2025/09/02 by Li, Ying, Chen, Jie, Wang, Ya-Xin +1
#FOS: Physical sciences #High Energy Physics - Experiment (hep-ex) #High Energy Physics - Phenomenology (hep-ph)
paper · doi:10.48550/arxiv.2509.02257
We investigate the semileptonic decays Λb → Λc ℓ- ν_ℓ (with ℓ = e, μ, τ) within the framework of perturbative QCD (pQCD). The six independent Λb → Λc transition form factors are first calculated in the low-q2 region using the kT factorization approach. These are then extrapolated to the full physical q2 range via the model-independent z-expansion, incorporating recent lattice QCD results at high q2. Based on the obtained form factors, we compute the branching fractions of Λb → Λc ℓ- ν_ℓ decays. Our prediction for the lepton flavor universality ratio, RΛc = 0.29+0.12-0.11, is slightly larger than the latest experimental measurement. In addition, we analyze several angular observables, including forward-backward asymmetries, lepton-side convexity parameters, and polarization asymmetries. These results offer valuable theoretical input for current and future experimental investigations of semileptonic heavy-to-heavy baryon transitions.