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J. T. McNeil

Publications and source records attributed to J. T. McNeil.

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Measurement of the Resonant and Non-Resonant Branching Ratios in $Ξ_{c}^{0} \rightarrow Ξ^{0} K^+ K^-$

Using the entire data sample of $980$ $fb^{-1}$ integrated luminosity collected with the Belle detector at the KEKB asymmetric-energy $e^{+}e^{-}$ collider, we present an amplitude analysis measuring the branching fractions of the Cabibbo-allowed, $W$-exchange resonant decay $Ξ_{c}^{0} \rightarrow Ξ^{0} ϕ(\to K^+ K^-)$ with a polarized $ϕ$ and the non-resonant decay via a direct process $Ξ_{c}^{0} \rightarrow Ξ^{0} K^+ K^-$. We present these measurements, relative to the normalization mode $Ξ^{-}π^{+}$, and find branching ratios $\frac{\mathcal{B}(Ξ_{c}^{0} \rightarrow Ξ^{0} ϕ(\rightarrow K^{+}K^{-}))}{\mathcal{B}(Ξ_{c}^{0} \rightarrow Ξ^{-} π^{+})} = 0.036 \pm 0.004 (stat.) \pm 0.002 (syst.)$ and $\frac{\mathcal{B}(Ξ_{c}^{0} \rightarrow Ξ^{0} K^{+} K^{-})}{\mathcal{B}(Ξ_{c}^{0} \rightarrow Ξ^{-} π^{+})} = 0.039 \pm 0.004 (stat.) \pm 0.002 (syst.)$ which suggest that only minor cusping peaks occur in the combinatorial background of $Ω^{*-} \to Ξ^{0}K^{-}$ due to these $Ξ_{c}^{0}$ decays.

hep-ex

Test of lepton-flavor universality in ${B\to K^\ast\ell^+\ell^-}$ decays at Belle

We present a measurement of $R_{K^{\ast}}$, the branching fraction ratio ${{\cal B}(B\to K^\ast μ^+ μ^-)}$/ ${{\cal B}(B\to K^\ast e^+ e^-)}$, for both charged and neutral $B$ mesons. The ratio for the charged case, $R_{K{^{\ast +}}}$, is the first measurement ever performed. In addition, we report absolute branching fractions for the individual modes in bins of the squared dilepton invariant mass, $q^2$. The analysis is based on a data sample of $711~\mathrm{fb}^{-1}$, containing $772\times 10^{6}$ $B\bar B$ events, recorded at the $Υ(4S)$ resonance with the Belle detector at the KEKB asymmetric-energy $e^+e^-$ collider. The obtained results are consistent with Standard Model expectations.

hep-ex