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Cunliffe, S.

Publications and source records attributed to Cunliffe, S..

At least 37 records · Page 2
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DOE OSTI2021

Search for lepton-flavor-violating tau-lepton decays to ℓγ at Belle

Charged lepton flavor violation is forbidden in the Standard Model but possible in several new physics scenarios. In many of these models, the radiative decays τ ± → ℓ ± γ (ℓ = e, μ) are predicted to have a sizeable probability, making them particularly interesting channels to search at various experiments. An updated search via τ ± → ℓ ± γ using full data of the Belle experiment, corresponding to an integrated luminosity of 988 fb –1 , is reported for charged lepton flavor violation. No significant excess over background predictions from the Standard Model is observed, and the upper limits on the branching fractions, B(τ ± → μ ± γ) ≤ 4.2 × 10 –8 and B(τ ± → e ± γ) ≤ 5.6 × 10 –8 , are set at 90% confidence level.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2021

Measurement of branching fractions and search for CP violation in $D^0 → π^+π^-η, D^0 → K^+K^-η$, and $D^0 → Φη$ at Belle

We measure the branching fractions and CP asymmetries for the singly Cabibbo-suppressed decays $D^0 → π^+π^-η, D^0 → K^+K^-η$, and $D^0 → Φη$, using 980 fb -1 of data from the Belle experiment at the KEKB e + e - collider. We obtain $$\mathcal{B}(D^0 → π^+π^-η = \mathrm{[1.22 ± 0.02 (stat) ± 0.02(syst) ± 0.03}(\mathcal{B}_{\mathrm{ref}})] \mathrm{x 10^{-3}}$$ $$\mathcal{B}(D^0 → K^+K^-η = \mathrm{[1.80^{+0.07}_{-0.06}(stat) ± 0.04 (syst) ± 0.05}(\mathcal{B}_{\mathrm{ref}})] \mathrm{x 10^{-4}}$$ $$\mathcal{B}(D^0 → Φη = \mathrm{[1.84 ± 0.09 (stat) ± 0.0 (syst) ± 0.05}(\mathcal{B}_{\mathrm{ref}})] \mathrm{x 10^{-4}}$$ where the third uncertainty ($\mathcal{B}_{\mathrm{ref}}$) is from the uncertainty in the branching fraction of the reference mode $D^0 → K^-π^+η$. The color-suppressed decay $D^0 → Φη$ is observed for the first time, with very high significance. The results for the CP asymmetries are $$A_{CP} (D^0 → π^+π^-η) = \mathrm{[0.9 ± 1.2 (stat) ± 0.5 (syst)]}\%$$ $$A_{CP} (D^0 → K^+K^-η) = \mathrm{[-1.4 ± 3.3 (stat) ± 1.1 (syst)]}\%$$ $$A_{CP} (D^0 → Φη) = \mathrm{[-1.9 ± 4.4 (stat) ± 0.6 (syst)]}\%$$ The results for $D^0 → π^+π^-η$ are a significant improvement over previous results. The branching fraction and A CP results for $D^0 → K^+K^-η$, and the ACP result for $D^0 → Φη$, are the first such measurements. No evidence for CP violation is found in any of these decays.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2021

Measurements of branching fractions and asymmetry parameters of $ {\Xi}_c^0\to \Lambda {\overline{K}}^{\ast 0} $, $ {\Xi}_c^0\to {\Sigma}^0{\overline{K}}^{\ast 0} $, and $ {\Xi}_c^0\to {\Sigma}^{+}{K}^{\ast -} $ decays at Belle

Using a data sample of 980 fb -1 collected with the Belle detector at the KEKB asymmetric-energy e + e - collider, we study the processes of ${\Xi}_c^0\to \Lambda {\overline{K}}^{\ast 0}$, ${\Xi}_c^0\to {\Sigma}^0{\overline{K}}^{\ast 0}$, and ${\Xi}_c^0\to {\Sigma}^{+}{K}^{\ast -}$ for the first time. The relative branching ratios to the normalization mode of ${\Xi}_c^0\to {\Xi}^{-}{\pi}^{+}$ are measured to be ${\displaystyle \begin{array}{c}\mathcal{B}\left({\Xi}_c^0\to \Lambda {\overline{K}}^{\ast 0}\right)/\mathcal{B}\left({\Xi}_c^0\to {\Xi}^{-}{\pi}^{+}\right)=0.18\pm 0.02\left(\mathrm{stat}.\right)\pm 0.01\left(\mathrm{syst}.\right),\\ {}\mathcal{B}\left({\Xi}_c^0\to {\Sigma}^0{\overline{K}}^{\ast 0}\right)/\mathcal{B}\left({\Xi}_c^0\to {\Xi}^{-}{\pi}^{+}\right)=0.69\pm 0.03\left(\mathrm{stat}.\right)\pm 0.03\left(\mathrm{syst}.\right),\\ {}\mathcal{B}\left({\Xi}_c^0\to {\Sigma}^{+}{K}^{\ast -}\right)/\mathcal{B}\left({\Xi}_c^0\to {\Xi}^{-}{\pi}^{+}\right)=0.34\pm 0.06\left(\mathrm{stat}.\right)\pm 0.02\left(\mathrm{syst}.\right),\end{array}}$ where the uncertainties are statistical and systematic, respectively. We obtain ${\displaystyle \begin{array}{c}\mathcal{B}\left({\Xi}_c^0\to \Lambda {\overline{K}}^{\ast 0}\right)=\left(3.3\pm 0.3\left(\mathrm{stat}.\right)\pm 0.2\left(\mathrm{syst}.\right)\pm 1.0\left(\mathrm{ref}.\right)\right)\times {10}^{-3},\\ {}\mathcal{B}\left({\Xi}_c^0\to {\Sigma}^0{\overline{K}}^{\ast 0}\right)=\left(12.4\pm 0.5\left(\mathrm{stat}.\right)\pm 0.5\left(\mathrm{syst}.\right)\pm 3.6\left(\mathrm{ref}.\right)\right)\times {10}^{-3},\\ {}\mathcal{B}\left({\Xi}_c^0\to {\Sigma}^{+}{K}^{\ast 0}\right)=\left(6.1\pm 1.0\left(\mathrm{stat}.\right)\pm 0.4\left(\mathrm{syst}.\right)\pm 1.8\left(\mathrm{ref}.\right)\right)\times {10}^{-3},\end{array}}$ where the uncertainties are statistical, systematic, and from $\mathcal{B}\left({\Xi}_c^0\to {\Xi}^{-}{\pi}^{+}\right)$, respectively. The asymmetry parameters $\alpha \left({\Xi}_c^0\to \Lambda {\overline{K}}^{\ast 0}\right)$ and $\alpha \left({\Xi}_c^0\to {\Sigma}^{+}{K}^{\ast -}\right)$ are 0.15 ± 0.22(stat.) ± 0.04(syst.) and -0.52 ± 0.30(stat.) ± 0.02(syst.), respectively, where the uncertainties are statistical followed by systematic.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗