Predictions onB→πl¯νl

Abstract

The f + form factors of the B → π, D → π and D → K transitions are calculated from QCD light-cone sum rules (LCSR) and used to predict the widths and differential distributions of the exclusive semileptonic decays B → πlν l , D → πlν l and D → Klν l , where l = e, µ. The current theoretical uncertainties are estimated. The LCSR results are found to agree with the results of lattice QCD calculations and with experimental data on exclusive semileptonic D decays. Comparison of the LCSR prediction on B → πlν l with the CLEO measurement yields a value of |V ub | in agreement with other determinations.

Heavy to light meson exclusive semileptonic decays in effective field theory of heavy quarks

“…In searching for reasonable and stable results, the quark-hadron duality and Borel transformation are generally applied to both sides of the equations. Different from the previous LCSR analysis in QCD framework [13][14][15][16], in the current study, we instead calculate the correlation functions in HQEFT, i.e., we adopt the Feynman rules in effective theory. In particular, we use 1+v / 2 ∞ 0 dtδ(x − y − vt) for the contraction of effective heavy quark fieldsQ + v (x) and Q + v (y).…”

“…Lat [6] 0.65 ± 0.10 0.65 ± 0.07 0.55 ± 0.10 1.1 ± 0.2 SR [19] 0.65 ± 0.11 SR [21] 0.50 ± 0.15 0.5 ± 0.2 0.4 ± 0.2 1.0 ± 0.2 D → K(K * )lν this work 0.67 ± 0.20 0.59 ± 0.10 0.55 ± 0.08 0.80 ± 0.10 E791 [42] 0.58 ± 0.03 0.41 ± 0.06 1.06 ± 0.09 QM [8] 0.78 0.66 0.49 1.03 QM [9] 0.78 0.66 0.43 1.04 Lat [2] 0.71(12) +10 Lat [6] 0.73 ± 0.07 0.70 ± 0.07 0.6 ± 0.1 1.2 ± 0.2 SR [19] 0.76 ± 0.03 SR [21] 0.60 ± 0.15 0.50 ± 0.15 0.60 ± 0.15 1.10 ± 0.25 The form factor ratios R V ≡ V (0)/A 1 (0), R 2 ≡ A 2 (0)/A 1 (0) for D → K * lν decay have been measured by several groups. We present in Table 4 the comparison of our results for these ratios with the measurements.…”

“…while for the kaon distribution amplitude φ K , when the light flavor SU(3) breaking effects are considered, we may use [16] …”

“…And similar monopole approximation formulae will be applied to other heavy mesons decaying into light pseudoscalar mesons. In our numerical calculations, we will take: [16], and f B * g B * BsK = 3.88 ± 0.31GeV [40].…”

“…Besides using lattice calculations [1][2][3][4][5][6][7] and quark models [8][9][10][11][12], these decays have been analyzed by using sum rules in full QCD [13][14][15][16][17][18][19][20][21]. Since the heavy meson B (s) or D (s) contains one heavy quark and one light quark, it is expected that the heavy quark symmetry (HQS) and the effective field theory of heavy quark may help to improve our understanding on heavy to light decays.…”