Approaches to inclusive semileptonic $B_{(s)}$-meson decays from Lattice QCD

Alessandro Barone, Shoji Hashimoto, Andreas Jüttner, Takashi Kaneko, Ryan Kellermann
High Energy Physics - Lattice, High Energy Physics - Lattice (hep-lat), High Energy Physics - Phenomenology (hep-ph)
KEK-CP-0394 CERN-TH-2023-087JHEP 07 (2023) 145
2023-05-22 16:00:00
We address the nonperturbative calculation of the inclusive decay rate of semileptonic $B_{(s)}$-meson decays from lattice QCD. Precise Standard-Model predictions are key ingredients in searches for new physics, and this type of computation may eventually provide new insight into the long-standing tension between the inclusive and exclusive determinations of the Cabibbo-Kobayashi-Maskawa (CKM) matrix elements $|V_{cb}|$ and $|V_{ub}|$. We present results from a pilot lattice computation for $B_s \rightarrow X_c\, l \nu_l$, where the initial $b$ quark described by the relativistic-heavy-quark (RHQ) formalism on the lattice and the other valence quarks discretised with domain-wall fermions are simulated approximately at their physical quark masses. We compare two different methods for computing the decay rate from lattice data of Euclidean $n$-point functions, namely Chebyshev and Backus-Gilbert approaches. We further study how much the ground-state meson dominates the inclusive decay rate and indicate our strategy towards a computation with a more comprehensive systematic error budget.
PDF: Approaches to inclusive semileptonic $B_{(s)}$-meson decays from Lattice QCD.pdf
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