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No description available.

No description available.

No description available.

No description available.

The recent discovery of a new maximally supersymmetric background for the type IIB superstring theory has revived the interest in light cone string field theory. This background is a plane wave background with the additional support of a non- trivial self dual Ramond-Ramond 5-form field strength. It can be quantised in the light cone gauge and hence it naturally fits into the framework of light cone string field theory. In this thesis we re-examine the causality and locality properties of string theory in the flat background and compare it with the recent results for string theory in this plane wave background. We formulate the causality requirement in terms of the commutativity of the string field, as it is usually done in point particle field theory. We find that the string light cone in the plane wave background shares similar properties with the string light cone in the flat background. Even more interesting is that, unlike the flat background theory, string interactions in the plane wave background do not modify the causal structure of the theory. This has interesting consequences for the choice of the 3-string vertex in the plane wave background, a topic that is still an active subject of research.

The start of data taking at the Large Hadron Collider should make a new frontier in particle physics accessible for the first time. The ATLAS experiment has been designed to take advantage of this opportunity to complete the standard model, whilst having the maximum possible sensitivity to the new physics. The alignment accuracy of the Silicon tracking detectors will be vital if ATLAS is to contribute optimally to precision and discovery physics. In response to this difficult challenge, a novel laser alignment system that can precisely measure 842 lengths between grid nodes attached to the detector support structure has been developed. Each of the lengths is monitored remotely via interferometry and this thesis reports on the punched corner cube retroreflectors that form the end nodes of each interferometer grid line. The development of a process to successfully manufacture, and to ensure the finished quality of, approximately 700 retroreflectors is reported. Optical surface profileometry of retroreflector surfaces has been used to investigate the flatness and angles between reflecting faces. A detailed optical simulation has modelled the observed features in the diffraction patterns from a variety of real retroreflectors. Additionally a method to calibrate B-field scale factors, for the solenoid tracking volume, based on Z-boson decay products is reported. The algorithm is able to retrieve applied changes to the magnetic field in 7]-binned regions of the tracking volume. The stability of the calibration algorithm is tested for 50'000 Z ~ f.1+ 11- decays.

The first part of this thesis is concerned with the companion equations. These are equations of motion for the companion Lagrangian which is proposed to be the Lagrangian for a field theory associated with strings and branes, similar to the Klein-Gordon field description for particles. The form of this Lagrangian can be related to the Hamilton-Jacobi formalism for strings and branes. Some solutions to the companion equations are found and their integrability is discussed. There is an equivalence between the equations of motion for different companion Lagrangians when some constraints are applied. Under these constraints, the companion equations for a Lagrangian without a square root are equivalent to the companion equations for a Lagrangian with a square root but in one dimension less. The appearance of Universal Field Equations, generalised Bateman equations, in the companion equations leads to the study of an iterative procedure for Lagrangians which are homogeneous of weight one in the first derivatives in the fields the theory describes. The Universal Field equations appear after several iterations. Also, it is shown how Lagrangians for a large family of field theories are a divergence or vanish on the space of solutions of the equations of motion. Such theories could be called 'pseudo-topological'.The second part of this thesis is concerned with finding solutions to the Moyal-Nahm equations in four and eight dimensions. These equations are the Nahm equations, which give a set of solutions to self-dual Yang-Mills, but with the commutators replaced with Moyal brackets. Solutions are found in terms of generalised Wigner functions. Also, matrix representations of the algebra generated by the equivalent Nahm equations in eight dimensions are obtained. Solutions to the Nahm equations in eight dimensions are also given.

An account is presented of an experiment performed to study the production of the Ø meson in the reaction π-+ p→K+ + K- + n at beam momenta just above the Ø threshold. The experiment was performed as part of a series of experiments designed to investigate the electron—positron dew mode of the isoscalar vector mesons. A description of the apparatus and its performance, and of the techniques of analysis employed, is given. The detection of the three final state particles and the beam pion was achieved using an arrangement of scintillation counters, Cerenkov counters, and spark chambers. In the mode employed, the system was capable of a high etc— effective mass resolution and a high collection efficiency. The system supplied enough information to allow the complete reconstruction of each event via geometry and kinematics analysis programmes. The experimental distributions of the variables used to parametrize the events were compared with corresponding theoretical distributions generated by Monte Carlo methods according to a specific model. The experimental distributions were compiled from ~ 250 events of the type π-p→K+K—n having K+K— effective masses in the range 986-1050 MeV/c2.

This thesis is a survey of the various high energy aspects of Kp interactions in a liquid hydrogen bubble chamber of an incident Kaon momentum of 10.12 GeV/c. The plan of the thesis is as follows: Chapters 1 and 2 are respectively brief descriptions of the instrumentation and of the data processing system. Chapter 3 deals with the interpretation of the events, biases, errors and estimation of cross-sections. Chapter 4 reviews the various theoretical models of high energy interactions. Chapters 5, 6 and 7 deal with the high energy aspects of elastic, inelastic two-body and quasi-three-body processes respectively, as observed in the present experiment, together with the comparison of the data with the various models available. Chapter 8 is a study of the transverse momentum and related variables in reactions of different multiplicities as observed in the present experiment.