The time alignment of the Scintillating Fibre Tracker and probing Lepton Flavour Universality with $\Lambda_b^0\rightarrow\Lambda^0\ell^+\ell^-$ at LHCb

by Dr Chishuai Wang (Universität Heidelberg)

Thursday 16 Jul 2026, 16:00 → 17:00 Europe/Berlin

CP-03-123 (TU Dortmund)

This talk aims to address two research topics, i.e. the time alignment of the Scintillating Fibre (SciFi) Tracker and a Lepton Flavour Universality (LFU) study using the rare baryonic decays $\Lambda_b^0\rightarrow\Lambda^0\ell^+\ell^-$ ($\ell=e,\mu$). The research was conducted within the context of the LHCb experiment.

 

As a part of the LHCb Upgrade I, the SciFi Tracker was installed in 2022 and has since been commissioned and operated during the LHCb Run3. An essential part of the detector commissioning and operation was the time synchronisation between the detector signal integration window and the beam-beam interactions of the LHC. This is referred to as the time alignment. Such a procedure is indispensable for the detector to achieve good hit detection efficiency. In this talk, the method for the time alignment will be discussed and the system latency stability study will be presented.

 

The LFU is a feature respected by the Standard Model (SM) of particle physics, which refers to the equality of the electroweak interaction couplings across the 3 generations of leptons. Apart from their mass differences, the 3 generations of leptons are expected to behave identically in the SM. However, potential New Physics (NP) does not necessarily follow LFU. The rare baryonic decays $\Lambda_b^0\rightarrow\Lambda^0\ell^+\ell^-$ ($\ell=e,\mu$), being Flavour Changing Neutral Current (FCNC) processes and thus highly suppressed in the SM, are sensitive probes for non-LFU NP. The study aims to compare the decay branching fractions $\mathcal{B}(\Lambda_b^0\rightarrow\Lambda^0e^+e^-)$ and $\mathcal{B}(\Lambda_b^0\rightarrow\Lambda^0\mu^+\mu^-)$, which are expected to be equal based on the SM (apart from the kinematic difference caused by their masses). This talk will present the methods for such a study and the expected sensitivity for the observable $\mathcal{B}(\Lambda_b^0\rightarrow\Lambda^0e^+e^-)/\mathcal{B}(\Lambda_b^0\rightarrow\Lambda^0\mu^+\mu^-)$.

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