Speaker
Description
We present the first lattice QCD determination of the Λ→N vector and axial-vector form factors, which are essential inputs for studying the semileptonic decay Λ→pℓνˉ. This channel provides a clean, theoretically controlled avenue for extracting the CKM matrix element ∣Vus∣ from the baryon sector. Our analysis uses a gauge ensemble with physical light, strange, and charm quark masses and yields the most precise determination to date of the full set of transition form factors -- including second-class contributions -- as well as the associated couplings, radii, and the ratio of muon-to-electron decay rates, an observable sensitive to possible non-standard scalar and tensor interactions. We compare our non-perturbative results with next-to-next-to-leading order expansions in the small parameter δ=(mΛ−mN)/mΛ≈0.16. We find that the common phenomenological approximation of neglecting the q^2-dependence of the form factors leads to a ∼4% deviation in the decay rate. This underscores the critical importance of precise, fully non-perturbative form factor inputs for achieving the sub-percent precision targets of upcoming experimental programs. (See https://inspirehep.net/literature/2945864)
| Parallel Session (for talks only) | Structure of hadrons and nuclei |
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