Unexpected properties of recently discovered mesons DsJ(2317) and DsJ(2460) have caused an excitement in the high energy community. These mesons are under experimental study in BaBar, Belle and CLEO. The experimental data on these mesons is quite limited at the moment, but it is expected to be improved in the following years. The unexpected properties of these mesons, such as the low mass, and small width, have caused speculations about their structure. Various models have been proposed which go beyond the simple quark-antiquark picture of the mesons, such as a meson molecule, or a four-quark state. Therefore, understanding the underlying structure of these mesons can reveal a deeper understanding of QCD. In this thesis, the strong decay of the DsJ(2317) meson, DsJ(2317)--&gt / Dspi0, is studied using three-point QCD Sum Rules method in the conventional cs framework. DsJ(2317) -&gt / Dspi0 decay violates isospin symmetry. Therefore, this decay is studied as a two stage process / an isospin conserving DsJ(2317) --&gt / Ds eta decay followed by the conversion of eta into a pi0 due to isospin violation.

The recently discovered DsJ(2317) and DsJ(2460) mesons had stimulated many theoretical and experimental studies due to their unexpected properties. In this thesis, we make a review of the predictions on the properties of these mesons using the quark model and QCD Sum Rules. We studied different models about the structure of these mesons, which are suggested because of their unexpected properties. Moreover, using the quark model which implies that the structure of DsJ meson as cs and QCD Sum Rules method, we investigated the semileptonic decay DsJ(2317)--&gt / D0 l nu.

Foundational problems of quantum theory, regarding the appearance of classicality and the measurement problem are stated and their link to studies of open quantum systems is discussed. This study&#039 / s main aim is to analyze the main approaches that are employed in the context of open quantum systems. The general form of Markovian master equations are derived by a constructive approach. The Quantum State Diffusion (QSD) formalism is stressed upon as an alternative method to the master equations. Using the Caldeira-Leggett model in the context of QSD, stationary solutions of a charged particle exposed to a uniform magnetic field are found. The important points are summarized and the results are discussed.

Hexagonal boron nitride (h-BN) thin films are deposited by plasma enhanced chemical vapor deposition (PECVD). Effects of heat treatment and source gases on the structure and physical properties are investigated. Chemical bonding is analyzed in comparison with the better understood isoelectronic carbon compound, graphite. It seems that the basic difference between h-BN and graphite arises from the different electronegativities of boron and nitrogen atoms. Optical absorptions in UV-visible range for crystalline and amorphous structures are outlined. The expressions used for the evaluation of mechanical stress induced in thin films are derived. The deposited films are considered to be turbostratic as they do not exhibit the characteristic optical absorption spectra of a crystal. A new system, stylus profilometer, is implemented and installed for thin film thickness and mechanical stress measurements. Hydrogen atom density within the films, estimated from FTIR spectroscopy, is found to be a major factor affecting the order and mechanical stress of the films. Heat treatment of the films reduces the hydrogen content, does not affect the optical gap and slightly increases the Urbach energy probably due to an increased disorder. Increasing the nitrogen gas flow rate in the source gas results in more ordered films. The virtual crystal of these films is detected to be unique. Relative bond concentrations of the constituent elements indicate a ternary boron-oxygen-nitrogen structure. The physical properties of h-BN such as high resistivity and wide band gap seem suitable for optoelectronic applications such as gate dielectrics in thin film transistors and light emitting devices in the blue region.

This thesis proposes algorithms to construct various nanosystems such as nanotori, nanogear and nanojunctions based on graphite type structures, exploiting the observed pentagonal and heptagonal defects. These produced systems are then simulated to test for their thermal stability and for their electronic properties. A brief review of the methods used is also included.

Applications of semiconductor nanocrystal in electronics are promising. Various techniques were developed to synthesize and analyze semiconductor nanocrystals for integrated circuit applications. In this study, silicon and germanium nanocrystals were synthesized in silicon dioxide matrix by magnetron sputtering deposition and following high temperature furnace annealing. Multilayer and single layer samples were prepared by co-sputtering depositions. Transmission electron microscopy measurements were carried out to analyze annealing effects on nanocrystal size distribution, change in shape, density and localization in silicon dioxide (SiO2). Ge-Ge Traverse Optical (TO) peak was monitored using Raman spectroscopy to investigate germanium nanocrystal formation and stress effects of silicon dioxide. Si-O-Si asymmetric stretching band is examined by Fourier transform infrared transmission spectroscopy to study silicon dioxide matrix recovery with germanium nanocrystal formation. Luminescence characteristics of silicon nanocrystals in visible and near infrared region (550nm-1050nm) with changing nanocrystal size and density were studied with photoluminescence spectroscopy.

Atomic Force Microscopy (AFM) and Kelvin Probe Microscopy (KPM) are two surface characterization methods suitable for semiconductor nanocrystal applications. In this thesis work, an AFM system with KPM capability was developed and implemented. It was observed that, the effect of electrostatic interaction of the probe cantilever with the sample can be significantly reduced by using higher order resonant modes for Kelvin force detection. Germanium nanocrystals were grown on silicon substrate using different growth conditions. Both characterization methods were applied to the nanocrystal samples. Variation of nanocrystal sizes with varying annealing temperature were observed. Kelvin spectroscopy measurements made on nanocrystal samples using the KPM apparatus displayed charging effects.

Being a puzzling feature of quantum mechanics, entanglement caused many debates since the infancy days of quantum theory. But it is the last two decades that it has started to be seen as a resource for physical tasks which are not possible or extremely infeasible to be done classically. Popular examples are quantum cryptography - secure communication based on laws of physics - and quantum computation - an exponential speedup for factoring large integers. On the other hand, with current technological restrictions it seems to be difficult to preserve specific entangled states and to distribute them among distant parties. Therefore a precise measurement of quantum entanglement is necessary. In this thesis, common bipartite and multipartite entanglement measures in the literature are reviewed. Mathematical definitions, proofs of satisfaction of basic axioms and significant properties for each are given as far as possible. For Tangle and Geometric Measure of Entanglement, which is a multipartite measure, results of numerical calculations for some specific states are shown.

In this work, the use of theoretical tools of molecular modeling for tailoring 1D novel nanomaterials is demonstrated. There are four selected nano-structures as examples, each tailored for a specic demand of nano-technology that is yet to be fullled. For the purpose of modeling/calculating the electronic and structural properties, various methods of dening the interatomic interaction, such as empirical potential energy functions, semi-empirical methods and density functional theory, are used. Each of these methods have a dierent level of approximations leading to limitations in their use. Furthermore, each method needs to be calibrated carefully in order to obtain physically meaningful results. Examples being novel nano-structures, there does not exist any experimental observations directly studying the material at hand. Thus, in order to obtain a parameter set that best describes the system, a series of pre-existing structures that are physically and/or chemically related are used. Among the methods employed, the density functional theory (DFT) is certainly the most popular one, due to its accuracy and more importantly the framework it provides for perturbative extensions otherwise nearly impossible to calculate in Hartree-Fock level.

Supersymmetry (SUSY) is the most motivated scenario beyond the Standard Model (SM) addressing the problems of the SM in an elegant way by establishing a symmetry which relates matter particles to interaction particles and vice versa. The simplest phenomenologically viable supersymmetric theory is the Minimal Supersymmetric Standard Model (MSSM) which can be accommodated to minimal Supergravity (mSuGra) theory in order to both take gravity into account and constrain its parameter space. CMS detector is one of the general purpose detectors constructed at LHC (Large Hadron Collider) which targets to search for SUSY signal. This thesis presents a search strategy for SUSY in three different fully hadronic jet topologies with the CMS detector. Di-jet, 3-jet, and 4-jet event topologies offer clear signatures for SUSY searches and the key SUSY decay modes of these jet topologies appear to be squark pair production, squark-gluino production, and gluino pair production, respectively. In these jet topologies, an important kinematical variable named alpha, &amp / #945 / is used to separate SUSY signal test points from the SM background events including QCD, EWK (Electroweak), and invisible decay of Z boson processes. Alpha variables are found to be very useful in terms of enhancing SUSY signal while rejecting all QCD events. Discriminating power of alpha variables are shown in terms of signal-to-background and signal significance calculations and the results are found to be promising which further encourage searches for SUSY signal in jet event topologies with the early CMS data at 1 f b^{&amp / #8722 / 1} integrated luminosity.