• DOI:10.1103/PhysRevD.107.055005
• Corpus ID: 254018333

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

@inproceedings{Fedele2022ImpactO,
  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},
  year={2022}
}

• M. Fedele, M. Blanke, +4 authors R. Watanabe
• Published 25 November 2022
• Physics

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 pattern of deviations, in particular in light of the sum rule relating these decays in a model-independent way. We find that no common new physics explanation of all ratios is possible (within $2\sigma$ or $1.5\sigma$, depending on the ${\cal R}(\Lambda_c)$ normalization to light lepton channels). While this inconsistency could be a statistical fluctuation, further measurements are required in order to converge to a coherent pattern of experimental results.