Impact of $\Lambda_b\to \Lambda_c\tau\nu$ measurement on New Physics in $b\to c \, l \nu$ transitions

  title={Impact of \$\Lambda\_b\to \Lambda\_c\tau\nu\$ measurement on New Physics in \$b\to c \, l \nu\$ transitions},
  author={Marco Fedele and Monika Blanke and Andreas Crivellin and Syuhei Iguro and Teppei Kitahara and Ulrich Nierste and Ryoutaro Watanabe},
Measurements of the branching ratios of $B \to D^{(*)}\tau\bar\nu/B \to D^{(*)}\ell\bar\nu$ and $B_c\to J/\psi\, \tau\bar\nu/B_c\to J/\psi\, \ell\bar\nu$ by the BaBar, Belle and LHCb collaborations consistently point towards an abundance of taus compared to channels with light leptons. However, the ratio $\Lambda_b \to\Lambda_c \tau\bar\nu/\Lambda_b \to\Lambda_c \ell\bar\nu$ shows a relative deficit in taus. In this paper, we critically address whether data still points towards a coherent… 

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