Higher order perturbative corrections to b ---> c transitions at zero recoil

Sep, 1994
9 pages
Published in:
  • Phys.Lett.B 341 (1995) 367-371
e-Print:
Report number:
  • CERN-TH-7454-94

Citations per year

19942002201020182024024681012
Abstract:
We estimate the two-loop perturbative corrections to zero-recoil matrix elements of the flavour-changing currents cˉγ μb\bar c\,\gamma~\mu b and cˉγ μγ5b\bar c\,\gamma~\mu\gamma_5\,b by calculating the terms of order nfαs 2n_f\,\alpha_s~2 and substituting the dependence on the number of flavours by the first coefficient of the β\beta-function. Both for vector and axial vector currents, we find moderate two-loop corrections below 1\% in magnitude. Using the Brodsky--Lepage--Mackenzie prescription to set the scale in the order-αs\alpha_s corrections in the MS\overline{\rm MS} scheme, we obtain μV0.92mbmc\mu_V\simeq 0.92\sqrt{m_b m_c} and μA0.51mbmc\mu_A\simeq 0.51\sqrt{m_b m_c} in the two cases. These scales are sufficiently large for perturbation theory to be well-behaved. The implications of our results to the extraction of Vcb|\,V_{cb}| are briefly discussed.
  • anti-B: semileptonic decay
  • semileptonic decay: anti-B
  • D*(2010)
  • bottom
  • charm
  • current: flavor changing
  • current: vector
  • current: axial-vector
  • HQET model
  • correction: mass