Interpreting LHCb's $\Lambda_b\to \Lambda_c\tau\bar\nu$ measurement and puzzles in semileptonic $\Lambda_b$ decays

Autor: Bernlochner, Florian U., Ligeti, Zoltan, Papucci, Michele, Robinson, Dean J.
Rok vydání: 2022
Předmět:
Druh dokumentu: Working Paper
DOI: 10.1103/PhysRevD.107.L011502
Popis: Normalizing the recent LHCb measurement of $\Lambda_b \to \Lambda_c \tau \bar\nu$ to the standard model (SM) prediction for the $\Lambda_b \to \Lambda_c \mu \bar\nu$ rate, instead of a LEP measurement, provides a more consistent comparison with the SM prediction for the lepton flavor universality ratio $R(\Lambda_c)$. This modestly increases $R(\Lambda_c)$ compared to the quoted LHCb result, such that it no longer hints at a suppression compared to the SM, which would be hard to accommodate in new physics scenarios that enhance $R(D^{(*)})$. We point out that the fraction of excited states in inclusive semileptonic $\Lambda_b$ decay may be significantly greater than the corresponding fraction in $B$ decays. Possible implications are speculated upon.
Comment: 3 pages
Databáze: arXiv