No description available.

No description available.

I review planned searches for the so far unobserved Higgs boson of the Standard Model of High Energy Physics. In particular a light 'intermediate' mass Higgs with mass in the range 80 GeV ≤ M(_H) ≤130 GeV will be hard to detect. I suggest several methods at planned future high energy particle colliders for observing this Higgs boson. At LEP I we have reasonable numbers of Higgs produced in association with a Z boson up to the limit imposed by phase space M(_H) ˂ √s - 100 GeV. Unfortunately if the Higgs is degenerate in mass with the Z boson we have large numbers of background events from double Z production. I investigate possible methods round this background. Firstly in polarizing the initial e+e- beams, and secondly in studying the differing topologies of the ZH signal, and ZZ background events. Moving on to the hadron super colliders the LHC and the SSC. These colliders typically produce very clean signals for 'heavy' Higgs. However for a light "'intermediate* mass Higgs all Higgs decays are either dominated by huge QCD backgrounds; or put very strong constraints upon our experimental apparatus. I investigate the signals and backgrounds for an alternative approach where rather than looking for the Higgs in isolation, we look for it produced in association with other heavy particles. Despite these production mechanisms having a far lower rate than isolated Higgs production they have far better signal to background ratios, which makes them look promising. Two modes in particular appear to give encouraging signals; WH production, and tiH production. Both these production modes can be detected in the isolated lepton and two photon channel.

The Standard Model of particle physics is examined in the context of high energy proton-antiproton collider experiments. The large energies available offer the possibility of producing new particles which may then be observed via their decay. Heavy quark production is examined through the production of unlike-sign lepton pairs. Methods for isolating several dilepton production mechanisms are given, including an eu signal for the top quark. Moreover, ψ production is shown to serve as a particularly clean tag for the production of particles containing b quarks. The possibility of observing a fourth generation heavy lepton via W decay is investigated. The hadronic decay mode leads to a promising signature of large missing accompanied by two hadronic jets and has a very healthy event rate. The monojet events found by the UA1 experiment are reviewed. Various extensions of the Standard Model are examined as possible explanations of these events. The first interpretation involves the production of SUSY particles. These are found to be compatible with the data if two squarks exist with mass 0(30GeV) and the gluino has mass > 0(60GeV). Secondly, interpretations based on four point effective interactions of the form qqZg are investigated, and are shown to be unable to account for the observed monojet rate. Finally, the production and decay of new heavy states (for example excited quarks) could account for the monojet data, but are found to predict large numbers of W + jet and γ + jet events which have not been seen.

Composite models of quarks, leptons and weak bosons are reviewed. It is shown that they can reproduce the low energy results of the Standard Weinberg-Salam Model of electroweak interactions. The consequences of assuming composite W and Z bosons are examined and many new particles are predicted, including excited W and Z states and their pseudoscalar partners. Estimates of the masses and decay widths of these particles are given. It is also shown that coloured weak bosons may exist in the energy range 100-200 GeV. The decays of a composite Z boson are studied in detail using both a potential model and an effective Lagrangian approach. It is found that the width is likely to be significantly different from that of the elementary Z of the Standard Model, In particular there are additional contributions to the decays Z → qqg and Z → ggg which are likely to affect the total Z width by an appreciable amount. The decay of the Z into hypercoloured particles is also examined and it is found that the width is likely to exceed greatly the current experimental bound. It is concluded that the W and Z bosons are likely to be elementary particles because if they were composite their decay widths would be much greater than is found experimentally, unless of course their internal dynamics are quite unlike the model which has been employed.

The measurement of isotopic ratios by inductively coupled plasma mass spectrometry (ICP-MS) has the benefits of ionising all metallic elements, simplifying sample preparation and reducing analysis time, when compared with thermal ionisation mass spectrometry (TIMS). However, the use of ICP-MS in isotopic ratio studies has been somewhat restricted by Its failure to offer the precision and accuracy required by a variety of applications. The precision achievable by ICPMS, typically 0.2 to 0.3 % RSD, for isotopic ratios, has generally been regarded as being primarily limited by instrumental instability. An investigation of the sources of instrumental noise in ICP-MS has been undertaken, utilising noise spectral analysis as a diagnostic md Study of parametric variation upon noise production has identified the methods by which modulation of the ion signal occurs Noise spectral analysis has allowed an understanding of the limitations imposed upon measurement precision by the various contributing noise sources to be established The key to improved measurement precision has been found to lie in the development of data acquisition methods which allow the predominant sources of instrumental noise to be effectively filtered from the ion signal The methodology developed for sequential measurement of isotopes, using a quadrupole mass analyser, to reduce the deleterious influences of instrumental noise is discussed. Results are given for isotopic ratio measurement which demonstrate that a precision of approximately 0 05 % RSD can be attained The factors which affect the accuracy of isotopic ratio measurement are shown to be many and varied and depend to a large extent on the particular Isotopes bemg studied Definition of an appropriate measurement strategy for high accuracy isotope ratio measurement involves consideration of all possible causes of bias and adoption of methods for their elimination or correction. To facilitate this process a protocol has been developed and subsequently applied to various elements and instrument systems.

No description available.

No description available.

No description available.

<p>This thesis discusses the process of extracting the longitudinal asymmetry, $A_L</p><p>{W\pm}$, describing $W\rightarrow\mu$ production in forward kinematic regimes. This asymmetry is used to constrain our understanding of the polarized parton distribution functions characterizing $\bar{u}$ and $\bar{d}$ sea quarks in the proton. This asymmetry will be used to constrain the overall contribution of the sea-quarks to the total proton spin. The asymmetry is evaluated over the pseudorapidity range of the PHENIX Muon Arms, $2.1 < |\eta|2.6$, for longitudinally polarized proton-proton collisions at 510 GeV $\sqrt{s}$. In particular, I will discuss the statistical methods used to characterize real muonic $W$ decays and the various background processes is presented, including a discussion of likelihood event selection and the Extended Unbinned Maximum Likelihood fit. These statistical methods serve estimate the yields of $W$ muonic decays, which are used to calculate the longitudinal asymmetry.