Zero-Recoil Sum Rules for $\Lambda_b \to \Lambda_c$ Form Factors

TL;DR

This paper develops a zero recoil sum rule to constrain the form factors of the mbda_b mbda_c transition and compares it with lattice calculations, revealing that lattice results nearly saturate the sum rules.

Contribution

It introduces a zero recoil sum rule for mbda_b mbda_c transitions and demonstrates its consistency with recent lattice results.

Findings

Lattice results nearly saturate the sum rules

No significant contribution from excited states

Consistency with previous B ^* transition analysis

Abstract

We set up a zero recoil sum rule to constrain the form factors of the $\Lambda_b \to \Lambda_c$ transition. Our results are compared with the recent lattice calculation for these transitions. We find the same situation as in the case for $B \to D^*$: The lattice results practically saturate the sum rules, leaving basically no room for excited states.