R. Kowalewski

activity

19982026

most citedFlavor Physics in the Quark Sector

246 citations · 1.2k across the 51 of their papers we have counts for

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56 papers · 1 filter

hep-ex2026

Observation of the decays $B^{+} \to Σ_{c} (2455)^{++} Ξ ˉ_{c}^{' -}$ and $B^{0} \to Σ_{c} (2455)^{0} Ξ ˉ_{c}^{'0}$

Belle, Belle II Collaborations, : +403

We report the first observation of the decays $B^{+} \to Σ_{c} (2455)^{++} Ξ ˉ_{c}^{' -}$ and $B^{0} \to Σ_{c} (2455)^{0} Ξ ˉ_{c}^{'0}$ , with significances of $6.4 σ$ a…

hep-ex2025

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

Belle, Belle II Collaborations, : +396

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

hep-ex2025

Observation of $e^{+} e^{-} \to η Υ (2 S)$ and search for $e^{+} e^{-} \to η Υ (1 S), γ X_{b}$ at $s$ near 10.75 GeV

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

We present an analysis of the processes $e^{+} e^{-} \to η Υ (1 S)$ , $η Υ (2 S)$ , and $γ X_{b}$ with $X_{b} \to π^{+} π^{-} χ_{b J}, χ_{b J} \to γ Υ (1 S)$ $(J = 1, 2)$ reconstructed from $γγπ^+π^-\ell^+\ell^-~(…

hep-ex2025★ 3 cited

Observation of the decays $B^{+} \to Σ_{c} (2455)^{++} Ξ_{c}^{-}$ and $B^{0} \to Σ_{c} (2455)^{0} Ξ_{c}^{0}$

Belle, Belle II Collaborations, : +386

We report the first observation of the two-body baryonic decays $B^{+} \to Σ_{c} (2455)^{++} Ξ_{c}^{-}$ and $B^{0} \to Σ_{c} (2455)^{0} Ξ_{c}^{0}$ with significance…

hep-ex2025★ 1 cited

Measurement of the $D^{0} \to K^{-} π^{+} e^{+} e^{-}$ branching fraction and search for $D^{0} \to π^{+} π^{-} e^{+} e^{-}$ 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 $D^{0} \to K^{+} K^{-} e^{+} e^{-}$ , $π^{+} π^{-} e^{+} e^{-}$ , and $K^{-} π^{+} e^{+} e^{-}$ using a 942 fb $^{- 1}$ data set c…

hep-ex2025★ 4 cited

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★ 5 cited

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^{(*)+} \,τ^- \, \overlineν_τ)}{{\cal B}(\overline{B}{}^0 \to…

hep-ex2025★ 4 cited

Measurement of $B^{+} \to τ^{+} ν_{τ}$ branching fraction with a hadronic tagging method at Belle II

Belle II Collaboration, I. Adachi, K. Adamczyk +341

We present a measurement of the branching fraction of $B^{+} \to τ^{+} ν_{τ}$ decays using $(387 \pm 6) \times 1 0^{6}$ $Υ (4 S)$ collected between 2019 and 2022 with the Belle II detector at the S…

hep-ex2024

Search for lepton flavor-violating decay modes $B^{0} \to K_{S}^{0} τ^{\pm} ℓ^{\mp} (ℓ = μ, e)$ with hadronic $B$ -tagging at Belle and Belle II

Belle, Belle II Collaborations, : +425

We present the first search for the lepton flavor-violating decay modes $B^{0} \to K_{S}^{0} τ^{\pm} ℓ^{\mp} (ℓ = μ, e)$ using the 711 fb $^{- 1}$ and 365 fb $^{- 1}$ data samples re…

hep-ex2024

Search for $C P$ violation in $D_{(s)}^{+} \to K_{S}^{0} K^{-} π^{+} π^{+}$ decays using triple and quadruple products

Belle, Belle II Collaborations, : +366

We perform the first search for $C P$ violation in $D_{(s)}^{+} \to K_{S}^{0} K^{-} π^{+} π^{+}$ decays. We use a combined data set from the Belle and Belle II experiments, which s…

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★ 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

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

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★ 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

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…

hep-ex2023★ 10 cited

Measurement of decay-time-dependent $CP$ violation in $B^{0} \to J / ψ K_{S}^{0}$ decays using 2019-2021 Belle II data

Belle II Collaboration, I. Adachi, L. Aggarwal +392

We report a measurement of the mixing-induced and direct $CP$ violation parameters $S_{CP}$ and $A_{CP}$ from $B^{0} \to J / ψ K_{S}^{0}$ decays reconstructed by the…

hep-ex2022★ 9 cited

Measurement of the $Λ_{c}^{+}$ lifetime

Belle II Collaboration, F. Abudinén, L. Aggarwal +360

An absolute measurement of the $Λ_{c}^{+}$ lifetime is reported using $Λ_{c}^{+} \to p K^{-} π^{+}$ decays in events reconstructed from data collected by the Belle II experiment at the…

hep-ex2021

Study of the reactions $e^{+} e^{-} \to π^{+} π^{-} π^{0} π^{0} π^{0} π^{0}$ and $π^{+} π^{-} π^{0} π^{0} π^{0} η$ at center-of-mass energies from threshold to 4.5 GeV using initial-state radiation

BaBar Collaboration

We study the processes $e^{+} e^{-} \to π^{+} π^{-} π^{0} π^{0} π^{0} π^{0} γ$ and $e^{+} e^{-} \to π^{+} π^{-} π^{0} π^{0} π^{0} η γ$ in which an energetic photon is radiated from the initial state. The data were collected with…

hep-ex2021★ 4 cited

Search for Darkonium in $e^{+} e^{-}$ Collisions

The BABAR Collaboration

Collider searches for dark sectors, new particles interacting only feebly with ordinary matter, have largely focused on identifying signatures of new mediators, leaving much of dar…

hep-ex2019★ 50 cited

Extraction of form Factors from a Four-Dimensional Angular Analysis of $B \to D^{*} ℓ^{-} ν_{ℓ}$

B. Dey

An angular analysis of the decay $B \to D^{*} ℓ^{-} ν_{ℓ}$ , $ℓ \in {e, μ}$ , is reported using the full $e^{+} e^{-}$ collision data set collected by t…

Observation of the decays B+→Σc​(2455)++Ξˉc′−​ and B0→Σc​(2455)0Ξˉc′0​

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

Observation of e+e−→ηΥ(2S) and search for e+e−→ηΥ(1S), γXb​ at s​ near 10.75 GeV

Observation of the decays B+→Σc​(2455)++Ξc−​ and B0→Σc​(2455)0Ξc0​

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

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

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

Measurement of B+→τ+ντ​ branching fraction with a hadronic tagging method at Belle II

Search for lepton flavor-violating decay modes B0→KS0​τ±ℓ∓ (ℓ=μ,e) with hadronic B-tagging at Belle and Belle II

Search for CP violation in D(s)+​→KS0​K−π+π+ decays using triple and quadruple products

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

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

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-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

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

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

Measurement of decay-time-dependent CP violation in B0→J/ψKS0​ decays using 2019-2021 Belle II data

Measurement of the Λc+​ lifetime

Study of the reactions e+e−→π+π−π0π0π0π0 and π+π−π0π0π0η at center-of-mass energies from threshold to 4.5 GeV using initial-state radiation

Search for Darkonium in e+e− Collisions

Extraction of form Factors from a Four-Dimensional Angular Analysis of B→D∗ℓ−νℓ​

Observation of the decays $B^{+} \to Σ_{c} (2455)^{++} Ξ ˉ_{c}^{' -}$ and $B^{0} \to Σ_{c} (2455)^{0} Ξ ˉ_{c}^{'0}$

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

Observation of $e^{+} e^{-} \to η Υ (2 S)$ and search for $e^{+} e^{-} \to η Υ (1 S), γ X_{b}$ at $s$ near 10.75 GeV

Observation of the decays $B^{+} \to Σ_{c} (2455)^{++} Ξ_{c}^{-}$ and $B^{0} \to Σ_{c} (2455)^{0} Ξ_{c}^{0}$

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

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

Measurement of $B^{+} \to τ^{+} ν_{τ}$ branching fraction with a hadronic tagging method at Belle II

Search for lepton flavor-violating decay modes $B^{0} \to K_{S}^{0} τ^{\pm} ℓ^{\mp} (ℓ = μ, e)$ with hadronic $B$ -tagging at Belle and Belle II

Search for $C P$ violation in $D_{(s)}^{+} \to K_{S}^{0} K^{-} π^{+} π^{+}$ decays using triple and quadruple products

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

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

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-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

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

Measurement of decay-time-dependent $CP$ violation in $B^{0} \to J / ψ K_{S}^{0}$ decays using 2019-2021 Belle II data

Measurement of the $Λ_{c}^{+}$ lifetime

Study of the reactions $e^{+} e^{-} \to π^{+} π^{-} π^{0} π^{0} π^{0} π^{0}$ and $π^{+} π^{-} π^{0} π^{0} π^{0} η$ at center-of-mass energies from threshold to 4.5 GeV using initial-state radiation

Search for Darkonium in $e^{+} e^{-}$ Collisions

Extraction of form Factors from a Four-Dimensional Angular Analysis of $B \to D^{*} ℓ^{-} ν_{ℓ}$