A. Frey

activity

19952026

e^{+} e^{-} \to π^{+} π^{-} J / ψ

and Observation of a Charged Charmonium-like State at Belle

739 citations · 7.5k across the 197 of their papers we have counts for

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hep-ex2026

Search for the decay $B^{+} \to K^{+} τ^{+} τ^{-}$ using data from the Belle and Belle II experiments

Belle, Belle II Collaborations, : +435

We report a search for the rare decay $B^{+} \to K^{+} τ^{+} τ^{-}$ using $1.2 \times 1 0^{9}$ $Υ (4 S)$ mesons produced near threshold in electron-positron collisions and colle…

hep-ex2026

Study of $B^{+} \to μ^{+} ν_{μ}$ decays at Belle and Belle II

Belle, Belle II Collaborations, : +412

We report a measurement of the branching fraction for the leptonic decay $B^{+} \to μ^{+} ν_{μ}$ . This work presents the first $B^{+} \to μ^{+} ν_{μ}$ result using Belle~II data, an updated Belle me…

hep-ex2024

Measurement of the inclusive branching fractions for $B_{s}^{0}$ decays into $D$ mesons via hadronic tagging

Belle, Belle II Collaborations, : +452

We report measurements of the absolute branching fractions $B (B_{s}^{0} \to D_{s}^{\pm} X)$ , $B (B_{s}^{0} \to D^{0} / D ˉ^{0} X)$ , and $B (B_{s}^{0} \to D^{\pm} X)$ , w…

hep-ex2024

Measurement of the energy dependence of the $e^{+} e^{-} \to B B ˉ$ , $B B ˉ^{}$ , and $B^{} B ˉ^{*}$ cross sections at Belle~II

Belle II Collaboration, I. Adachi, L. Aggarwal +466

We report measurements of the $e^{+} e^{-} \to B B ˉ$ , $B B ˉ^{*}$ , and $B^{*} B ˉ^{*}$ cross sections at four energies, 10653, 10701, 10746 and 10805 MeV, using data collected b…

hep-ex2024★ 2 cited

Test of light-lepton universality in $τ$ decays with the Belle II experiment

Belle II Collaboration, I. Adachi, K. Adamczyk +428

We present a measurement of the ratio $R_{μ} = B (τ^{-} \to μ^{-} ν ˉ_{μ} ν_{τ}) / B (τ^{-} \to e^{-} ν ˉ_{e} ν_{τ})$ of branching fractions $B$ of the $τ$ lepton decaying t…

hep-ex2024★ 8 cited

Search for lepton-flavor-violating $τ^{-} \to μ^{-} μ^{+} μ^{-}$ decays at Belle II

Belle II Collaboration, I. Adachi, L. Aggarwal +429

We present the result of a search for the charged-lepton-flavor violating decay $τ^{-} \to μ^{-} μ^{+} μ^{-}$ using a $424 f b^{- 1}$ sample of data recorded by the Belle II experiment at the S…

hep-ex2024

Measurement of $C P$ asymmetries in $B^{0} \to K_{S}^{0} K_{S}^{0} K_{S}^{0}$ decays at Belle II

Belle II Collaboration, I. Adachi, L. Aggarwal +450

We report a measurement of decay-time dependent charge-parity ( $C P$ ) asymmetries in $B^{0} \to K_{S}^{0} K_{S}^{0} K_{S}^{0}$ decays. We use $387 \times 1 0^{6} B B ˉ$ pairs collected at…

hep-ex2024★ 10 cited

Search for a $μ^{+} μ^{-}$ resonance in four-muon final states at Belle II

Belle II Collaboration, I. Adachi, K. Adamczyk +401

We report on a search for a resonance $X$ decaying to a pair of muons in $e^{+} e^{-} \to μ^{+} μ^{-} X$ events in the 0.212-9.000 GeV/ $c^{2}$ mass range, using 178 fb $^{- 1}$ of…

hep-ex2024★ 13 cited

New graph-neural-network flavor tagger for Belle II and measurement of $sin 2 ϕ_{1}$ in $B^{0} \to J / ψ K_{S}^{0}$ decays

Belle II Collaboration, I. Adachi, L. Aggarwal +413

We present GFlaT, a new algorithm that uses a graph-neural-network to determine the flavor of neutral $B$ mesons produced in $Υ (4 S)$ decays. It improves previous algorithms by usin…

hep-ex2024

A test of lepton flavor universality with a measurement of $R (D^{*})$ using hadronic $B$ tagging at the Belle II experiment

Belle II Collaboration, I. Adachi, K. Adamczyk +434

The ratio of branching fractions $R (D^{*}) = B (B \to D^{*} τ^{-} ν_{τ})$ /$\mathcal{B} (\overline{B} \rightarrow D^{*} \ell^{-} \overlineν_{\ell}…

hep-ex2024

Study of $Υ (10753)$ decays to $π^{+} π^{-} Υ (n S)$ final states at Belle II

Belle II Collaboration, I. Adachi, L. Aggarwal +393

We present an analysis of the process $e^{+} e^{-} \to π^{+} π^{-} Υ (n S)$ (where $n$ = 1, 2, or 3) reconstructed in $19.6$ $f b^{- 1}$ of Belle II data during a special run of the…

hep-ex2023

Search for the $e^{+} e^{-} \to η_{b} (1 S) ω$ and $e^{+} e^{-} \to χ_{b 0} (1 P) ω$ processes at $s = 10.745 GeV$

Belle II Collaboration, I. Adachi, L. Aggarwal +419

We search for the $e^{+} e^{-} \to η_{b} (1 S) ω$ and $e^{+} e^{-} \to χ_{b 0} (1 P) ω$ processes at a center-of-mass energy of 10.745 GeV, which is close to the peak of the $Υ (10753)$ state. We use data…

hep-ex2023★ 8 cited

Measurement of branching fractions and direct $C P$ asymmetries for $B \to K π$ and $B \to π π$ decays at Belle II

Belle II Collaboration, I. Adachi, L. Aggarwal +435

We report measurements of the branching fractions and direct $CP$ asymmetries of the decays $B^{0} \to K^{+} π^{-}$ , $B^{+} \to K^{+} π^{0}$ , $B^{+} \to K^{0} π^{+}$ , and $B^{0} \to K^{0} π^{0}$ , and…

hep-ex2023

Measurement of branching-fraction ratios and $C P$ asymmetries in $B^{\pm} \to D_{C P \pm} K^{\pm}$ decays at Belle and Belle II

The Belle, Belle II Collaborations, : +427

We report results from a study of $B^{\pm} \to D K^{\pm}$ decays followed by $D$ decaying to $C P$ ~eigenstates, where $D$ indicates a $D^{0}$ or $D ˉ^{0}$ meson. These decays a…

hep-ex2023★ 7 cited

Tests of light-lepton universality in angular asymmetries of $B^{0} \to D^{*-} ℓ ν$ decays

Belle II Collaboration, I. Adachi, K. Adamczyk +416

We present the first comprehensive tests of light-lepton universality in the angular distributions of semileptonic $B^{0}$ -meson decays to charged spin-1 charmed mesons. We measure f…

hep-ex2023★ 10 cited

Search for a $τ^{+} τ^{-}$ resonance in $e^{+} e^{-} \to μ^{+} μ^{-} τ^{+} τ^{-}$ events with the Belle II experiment

Belle II Collaboration, I. Adachi, K. Adamczyk +464

We report the first search for a non-standard-model resonance decaying into $τ$ pairs in $e^{+} e^{-} \to μ^{+} μ^{-} τ^{+} τ^{-}$ events in the 3.6-10 GeV/ $c^{2}$ mass range. We u…

hep-ex2023★ 16 cited

Search for a long-lived spin-0 mediator in $b \to s$ transitions at the Belle II experiment

Belle II Collaboration, I. Adachi, K. Adamczyk +411

Additional spin-0 particles appear in many extensions of the standard model. We search for long-lived spin-0 particles $S$ in $B$ -meson decays mediated by a $b \to s$ quark transiti…

hep-ex2023★ 5 cited

Precise measurement of the $D_{s}^{+}$ lifetime at Belle II

Belle II Collaboration, I. Adachi, L. Aggarwal +359

We measure the lifetime of the $D_{s}^{+}$ meson using a data sample of 207 fb $^{- 1}$ collected by the Belle II experiment running at the SuperKEKB asymmetric-energy $e^{+} e^{-}$ collider…

hep-ex2023

Search for $C P$ violation using $T$ -odd correlations in $D_{(s)}^{+} \to K^{+} K^{-} π^{+} π^{0}$ , $D_{(s)}^{+} \to K^{+} π^{-} π^{+} π^{0}$ , and $D^{+} \to K^{-} π^{+} π^{+} π^{0}$ decays

Belle Collaboration, L. K. Li, A. J. Schwartz +174

We search for $C P$ violation using $T$ -odd correlations in five $D_{(s)}^{+}$ and $D_{(s)}^{-}$ four-body decays. Our analysis is based on 980 $f b^{- 1}$ of data collected by…

hep-ex2023

Search for lepton-flavor-violating $τ^{-} \to ℓ^{-} ϕ$ decays in 2019-2021 Belle II data

Belle II Collaboration, F. Abudinén, I. Adachi +575

We report a search for lepton-flavor-violating decays $τ^{-} \to ℓ^{-} ϕ$ ( $ℓ^{-} = e^{-}, μ^{-}$ ) at the Belle II experiment, using a sample of electron-positron data produced at the Su…

hep-ex2023★ 2 cited

Observation of $B \to D^{(*)} K^{-} K_{S}^{0}$ decays using the 2019-2022 Belle II data sample

Belle II Collaboration, F. Abudinén, I. Adachi +575

We present a measurement of the branching fractions of four $B^{0, -} \to D^{(*) +, 0} K^{-} K_{S}^{0}$ decay modes. The measurement is based on data from SuperKEKB electron-positron colli…

hep-ex2023★ 6 cited

Novel method for the identification of the production flavor of neutral charmed mesons

Belle II Collaboration, I. Adachi, L. Aggarwal +396

We propose a new algorithm for the identification of the production flavor of neutral $D$ mesons in the Belle II experiment. The algorithm exploits the correlation between the flav…

hep-ex2023★ 6 cited

Measurement of the branching fraction and $CP$ asymmetry of $B^{0} \to π^{0} π^{0}$ decays using $198 \times 1 0^{6}$ $B B$ pairs in Belle II data

Belle II Collaboration, F. Abudinén, I. Adachi +425

We report measurements of the branching fraction and $CP$ asymmetry in $B^{0} \to π^{0} π^{0}$ decays reconstructed at Belle II in an electron-positron collision sample contain…

hep-ex2023★ 10 cited

Measurement of the $B^{0}$ lifetime and flavor-oscillation frequency using hadronic decays reconstructed in 2019-2021 Belle II data

Belle II Collaboration, F. Abudinén, I. Adachi +393

We measure the $B^{0}$ lifetime and flavor-oscillation frequency using $B^{0} \to D^{(*) -} π^{+}$ decays collected by the Belle II experiment in asymmetric-energy $e^{+} e^{-}$ collisions produ…

Search for the decay B+→K+τ+τ− using data from the Belle and Belle II experiments

Study of B+→μ+νμ​ decays at Belle and Belle II

Measurement of the inclusive branching fractions for Bs0​ decays into D mesons via hadronic tagging

Measurement of the energy dependence of the e+e−→BBˉ, BBˉ∗, and B∗Bˉ∗ cross sections at Belle~II

Test of light-lepton universality in τ decays with the Belle II experiment

Search for lepton-flavor-violating τ−→μ−μ+μ− decays at Belle II

Measurement of CP asymmetries in B0→KS0​KS0​KS0​ decays at Belle II

Search for a μ+μ− resonance in four-muon final states at Belle II

New graph-neural-network flavor tagger for Belle II and measurement of sin2ϕ1​ in B0→J/ψKS0​ decays

A test of lepton flavor universality with a measurement of R(D∗) using hadronic B tagging at the Belle II experiment

Study of Υ(10753) decays to π+π−Υ(nS) final states at Belle II

Search for the e+e−→ηb​(1S)ω and e+e−→χb0​(1P)ω processes at s​=10.745GeV

Measurement of branching fractions and direct CP asymmetries for B→Kπ and B→ππ decays at Belle II

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

Tests of light-lepton universality in angular asymmetries of B0→D∗−ℓν decays

Search for a τ+τ− resonance in e+e−→μ+μ−τ+τ− events with the Belle II experiment

Search for a long-lived spin-0 mediator in b→s transitions at the Belle II experiment

Precise measurement of the Ds+​ lifetime at Belle II

Search for CP violation using T-odd correlations in D(s)+​→K+K−π+π0, D(s)+​→K+π−π+π0, and D+→K−π+π+π0 decays

Search for lepton-flavor-violating τ−→ℓ−ϕ decays in 2019-2021 Belle II data

Observation of B→D(∗)K−KS0​ decays using the 2019-2022 Belle II data sample

Novel method for the identification of the production flavor of neutral charmed mesons

Measurement of the branching fraction and CP asymmetry of B0→π0π0 decays using 198×106 BB pairs in Belle II data

Measurement of the B0 lifetime and flavor-oscillation frequency using hadronic decays reconstructed in 2019-2021 Belle II data

Search for the decay $B^{+} \to K^{+} τ^{+} τ^{-}$ using data from the Belle and Belle II experiments

Study of $B^{+} \to μ^{+} ν_{μ}$ decays at Belle and Belle II

Measurement of the inclusive branching fractions for $B_{s}^{0}$ decays into $D$ mesons via hadronic tagging

Measurement of the energy dependence of the $e^{+} e^{-} \to B B ˉ$ , $B B ˉ^{}$ , and $B^{} B ˉ^{*}$ cross sections at Belle~II

Test of light-lepton universality in $τ$ decays with the Belle II experiment

Search for lepton-flavor-violating $τ^{-} \to μ^{-} μ^{+} μ^{-}$ decays at Belle II

Measurement of $C P$ asymmetries in $B^{0} \to K_{S}^{0} K_{S}^{0} K_{S}^{0}$ decays at Belle II

Search for a $μ^{+} μ^{-}$ resonance in four-muon final states at Belle II

New graph-neural-network flavor tagger for Belle II and measurement of $sin 2 ϕ_{1}$ in $B^{0} \to J / ψ K_{S}^{0}$ decays

A test of lepton flavor universality with a measurement of $R (D^{*})$ using hadronic $B$ tagging at the Belle II experiment

Study of $Υ (10753)$ decays to $π^{+} π^{-} Υ (n S)$ final states at Belle II

Search for the $e^{+} e^{-} \to η_{b} (1 S) ω$ and $e^{+} e^{-} \to χ_{b 0} (1 P) ω$ processes at $s = 10.745 GeV$

Measurement of branching fractions and direct $C P$ asymmetries for $B \to K π$ and $B \to π π$ decays at Belle II

Measurement of branching-fraction ratios and $C P$ asymmetries in $B^{\pm} \to D_{C P \pm} K^{\pm}$ decays at Belle and Belle II

Tests of light-lepton universality in angular asymmetries of $B^{0} \to D^{*-} ℓ ν$ decays

Search for a $τ^{+} τ^{-}$ resonance in $e^{+} e^{-} \to μ^{+} μ^{-} τ^{+} τ^{-}$ events with the Belle II experiment

Search for a long-lived spin-0 mediator in $b \to s$ transitions at the Belle II experiment

Precise measurement of the $D_{s}^{+}$ lifetime at Belle II

Search for $C P$ violation using $T$ -odd correlations in $D_{(s)}^{+} \to K^{+} K^{-} π^{+} π^{0}$ , $D_{(s)}^{+} \to K^{+} π^{-} π^{+} π^{0}$ , and $D^{+} \to K^{-} π^{+} π^{+} π^{0}$ decays

Search for lepton-flavor-violating $τ^{-} \to ℓ^{-} ϕ$ decays in 2019-2021 Belle II data

Observation of $B \to D^{(*)} K^{-} K_{S}^{0}$ decays using the 2019-2022 Belle II data sample

Measurement of the branching fraction and $CP$ asymmetry of $B^{0} \to π^{0} π^{0}$ decays using $198 \times 1 0^{6}$ $B B$ pairs in Belle II data

Measurement of the $B^{0}$ lifetime and flavor-oscillation frequency using hadronic decays reconstructed in 2019-2021 Belle II data