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T: Fachverband Teilchenphysik

T 79: Data Analysis, Information Technology and Artificial Intelligence 4

T 79.1: Vortrag

Mittwoch, 23. März 2022, 16:15–16:30, T-H38

K_S⁰ tracking efficiency studies at Belle II — •Elisabetta Prencipe¹, Oleksandr Skorenok², and Jens Soeren Lange¹ — ¹JLU-Giessen, Giessen, Germany — ²TSNU-Kyiv, Kyiv, Ukraine

Reconstruction efficiency of low momentum tracks in particle physics is a very important issue. Here we report about a study conducted at Belle II, with MC samples and Phase-3 data, and present a dedicated study of the efficiency to correctly reconstruct K_S⁰ → π⁺ π⁻, whose daughter tracks can have a different efficiency due to their displacement from the primary event origin.

A significant number of analyses in Belle II involve the reconstruction of K_S⁰ → π⁺ π⁻. The reconstruction efficiency of the K_S⁰ daughters depends on the K_S⁰ transverse momentum, p_T, polar angle, θ_LAB and transverse (XY) flight distance, d_XY, which is computed as the distance between the primary vertex of the event and the refitted K_S⁰ decay vertex.

The general strategy is to subdivide the data and MC events into a large number of samples by choosing an appropriate binning in these variables, determine the number of K_S⁰ in each bin, in data and MC samples, and for each of the momentum and polar angle ranges, normalize the ratio of its value in the first bin in d_XY, where all tracking effects are well understood. The results here presented are acquired by studying the B → K⁺ K⁻ K_S⁰ and B → π⁺ π⁻ K_S⁰ decay channels at Belle II. They will help in understanding systematic effects of analysis where K_S⁰ are involved.