Type of Document	Dissertation
Author	Mott, Lonnie James
URN	etd-07202011-181601
Title	Rare Exclusive Dileptonic and Radiative Decays of $Lambda_b$ Baryons in a Quark Model
Degree	Doctor of Philosophy
Department	Physics, Department of
Advisory Committee	Advisor Name Title Winston Roberts Committee Chair Alexander Volya Committee Member Joseph Owens Committee Member Volker Crede Committee Member Michael Ruse University Representative
Keywords	Heavy Hadrons Quark Model Form Factors Rare Decays HQET
Date of Defense	2011-06-27
Availability	unrestricted
Abstract Hadronic form factors for the rare weak transitions $Lambda_{b} ightarrowLambda^{(*)}$ are calculated using a nonrelativistic quark model. The form factors are extracted in two ways. An analytic extraction using single component wave functions (SCA) with the quark current being reduced to its nonrelativistic Pauli form is employed in the first method. In the second method, the form factors are extracted numerically using the full quark model wave function (MCN) with the full relativistic form of the quark current. Both sets of form factors are found to satisfy the relationships expecetd from the heavy quark effective theory (HQET). Differential decay rates, branching ratios and forward-backward asymmetries (FBAs) are calculated for the dileptonic decays $Lambda_{b} ightarrowLambda^{(*)}ell^{+}ell^{-}$, for transitions to both ground state and excited daughter baryons. Inclusion of the long distance contributions from charmonium resonances significantly enhances the decay rates. It is found that in the MCN model the $Lambda(1600)$ mode is the dominant mode in the $mu$ channel when charmonium resonances are considered; the $Lambda(1520)$ mode is also found to have a comparable branching ratio to that of the ground state in the $mu$ channel. It has been found that the FBAs for decays to $Lambda(1115)$, $Lambda(1600)$ and $Lambda(1405)$ are less sensitive to the form of the form factors in certain kinematic regions.
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