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Constraining Extensions of the Quark Sector with the CP Asymmetry in $B\to ψK_{S}$

Galit Eyal·Yosef Nir
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Abstract

Models with extended quark sector affect the CP asymmetry in the $B\to ψK_{S}$ decay, $a_{ψK_{S}}$, in two ways: First, the top-mediated box diagram is not necessarily the only important contribution to $B-\bar{B}$ mixing. Second, the $3\times 3$ CKM matrix is no longer unitary. We analyze the constraints that follow from the CDF measurement, $a_{ψK_{S}} =0.79^{+0.41}_{-0.44}$, on the mixing parameters of extended quark sectors. Most noticeably, we find significant constraints on the phase of the relevant flavor changing $Z$ coupling in models with extra down quarks in vector-like representations. Further implications for the CP asymmetry in semileptonic $B$ decays are discussed.

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Galit Eyal, Yosef Nir. 1999-08-08. Constraining Extensions of the Quark Sector with the CP Asymmetry in $B\to ψK_{S}$. https://doi.org/10.1088/1126-6708%2F1999%2F09%2F013

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