Speaker
Description
The heavy quark effective theory makes model independent
predictions for semileptonic $\Lambda_b$ baryon decays in terms of a small
set of parameters. No subleading Isgur-Wise function occurs at order
$\Lambda_{QCD}/m_{c,b}$, and only two sub-subleading functions enter at order
$\left(\Lambda_{QCD}/m_{c}\right)^2$. These features allow us to fit the form factors and decay
rates calculated up to order $\left(\Lambda_{QCD}/m_{c}\right)^2$ to LHCb data and lattice QCD calculations. We derive a significantly more precise standard model
prediction than prior results for the ratio of the rates for
semi-tauonic vs. light-lepton decays. In addition, we investigate the
influence of all possible beyond standard model four-Fermi interactions
and present model independent predictions for them.
