Dortmund 2021 – wissenschaftliches Programm

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T: Fachverband Teilchenphysik

T 56: Flavour physics III

T 56.1: Vortrag

Mittwoch, 17. März 2021, 16:00–16:15, Tf

Contribution of the Darwin operator to non-leptonic decays of heavy quarks — •Maria Laura Piscopo, Aleksey Rusov, and Alexander Lenz — Center for Particle Physics Siegen, Theoretische Physik 1, Universität Siegen

We compute the Darwin operator contribution (1/m_b³ correction) to the width of the inclusive non-leptonic decay of a B meson (B⁺, B_d or B_s), stemming from the quark flavour-changing transition b → q₁ q₂ q₃, where q₁,q₂ = u, c and q₃ = d, s. The key ideas of the computation are the local expansion of the quark propagator in the external gluon field including terms with a covariant derivative of the gluon field strength tensor and the standard technique of the Heavy Quark Expansion (HQE). We confirm the previously known expressions of the 1/m_b³ contributions to the semi-leptonic decay b → q₁ ℓ ν_ℓ, with ℓ = e, µ, τ and of the 1/m_b² contributions to the non-leptonic modes. We find that this new term can give a sizeable correction of about − 4   % to the non-leptonic decay width of a B meson. For B_d and B_s mesons this turns out to be the dominant correction to the free b-quark decay, while for the B⁺ meson the Darwin term gives the second most important correction - roughly 1/2 to 1/3 of the phase space enhanced Pauli interference contribution. Due to the tiny experimental uncertainties in lifetime measurements the incorporation of the Darwin term contribution is crucial for precision tests of the Standard Model.