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We calculate the $\Lambda_b \to \Lambda_c^*(2595) l \nu$ and $\Lambda_b \to\Lambda_c^*(2625) l \nu$ form factors and decay rates for all possible $b \to cl \bar\nu$ four-Fermi interactions in and beyond the Standard Model (SM),including nonzero charged lepton masses and terms up to order$\mathcal{O}(\alpha_s, 1/m_{c,b})$ in the heavy quark effective theory (HQET).We point out a subtlety involving the overcompleteness of the representation ofthe spin-parity $1/2^+ \to 3/2^-$ antisymmetric tensor form factors, relevantalso to other higher excited-state transitions, and present a general methodfor the counting of the physical form factors for any hadronic transitionmatrix element and their matching onto HQET. We perform a preliminary fit of asimple HQET-based parametrization of the $\Lambda_b \to \Lambda_c^*$ formfactors at $\mathcal{O}(\alpha_s, 1/m_{c,b})$ to an existing quark model,providing preliminary predictions for the lepton universality ratios$R(\Lambda_c^*)$ beyond the SM. Finally, we examine the possibleincompatibility of recent lattice QCD results with expectations from theheavy-quark expansion and available experimental data.

Form Factor Counting and HQET Matching for New Physics in $\Lambda_b \to \Lambda_c^*l\nu$