Alain Le Yaouanc, Jean-Pierre Leroy, Patrick Roudeau

Phys. Rev. D 105, 013004, 6 Janvier 2022

We present a model for the vector and axial form factors of the transitions ¯B0→D** in good agreement with the presently available data and based on the present theoretical knowledge, combining (a) the safe lattice QCD predictions at mQ=∞ and w=1; (b) the predictions at general w of a relativistic, covariant quark model at mQ=∞, including the well-tested Godfrey and Isgur spectroscopic model and which agrees with lattice QCD at w=1; (c) the constraint of Bjorken and Neubert relating semileptonic and class I nonleptonic decays, which shows that ¯B0→D0(2300)+π− strongly constrains τ1/2(w) to be much smaller than τ3/2(w), in agreement with the theoretical expectation; and (d) the general HQET expansion which constrains the 1/mQ corrections (cf. Leibovich et al. Phys. Rev. Lett. 78, 3995 (1997)., denoted hereafter as LLSW). An important element in the understanding of data is the large contribution of virtual D(*)V to the broad structures seen in SL decays at low D(*)π masses—which makes it difficult to isolate the broad resonances denoted as D1/2 in the following.

12/01/2022 16:22