Heidelberg 2022 – scientific programme

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T: Fachverband Teilchenphysik

T 63: Search for New Particles 4

T 63.5: Talk

Wednesday, March 23, 2022, 17:15–17:30, T-H22

Sensitivity study in the Search for B^±→ K^±a (displaced a→γγ) Decays at Belle II — •Alexander Heidelbach, Pablo Goldenzweig, and Torben Ferber — Institute of Experimental Particle Physics, Karlsruhe Institute of Technology, Karlsruhe, Germany

In a set of extensions of the Standard Model, Axion Like Particles (ALPs) arise as (pseudo) Nambu-Goldstone bosons of an additional spontaneously broken U(1) symmetry. Due to constraints in flavour-changing processes, involving the coupling of ALPs directly to Standard Model fermions and gluons, direct couplings of ALPs to the electroweak gauge bosons are particularly interesting. As a result of coupling to W bosons, ALPs can emerge in flavour-changing-neutral-current b→ s transitions. Depending on the ALP model, mass and the coupling to photons possible signatures become probeable in B→ Ka transitions which can be studied at e⁺ e⁻ colliders like the Belle II experiment. I present a search for B^±→ K^±a, a→γγ with long-lived ALPs. We investigate the mentioned decay based on a full Belle II Monte Carlo study. In this talk, I will show sensitivity estimates established by the reconstruction of the B meson, an optimised candidate selection and a scan of the invariant di-photon mass spectrum for different ALP lifetimes.