Semileptonic decay of double strangeness heavy flavor baryons

TL;DR

The paper addresses the weak, Cabibbo-suppressed semileptonic decays Ω_c^0→Ξ^− and Ω_b^−→Ξ^0 by applying QCD light-cone sum rules to extract the transition form factors. It contrasts two LCDA inputs—final-state Ξ and initial-state Ω_Q—paired with a helicity formalism to obtain differential widths and branching fractions, followed by a $z$-series extrapolation to the full kinematic range. A central finding is that Ξ LCDAs yield form factors and branching fractions in line with other approaches, whereas Ω_Q LCDAs lead to discrepancies of about three orders of magnitude, calling into question the reliability of double-strangeness baryon LCDAs in this context. The work underscores the need for improved LCDAs for double-strangeness heavy baryons and motivates further theoretical development before these channels can be used for precision CKM studies or experimental comparisons.

Abstract

This paper investigates the double strangeness heavy flavor baryons $Ω_c^0$ and $Ω_b^-$, which contain two strange quarks. Using QCD light-cone sum rules (LCSRs), we calculate the form factors for the Cabibbo-suppressed processes $Ω_c^0\toΞ^-$ and $Ω_b^-\toΞ^0$, corresponding to the heavy-quark transitions $c\to d$ and $b\to u$, respectively. Combining these with the helicity amplitude formalism for semileptonic decay differential widths, we computed the branching fractions of their corresponding semileptonic decay processes. Our analysis reveals significant discrepancies between two versions of QCD LCSRs: one using the light-cone distribution amplitudes (LCDAs) of the final-state $Ξ$ baryon and the other using the LCDAs of the initial-state double strangeness heavy flavor baryons. The results obtained with the $Ξ$ baryon's LCDAs show excellent agreement with other theoretical calculations. However, when using the LCDAs of the double strangeness heavy flavor baryons, the results differ by orders of magnitude, warranting further investigation.

Figures (6)

• Figure 1: The Borel parameter dependence of the $\Omega_c^0 \to \Xi^-$ transition form factors at $q^2=0~\rm{GeV^2}$ within the $\Xi$ baryon LCDAs.
• Figure 2: The Borel parameter dependence of the $\Omega_b^- \to \Xi^0$ transition form factors at $q^2=0~\rm{GeV^2}$ within the $\Xi$ baryon LCDAs.
• Figure 3: Form factors $f_i (i=1, 2)$ of $\Omega_c^0$ transition to $\Xi^-$ with $q^2$ dependence within $\Xi$ baryon LCDAs.
• Figure 4: Form factors $f_i (i=1,2)$ of $\Omega_b^-$ transition to $\Xi^0$ with $q^2$ dependence within $\Xi$ baryon LCDAs.
• Figure 5: The differential decay width of $\Omega_c^0\to\Xi^-\ell^+\bar{\nu}_\ell$ within $\Xi$ baryon LCDAs.