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T: Fachverband Teilchenphysik

T 22: Flavour physics 1

T 22.4: Vortrag

Montag, 4. März 2024, 16:45–17:00, Geb. 30.41: HS 4

Time-dependent studies of B_s⁰-meson decays at the LHCb experiment — Johannes Albrecht and •Quentin Führing — TU Dortmund University, Dortmund, Germany

The system of neutral B_s⁰ mesons provides experimental access to the CKM sector of the Standard Model. The neutral meson oscillation is not only a measurable observable itself but also enables CP-violating effects in the interference of direct decay and decay after mixing.

Flavour-specific decay modes, like B_s⁰ → D_s⁻ π⁺, can be used for a clean measurement of the oscillation frequency Δ m_s. This frequency itself can be utilized to constrain the sides of the unitarity triangles. More importantly, it is a crucial input to all time-dependent measurements of CP violation in B_s⁰-meson decays.

The decay to a CP eigenstate, such as B_s⁰ → J/ψ  φ, gives access to the CP-violating phase φ_s. Together with this information the analysis of B_s⁰ → D_s^∓K^± decays allows for the determination of the CKM angle γ. While these decay modes, dominated by tree-level processes, allow for clean measurements of the CP-violating phases, in other modes effects from the presence of loop processes have to be accounted for.

At the LHCb experiment, these decay-time-dependent studies can be performed with high sensitivity, as the fast B_s⁰ oscillation can be well resolved due to the O(50 fs) decay-time resolution of the detector. The crucial information of the B_s⁰-meson flavour at the time of its production is derived by various flavour-tagging algorithms.

An overview of the latest published analyses and ongoing developments in this field will be presented.

Keywords: LHCb; Mixing; CPV; CKM; Flavour Tagging