Form factors of Λb⁰ → Λc(2595)⁺ within light-cone QCD sum rules

In this work, we calculated the form factors of the weak decay process Λb⁰ → Λc(2595)⁺, where the final charm baryon represents an excited state with spin-parity 1/2⁻. Utilizing the light-cone QCD sum rules approach, we incorporated the contributions of the lowest two charm baryon states: the ground state Λc with JP=1/2⁺ and the excited state Λc(2595)⁺ with JP=1/2⁻ in the hadronic representation of the Λb to Λc(2595) transition correlation function. This approach allowes us to extract the form factors of the Λb⁰ → Λc(2595)⁺ from Λb⁰ → Λc⁺ transition. During the light-cone QCD sum rules procedure, we employed the light-cone distribution amplitudes (LCDAs) of the Λb baryon. Furthermore, by combining these form factors with the helicity amplitudes of the bottom baryon transition matrix elements, we calculated the differential decay widths for the processes Λb⁰ → Λc(2595)⁺⁻ν̄_. Additionally, within the lifetime of Λb⁰, we obtained the absolute branching fractions for the semileptonic decays Λb⁰ → Λc(2595)⁺ ⁻ ν̄_. With the branching fractions of Λb⁰ → Λc(2595)⁺ ⁻ ν̄_ calculated in this work, we also determined the parameter R(Λc(2595)⁺) which tests the lepton flavor universality. This parameter is defined as the ratio of branching fractions Br(Λb⁰ → Λc(2595)⁺τ⁻ν̄_τ) and Br(Λb⁰ → Λc(2595)⁺μ⁻ν̄_μ). Our results provide a valuable theoretical test for these decay channels and offer insights into the LCDAs of bottom baryons, paving the way for further in-depth investigations.