K. Hayasaka

activity

20242026

collaborators

24 papers

hep-ex2026

First measurement of the masses of the $I^¥_{1} (1 D)$ and $I^¥_{3} (1 D)$ states and the energy dependence of the cross sections for $e^{+} e^{-} \to I^¥_{J} (1 D) I^\cdot$ and $e^{+} e^{-} \to I^¥_{J} (1 D) I ¨ ^{+} I ¨ ^{-}$

Belle, Belle II Collaborations, : +398

We study the processes $e^{+} e^{-} \to I^¥_{J} (1 D) I^\cdot$ and $e^{+} e^{-} \to I^¥_{J} (1 D) I ¨ ^{+} I ¨ ^{-}$ at center-of-mass energies $s$ =(10.73 -- 11.02) GeV using a $142.5 fb^{- 1}$ data sampl…

hep-ex2026

Search for the lepton-flavor-violating $I ¨ ^{-} \to e^{\mp} ℓ^{\pm} ℓ^{\mp}$ decays at Belle II

Belle II Collaboration, I. Adachi, L. Aggarwal +447

We present the result of a search for the charged-lepton-flavor violating decays $I ¨ ^{-} \to e^{\mp} ℓ^{\pm} ℓ^{-}$ , where $ℓ$ is a muon or an electron, using a data sampl…

hep-ex2026

Test of lepton flavor universality with measurements of $R (D^{+})$ and $R (D^{*+})$ using semileptonic $B$ tagging at the Belle II experiment

Belle II Collaboration, I. Adachi, K. Adamczyk +450

We report measurements of the ratios of branching fractions ${\cal R}(D^{(*)+}) = \frac{{\cal B}(\overline{B}{}^0 \to D^{(*)+} \,Ï^- \, \overlineÎ½_Ï)}{{\cal B}(\overline{B}{}^0…

hep-ex2026

Averages of $b$ -hadron, $c$ -hadron, and $I ¨ $ -lepton properties as of 2023

Sw. Banerjee, E. Ben-Haim, F. Bernlochner +35

This paper reports world averages of measurements of $b$ -hadron, $c$ -hadron, and $I ¨ $ -lepton properties obtained by the Heavy Flavour Averaging Group using results available before…

hep-ex2025

Search for a Dark Higgs Boson Produced in Association with Inelastic Dark Matter at the Belle II Experiment

Belle II Collaboration, I. Adachi, L. Aggarwal +437

Inelastic dark matter models that have two dark matter particles and a massive dark photon can reproduce the observed relic dark matter density without violating cosmological limit…

hep-ex2025

Measurement of the $D^{0} \to K^{-} I ¨ ^{+} e^{+} e^{-}$ branching fraction and search for $D^{0} \to I ¨ ^{+} I ¨ ^{-} e^{+} e^{-}$ and $D^{0} \to K^{+} K^{-} e^{+} e^{-}$ decays at Belle

Belle, Belle II Collaborations, : +481

We present a study of the rare charm meson decays $D^{0} \to K^{+} K^{-} e^{+} e^{-}$ , $I ¨ ^{+} I ¨ ^{-} e^{+} e^{-}$ , and $K^{-} I ¨ ^{+} e^{+} e^{-}$ using a 942 fb $^{- 1}$ data se…

First measurement of the masses of the I^¥1​(1D) and I^¥3​(1D) states and the energy dependence of the cross sections for e+e−→I^¥J​(1D)I^⋅ and e+e−→I^¥J​(1D)I¨+I¨−

Search for the lepton-flavor-violating I¨−→e∓ℓ±ℓ∓ decays at Belle II

Test of lepton flavor universality with measurements of R(D+) and R(D∗+) using semileptonic B tagging at the Belle II experiment

Averages of b-hadron, c-hadron, and I¨-lepton properties as of 2023

Search for a Dark Higgs Boson Produced in Association with Inelastic Dark Matter at the Belle II Experiment

Measurement of the D0→K−I¨+e+e− branching fraction and search for D0→I¨+I¨−e+e− and D0→K+K−e+e− decays at Belle

First measurement of the masses of the $I^¥_{1} (1 D)$ and $I^¥_{3} (1 D)$ states and the energy dependence of the cross sections for $e^{+} e^{-} \to I^¥_{J} (1 D) I^\cdot$ and $e^{+} e^{-} \to I^¥_{J} (1 D) I ¨ ^{+} I ¨ ^{-}$

Search for the lepton-flavor-violating $I ¨ ^{-} \to e^{\mp} ℓ^{\pm} ℓ^{\mp}$ decays at Belle II

Test of lepton flavor universality with measurements of $R (D^{+})$ and $R (D^{*+})$ using semileptonic $B$ tagging at the Belle II experiment

Averages of $b$ -hadron, $c$ -hadron, and $I ¨ $ -lepton properties as of 2023

Measurement of the $D^{0} \to K^{-} I ¨ ^{+} e^{+} e^{-}$ branching fraction and search for $D^{0} \to I ¨ ^{+} I ¨ ^{-} e^{+} e^{-}$ and $D^{0} \to K^{+} K^{-} e^{+} e^{-}$ decays at Belle