# Measurement of CP-Violating Parameters in $B\\to \\eta^\\prime K$ Decays

Source: [Measurement of CP-Violating Parameters in $B\\to \\eta^\\prime K$ Decays](<https://www.sota2.com/research/paper/68fa292b1e209131ce831711>)

Collection index: [llms.txt](<https://www.sota2.com/research/llms.txt>)

Data updated: 2025-10-24T12:43:01.807Z

Authors: K. F. Chen, K. Hara, et al.

Published: 2002-07-15T13:21:59.000Z

## Abstract

We present measurements of CP-violating parameters in $B^0(\\bar{B}{}^0) \\to \\eta^\\prime K\_S^0$ and $B^{\\pm} \\to \\eta' K^{\\pm}$ decays based on a 41.8 fb$^{-1}$ data sample collected at the $\\Upsilon(4S)$ resonance with the Belle detector at the KEKB asymmetric-energy $e^{+} e^{-}$ collider. We fully reconstruct one neutral $B$ meson as a $B^0(\\bar{B}{}^0) \\to \\eta^\\prime K\_S^0$ CP eigenstate and identify the flavor of the accompanying $B$ from its decay products. From the distribution of time intervals between pairs of $B$ meson decay points, we obtain the CP-violating asymmetry parameters ${\\mathcal S}\_{\\eta^\\prime K\_S^0} = 0.28\\pm0.55(stat)^{+0.07}\_{-0.08}(syst)$, and ${\\mathcal A}\_{\\eta^\\prime K\_S^0} = 0.13\\pm0.32(stat)^{+0.09}\_{-0.06}(syst)$. We also reconstruct charged $B^{\\pm} \\to \\eta^\\prime K^{\\pm}$ decays and determine a direct-CP violating asymmetry value of ${\\mathcal A}\_{\\eta^\\prime K^\\pm}=(-1.5\\pm7.0(stat)\\pm0.9(syst))%$.

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## Original sources and implementation

[Original paper](<https://arxiv.org/abs/hep-ex/0207033>)

[PDF](<https://arxiv.org/pdf/hep-ex/0207033.pdf>)