Lifespan Determination of B – CERN Courier

The LHCb experiment will use detectors upgraded for LHC Run 3 to prepare for data acquisition, thus continuing the rich collection of results using data collected in Runs 1 and 2 of the LHC. .

An attractive research area is the quantum mechanical oscillation between the particle and antiparticle states of neutrons, implying a coupled system of two mesons with different lifetimes. Phenomenology of B_s The system is of particular interest because it provides a sensitive probe to physics beyond the standard model. AB_s Mesons vibrate at a frequency of about 3.×Ten¹²Hz, or about 9 times on average during lifetime, τ. In addition, heavy (Γ_H.) and lights (Γ_L.) mass eigenstates are expected. Lifetime measurements of CP-even B_s-decay mode is determined τ_L.= 1/Γ_L..

The LHCb recently released new precise measurements of this parameter._s → J/ψη Decay selected from 5.7 fb^–1 Run 2 of the data. This study shows a 2x improvement in accuracy over the previous run 1. Due to the combinatorial background, η Mesons by two-photon decay mode are a particular challenge for this analysis. Nevertheless, even the modest energy resolution of the calorimeter leads to relatively broad mass peaks that partially overlap the signal from B.⁰ → J/ψηDamping, competitive accuracy achieved. Leveraging modern machine learning techniques to reduce background and well-understood LHCb detectors, B_s →J/ψηcollapse was observed (Fig. 1), and τ_L. Extracted from a two-dimensional fit to mass and decay time.

result of analysis τ_L.= 1.445 ± 0.016 (stat) ± 0.008 (syst) ps, which is the most accurate measurement of this quantity.Combine this with B’s LHCb Run 1 study_s →D._s⁺ D._s^– attenuation mode, τ_L.= 1.437 ± 0.014 ps, which is the expected value of the standard model (τ_L.= 1.422 ± 0.013 ps) value inferred from the measured value Γ_s and ΔΓ_s in B_s →J/ψφ collapse.Better knowledge τ_L. Both are expected by considering the other CP-even B_s collapses into a final state containing η Also η’ Meson, B._s →D._s⁺ D._s^– Dataset collected in run 2 and following run 3.