Search for rare electroweak decay 𝐵+→𝐾+νν in early Belle II dataset

Sumitted to PubDB: 2021-07-30

Category: Talk, Visibility: Public

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Authors	Simon Kurz
Date	July 26, 2021
Belle II Number	BELLE2-TALK-CONF-2021-083
Abstract	In the recent years, several measurements of 𝐵-decays with flavor changing neutral currents (FCNC), i.e. 𝑏→𝑠ℓℓ transitions, hint at deviations from the Standard Model (SM) predictions.A search for the flavor-changing neutral current decay 𝐵+→𝐾+𝜈𝜈¯ is performed with data sample corresponding to 63 𝑓𝑏−1 collected at the Υ(4S) resonance by the Belle II experiment. A novel measurement method is developed, which exploits topological properties of the decay that differ from both generic B-meson decays and light-quark pair-production. This inclusive tagging approach has the benefit of a higher signal efficiency compared to previous searches for this rare decay. As no significant signal is observed, an upper limit on the branching fraction of 𝐵+→𝐾+𝜈𝜈¯ = 4.1×10−5 is set at the 90% confidence level. We will talk about this novel analysis technique and the result.
Conference	EPS-HEP 2021