This web page contains the averages of the ratios of Branching Fractions
R(D*)=BF(B→D*τν_{τ})/BF(B→D* l ν_{l})
and R(D)=BF(B→Dτν_{τ})/BF(B→D l ν_{l}).
In the present average we consider the following measurements:
Experiment | R(D*) | R(D) | Rescaled Correlation (stat/syst/total) | Parameters | Remarks |
---|---|---|---|---|---|
BaBar | 0.332 +/- 0.024+/- 0.018 | 0.440 +/- 0.058 +/- 0.042 | -0.45/-0.07/-0.27 | input | Phys.Rev.Lett. 109,101802 (2012) [arXiv:1205.5442 [hep-ex]] Phys.Rev.D 88, 072012 (2013) [arXiv:1303.0571] |
BELLE | 0.293 +/- 0.038 +/- 0.015 | 0.375 +/- 0.064 +/- 0.026 | -0.56/-0.11/-0.49 | input | Phys.Rev.D 92, 072014 (2015) [arXiv:1507.03233 [hep-ex]] |
BELLE | 0.302 +/- 0.030 +/- 0.011 | - | - | input | Phys.Rev. D94,072007 (2016) [arXiv:1607.07923 [hep-ex]] |
LHCb | 0.336 +/- 0.027 +/- 0.030 | - | - | input | Phys.Rev.Lett.115,111803 (2015) [arXiv:1506.08614 [hep-ex]] |
BELLE | 0.270 +/- 0.035 ^{+ 0.028}_{-0.025} | - | - | input | Phys.Rev.Lett.118,211801 (2017) [arXiv:1612.00529 [hep-ex]] Phys.Rev.D 97, 012004 (2018) [arXiv:1709.00129] |
LHCb | 0.291 +/- 0.019 +/- 0.029 | - | - | input | Phys.Rev.Lett.120,171802 (2018)[arXiv:1708.08856] Phys.Rev.D 97, 072013 (2018) [arXiv:1709.02505] |
Average .txt | 0.306 +/- 0.013 +/- 0.007 | 0.407 +/- 0.039 +/- 0.024 | -0.20 | chi2/dof = 3.51/6 (CL = 0.74) |
R(D)-R(D*).pdf
.png
.C (dashed curves correspond to 2 and 4 σ contours) R(D) .pdf .png .C R(D*) .pdf .png .C |
SM predictions for R(D) based on recent Lattice calculations:
The SM prediction for R(D*) widely used in previous HFLAV averages was:
R(D) | R(D*) | |
---|---|---|
D.Bigi, P.Gambino, Phys.Rev. D94 (2016) no.9, 094008 [arXiv:1606.08030 [hep-ph]] | 0.299 +- 0.003 | |
F.Bernlochner, Z.Ligeti, M.Papucci, D.Robinson, Phys.Rev. D95 (2017) no.11, 115008 [arXiv:1703.05330 [hep-ph]] | 0.299 +- 0.003 | 0.257 +- 0.003 |
D.Bigi, P.Gambino, S.Schacht, JHEP 1711 (2017) 061 [arXiv:1707.09509 [hep-ph]] | 0.260 +- 0.008 | |
S.Jaiswal, S.Nandi, S.K.Patra, JHEP 1712 (2017) 060 [arXiv:1707.09977 [hep-ph]] | 0.299 +- 0.004 | 0.257 +- 0.005 |
Arithmetic average | 0.299 +- 0.003 | 0.258 +- 0.005 |
The arithmetic average is used only for illustration and doesn't imply consent from the authors of the calculations. The SM uncertainty is currently subject to debate that HFLAV is following without taking a stance in this.
R(D) and R(D*) exceed the SM predictions given in the last row of the table above, by 2.3σ and 3.0σ respectively.
Considering the R(D)-R(D*) correlation of -0.203, the resulting combined χ^{2} is 17.55 for 2 degree of freedom,
corresponding to a p-value of 1.57 x 10^{-4}. The difference with the SM predictions reported above, corresponds to about 3.78σ. Using the R(D*) prediction with the largest theoretical uncertainty, D.Bigi et al. arXiv:1707.09509 [hep-ph], the difference with the SM is reduced to 3.62σ.