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Since some time I started to study the semilptonic decay of B meson : ## B \to D \tau \nu ## that there is an excess in the value R (D) = ## \frac{ Br ( B \to D \tau \nu) } {Br (B \to D l \nu) } ## in BABAR experiment than the SM expectations- See for example arXiv:1302.7031v5- Now I have two questions about the numirecal results of such decay, if any one has an experience about ..

* Since Br = the partial decay width/ the total decay width, won't R(D) = ## \frac{d \Gamma ( B \to D \tau \nu) }{ d q^2 d \cos \theta_l } รท \frac{d \Gamma ( B \to D l \nu) }{ d q^2 d \cos \theta_l} ## ?

According to [1302.7031v5] notation. Where q^2 is the centre of mass energy squared and ## \cos \theta_l ## is the angle of the lepton relative to the B rest frame.

* If we used ## d q^2 = 2 q dq ##, are the integration limits for ## \cos \theta ## : 0 < ## \cos\theta ## < ## \pi ## and for q: 0 < q < ## \sqrt{10} ## .. I think if we set all NP couplings to zero in Equ. 2.2 [1302.7031v5] we should have the SM value of R(D) ..

Thanx.

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# Semilptonic decay of B mesons

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