A search for the flavor-changing neutral-current decay B+→K+νν¯ is performed at the Belle II experiment at the SuperKEKB asymmetric energy electron-positron collider. The data sample corresponds to an integrated luminosity of 63 fb−1 collected at the ϒ(4S) resonance and a sample of 9 fb−1 collected at an energy 60 MeV below the resonance. Because the measurable decay signature involves only a single charged kaon, a novel measurement approach is used that exploits not only the properties of the B+→K+νν¯ decay, but also the inclusive properties of the other B meson in the ϒ(4S)→BB¯ event, to suppress the background from other B meson decays and light-quark pair production. This inclusive tagging approach offers a higher signal efficiency compared to previous searches. No significant signal is observed. An upper limit on the branching fraction of B+→K+νν¯ of 4.1×10−5 is set at the 90% confidence level.
Abudinén, F., Adachi, I., Adamczyk, K., Ahlburg, P., Aihara, H., Akopov, N., et al. (2021). Search for B+→K+νν¯ Decays Using an Inclusive Tagging Method at Belle II. PHYSICAL REVIEW LETTERS, 127(18) [10.1103/PhysRevLett.127.181802].
Search for B+→K+νν¯ Decays Using an Inclusive Tagging Method at Belle II
Bernieri, E.Membro del Collaboration Group
;Budano, A.Membro del Collaboration Group
;Bussino, S.Membro del Collaboration Group
;De Pietro, G.Membro del Collaboration Group
;Laurenza, M.Membro del Collaboration Group
;
2021-01-01
Abstract
A search for the flavor-changing neutral-current decay B+→K+νν¯ is performed at the Belle II experiment at the SuperKEKB asymmetric energy electron-positron collider. The data sample corresponds to an integrated luminosity of 63 fb−1 collected at the ϒ(4S) resonance and a sample of 9 fb−1 collected at an energy 60 MeV below the resonance. Because the measurable decay signature involves only a single charged kaon, a novel measurement approach is used that exploits not only the properties of the B+→K+νν¯ decay, but also the inclusive properties of the other B meson in the ϒ(4S)→BB¯ event, to suppress the background from other B meson decays and light-quark pair production. This inclusive tagging approach offers a higher signal efficiency compared to previous searches. No significant signal is observed. An upper limit on the branching fraction of B+→K+νν¯ of 4.1×10−5 is set at the 90% confidence level.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
