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The European Physical Journal C
ISSN: 1434-6044 (printed version)
ISSN: 1434-6052 (electronic version)
Abstract Volume 1 Issue 1/2 (1998) pp 221-233
theoretical physics:
Inclusive semileptonic decays of polarized $\Lambda_b$ Baryons into polarized $\tau$-Leptons
S. Balk (1), J.G. Körner (1), D. Pirjol (2) (a)
(1) Johannes Gutenberg-Universität, Institut für Physik, Staudingerweg 7, D-55099 Mainz, Germany
(2) Department of Physics, Technion-Israel Institute of Technology, Haifa 32000, Israel
Received: 3 April 1997
Abstract. We employ OPE techniques within HQET to calculate the inclusive semileptonic decays of polarized $\Lambda_b$ baryons. Lepton mass effects are included which enables us to also discuss rates into polarized $\tau$-leptons. We present explicit results for the longitudinal polarization of the $\tau$ in the $\Lambda_b$ rest frame as well as in the $(\tau ^-, \bar \nu_\tau)$ c.m. frame. In both the $\Lambda_b$ rest frame and in the $(\tau ^-, \bar \nu_\tau)$ c.m. frame we make use of novel calculational techniques which considerably simplify the calculations. The transverse polarization components of the $\tau$ are calculated in the $(\tau ^-, \bar \nu_\tau)$ c.m. frame. We delineate how to measure the full set of 14 polarized and unpolarized structure functions of the decay process by angular correlation measurements. A set of observables are identified that allow one to isolate the contributions of the two $O(1/m_b^2)$ nonperturbative matrix elements $K_b$ and $\epsilon_b$.
(a) Supported in part by the BMFT, FRG under contract 06MZ566
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Online publication: December 11, 1997
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