118344053
Identifying the colour of TeV-scale resonances
A bstractWe explore how the colour of any new TeV-scale resonances that decay into top quark pairs can be identified by studying the dependence of the observed cross-section on a central jet veto. To facilitate this study, colour octet resonance production was implemented in Pythia8 and colour singlet resonance production is simulated after minor modifications. We find that the colour of a 2 TeV resonance can be identified with 10 fb−1 of data at a centre-of-mass energy of 14 TeV for a wide range of couplings, but only if the uncertainty in the theoretical prediction is dramatically reduced from its current level.
56099774
Construction of a Prototype Spark Chamber
A small demonstration spark chamber is to be built at the Cavendish laboratory. A prototype chamber consisting of five 20x22.5cm plates has been built and descriptions of its properties and construction are given, while a second chamber with a somewhat novel design is nearly complete. A discussion of the issues surrounding the final design is presented, and recommendations are made in light of the results of this work.
121385558
Superdense Matter: Neutrons Or Asymptotically Free Quarks?
417786
The Problem Of Scales: Renormalization and All That
I explain the methods that are used in field theory for problems involving typical momenta on two or more widely disparate scales. The principal topics are: (a) renormalization, which treats the problem of taking an ultra-violet cut-off to infinity, (b) the renormalization group, which is used to relate phenomena on different scales, (c) the operator product expansion, which shows how to obtain the asymptotics of amplitudes when some of its external momenta approach infinity.
118784754
QCD aspects of polarized hard scattering processes
I give an overview of what our present knowledge of QCD predicts and does not predict for polarized hard scattering. For experimental programs, a big issue is how much further we can expect our theoretical understanding of QCD to improve.
122932974
Theory problems at small x
It is shown how the standard methods of perturbative QCD are valid to extremely small x. The methods are valid provided a quantity we call the packing fraction of partons in a hadron is much less than one. One surprising consequence is that the cross-section for production of jets of a few GeV energy can be reliably calculated. Since this cross-section in tens of millibarns, the phenomenology of minimum bias events at the SSC will be different than at lower energy; this will have a significant effect on the backgrounds for new physics events. 8 references.
15966703
Fragmentation of transversely polarized quarks probed in transverse momentum distributions
It is shown that the azimuthal dependence of the distribution of hadrons in a quark jet is a probe of the transverse spin of the quark initiating the jet. This results in a new spin-dependent fragmentation function that acts at the twist-2 level. One example of a process where it contributes is semi-inclusive deeply inelastic scattering with a transversely polarized nucleon target but with an unpolarized electron beam. This process is treated in detail. Another process in the cross section for singly polarized hadron-hadron scattering when two high-p ⊥ hadrons are measured in the final state and are close to back-to-back in azimuth. The new fragmentation function is sensitive to the coupling of the fragmentation process to (spontaneous) chiral symmetry breaking.