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Kichimi, H.

Publications and source records attributed to Kichimi, H..

At least 19 records

First measurement of the \( {\Lambda}_c^{+} \) → pη ' decay

We present the first measurement of the branching fraction of the singly Cabibbo-suppressed (SCS) decay \( {\Lambda}_c^{+} \) → pη ' with η ' → ηπ + π – , using a data sample corresponding to an integrated luminosity of 981 fb – 1 , collected by the Belle detector at the KEKB e + e – asymmetric-energy collider. A significant \( {\Lambda}_c^{+} \) → pη ' signal is observed for the first time with a signal significance of 5.4 σ . The relative branching fraction with respect to the normalization mode \( {\Lambda}_c^{+} \) → pK – π + is measured to be $$ \frac{\mathcal{B}\left({\Lambda}_c^{+}\to p\eta^{\prime}\right)}{\mathcal{B}\left({\Lambda}_c^{+}\to {pK}^{-}{\pi}^{+}\right)}=\left(7.54\pm 1.32\pm 0.73\right)\times {10}^{-3}, $$ where the uncertainties are statistical and systematic, respectively. Using the world-average value of \( \mathcal{B}\left({\Lambda}_c^{+}\to {pK}^{-}{\pi}^{+}\right) \) = (6 . 28 ± 0 . 32) × 10 – 2 , we obtain $$ \mathcal{B}\left({\Lambda}_c^{+}\to p\eta^{\prime}\right)=\left(4.73\pm 0.82\pm 0.46\pm 0.24\right)\times {10}^{-4}, $$ where the uncertainties are statistical, systematic, and from \( \mathcal{B}\left({\Lambda}_c^{+}\to {pK}^{-}{\pi}^{+}\right) \) , respectively.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

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 ↗

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 ↗