We show that the longitudinal polarization of the top quarks produced in the annihilation of e+e- or μ+μ- into t̄t at energies near the threshold is not affected by the large Coulomb-type corrections, which modify the total cross-section significantly. Thus the longitudinal polarization, though small, may give an independent information on the mass and the width of the top quark, largely independent of the uncertainty in αs.
Bibliographical noteFunding Information:
The work of K.L. was supported in part by the NSF Presidential Young Investigator Fellowship. The work of O.T. was supported in part by the U.S. Department of Energy and Japan NEDO. The part of this work was done in Aspen Center for Physics. We thank Elihu Abrahams, Sidney Coleman, David Ceperley, Miklos Gyulassy, T. D. Lee, John Negele, Michael Stone, and Tomo Uemura for useful discussions.