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William Palmer currently is working on a program of B-physics tests
of the Standard Model, with a view to estimating branching ratios, polarization,
angular correlations, CKM parameter measurements, and CP-violation signals.
With collaborators G. Kramer, T. Mannel, E. Paschos, H. Simma, B. Stech and Y-L. Wu, he has worked on non-leptonic and semileptonic, exclusive and inclusive decays, of B and D mesons. He has used variations of the BSW model, quark-parton model, heavy quark effective theory, and the QCD improved effective weak hamiltonian to calculate rate asymmetries, angular correlations, and time dependence of neutral decays. These calculations require estimates of the tree and penguin diagrams, strong phases, and some kind of model for taking hadronic matrix elements. QCD and electroweak one-loop corrections to weak decays yield perturbative strong phases that develop at order alpha_s and alpha. The BSW model improved by HQET form factors and the parton model have been used in semileptonic decays and inclusive B-decays to J/psi to evaluate hadronic matrix elements. In the next years Palmer intends to continue his interests in -meson decays, with a view to improving on the factorization assumption that plagues non-leptonic decay calculations. This is needed to make progress in the study of CP asymmetries, providing an important test of the Standard Model and how it accommodates CP violation. Kramer, Wu
and Palmer investigated the influence of strong and electroweak penguin
amplitudes in the decay of neutral B-mesons to positive and negative pions
in connection with the determination of the unitarity triangle angle alpha
of the CKM matrix. A relation between the observable asymmetry,
the angle alpha, and the penguin amplitude was established. A model
calculation of the penguin amplitude suggests that the CP asymmetry
in these decays is only mildly influenced by the penguin amplitudes. Experimental
limits on pure penguin and penguin dominated processes are consistent with
the model. This information also suggests in a rather model independent
way that penguin amplitudes will not be a serious complicating factor in
the determination of alpha from the time dependent asymmetry.
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