Asymmetry Parameter in the Polarized ¤b ! ¤cl¹º Decay

Hsien-Hung Shih；Shih-Chang Lee；Hsiang-Nan Li

Chinese Journal of Physics

39卷4期（2001 / 08 / 01）

328 - 335

英文

We predict an asymmetry parameter ® (ê) involved in the polarized ¤ b baryon semileptonic decay ¤ b ! ¤ c l¹º. Employing the heavy baryon transition form factors calculated in our previous work based on the perturbative QCD factorization theorem, we derive ® (ê) ´ (N+ i Ni )=(N+ + Ni ) = (i 0.31 § 0.6)P ¢ê, where P is the ¤ b baryon polarization, ê a unit vector perpendicular to the ¤ b baryon momentum, and N+(Ni ) the number of leptons with positive (negative) components of momenta along ê. This result is useful for extracting the transverse polarization of a ¤ b baryon from the data of exclusive semileptonic decays.