M. Watanabe

activity

20242026

collaborators

21 papers

hep-ex2026

Search for axion-like particles decaying to two photons at Belle II

Belle II Collaboration, M. Abumusabh, I. Adachi +450

Axion-like particles (ALPs) are predicted in many extensions of the Standard Model and provide a well-motivated portal between visible and hidden sectors through their coupling to…

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-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

Measurements of the mass difference $m (B^{0}) - m (B^{+})$ and the energy dependence of the cross-section ratio $I ¨ (e^{+} e^{-} \to B^{0} B ˉ^{0}) / I ¨ (e^{+} e^{-} \to B^{+} B^{-})$ at Belle and Belle II

Belle, Belle II Collaborations, : +396

Using data samples collected by the Belle and Belle II experiments at the $I^¥ (4 S)$ resonance with integrated luminosities of 571 fb $^{- 1}$ and 365 fb $^{- 1}$ , respectively, we measu…

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…

Search for axion-like particles decaying to two photons at Belle II

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

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

Measurements of the mass difference m(B0)−m(B+) and the energy dependence of the cross-section ratio I¨(e+e−→B0Bˉ0)/I¨(e+e−→B+B−) at Belle and Belle II

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

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

Measurements of the mass difference $m (B^{0}) - m (B^{+})$ and the energy dependence of the cross-section ratio $I ¨ (e^{+} e^{-} \to B^{0} B ˉ^{0}) / I ¨ (e^{+} e^{-} \to B^{+} B^{-})$ at Belle and Belle II

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