Göttingen 2025 – wissenschaftliches Programm

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T: Fachverband Teilchenphysik

T 73: Flavour Physics IV

T 73.3: Vortrag

Donnerstag, 3. April 2025, 16:45–17:00, VG 1.103

Entanglement studies with Belle Υ (5S) data — •Vanessa Geier — Max-Planck-Institute for Physics Garching

Compared to the Υ (4S) the Υ (5S) can decay in excited B⁰ giving rise to B^0(*)/ B^0(*) states with different quantum numbers. Directly after the decay of the Υ (5S) the B^0(*)/ B^0(*) pairs are supposed to be in the J^PC= 1^– state. After the transition of the excited state into the B⁰/ B⁰ state via photon emission, the B⁰/ B⁰ pairs are supposed to be in the states J^PC= 1⁻⁺. Depending on the C parity the B^0(*)/ B^0(*) can be in a symmetric or antisymmetric wave function leading to different time evolutions of the entangled states. Possibly the gamma transition of the excited state can also disrupt the entanglement. We will study these effects using Υ (5S) data collected by the Belle experiment. The Analysis includes the reconstruction of the signal B^0(*) mesons as well as the tag-side reconstruction through the decay chain B⁰ → D⁻ (→ K⁺ π⁻ π⁻) π⁺. In addition the resulting B⁰/ B⁰ mesons need to be separated with the help of M_bc and ΔE variables. Reconstruction and selection efficiencies will be studied with MC events. Then the time evolution of the B-mesons will be investigated to study possible (dis)entanglement properties of the produced B⁰/ B⁰ meson pairs.

Keywords: Belle; Belle II; Entanglement