We report the results of the first search for the decay ${B}_{s}^{0}\ensuremath{\rightarrow}{\ensuremath{\eta}}^{\ensuremath{'}}{K}_{S}^{0}$ using $121.4\text{ }\text{ }{\mathrm{fb}}^{\ensuremath{-}1}$ of data collected at the $\mathrm{\ensuremath{\Upsilon}}(5S)$ resonance with the Belle detector at the KEKB asymmetric-energy ${e}^{+}{e}^{\ensuremath{-}}$ collider. We observe no signal and set a 90% confidence-level upper limit of $8.16\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}6}$ on the ${B}_{s}^{0}\ensuremath{\rightarrow}{\ensuremath{\eta}}^{\ensuremath{'}}{K}_{S}^{0}$ branching fraction.

KEKB

Branching fraction

10.1103/physrevd.106.l051103

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Measurements of the branching fractions of $$ {\Xi}_c^0\to {\Xi}^0{\pi}^0 $$, $$ {\Xi}_c^0\to {\Xi}^0\eta $$, and $$ {\Xi}_c^0\to {\Xi}^0{\eta}^{\prime } $$ and asymmetry parameter of $$ {\Xi}_c^0\to {\Xi}^0{\pi}^0 $$

Journal of High Energy Physics (2024)

I. Adachi L. Aggarwal H. Aihara Н. Акопов A. Aloisio

A bstract We present a study of $$ {\Xi}_c^0\to {\Xi}^0{\pi}^0 $$ Ξ c 0 → Ξ 0 π 0 , $$ {\Xi}_c^0\to {\Xi}^0\eta $$ Ξ c 0 → Ξ 0 η , and $$ {\Xi}_c^0\to {\Xi}^0{\eta}^{\prime } $$ Ξ c 0 → Ξ 0 η ′ decays using the Belle and Belle II data samples, which have integrated luminosities of 980 fb − 1 and 426 fb − 1 , respectively. We measure the following relative branching fractions $$ {\displaystyle \begin{array}{c}\mathcal{B}\left({\Xi}_c^0\to {\Xi}^0{\pi}^0\right)/\mathcal{B}\left({\Xi}_c^0\to {\Xi}^{-}{\pi}^{+}\right)=0.48\pm 0.02\left(\textrm{stat}\right)\pm 0.03\left(\textrm{syst}\right),\\ {}\mathcal{B}\left({\Xi}_c^0\to {\Xi}^0\eta \right)/\mathcal{B}\left({\Xi}_c^0\to {\Xi}^{-}{\pi}^{+}\right)=0.11\pm 0.01\left(\textrm{stat}\right)\pm 0.01\left(\textrm{syst}\right),\\ {}\mathcal{B}\left({\Xi}_c^0\to {\Xi}^0{\eta}^{\prime}\right)/\mathcal{B}\left({\Xi}_c^0\to {\Xi}^{-}{\pi}^{+}\right)=0.08\pm 0.02\left(\textrm{stat}\right)\pm 0.01\left(\textrm{syst}\right)\end{array}} $$ B Ξ c 0 → Ξ 0 π 0 / B Ξ c 0 → Ξ − π + = 0.48 ± 0.02 stat ± 0.03 syst , B Ξ c 0 → Ξ 0 η / B Ξ c 0 → Ξ − π + = 0.11 ± 0.01 stat ± 0.01 syst , B Ξ c 0 → Ξ 0 η ′ / B Ξ c 0 → Ξ − π + = 0.08 ± 0.02 stat ± 0.01 syst for the first time, where the uncertainties are statistical (stat) and systematic (syst). By multiplying by the branching fraction of the normalization mode, $$ \mathcal{B}\left({\Xi}_c^0\to {\Xi}^{-}{\pi}^{+}\right) $$ B Ξ c 0 → Ξ − π + , we obtain the following absolute branching fraction results $$ {\displaystyle \begin{array}{c}\mathcal{B}\left({\Xi}_c^0\to {\Xi}^0{\pi}^0\right)=\left(6.9\pm 0.3\left(\textrm{stat}\right)\pm 0.5\left(\textrm{syst}\right)\pm 1.3\left(\operatorname{norm}\right)\right)\times {10}^{-3},\\ {}\mathcal{B}\left({\Xi}_c^0\to {\Xi}^0\eta \right)=\left(1.6\pm 0.2\left(\textrm{stat}\right)\pm 0.2\left(\textrm{syst}\right)\pm 0.3\left(\operatorname{norm}\right)\right)\times {10}^{-3},\\ {}\mathcal{B}\left({\varXi}_c^0\to {\Xi}^0{\eta}^{\prime}\right)=\left(1.2\pm 0.3\left(\textrm{stat}\right)\pm 0.1\left(\textrm{syst}\right)\pm 0.2\left(\operatorname{norm}\right)\right)\times {10}^{-3},\end{array}} $$ B Ξ c 0 → Ξ 0 π 0 = 6.9 ± 0.3 stat ± 0.5 syst ± 1.3 norm × 10 − 3 , B Ξ c 0 → Ξ 0 η = 1.6 ± 0.2 stat ± 0.2 syst ± 0.3 norm × 10 − 3 , B Ξ c 0 → Ξ 0 η ′ = 1.2 ± 0.3 stat ± 0.1 syst ± 0.2 norm × 10 − 3 , where the third uncertainties are from $$ \mathcal{B}\left({\Xi}_c^0\to {\Xi}^{-}{\pi}^{+}\right) $$ B Ξ c 0 → Ξ − π + . The asymmetry parameter for $$ {\Xi}_c^0\to {\Xi}^0{\pi}^0 $$ Ξ c 0 → Ξ 0 π 0 is measured to be $$ \alpha \left({\Xi}_c^0\to {\Xi}^0{\pi}^0\right)=-0.90\pm 0.15\left(\textrm{stat}\right)\pm 0.23\left(\textrm{syst}\right) $$ α Ξ c 0 → Ξ 0 π 0 = − 0.90 ± 0.15 stat ± 0.23 syst .

10.1007/jhep10(2024)045

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Search for charmed baryons in the Λc+η system and measurement of the branching fractions of Λc(2880

Physical review. D/Physical review. D. (2024)

S. X. Li C. P. Shen I. Adachi J. K. Ahn H. Aihara

We search for excited charmed baryons in the Λc+η system using a data sample corresponding to an integrated luminosity of 980 fb−1. The data were collected by the Belle detector at the KEKB e+e− asymmetric-energy collider. No significant signals are found in the Λc+η mass spectrum, including the known Λc(2880)+ and Λc(2940)+. Clear Λc(2880)+ and Λc(2940)+ signals are observed in the pD0 mass spectrum. We set upper limits at 90% credibility level on ratios of branching fractions of Λc(2880)+ and Λc(2940)+ decaying to Λc+η relative to Σc(2455)π of <0.13 for the Λc(2880)+ and <1.11 for the Λc(2940)+. We measure ratios of branching fractions of Λc(2880)+ and Λc(2940)+ decaying to pD0 relative to Σc(2455)π of 0.75±0.03(stat)±0.07(syst) for the Λc(2880)+ and 3.59±0.21(stat)±0.56(syst) for the Λc(2940)+. Published by the American Physical Society 2024

10.1103/physrevd.110.032021

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Measurement of branching-fraction ratios and CP asymmetries in B± → DCP±K± decays at Belle and Belle II

Journal of High Energy Physics (2024)

I. Adachi L. Aggarwal H. Aihara Н. Акопов A. Aloisio

A bstract We report results from a study of B ± → DK ± decays followed by D decaying to the CP -even final state K + K − and CP-odd final state $$ {K}_S^0{\pi}^0 $$ K S 0 π 0 , where D is an admixture of D 0 and $$ {\overline{D}}^0 $$ D ¯ 0 states. These decays are sensitive to the Cabibbo-Kobayashi-Maskawa unitarity-triangle angle ϕ 3 . The results are based on a combined analysis of the final data set of 772 × 10 6 $$ B\overline{B} $$ B B ¯ pairs collected by the Belle experiment and a data set of 198 × 10 6 $$ B\overline{B} $$ B B ¯ pairs collected by the Belle II experiment, both in electron-positron collisions at the Υ(4 S ) resonance. We measure the CP asymmetries to be $$ \mathcal{A} $$ A CP + = (+12.5 ± 5.8 ± 1.4)% and $$ \mathcal{A} $$ A CP− = ( − 16.7 ± 5.7 ± 0.6)%, and the ratios of branching fractions to be $$ \mathcal{R} $$ R CP + = 1.164 ± 0.081 ± 0.036 and $$ \mathcal{R} $$ R CP− = 1.151 ± 0.074 ± 0.019. The first contribution to the uncertainties is statistical, and the second is systematic. The asymmetries $$ \mathcal{A} $$ A CP + and $$ \mathcal{A} $$ A CP− have similar magnitudes and opposite signs; their difference corresponds to 3.5 standard deviations. From these values we calculate 68.3% confidence intervals of (8.5 ° < ϕ 3 < 16.5 ° ) or (84.5 ° < ϕ 3 < 95.5 ° ) or (163.3 ° < ϕ 3 < 171.5 ° ) and 0.321 < r B < 0.465.

Branching (polymer chemistry)

Branching fraction

10.1007/jhep05(2024)212

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Evidence ofϒ(1S)→J/ψ+χc1

Physical review. D. Particles, fields, gravitation, and cosmology/Physical review. D, Particles, fields, gravitation, and cosmology (2014)

Shuo Yang C. P. Shen Y. Ban A. Abdesselam I. Adachi

Using data samples of $102\times10^6$ $\Upsilon(1S)$ and $158\times10^6$ $\Upsilon(2S)$ events collected with the Belle detector, a first experimental search has been made for double-charmonium production in the exclusive decays $\Upsilon(1S,2S)\rightarrow J/\psi(\psi')+X$, where $X=\eta_c$, $\chi_{cJ} (J=~0,~1,~2)$, $\eta_c(2S)$, $X(3940)$, and $X(4160)$. No significant signal is observed in the spectra of the mass recoiling against the reconstructed $J/\psi$ or $\psi'$ except for the evidence of $\chi_{c1}$ production with a significance of $4.6\sigma$ for $\Upsilon(1S)\rightarrow J/\psi+\chi_{c1}$. The measured branching fraction $\BR(\Upsilon(1S)\rightarrow J/\psi+\chi_{c1})$ is $(3.90\pm1.21(\rm stat.)\pm0.23 (\rm syst.))\times10^{-6}$. The $90\%$ confidence level upper limits on the branching fractions of the other modes having a significance of less than $3\sigma$ are determined. These results are consistent with theoretical calculations using the nonrelativistic QCD factorization approach.

Branching fraction

10.1103/physrevd.90.112008

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Search for the 0−− glueball in ϒ(1S) and Physical review. D/Physical review. D. (2017)

S. Jia Chun Shen C. Z. Yuan I. Adachi H. Aihara

We report the first search for the ${J}^{PC}={0}^{\ensuremath{-}\ensuremath{-}}$ glueball in $\mathrm{\ensuremath{\Upsilon}}(1S)$ and $\mathrm{\ensuremath{\Upsilon}}(2S)$ decays with data samples of $(102\ifmmode\pm\else\textpm\fi{}2)\ifmmode\times\else\texttimes\fi{}1{0}^{6}$ and $(158\ifmmode\pm\else\textpm\fi{}4)\ifmmode\times\else\texttimes\fi{}1{0}^{6}$ events, respectively, collected with the Belle detector. No significant signals are observed in any of the proposed production modes, and the 90% credibility level upper limits on their branching fractions in $\mathrm{\ensuremath{\Upsilon}}(1S)$ and $\mathrm{\ensuremath{\Upsilon}}(2S)$ decays are obtained. The inclusive branching fractions of the $\mathrm{\ensuremath{\Upsilon}}(1S)$ and $\mathrm{\ensuremath{\Upsilon}}(2S)$ decays into final states with a ${\ensuremath{\chi}}_{c1}$ are measured to be $\mathcal{B}(\mathrm{\ensuremath{\Upsilon}}(1S)\ensuremath{\rightarrow}{\ensuremath{\chi}}_{c1}+\text{anything})=(1.90\ifmmode\pm\else\textpm\fi{}0.43(\text{stat})\ifmmode\pm\else\textpm\fi{}0.14(\text{syst}))\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}4}$ with an improved precision over prior measurements and $\mathcal{B}(\mathrm{\ensuremath{\Upsilon}}(2S)\ensuremath{\rightarrow}{\ensuremath{\chi}}_{c1}+\text{anything})=(2.24\ifmmode\pm\else\textpm\fi{}0.44(\text{stat})\ifmmode\pm\else\textpm\fi{}0.20(\text{syst}))\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}4}$ for the first time.

10.1103/physrevd.95.012001

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Search for an Invisible Z′ in a Final State with Two Muons and Missing Energy at Belle II

Physical Review Letters (2023)

I. Adachi K. Adamczyk L. Aggarwal H. Ahmed H. Aihara

The $L_{\mu}-L_{\tau}$ extension of the standard model predicts the existence of a lepton-flavor-universality-violating $Z^{\prime}$ boson that couples only to the heavier lepton families. We search for such a $Z^\prime$ through its invisible decay in the process $e^+ e^- \to \mu^+ \mu^- Z^{\prime}$. We use a sample of electron-positron collisions at a center-of-mass energy of 10.58GeV collected by the Belle II experiment in 2019-2020, corresponding to an integrated luminosity of 79.7fb$^{-1}$. We find no excess over the expected standard-model background. We set 90$\%$-confidence-level upper limits on the cross section for this process as well as on the coupling of the model, which ranges from $3 \times 10^{-3}$ at low $Z^{\prime}$ masses to 1 at $Z^{\prime}$ masses of 8$GeV/c^{2}$.

Bhabha scattering

Electron–positron annihilation

10.1103/physrevlett.130.231801

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Citations (13)