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Detail
BukuAn S(3) symmetry of nonrelative quark models and a top-quark seesaw model
Bibliografi
Author: Collins, Hael Switzer ; Georgi, Howard (Advisor)
Topik: PHYSICS; ELEMENTARY PARTICLES AND HIGH ENERGY
Bahasa: (EN )    ISBN: 0-599-36845-4    
Penerbit: Harvard University Press     Tahun Terbit: 1999    
Jenis: Theses - Dissertation
Fulltext: 9935759.pdf (0.0B; 0 download)
Abstract
This work explores problems in three areas of particle physics: electroweak symmetry breaking, the spectrum of the L = 1 baryons and the theory of large N baryons. The first chapter investigates the phenomenological consequences of the top quark seesaw mechanism for breaking electroweak symmetry. We first establish some criteria for a sound top quark seesaw model and then study two models that emerge from these requirements. Both models contain a heavy weak-inert fermion with the same hypercharge as the top quark but the second model contains an additional heavy weak-inert partner for the bottom quark. The low energy spectra of these theories have respectively one and two Higgs doublets. We then show that the current measurements of the rho-parameter require that the heavy fermion in the one doublet model have a mass of 5–7 TeV while in the two doublet model, the heavy partner of the bottom quark must have a mass of at least 10 TeV to agree with the measured decay width of the Z0. The second chapter presents a study of the L = 1 baryons in the quark model and the chiral quark model using an S3 symmetry, which corresponds to permuting the positions of the quarks within a baryon. Given a set of operators with known transformation properties under S3 and the spin-flavor group, the masses of the L = 1 baryons are determined in terms of a small number of unknown parameters. These parameters are fit to the observed mass spectrum for both the quark model and the chiral quark model. The latter model leads to a more satisfactory fit with the measured baryon masses. We also make predictions for the unobserved L = 1 baryons. The final chapter examines the large N limit of the generators of the completely symmetric N index representation of SU(m). In this limit, the group generators behave essentially like classical variables. We use this observation to derive an integral formula for the matrix elements of an arbitrary polynomial of the group generators between low-spin, s-wave baryon states.
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