{"@context":"http://schema.org","@id":"https://doi.org/10.17182/hepdata.169553.v1","@reverse":{"isBasedOn":[{"@type":"ScholarlyArticle","identifier":{"@type":"PropertyValue","propertyID":"URL","value":"https://inspirehep.net/literature/3083443"}},{"@id":"https://doi.org/10.1103/kf73-hw61","@type":"JournalArticle"}]},"@type":"Dataset","additionalType":"Collection","author":{"@type":"Organization","name":"Belle-II Collaboration"},"creator":{"@type":"Organization","name":"Belle-II Collaboration"},"datePublished":"2026","description":"We report the first search for the flavor-changing neutral-current decays $B \\rightarrow X_{s} \\nu \\bar{\\nu}$, where $X_{s}$ is a hadronic system with strangeness equal to 1, in data collected with the Belle~II detector at the SuperKEKB asymmetric-energy $e^+e^-$ collider.The data sample corresponds to an integrated luminosity of $365~\\textrm{fb}^{-1}$ collected at the $\\Upsilon(4S)$ resonance and $43~\\textrm{fb}^{-1}$ collected at a center-of-mass energy $60~\\textrm{MeV}$ below resonance for estimation of $e^+e^-\\to q\\bar{q}$ continuum background.One of the $B$ mesons from the $\\Upsilon(4S) \\to B\\bar{B}$ decay is fully reconstructed in a hadronic decay mode. The $B \\to X_s \\nu \\bar{\\nu}$ decay is reconstructed with a sum-of-exclusives approach that uses 30 $X_s$ decay modes. This approach provides high sensitivity to the inclusive decay, despite the presence of two undetected neutrinos.The search is performed in three regions of the $X_{s}$ mass, $M_{X_{s}}^{\\textrm{true}}$, chosen to separate contributions from $K$, $K^{*}(892)$, and heavier strange final states.We do not observe a significant signal and set upper limits at 90% confidence level on the partial branching fractions for the regions $0.0 < M_{X_{s}}^{\\textrm{true}} < 0.6~\\textrm{GeV}/c^2$, $0.6 < M_{X_{s}}^{\\textrm{true}} < 1.0~\\textrm{GeV}/c^2$, and $1.0~\\textrm{GeV}/c^2 < M_{X_{s}}^{\\textrm{true}}$ of $2.2 \\times 10^{-5}$, $9.5 \\times 10^{-5}$, and $31.2 \\times 10^{-5}$, respectively. Combining the three mass regions, we obtain the upper limit on the branching fraction, $B(B \\to X_s \\nu \\bar{\\nu}) < 3.2 \\times 10^{-4}$.","hasPart":[{"@id":"https://doi.org/10.17182/hepdata.169553.v1/t1","@type":"Dataset","description":"The bin index distribution after the fit, for data and histogram templates. The background templates are separated into 6 categories:...","name":"Postfit yields"},{"@id":"https://doi.org/10.17182/hepdata.169553.v1/t2","@type":"Dataset","description":"$\\textrm{CL}{s}$ values as a function of the assumed branching fraction for $B \\rightarrow X_{s} \\nu \\bar{\\nu}$ in the $0.0 <...","name":"Expected and observed limit 1"},{"@id":"https://doi.org/10.17182/hepdata.169553.v1/t3","@type":"Dataset","description":"$\\textrm{CL}{s}$ values as a function of the assumed branching fraction for $B \\rightarrow X_{s} \\nu \\bar{\\nu}$ in the $0.6 <...","name":"Expected and observed limit 2"},{"@id":"https://doi.org/10.17182/hepdata.169553.v1/t4","@type":"Dataset","description":"$\\textrm{CL}{s}$ values as a function of the assumed branching fraction for $B \\rightarrow X_{s} \\nu \\bar{\\nu}$ in the $1.0~\\textrm{GeV}/c^{2} <...","name":"Expected and observed limit 3"},{"@id":"https://doi.org/10.17182/hepdata.169553.v1/t5","@type":"Dataset","description":"$\\textrm{CL}{s}$ values as a function of the assumed branching fraction for $B \\rightarrow X_{s} \\nu \\bar{\\nu}$ in the entire $M_{X_{s}}^{\\textrm{true}}$...","name":"Expected and observed limit 4"},{"@id":"https://doi.org/10.17182/hepdata.169553.v1/t6","@type":"Dataset","description":"Distribution of the mass $M_{X_{s}}^{\\textrm{true}}$ of the $X_{s}$ system in signal simulation samples. The values are given in arbitrary units....","name":"Fragmentation of $X_{s}$"},{"@id":"https://doi.org/10.17182/hepdata.169553.v1/t7","@type":"Dataset","description":"Fraction of signal events in the $M_{X_{s}}^{\\textrm{true}}$-bin index plane before the fit. The uncertainty is the statistical uncertainty from the...","name":"Fraction of signal events"},{"@id":"https://doi.org/10.17182/hepdata.169553.v1/t8","@type":"Dataset","description":"Signal efficiency as a function of $M_{X_s}^{\\mathrm{true}}$, evaluated before the fit. The uncertainty is the statistical uncertainty from the simulation...","name":"Signal efficiency"}],"identifier":[{"@type":"PropertyValue","propertyID":"HEPDataRecord","value":"https://www.hepdata.net/record/ins3083443?version=1"},{"@type":"PropertyValue","propertyID":"HEPDataRecordAlt","value":"https://www.hepdata.net/record/169553"}],"inLanguage":"en","name":"First search for $B \\rightarrow X_{s} \u03bd\\bar\u03bd$ decays","provider":{"@type":"Organization","name":"HEPData"},"publisher":{"@type":"Organization","name":"HEPData"},"url":"https://www.hepdata.net/record/ins3083443?version=1","version":1}