system at very long times. We determine the values of parameters describing asymptotics and examine their dependence on the value of dimensionless coupling constant of the model.


Excited Quark Production at Future \(\gamma p\) Colliders

abstract

Excited quark production at future \(\gamma p\) colliders is studied. Namely, \(\gamma p \rightarrow q^{*}X\) with subsequent \(q^{*}\rightarrow gq\) and \(\gamma q \) decay channels are considered. Signatures for discovery of the excited quark and corresponding standard model backgrounds are discussed in detail. Discovery limits for excited quark masses and achievable values of compositeness parameters \(f_s\), \(f\) and \(f\,'\) are determined.


Bounds on the Higgs Mass from Renormalization Group Improved Potential for GWS Model

abstract

The exact value of Higgs boson mass cannot be determined theoretically due to lack of knowledge on the definite value of the Higgs self coupling constant \(\lambda \). Following a result of P. Kielanowski and S.R. Juarez W. that for \(0.369\leq \lambda \,(m_{\rm t})\leq 0.613\) the Standard Model is valid in the whole range \([m_{\rm t},\, E_{\rm GU}=10^{14}\) GeV], we obtain the bounds on the Higgs mass in the effective potential method from the renormalization group improved potential for Glashow–Weinberg–Salam (GWS) model. The above limits for \(\lambda \,(m_{\rm t})\) corresponds to the following Higgs mass bounds 150.4 GeV \(\leq m_{H}\leq 195.9\) GeV for the mass scale \(M=180\) GeV and the bounds are almost independent of the mass scale \((M)\).


Restoration of the Residue Factorizability in the Bound-State Pole by Instanton–Antiinstanton Configurations

abstract

The instanton-antiinstanton contributions to the \(q\overline {q}\) bound state pole in the four-point Green function in the Schwinger Model are calculated. It is shown that these configurations, thanks to the cancellation of all unwanted terms, are responsible for the restoration of the perfect factorizability of the residue.


Evolution Equations of the Truncated Moments of the Parton Densities. A Possible Application

abstract

A possible application of the evolution equation for the truncated Mellin moments to determination of the parton distributions in the nucleon is presented. We find that the reconstruction of the initial parton densities at scale \(Q_0^2\) from their truncated moments at a given scale \(Q^2\) is exact and unique for small number of free parameters (\(\leq 3\)), even for the limited \(x\)-region of experimental data. For larger number of adjustable parameters the obtained fits are not unique and one needs an additional knowledge of the small-\(x\) behaviour of the parton densities to make the reconstruction procedure reliable. We apply successfully our method to HERMES and COMPASS spin-dependent valence quark data.


all authors

K. Ciba, P. Morawski, B. Muryn, A. Oblakowska-Mucha, K. Senderowska, G. Polok, M. Witek

Prospect of the \(\gamma \) CKM Angle Determination from \(B_d^0 \to D^{*\pm } a_1^\mp (1260)\) Decay Process

abstract

The selection efficiencies and approximate background for the \(B_d^0 \to D^{*\pm } a_1^\mp (1260)\) mode are determined from studies based on Monte Carlo generated samples. It was found that evaluated annual rate of such decay events makes a hope for a better than at present precision of the CKM unitary triangle angle measurement. Estimated uncertainties depending on value of the \(\gamma \) angle are \(10.0 \pm 1.1\) for \(\gamma = 40^{\rm o}\), \(7.8 \pm 0.3\) for \(\gamma = 60^{\rm o}\) and finally \(7.0\pm 0.2\) for \(\gamma = 80^{\rm o}\).


A Shell Model Calculation for \(^{52}\)Fe in the Full \(fp\) Space

abstract

We discuss a shell model calculation for \(^{52}\)Fe in the full \(fp\) space using the GXPF1A interaction. Several energy levels for the same angular momentum are obtained. The results for the energy levels and transition rates are compared with previous calculations. Using collective models an attempt is made to classify the spectrum into bands.


Dynamical and Statistical Fragment Production in Heavy-Ion Collisions at Intermediate Energies

abstract

A large set of experimental data was analyzed in terms of characteristic signatures of different interaction as well as product emission scenarios. The analysis confirms that the reaction cross-section appears still dominated by dissipative binary reactions involving the survival of well-defined projectile- and target-like fragments. Consistent with such a “gentle” collision scenario are the Galilei-invariant velocity distributions of charged products featuring statistical emission from two fully accelerated projectile- and target-like fragments. On the other hand, the Galilei-invariant velocity plots reveal the presence of a third effective emission source with velocity intermediate between the velocities of projectile- and target-like fragments. Fragments emitted from the intermediate-velocity source appear to be produced dynamically in the overlap zone of the projectile and target nuclei. The experimental multidimensional joint distributions of neutrons and charged reaction products were found to exhibit several different types of prominent correlation patterns. It makes them a useful tool for probing reactions scenarios, different from the traditional approach of interpreting inclusive yields of individual reaction products.


Comparison Between Rational Chebyshev and Modified Generalized Laguerre Functions Pseudospectral Methods for Solving Lane–Emden and Unsteady Gas Equations

abstract

In this paper we provide a pseudospectral method for Lane–Emden equation which models many phenomena in mathematical physics and astrophysics. We also use this method for solving unsteady gas equation which model unsteady flow of a gas through a semi-infinite porous medium. This approach is based on some orthogonal functions which will be defined. Pseudospectral method reduces the solution of these problems to the solution of systems of algebraic equations. We also compare this work with some other numerical results.


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