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Spinodal Instabilities In Symmetric Nuclear Matter Within A Density-dependent Relativistic Mean-field ApproachDanisman, Betul 01 August 2011 (has links) (PDF)
The nuclear matter liquid-gas phase transition is expected to be a signal of nuclear
spinodal instabilities as a result of density fluctuations. Nuclear spinodal
instabilities in symmetric nuclear matter are studied within a stochastic relativistic
density-dependent model in semi-classical approximation. We use two
parameterization for the Lagrange density, DDME1 and TW sets. The early
growth of density fluctuations is investigated by employing relativistic Vlasov
equation based on QHD and discussed the cluster size of the condensations
from the early growth of density correlation functions. Expectations are that
hot nuclear matter behaves unstable around &rho / b &asymp / &rho / 0/4 (below the saturation
density) and at low temperatures. We therefore present our results at low temperature
T=1 MeV and at higher temperature T=5 MeV, and also at a lower
initial baryon density &rho / b = 0.2 &rho / 0 and a higher value &rho / b = 0.4 &rho / 0 where unstable
behavior is within them.
Calculations in density-dependent model are compared with the other calculations
obtained in a relativistic non-linear model and in a Skyrme type nonivrelativistic model. Our results are consistent with them. Qualitatively similar
results show that the physics of the quantities are model-independent. The size
of clusterization is estimated in two ways, by using half-wavelength of the most
unstable mode and from the width of correlation function at half maximum. Furthermore,
the average speed of condensing fragments during the initial phase of
spinodal decomposition are determined by using the current density correlation
functions.
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Analysis Of Kappa Meson In Light Cone Qcd Sum RulesBaytemir, Gulsen 01 September 2011 (has links) (PDF)
In the present work some hadronic properties of the scalar &kappa / meson are studied.
Using the QCD sum rules approach, which is a nonperturbative method, the
mass and the overlap amplitude of this meson are calculated. As well as the
mass and the overlap amplitude, &kappa / &rarr / K^+&pi / ^&minus / decay is also studied. For this
decay the coupling constant g_&kappa / K^+&pi / ^&minus / is obtained using light cone QCD sum rules
which is an extension of the QCD sum rules method. Moreover, the coupling
constant is calculated using the experimental decay width and it is compared
with the value obtained in light cone QCD sum rules approach. The result of
the calculation of g_&kappa / K^+&pi / ^&minus / , the one obtained from light cone QCD sum rules
approach, is also applied to acquire the f_0 &minus / &sigma / scalar mixing angle, &theta / s, using
the ratio g^2 (&kappa / &rarr / K^+&pi / ^&minus / )/g^2 (&sigma / &rarr / &pi / &pi / ) obtained from experimental decay width.
The value of scalar mixing angle is also compared with its experimental results.
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Theoretische Fragestellungen zur Bewertung von UnternehmenLahmann, Alexander D. F. 31 January 2013 (has links)
Die vorliegende kumulative Dissertationsschrift beschäftigt sich mit theoretischen Fragestellungen der Finanzwissenschaft im Bereich des Asset Pricing und im Detail der Unternehmensbewertung. Dabei wird sowohl auf Problemstellungen der akademischen und praxisnahen Forschung eingegangen. Der erste Artikel beschäftigt sich mit der Fragestellung welche Implikationen die Annahme einer arithmetischen Brownschen Bewegung auf bestimmte Aspekte der Unternehmensbewertung hat. Es folgen drei Artikel die sich auf unterschiedlicher Weise mit der Zinsschrankenregelung auseinandersetzen. Die darauf folgenden zwei Artikel behandeln hauptsächlich die Modellierung von Insolvenz im Rahmen der Unternehmensbewertung bei Annahme verschiedener Finanzierungspolitiken. Der achte Artikel geht näher auf die Thematik der empirischen Bestätigung bestimmter Kapitalstrukturtheorien ein. Die Dissertation schließt mit einem Artikel zu wichtigen Parametern für die Unternehmensbewertung.
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Aktuelle Themen in der UnternehmensbewertungArnold, Sven 31 January 2013 (has links)
Die vorliegende kumulative Dissertationsschrift beschäftigt sich mit finanzwissenschaftlichen Fragestellungen im Bereich der Unternehmensbewertung. Dabei wurden aktuelle Themen diskutiert, die in Theorie oder Praxis ungelöste Probleme darstellen. Hervorzuheben ist an dieser Stelle, dass sich die ersten drei Artikel mit dem Werteinfluss der Zinsschanke auf den Wert von fremdfinanzierungsbedingten Steuerersparnissen (Tax Shield) beschäftigen. Die drei darauf folgenden Artikel beschäftigen sich schwerpunktmäßig mit der konsistenten Modellierung von Finanzierungspolitiken und dem Werteinfluss der Insolvenzmöglichkeit von Unternehmen. Der siebte und achte Artikel haben die Kapitalstruktur und weitere wichtige Parameter für die Unternehmensbewertung zum Thema.
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Ein Beitrag zum Entladungsverhalten langer Luftfunkenstrecken bei Blitzspannung / A Contribution to the Breakdown of Long Air Gaps by Lightning VoltagesShirvani Boroujeni, Ali 26 February 2015 (has links) (PDF)
Für die Menschen zählen Gewitter mit Donner und Blitz zu den ältesten bekannten Phänomenen der Natur. Die Tatsache, dass Blitze dennoch bis heute nicht abschließend erforscht sind, liegt in dem äußerst komplexen, schnellen und stochastischen Verhalten der Blitzentladung begründet.
Der Autor befasste sich in Rahmen dieser Arbeit u.a. mit der Entwicklung eines modernen Messsystems, durch das die Erfassung von sowohl elektrischen als auch optischen Parametern der im Nanosekundenbereich ablaufenden Prozesse der Entladungen möglich wurde. Es handelt sich um technisch anspruchsvolle Messungen von hohen Stoßspannungen und schwachen Vorentladungsströmen in einem großen Frequenzbereich. Außerdem gelang es durch eine geschickte Synchronisation, die Entladungsprozesse präzise und erstmalig in einer Fotosequenz aufzunehmen.
Auf Grundlage der Messergebnisse konnte der Entladungsprozess in mehrere Phasen der Vorentladung unterteilt und beschrieben werden. Vor allem beweisen die Messergebnisse die Existenz einer kanalartigen Vorentladung, die nicht zwingend zu einem Durchschlag führt. Dieser Mechanismus, der bei langsam ansteigenden Spannungen als stabile Leaderentladung benannt und mit Thermoionisation gekennzeichnet ist, war bei Blitzstoßspannungen bisher umstritten. / The breakdown behavior of long air gaps by Lightning Voltages has been investigated and the results of a new measurement system are reported. A series of up to eight photos (made by a high-speed camera) have recorded the expansion of discharge activities during the breakdown process. The pre-discharge current and voltage have been measured as well. The modern measurement techniques have made possible the synchronization of the photos with the current and voltage measurements in nanosecond-ranges. The combination of the measured current, voltage, and photos can precisely explain the breakdown process.
The experiments have been carried out with the lightning impulses up to 2.4 MV and the air gaps up to 4 m. Despite of such high voltages, the experimental system has been verified to be appropriate for measuring the pre-discharge current in mA-ranges.
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The Inclusive Semileptonic Decays Of The B-meson In A Cp Softly Broken Two Higgs Doublet ModelAcar, Hilal 01 January 2004 (has links) (PDF)
In this work, the B-> / X_dell ell decays are examined in the context of a
CP softly broken two Higgs doublet model. The differential
branching ratio, forward-backward asymmetry, CP-violating
asymmetry, CP-violating asymmetry in the forward-backward
asymmetry and polarization asymmetries of the final lepton in this
decay are studied. The dependencies of these physical parameters
on the model parameters are analyzed by paying a special attention
to the effects of neutral Higgs boson (NHB) exchanges and possible
CP violating effects. It has been found that NHB effects are
quite significant for the tau mode and the above-mentioned
observables seems to be promising as a testing ground for new
physics beyond the SM, especially for the existence of the
CP-violating phase in the theory.
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Nuclear Dissipative Dynamics In Langevin ApproachTanriverdi, Vedat 01 June 2004 (has links) (PDF)
In this thesis Langevin approach is applied to analyze the nuclear
dissipative dynamics in fission and fusion reactions. In these
investigations, the nuclear elongation coordinate and the
corresponding momentum are chosen as collective variables. By
considering changes in these variables the decay rate of fission
and the formation probability of fusion for heavy ion reactions
are calculated. These calculations are performed using simulation
techniques and the results thus obtained are compared with the
corresponding results of analytic solutions.
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Multidimensional Quantum Tunnelling Formulation Of Oxygen-16 And Uranium-238 ReactionAtaol, Murat Tamer 01 June 2004 (has links) (PDF)
Multidimensional quantum tunnelling is an important tool that is used in many areas of physics and chemistry. Sub-barrier fusion reactions of heavy-ions are governed by quantum tunnelling. However, the complexity of the structures of
heavy-ions does not allow us to use simple one-dimensional tunnelling equations to and the tunnelling probabilities. Instead of this one should consider all the degrees of freedom which affect the phenomenon and accordingly the intrinsic
structure or the deformation of the nuclei must be taken into account in the modelling of heavy-ion fusion. These extra degrees of freedom result in a coupling potential term in the Schrodinger equation of the fusing system. In this thesis
16O + 238 U system is considered. Only the rotational deformation of Uranium is assumed and the coupling potential term is calculated for this system by using two diffrent potential types, namely the Woods-Saxon potential and the double folding potential. Using this term in the Schrodinger equation fusion probability and theoretical cross section are calculated. A discussion that addresses then necessity of multidimensional formulation is given. Besides this point the effects of the choice of the potential type are shown.
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Matrix Quantum Mechanics And Integrable SystemsPehlivan, Yamac 01 July 2004 (has links) (PDF)
In this thesis we improve and extend an algebraic technique pioneered by M. Gaudin. The technique is based on an infinite dimensional Lie algebra and a related family of mutually commuting Hamiltonians. In order to find energy eigenvalues of such Hamiltonians one has to solve the equations of Bethe ansatz. However, in most cases analytical solutions are not available. In this study we examine a special case for which analytical solutions of Bethe ansatz equations are not needed. Instead, some special properties of these equations are utilized to evaluate the energy eigenvalues. We use this method to find exact expressions for the energy eigenvalues of a class of interacting boson models.
In addition to that, we also introduce a q-deformation of the algebra of Gaudin. This deformation leads us to another family of mutually commuting Hamiltonians which we diagonalize using algebraic Bethe ansatz technique. The motivation for this deformation comes from a relationship between Gaudin algebra and a spin extension of the integrable model of F. Calogero. Observing this relation, we then consider a well known periodic version of Calogero' / s model which is due to B. Sutherland. The search for a Gaudin-like algebraic structure which is in a similar relationship with the spin extension of Sutherland' / s model naturally leads to the above mentioned q-deformation of Gaudin algebra. The deformation parameter q and the periodicity d of the Sutherland model are related by the formula q=i{pi}/d.
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The Polarization Properties Of The Final State Particles In The Rare Radiative B-meson DecayYilmaz, Umit Oktay 01 May 2005 (has links) (PDF)
A general analysis of the photon and lepton polarizations in the rare Bs & / #8594 / & / #61543 / l+l- decay by using the most general model independent form of the effective Hamiltonian is presented. The total and the differential branching ratios for these decays, when photon is in the positive and negative helicity states, are studied. The sensitivity of " / photon polarization asymmetry" / and the longitudinal, transverse and normal polarization asymmetries of final state leptons, as well as lepton-antilepton combined asymmetries in Bs & / #8594 / & / #61543 / l+l- decay to the new Wilson coefficients are also investigated.
It is shown that all these physical observables are very sensitive to the existence of new physics beyond SM and their experimental measurements can give valuable information about it.
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