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Towards a quantitative understanding of the $D\to \pi$ and $B\to \pi$ semileptonic decays

Abstract : The charm semileptonic decay $D \to \pi e \nu$ has been measured by several experiments. Conversely to other semileptonic decays, this channel presents the interest that contributions from the two first poles can be predicted. We have computed accurately in LQCD the ratio of decay constants $f_{D^\ast}/f_D$ making the evaluation of the $D^\ast$-pole contribution quite accurate. Measurements of the above charm semileptonic decay have been analyzed using a model with $3$ poles, the last one being effective. It is found that data agree with the superconvergence condition according to which the sum of the residues at the various poles amounts to zero. This analysis is extended to $B\to \pi e \nu$ decays for which we compute the ratio $f_{B^\ast}/f_B$. We find that both decays verify the superconvergence condition which also assures validity of the heavy quark scaling law in the large recoil limit. We then verify that the value of $V_{ub}$ we extract from a comparison with the experimental data is consistent with those previously found from the exclusive semileptonic decays.
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Contributor : Sabine Starita <>
Submitted on : Friday, July 4, 2014 - 4:35:55 PM
Last modification on : Wednesday, September 16, 2020 - 5:43:28 PM


  • HAL Id : in2p3-01018688, version 1




D. Becirevic, A. Le Yaouanc, A. Oyanguren, P. Roudeau, F. Sanfilippo. Towards a quantitative understanding of the $D\to \pi$ and $B\to \pi$ semileptonic decays. 37th International Conference on High Energy Physics (ICHEP 2014), Jul 2014, Valencia, Spain. ⟨in2p3-01018688⟩



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