2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/198500Rare $B$ decays provide an opportunity to probe for new physics beyond the Standard Model. In this paper, we propose to measure the tau polarization in the inclusive decay $B\to X_sτ^+τ^-$ and discuss how it can be used, in conjunction with other observables, to completely determine the parameters of the flavor-changing low-energy effective Hamiltonian. Both the Standard Model and several new physics scenarios are examined. This process has a large enough branching fraction, $\sim {\rm few}\times 10^{-7}$, such that sufficient statistics will be provided by the B-Factories currently under construction.11 pages, LaTex file with psfig. Figures included via uufiles. Lengthened version. Includes new calculation of Monte Carlo fit to Wilson coefficientsHigh Energy Physics - Phenomenologytext