NEPAL

Abstract: We search for Lepton Flavour Violation in the decay \( B^0\to K^{*0}\tau\ell\) using the full available data sets from Belle (711 fb-1) and Belle II (362 fb-1). The analysis is performed using a hadronic tagging and the signal is extracted from the reconstruction of the recoil mass thanks to the kinematic information of the tagged meson and the system.

Abstract: In this note we present the search for the charged lepton-flavour-violation with \( \tau\to e\ell\ell\) decays using 423.5fb-1 of data recorded by the Belle II experiment. The analysis strategy exploits the untagged reconstruction approach, already devised for previous LFV analysis, followed by a BDT-based selection trained directly on the data.

Abstract: This note presents the fake tracks rate results obtained using the 362fb data recorded at the resonance with the Belle II detector between 2019 and 2022 reprocessed with the basf2 release-06 and the corresponding MC15 run-dependent and independent simulations. The fake rate is measured with a tag-and-probe method in tau-pair events where one decays hadronically into three pions and the other one decays leptonically.

Abstract: In this note, we present the search for the lepton flavour violating \(\tau\to 3\mu\) decay, using 424 fb-1 of data recorded Belle II experiment. Two independent strategies are presented, one using a 3x1 topology reconstruction and a cut-based approach and another one using an untagged reconstruction followed by a BDT-based selection.

Abstract: In this note, we present the search for the lepton flavour violating \(\tau\to\ell K^0_s\) decays, where \( \ell=e,\mu\), u sing 1.4 fb-1 of data recorded by the Belle and Belle II experiments.

Abstract: In this note, we present the search for the lepton flavour violating \(\tau\to\ell\ell\ell)\) decays, where \( \ell=e,\mu\), using 363 fb-1 of data recorded by the Belle II experiment. The strategy is based on an inclusive selection, reconstructing only the tau signal decay, followed by a BDT-basd background rejection.

Abstract: In this note, we present the search for the lepton flavour violating \(\tau\to\ell\phi\) decays, where \( \ell=e,\mu\), using 189 fb-1 of data recorded by the Belle II experiment. The strategy is based on an inclusive selection, reconstructing only the tau signal decay, contrary to what was done previousle by Belle and Babar that used the so-called 3x1 topology.

Abstract: We discuss the theoretical methods, their implementations and the results of the measurement of the SVD Cluster Position resolution with data collected in 2020.

Abstract: This note presents a method to measure the fake tracks rate with Bhabha events. Results are shown for a subset of proc 11 data and MC13.

Abstract: This note presents a study aiming at defining the track selection for tau events. It is based on MC13b sample. Three IP cut combinations are identified allowing to reach a signal efficiency larger than 96% for a background rejection above 70%. Additional selections on other variables are also discussed.