Hadronic form factors for semileptonic decay of the Λ[subscript c] are calculated in a nonrelativistic quark model. The full quark model wave functions are employed to numerically calculate the form factors to all orders in (1/m[subscript c], 1/m[subscript s]). The form factors satisfy relationships expected from the heavy quark effective theory (HQET) form factors. No other semileptonic decays of Λ[subscript c] has been reported other than the decay to the ground state Λ that implies f = B(Λ[subscript c]⁺ → Λl⁺ν[subscript l])/B(Λ[subscript c]⁺ → X[subscript s]l⁺ν[subscript l]) = 1. In this work, the differential decay rates and branching fractions are calculated for transitions to the ground state and a number of excited states of Λ. The branching fraction of the semileptonic decay width to the total width of Λ[subscript c] has been calculated and compared with other theoretical estimates and experimental results. The branching fractions for Λ[subscript c] → Λ*l⁺ν[subscript l] → Σπl⁺ν[subscript l] and Λ[subscript c] → Λ*l⁺ν[subscript l] → NǨl⁺ν[subscript l] are also calculated. Apart from decays to the ground state Λ(1115), it is found that decays through the Λ(1405) provide a significant portion of the branching fraction Λ[subscript c] → X[subscript s]lν[subscript l]. There are various conjectures on the structure of the Λ(1405) while we treated it as a three quark state. A new estimate for f = B(Λ[subscript c]⁺ → Λl⁺ν[subscript l] is obtained. / A Dissertation submitted to the Department of Physics in partial fulfillment of the requirements for the degree of Doctor of Philosophy. / Spring Semester 2017. / March 20, 2017. / Includes bibliographical references. / Winston Roberts, Professor Directing Dissertation; Kenneth Goldsby, University Representative; Alexander Volya, Committee Member; Volker Crede, Committee Member; Joseph Owens, Committee Member.

No description available.

No description available.

In this thesis we present three distinct contributions to the study of light flavor physics using the techniques of lattice QCD. These results are arranged into four self-contained papers. The first two papers concern global fits of the quark mass, lattice spacing, and finite volume dependence of the pseudoscalar meson masses and decay constants, computed in a series of lattice QCD simulations, to partially quenched SU(2) and SU(3) chiral perturbation theory (χPT). These fits determine a subset of the low energy constants of chiral perturbation theory — in some cases with increased precision, and in other cases for the first time — which, once determined, can be used to compute other observables and amplitudes in χPT. We also use our formalism to self-consistently probe the behavior of the (asymptotic) chiral expansion as a function of the quark masses by repeating the fits with different subsets of the data. The third paper concerns the first lattice QCD calculation of the semileptonic K0 → π −` +ν` (K`3) form factor at vanishing momentum transfer, f Kπ + (0), with physical mass domain wall quarks. The value of this form factor can be combined with a Standard Model analysis of the experimentally measured K0 → π −` +ν` decay rate to extract a precise value of the Cabibbo-Kobayashi-Maskawa (CKM) matrix element Vus, and to test unitarity of the CKM matrix. We also discuss lattice calculations of the pion and kaon decay constants, which can be used to extract Vud through an analogous Standard Model analysis of experimental constraints on leptonic pion and kaon decays. The final paper explores the recently proposed exact one flavor algorithm (EOFA). This algorithm has been shown to drastically reduce the memory footprint required to simulate single quark flavors on the lattice relative to the widely used rational hybrid Monte Carlo (RHMC) algorithm, while also offering modest O(20%) speed-ups. We independently derive the exact one flavor action, explore its equivalence to the RHMC action, and demonstrate that additional preconditioning techniques can be used to significantly accelerate EOFA simulations. We apply EOFA to the ongoing RBC/UKQCD calculation of the ∆I = 1/2 K → ππ decay amplitude, and demonstrate that, in this context, gauge field configurations can be generated a factor of 4.2 times faster using an EOFAbased simulation rather than the previous RHMC-based simulations. We expect that EOFA will help to significantly reduce the statistical error in the first-principles determination of the Standard Model CP-violation parameters ε and ε′ offered by the K → ππ calculation.

Thesis (Ph. D.)--Carleton University, 2003. / Includes bibliographical references (p. 138-146). Also available in electronic format on the Internet.

No description available.

Digitized by Kansas State University Libraries

published_or_final_version / Physics / Doctoral / Doctor of Philosophy

We present an analysis of the formation of charmonium resonances of heavy quark pairs immersed in a deconfined environment for a finite time interval. This is intended to model the J/ψ suppression due to the possible formation of a color screening quark gluon plasma in heavy ion collisions. In particular, we examine how the the χ(c) and J/ψ states are affected in a quantum mechanical suppression model. We then investigate how the momentum dependence of the fraction of J/ψ's that come from radiative χ(c) decays or that are directly created can affect the momentum dependence of the resulting J/ψ suppression. We examine under what circumstances could this suppression momentum dependence be enhanced. This is of interest since previous quantum mechanical analyses have failed to model the strong momentum dependence observed in heavy ion collisions.

We use the nonperturbative techniques of current algebra and PCAC (partial conservation of axial-vector currents) to compute the nonleptonic weak decays K → 2π and 3π, as well as the two-body and nonresonant three-body decays of the charmed D and F(D(s)) mesons. In the case of two-body decays, the constituent quark model is employed to calculate the resulting unphysical meson-meson reduced matrix elements. Using an analogous current algebra - PCAC prescription, the three-body meson decays are expressed in terms of the previously determined two-body amplitudes. We utilize the pole model to extract baryon-baryon reduced matrix elements from the B → B' π and B'γ weak decays, which are then also computed in the constituent quark model. We make predictions for more than sixty decays with essentially no free parameters and, in most cases, find reasonable agreement with the data.