S. Stefkova

activity

20162026

most citedSearch for Axion-Like Particles produced in

e^{+} e^{-}

collisions at Belle II

99 citations · 1.1k across the 112 of their papers we have counts for

collaborators

Showing 2026Show all

16 papers · 1 filter

hep-ex2026

Test of lepton flavor universality with $B ˉ \to D^{()} τ^{-} ν ˉ_{τ}$ and $B ˉ \to D^{()} ℓ^{-} ν ˉ_{ℓ}$ decays at Belle II

Belle II Collaboration, M. Abumusabh, I. Adachi +494

We test lepton flavor universality with a measurement of the branching-fraction ratios $R(D^{(*)}) \equiv \mathcal{B}(\bar{B} \rightarrow D^{(*)} τ^{-} \barν_τ)/\mathcal{B}(\bar{B}…

hep-ex2026

Search for the lepton-flavor-violating decay $τ^{\pm} \to μ^{\pm} γ$ at Belle II

Belle II Collaboration, M. Abumusabh, I. Adachi +466

We present a search for the lepton-flavor-violating decay $τ^{\pm} \to μ^{\pm} γ$ using a data sample that corresponds to an integrated luminosity of 428 fb $^{- 1}$ recorded by the Bel…

hep-ex2026

Search for the $B^{0} \to K_{S}^{0} τ^{+} τ^{-}$ decay

Belle, Belle II Collaborations, : +432

We present the first search for $B^{0} \to K_{S}^{0} τ^{+} τ^{-}$ decays. We look for signal decays in $B^{0} B ˉ^{0}$ events produced in asymmetric-energy electron-positron collisions. T…

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

First measurement of the masses of the $Υ_{1} (1 D)$ and $Υ_{3} (1 D)$ states and the energy dependence of the cross sections for $e^{+} e^{-} \to Υ_{J} (1 D) η$ and $e^{+} e^{-} \to Υ_{J} (1 D) π^{+} π^{-}$

Belle, Belle II Collaborations, : +398

We study the processes $e^{+} e^{-} \to Υ_{J} (1 D) η$ and $e^{+} e^{-} \to Υ_{J} (1 D) π^{+} π^{-}$ at center-of-mass energies $s$ =(10.73 -- 11.02) GeV using a $142.5 fb^{- 1}$ data sample, in…

hep-ex2026

Charged-lepton identification at Belle~II

Belle II Collaboration, M. Abumusabh, I. Adachi +409

Effective particle identification capabilities are a strategic priority for the physics program of the Belle~II experiment. We describe the algorithms used at Belle~II for identify…

hep-ex2026

First evidence of $X (3872) \to π^{0} χ_{c 0} (1 P)$ and search for $X (3915) \to π^{0} χ_{c 1} (1 P)$

Belle, Belle II Collaborations, : +412

We search for the pionic transitions $X (3872) \to π^{0} χ_{c J} (1 P)$ $(J = 0, 1, 2)$ and $X (3915) \to π^{0} χ_{c 1}$ in $B^{+} \to π^{0} χ_{c J} K^{+}$ decays using the Belle and Belle~II data samples c…

hep-ex2026

Measurement of mixing-induced CP violation in the decay $B^{0} \to π^{0} π^{0}$

Belle II Collaboration, M. Abumusabh, I. Adachi +437

Measurements of charge-parity (CP) violation in quark transitions provide stringent tests of the current theory and sensitive probes of particles or interactions beyond it. We repo…

hep-ex2026

Measurement of time-dependent $C P$ violation parameters in $B^{0} \to K_{S}^{0} π^{0} γ$ decays at Belle and Belle II

Belle, Belle II Collaborations, : +417

We perform a measurement of time-dependent $C P$ violation parameters in $B^{0} \to K_{S}^{0} π^{0} γ$ decays using a dataset of approximately $772 \times 1 0^{6}$ and $521 \times 10^6…

hep-ex2026

Search for $Ξ^{0} p$ , $Ω^{-} p$ , and $Ω^{-} n$ dibaryons in $Υ (1 S)$ and $Υ (2 S)$ decays at Belle

Belle, Belle II Collaborations, : +367

We search for $Ξ^{0} p$ , $Ω^{-} p$ , and $Ω^{-} n$ dibaryon states in $Υ (1 S)$ and $Υ (2 S)$ decays, probing mass regions near the corresponding baryon-pair thresholds. Multistrange baryon-bary…

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 $e^{+} e^{-} \to π^{+} π^{-} Υ (1 D)$ at Belle II

Belle II Collaboration, M. Abumusabh, I. Adachi +404

The bottomonium spectrum, consisting of bound states of a $b$ quark and an anti- $b$ quark, provides an excellent laboratory for probing quantum chromodynamics in the non-pertur…

hep-ex2026

Study of $e^{+} e^{-} \to h^{+} h^{-} J / ψ (h = π, K, p)$ via initial-state radiation at Belle~II

Belle II Collaboration, M. Abumusabh, I. Adachi +417

Using a data sample of 427.9 fb $^{- 1}$ collected by the Belle~II detector at or near the $Υ (4 S)$ and $Υ (10753)$ resonances, the cross sections for $e^{+} e^{-} \to h^{+} h^{-} J / ψ$ $(h = π / K / p)$ …

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-ph2026

Constraints on invisible $B^{+} \to K^{+} X$ decays from the Belle II $B^{+} \to K^{+} ν ν ˉ$ measurement

Lorenz Gärtner, Nikolai Krug, Thomas Kuhr +3

The Belle II measurement of the branching fraction for $B^{+} \to K^{+} ν ν ˉ$ shows a $2.7 σ$ excess over the Standard Model prediction and motivates new-physics explanations such as ax…

hep-ex2026

A search for feebly-interacting particles in $B$ decays with missing energy at Belle

Belle, Belle II Collaborations, : +406

We present a search for an invisible hidden-sector particle $X_{inv}$ , produced in $B^{0} \to D ˉ^{0} X_{inv}$ and $B^{\pm} \to h X_{inv}$ decays, where $h = π^{\pm}$ , $…

Test of lepton flavor universality with Bˉ→D(∗)τ−νˉτ​ and Bˉ→D(∗)ℓ−νˉℓ​ decays at Belle II

Search for the lepton-flavor-violating decay τ±→μ±γ at Belle II

Search for the B0→KS0​τ+τ− decay

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

First measurement of the masses of the Υ1​(1D) and Υ3​(1D) states and the energy dependence of the cross sections for e+e−→ΥJ​(1D)η and e+e−→ΥJ​(1D)π+π−

Charged-lepton identification at Belle~II

First evidence of X(3872)→π0χc0​(1P) and search for X(3915)→π0χc1​(1P)

Measurement of mixing-induced CP violation in the decay B0→π0π0

Measurement of time-dependent CP violation parameters in B0→KS0​π0γ decays at Belle and Belle II

Search for Ξ0p, Ω−p, and Ω−n dibaryons in Υ(1S) and Υ(2S) decays at Belle

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

Study of e+e−→π+π−Υ(1D) at Belle II

Study of e+e−→h+h−J/ψ (h=π, K, p) via initial-state radiation at Belle~II

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

Constraints on invisible B+→K+X decays from the Belle II B+→K+ννˉ measurement

A search for feebly-interacting particles in B decays with missing energy at Belle

Test of lepton flavor universality with $B ˉ \to D^{()} τ^{-} ν ˉ_{τ}$ and $B ˉ \to D^{()} ℓ^{-} ν ˉ_{ℓ}$ decays at Belle II

Search for the lepton-flavor-violating decay $τ^{\pm} \to μ^{\pm} γ$ at Belle II

Search for the $B^{0} \to K_{S}^{0} τ^{+} τ^{-}$ decay

First measurement of the masses of the $Υ_{1} (1 D)$ and $Υ_{3} (1 D)$ states and the energy dependence of the cross sections for $e^{+} e^{-} \to Υ_{J} (1 D) η$ and $e^{+} e^{-} \to Υ_{J} (1 D) π^{+} π^{-}$

First evidence of $X (3872) \to π^{0} χ_{c 0} (1 P)$ and search for $X (3915) \to π^{0} χ_{c 1} (1 P)$

Measurement of mixing-induced CP violation in the decay $B^{0} \to π^{0} π^{0}$

Measurement of time-dependent $C P$ violation parameters in $B^{0} \to K_{S}^{0} π^{0} γ$ decays at Belle and Belle II

Search for $Ξ^{0} p$ , $Ω^{-} p$ , and $Ω^{-} n$ dibaryons in $Υ (1 S)$ and $Υ (2 S)$ decays at Belle

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

Study of $e^{+} e^{-} \to π^{+} π^{-} Υ (1 D)$ at Belle II

Study of $e^{+} e^{-} \to h^{+} h^{-} J / ψ (h = π, K, p)$ via initial-state radiation at Belle~II

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

Constraints on invisible $B^{+} \to K^{+} X$ decays from the Belle II $B^{+} \to K^{+} ν ν ˉ$ measurement

A search for feebly-interacting particles in $B$ decays with missing energy at Belle