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A. Frey

Publications and source records attributed to A. Frey.

At least 37 records · Page 2Linked to original sources
arXiv2023

Search for the $e^+e^-\toη_{b}(1S)ω$ and $e^+e^-\toχ_{b0}(1P)ω$ processes at $\sqrt{s}=10.745\,\mathrm{GeV}$

We search for the $e^+e^-\toη_b(1S)ω$ and $e^+e^-\toχ_{b0}(1P)ω$ 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 collected by the Belle II experiment during a special run, corresponding to an integrated luminosity of $9.8\,\mathrm{fb}^{-1}$. We reconstruct $ω\toπ^+π^-π^0$ decays and use the $ω$ meson's recoil mass to search for the signals. We do not find evidence for either process, and set upper limits on the corresponding Born-level cross sections of 2.5 pb and 7.8 pb, respectively, at the 90% confidence level. The $χ_{b0}(1P)ω$ limit is the result of a combination of this analysis and a previous search using full reconstruction.

hep-ex↗
arXiv2023

Upgrade of Belle II Vertex Detector with CMOS Pixel Technology

The Belle II experiment at KEK in Japan considers upgrading its vertex detector system to address the challenges posed by high background levels caused by the increased luminosity of the SuperKEKB collider. One proposal for upgrading the vertex detector aims to install a 5-layer all monolithic pixel vertex detector based on fully depleted CMOS sensors in 2027. The new system will use the OBELIX MAPS chips to improve background robustness and reduce occupancy levels through small and fast pixels. This causes better track finding, especially for low transverse momenta tracks. This text will focus on the predecessor of the OBELIX sensor, the TJ-Monopix2, presenting laboratory and test beam results on pixel response, efficiency, and spatial resolution.

physics.ins-det↗
arXiv2023

Measured and projected beam backgrounds in the Belle II experiment at the SuperKEKB collider

The Belle II experiment at the SuperKEKB electron-positron collider aims to collect an unprecedented data set of $50~{\rm ab}^{-1}$ to study $CP$-violation in the $B$-meson system and to search for Physics beyond the Standard Model. SuperKEKB is already the world's highest-luminosity collider. In order to collect the planned data set within approximately one decade, the target is to reach a peak luminosity of $\rm 6 \times 10^{35}~cm^{-2}s^{-1}$ by further increasing the beam currents and reducing the beam size at the interaction point by squeezing the betatron function down to $β^{*}_{\rm y}=\rm 0.3~mm$. To ensure detector longevity and maintain good reconstruction performance, beam backgrounds must remain well controlled. We report on current background rates in Belle II and compare these against simulation. We find that a number of recent refinements have significantly improved the background simulation accuracy. Finally, we estimate the safety margins going forward. We predict that backgrounds should remain high but acceptable until a luminosity of at least $\rm 2.8 \times 10^{35}~cm^{-2}s^{-1}$ is reached for $β^{*}_{\rm y}=\rm 0.6~mm$. At this point, the most vulnerable Belle II detectors, the Time-of-Propagation (TOP) particle identification system and the Central Drift Chamber (CDC), have predicted background hit rates from single-beam and luminosity backgrounds that add up to approximately half of the maximum acceptable rates.

hep-ex↗
arXiv2023

First Simultaneous Determination of Inclusive and Exclusive $\left|V_{ub}\right|$

The first simultaneous determination of the absolute value of the Cabibbo-Kobayashi-Maskawa matrix element $V_{ub}$ using inclusive and exclusive decays is performed with the full Belle data set at the $Υ(4S)$ resonance, corresponding to an integrated luminosity of 711 fb${}^{-1}$. We analyze collision events in which one $B$ meson is fully reconstructed in hadronic modes. This allows for the reconstruction of the hadronic $X_u$ system of the semileptonic $b \to u \ell \bar ν_\ell$ decay. We separate exclusive $B \to π\, \ell\, \bar ν_{\ell}$ decays from other inclusive $B \to X_u \, \ell\, \bar ν_{\ell}$ and backgrounds with a two-dimensional fit, that utilizes the number of charged pions in the $X_u$ system and the four-momentum transfer $q^2$ between the $B$ and $X_u$ system. Combining our measurement with information from lattice QCD and QCD calculations of the inclusive partial rate as well as external experimental information on the shape of the $B \to π\, \ell\, \bar ν_{\ell}$ form factor, we determine $\left|V_{ub}^{\mathrm{excl.}} \right| = (3.78 \pm 0.23 \pm 0.16 \pm 0.14)\times 10^{-3}$ and $\left|V_{ub}^{\mathrm{incl.}} \right| = (3.88 \pm 0.20 \pm 0.31 \pm 0.09)\times 10^{-3}$, respectively, with the uncertainties being the statistical error, systematic errors, and theory errors. The ratio of $\left|V_{ub}^{\mathrm{excl.}} \right| / \left|V_{ub}^{\mathrm{incl.}} \right| = 0.97 \pm 0.12$ is compatible with unity.

hep-ex↗
arXiv2023

First measurement of the Q^2 distribution of X(3915) single-tag two-photon production

We report the first measurement of the $Q^2$ distribution of $X(3915)$ produced by single-tag two-photon interactions. The decay mode used is $X(3915) \rightarrow J/ψω$. The covered $Q^2$ region is from 1.5 (GeV/$c$)$^2$ to 10.0 (GeV/$c$)$^2$. We observe $7.9\pm 3.1({\rm stat.})\pm 1.5({\rm syst.})$ events, where we expect $4.1\pm 0.7$ events based on the $Q^2=0$ result from the no-tag two-photon process, extrapolated to higher $Q^2$ region using the $c\bar{c}$ model of Schuler, Berends, and van Gulik. The shape of the distribution is also consistent with this model; we note that statistical uncertainties are large.

hep-ex↗
arXiv2023

Search for a dark photon and an invisible dark Higgs boson in $μ^+μ^-$ and missing energy final states with the Belle II experiment

The dark photon $A^\prime$ and the dark Higgs boson $h^\prime$ are hypothetical particles predicted in many dark sector models. We search for the simultaneous production of $A^\prime$ and $h^\prime$ in the dark Higgsstrahlung process $e^{+}e^{-}\rightarrow A^\prime \, h^\prime$ with $A^\prime \rightarrow μ^+μ^-$ and $ h^\prime$ invisible in electron-positron collisions at a center-of-mass energy of 10.58 GeV collected by the Belle II experiment in 2019. With an integrated luminosity of 8.34 fb$^{-1}$, we observe no evidence for signal. We obtain exclusion limits at 90% Bayesian credibility in the range of 1.7--5.0 fb on the cross section and in the range of $1.7 \times10^{-8}$--$200 \times10^{-8}$ on the effective coupling $\varepsilon^2 \times α_D$ for the $A^\prime$ mass in the range of 4.0 GeV/$c^2$ $< M_{A^\prime}< 9.7$ GeV/$c^2$ and for the $h^\prime$ mass $M_{h^\prime} < M_{A^\prime}$, where $\varepsilon$ is the mixing strength between the standard model and the dark photon and $α_D$ is the coupling of the dark photon to the dark Higgs boson. Our limits are the first in this mass range.

hep-ex↗
arXiv2023

A test of light-lepton universality in the rates of inclusive semileptonic $B$-meson decays at Belle II

We present the first measurement of the ratio of branching fractions of inclusive semileptonic $B$-meson decays, $R(X_{e/μ}) = \mathcal{B}(B\to X \, e \, ν) / \mathcal{B}(B\to X \, μ\, ν)$, a precision test of electron-muon universality, using data corresponding to $189\,\mathrm{fb}^{-1}$ from electron-positron collisions collected with the Belle II detector. In events where the partner $B$ meson is fully reconstructed, we use fits to the lepton momentum spectra above $1.3\,\mathrm{GeV}/c$ to obtain $R(X_{e/μ}) = 1.007 \pm 0.009~(\mathrm{stat}) \pm 0.019~(\mathrm{syst})$, which is the most precise lepton-universality test of its kind and agrees with the standard-model expectation.

hep-ex↗
arXiv2023

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

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 $\rm fb^{-1}$ of data collected by the Belle detector at the KEKB energy-asymmetric $e^+e^-$ collider. Our results for the $T$-odd $C\!P$-violating parameter $a^{T\text{-odd}}_{C\!P}$ are: $a^{T\text{-odd}}_{C\!P}({D^{+}\to K^{-}K^{+}π^{+}π^{0}}) = (+2.6\pm 6.6\pm 1.3 )\times10^{-3}$, $a^{T\text{-odd}}_{C\!P}({D^{+}\to K^{+}π^{-}π^{+}π^{0}}) = (-1.3\pm 4.2\pm 0.1 )\times10^{-2}$, $a^{T\text{-odd}}_{C\!P}({D^{+}\to K^{-}π^{+}π^{+}π^{0}}) = (+0.2\pm 1.5\pm 0.8 )\times10^{-3}$, $a^{T\text{-odd}}_{C\!P}({D_s^{+}\to K^{+}π^{-}π^{+}π^{0}}) = (-1.1\pm 2.2\pm 0.1 )\times10^{-2}$, and $a^{T\text{-odd}}_{C\!P}({D_s^{+}\to K^{-}K^{+}π^{+}π^{0}}) = (+2.2\pm 3.3\pm 4.3 )\times10^{-3}$, where the uncertainties are statistical and systematic, respectively. These results are the first such measurements and are all consistent with zero. They include the first measurement for a $D^+_s$ singly Cabibbo-suppressed decay, and the first measurement for a $D$ meson doubly Cabibbo-suppressed decay. We also measure $a^{T\text{-odd}}_{C\!P}$ in different subregions of phase space, where the decays are dominated by different intermediate resonance states such as $D^+\toϕρ^+$, $\bar{K}^{*0}K^{*+}$, and $\bar{K}^{*0}ρ^+$; and $D_s^+\to K^{*+}ρ^{0}$, $K^{*0}ρ^{+}$, $ϕρ^+$, and $\bar{K}^{*0}K^{*+}$. No evidence for $C\!P$ violation is found.

hep-ex↗
arXiv2023

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

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 produced by the SuperKEKB collider operating at the $Υ(4S)$ resonance. We fit the decay-time distribution of signal decays, where the initial flavor is determined by identifying the flavor of the other $B$ meson in the event. The results, based on $33000$ signal decays reconstructed in a data sample corresponding to ${190}\text{fb}^{-1}$, are $τ_{B^0} = {1.499}\pm{0.013}\pm{0.008}\;\text{ps}$, $Δm_d = {0.516}\pm{0.008}\pm{0.005}\;\text{ps}^{-1}$, where the first uncertainties are statistical and the second are systematic. These results are consistent with the world-average values.

hep-ex↗
arXiv2023

Search for $C\!P$ violation and measurement of branching fractions and decay asymmetry parameters for $Λ_c^+\toΛh^+$ and $Λ_c^+\toΣ^{0} h^+$ ($h\!=\!K,\,π$)

We report a study of $Λ_c^+\toΛh^+$ and $Λ_c^+\toΣ^{0} h^+$ ($h\!=\!K,\,π$) decays based on a data sample of 980~${\rm fb}^{-1}$ collected with the Belle detector at the KEKB energy-asymmetric $e^+e^-$ collider. The first results of direct $C\!P$ asymmetry in two-body singly Cabibbo-suppressed (SCS) decays of charmed baryons are measured, $A_{C\!P}^{\rm{dir}}(Λ_c^+\toΛK^+)\!=\!+0.021\pm0.026\pm0.001$ and $A_{C\!P}^{\rm{dir}}(Λ_c^+\toΣ^0K^+)\!=\!+0.025\pm0.054\pm0.004$. We also make the most precise measurement of the decay asymmetry parameters ($α$) for the four modes of interest and search for $C\!P$ violation via the $α$-induced $C\!P$ asymmetry ($A_{C\!P}^α$). We measure $A_{C\!P}^α(Λ_c^+\toΛK^+)\!=\!{-0.023\pm0.086\pm0.071}$ and $A_{C\!P}^α(Λ_c^+\toΣ^0K^+)\!=\!{+0.08\pm 0.35\pm 0.14}$, which are the first $A_{C\!P}^α$ results for SCS decays of charmed baryons. We search for $Λ$-hyperon $C\!P$ violation in $Λ_c^+\to(Λ,\,Σ^0)π^+$ and find $A_{C\!P}^α(Λ\to pπ^{-})\!=\!{+0.013\pm0.007\pm0.011}$. This is the first time that hyperon $C\!P$ violation has been measured via Cabibbo-favored charm decays. No evidence of baryon $C\!P$ violation is found. We also obtain the most precise branching fractions for two SCS $Λ_c^+$ decays, $\mathcal{B}(Λ_c^+\toΛK^+)\!=\!(6.57\pm0.17\pm0.11\pm0.35)\times10^{-4}$ and $\mathcal{B}(Λ_c^+\toΣ^0K^+)\!=\!(3.58\pm0.19\pm0.06\pm0.19)\times10^{-4}$. The first uncertainties are statistical and the second systematic, while the third uncertainties come from the uncertainties on the world average branching fractions of $Λ_c^+\to(Λ,\,Σ^0)π^+$.

hep-ex↗
arXiv2023

Search for the decay $B^0_s \rightarrow π^0 π^0$ at Belle

We report the results of the first search for the decay $B_s^0\rightarrowπ^0π^0$ using $121.4\ \rm fb^{-1}$ of data collected at the $Υ(5\rm S)$ resonance with the Belle detector at the KEKB asymmetric-energy $e^+e^-$ collider. We observe no signal and set a 90\% confidence level upper limit of $7.7\times 10^{-6}$ on the $B_s^0\rightarrowπ^0π^0$ decay branching fraction.

hep-ex↗
arXiv2023

Measurement of Differential Distributions of $B \to D^* \ell \bar ν_\ell$ and Implications on $|V_{cb}|$

We present a measurement of the differential shapes of exclusive $B\to D^* \ell \barν_\ell$ ($B = B^-, \bar{B}^0 $ and $\ell = e, μ$) decays with hadronic tag-side reconstruction for the full Belle data set of $711\,\mathrm{fb}^{-1}$ integrated luminosity. We extract the Caprini-Lellouch-Neubert (CLN) and Boyd-Grinstein-Lebed (BGL) form factor parameters and use an external input for the absolute branching fractions to determine the Cabibbo-Kobayashi-Maskawa matrix element and find $|V_{cb}|_\mathrm{CLN} = (40.1\pm0.9)\times 10^{-3}$ and $|V_{cb}|_\mathrm{BGL} = (40.6\pm 0.9)\times 10^{-3}$ with the zero-recoil lattice QCD point $\mathcal{F}(1) = 0.906 \pm 0.013$. We also perform a study of the impact of preliminary beyond zero-recoil lattice QCD calculations on the $|V_{cb}|$ determinations. Additionally, we present the lepton flavor universality ratio $R_{eμ} = \mathcal{B}(B \to D^* e \barν_e) / \mathcal{B}(B \to D^* μ\barν_μ) = 0.990 \pm 0.021 \pm 0.023$, the electron and muon forward-backward asymmetry and their difference $ΔA_{FB}=0.022\pm0.026\pm 0.007$, and the electron and muon $D^*$ longitudinal polarization fraction and their difference $ΔF_L^{D^*} = 0.034 \pm 0.024 \pm 0.007$. The uncertainties quoted correspond to the statistical and systematic uncertainties, respectively.

hep-ex↗
arXiv2023

A neural network for beam background decomposition in Belle II at SuperKEKB

We describe a neural network for predicting the background hit rate in the Belle II detector produced by the SuperKEKB electron-positron collider. The neural network, BGNet, learns to predict the individual contributions of different physical background sources, such as beam-gas scattering or continuous top-up injections into the collider, to Belle II sub-detector rates. The samples for learning are archived 1 Hz time series of diagnostic variables from the SuperKEKB collider subsystems and measured hit rates of Belle II used as regression targets. We test the learned model by predicting detector hit rates on archived data from different run periods not used during training. We show that a feature attribution method can help interpret the source of changes in the background level over time.

hep-ex↗
arXiv2022

Measurements of branching fractions of $Λ_c^+ \to Σ^+ η$ and $Λ_c^+ \to Σ^+ η'$ and asymmetry parameters of $Λ_c^+ \to Σ^+ π^0$, $Λ_c^+ \to Σ^+ η$, and $Λ_c^+ \to Σ^+ η'$

We report a study of $Λ_c^+ \to Σ^+ π^0$, $Λ_c^+ \to Σ^+ η$, and $Λ_c^+ \to Σ^+ η'$ using the data sample corresponding to an integrated luminosity of 980 $\rm fb^{-1}$ collected with the Belle detector at the KEKB asymmetric-energy $e^+e^-$ collider. The branching fractions relative to $Λ_c^+ \to Σ^+ π^0$ are measured as: $\mathcal{B}_{Λ_c^+ \to Σ^+ η}/\mathcal{B}_{Λ_c^+ \to Σ^+ π^0}=0.25 \pm 0.03 \pm 0.01$ and $\mathcal{B}_{Λ_c^+ \to Σ^+ η'}/\mathcal{B}_{Λ_c^+ \to Σ^+ π^0}=0.33 \pm 0.06 \pm 0.02$. Using $\mathcal{B}_{Λ_c^+ \to Σ^+ π^0}=(1.25 \pm 0.10)\%$, we obtain $\mathcal{B}_{Λ_c^+ \to Σ^+ η}=(3.14 \pm 0.35 \pm 0.11 \pm 0.25)\times10^{-3}$ and $\mathcal{B}_{Λ_c^+ \to Σ^+ η'}=(4.16 \pm 0.75 \pm 0.21 \pm 0.33)\times10^{-3}$. Here the uncertainties are statistical, systematic, and from $\mathcal{B}_{Λ_c^+ \to Σ^+ π^0}$, respectively. The ratio of the branching fraction of $Λ_c^+ \to Σ^+ η'$ with respect to that of $Λ_c^+ \to Σ^+ η$ is measured to be $\mathcal{B}_{Λ_c^+ \to Σ^+ η'}/\mathcal{B}_{Λ_c^+ \to Σ^+ η}=1.34 \pm 0.28 \pm 0.06$. We update the asymmetry parameter of $Λ_c^+ \to Σ^+ π^0$, $α_{Σ^+ π^0} = -0.48 \pm 0.02 \pm 0.02$, with a considerably improved precision. The asymmetry parameters of $Λ_c^+ \to Σ^+ η$ and $Λ_c^+ \to Σ^+ η'$ are measured to be $α_{Σ^+ η} = -0.99 \pm 0.03 \pm 0.05$ and $α_{Σ^+ η'} = -0.46 \pm 0.06 \pm 0.03$ for the first time.

hep-ex↗
arXiv2022

Measurement of the branching fractions for Cabibbo-suppressed decays $D^{+}\to K^{+} K^{-}π^{+}π^{0}$ and $D_{(s)}^{+}\to K^{+}π^{-}π^{+}π^{0}$ at Belle

We present measurements of the branching fractions for the singly Cabibbo-suppressed decays $D^+\to K^{+}K^{-}π^{+}π^{0}$ and $D_s^{+}\to K^{+}π^{-}π^{+}π^{0}$, and the doubly Cabibbo-suppressed decay $D^{+}\to K^{+}π^{-}π^{+}π^{0}$, based on 980 ${\rm fb}^{-1}$ of data recorded by the Belle experiment at the KEKB $e^{+}e^{-}$ collider. We measure these modes relative to the Cabibbo-favored modes $D^{+}\to K^{-}π^{+}π^{+}π^{0}$ and $D_s^{+}\to K^{+}K^{-}π^{+}π^{0}$. Our results for the ratios of branching fractions are $B(D^{+}\to K^{+}K^{-}π^{+}π^{0})/B(D^{+}\to K^{-}π^{+}π^{+}π^{0}) = (11.32 \pm 0.13 \pm 0.26)\%$, $B(D^{+}\to K^{+}π^{-}π^{+}π^{0})/B(D^{+}\to K^{-}π^{+}π^{+}π^{0}) = (1.68 \pm 0.11\pm 0.03)\%$, and $B(D_s^{+}\to K^{+}π^{-}π^{+}π^{0})/B(D_s^{+}\to K^{+}K^{-}π^{+}π^{0}) = (17.13 \pm 0.62 \pm 0.51)\%$, where the uncertainties are statistical and systematic, respectively. The second value corresponds to $(5.83\pm 0.42)\times\tan^4θ_C$, where $θ_C$ is the Cabibbo angle; this value is larger than other measured ratios of branching fractions for a doubly Cabibbo-suppressed charm decay to a Cabibbo-favored decay. Multiplying these results by world average values for $B(D^{+}\to K^{-}π^{+}π^{+}π^{0})$ and $B(D_s^{+}\to K^{+}K^{-}π^{+}π^{0})$ yields $B(D^{+}\to K^{+}K^{-}π^{+}π^{0})= (7.08\pm 0.08\pm 0.16\pm 0.20)\times10^{-3}$, $B(D^{+}\to K^{+}π^{-}π^{+}π^{0})= (1.05\pm 0.07\pm 0.02\pm 0.03)\times10^{-3}$, and $B(D_s^{+}\to K^{+}π^{-}π^{+}π^{0}) = (9.44\pm 0.34\pm 0.28\pm 0.32)\times10^{-3}$, where the third uncertainty is due to the branching fraction of the normalization mode. The first two results are consistent with, but more precise than, the current world averages. The last result is the first measurement of this branching fraction.

hep-ex↗
arXiv2022

Measurement of the branching fractions of the $B^+ \to η\ell^+ ν_{\ell} $ and $B^+ \to η^{\prime} \ell^+ ν_{\ell} $ decays with signal-side only reconstruction in the full $q^2$ range

The branching fractions of the decays $B^{+} \to η\ell^{+} ν_{\ell}$ and $B^{+} \to η^{\prime} \ell^{+} ν_{\ell}$ are measured, where $\ell$ is either an electron or a muon, using a data sample of $711\,{\rm fb}^{-1}$ containing $772 \times 10^6 B\bar{B}$ pairs collected at the $Υ(4S)$ resonance with the Belle detector at the KEKB asymmetric-energy $e^+ e^-$ collider. To reduce the dependence of the result on the form factor model, the measurement is performed over the entire $q^2$ range. The resulting branching fractions are ${\cal B}(B^{+} \rightarrow η\ell^{+} ν_{\ell}) = (2.83 \pm 0.55_{\rm (stat.)} \pm 0.34_{\rm (syst.)}) \times 10^{-5}$ and ${\cal B}(B^{+} \rightarrow η' \ell^{+} ν_{\ell}) = (2.79 \pm 1.29_{\rm (stat.)} \pm 0.30_{\rm (syst.)}) \times 10^{-5}$.

hep-ex↗
arXiv2022

Search for charged lepton flavor violating decays of $Υ(1S)$

We present a search for the charged lepton-flavor-violating decays $Υ(1S)\rightarrow\ell\ell^\prime$ and radiative charged lepton-flavour-violating decays $Υ(1S)\rightarrowγ\ell\ell^\prime$ [$\ell,\ell^\prime = e, μ, τ$] using the 158 million $Υ(2S)$ sample collected by the Belle detector at the KEKB collider. This search uses $Υ(1S)$ mesons produced in $π^+π^-Υ(1S)$ transitions. We do not find any significant signal, so we provide upper limits on the branching fractions at the 90% confidence level.

hep-ex↗
arXiv2022

Search for tetraquark states $X_{cc\bar{s}\bar{s}}$ in $D_{s}^{+}D_{s}^{+}~(D_{s}^{*+}D_{s}^{*+})$ final states at Belle

A search for double-heavy tetraquark state candidates $X_{cc\bar{s}\bar{s}}$ decaying to $D_{s}^{+}D_{s}^{+}$ and $D_{s}^{*+} D_{s}^{*+}$ is presented for the first time using the data samples of 102 million $Υ(1S)$ and 158 million $Υ(2S)$ events, and the data samples at $\sqrt{s}$ = 10.52~GeV, 10.58~GeV, and 10.867~GeV corresponding to integrated luminosities of 89.5~fb$^{-1}$, 711.0~fb$^{-1}$, and 121.4~fb$^{-1}$, respectively, accumulated with the Belle detector at the KEKB asymmetric energy electron-positron collider. The invariant-mass spectra of the $D_{s}^{+}D_{s}^{+}$ and $D_{s}^{*+} D_{s}^{*+}$ are studied to search for possible resonances. No significant signals are observed, and the 90\% confidence level upper limits on the product branching fractions [${\cal B}(Υ(1S,2S) \to X_{cc\bar{s}\bar{s}} + anything) \times {\cal B}(X_{cc\bar{s}\bar{s}} \to D_{s}^{+}D_{s}^{+}(D_{s}^{*+} D_{s}^{*+}))$] in $Υ(1S,2S)$ inclusive decays and the product values of Born cross section and branching fraction [$σ(e^+e^- \to X_{cc\bar{s}\bar{s}} + anything ) \times {\cal B}(X_{cc\bar{s}\bar{s}} \to D_{s}^{+}D_{s}^{+}(D_{s}^{*+} D_{s}^{*+}))$] in $e^+e^-$ collisions at $\sqrt{s}$ = 10.52~GeV, 10.58~GeV, and 10.867~GeV under different assumptions of $X_{cc\bar{s}\bar{s}}$ masses and widths are obtained.

hep-ex↗