First Measurement of R(X_{τ/â}) as an Inclusive Test of the bâcτν Anomaly.
Phys Rev Lett
; 132(21): 211804, 2024 May 24.
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| ID: mdl-38856254
ABSTRACT
We measure the tau-to-light-lepton ratio of inclusive B-meson branching fractions R(X_{τ/â})≡B(BâXτν)/B(BâXâν), where â indicates an electron or muon, and thereby test the universality of charged-current weak interactions. We select events that have one fully reconstructed B meson and a charged lepton candidate from 189 fb^{-1} of electron-positron collision data collected with the Belle II detector. We find R(X_{τ/â})=0.228±0.016(stat)±0.036(syst), in agreement with standard-model expectations. This is the first direct measurement of R(X_{τ/â}).
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01-internacional
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MEDLINE
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En
Revista:
Phys Rev Lett
Año:
2024
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Article