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A search for the charged lepton flavor violating decay 𝐽/𝜓→𝑒±𝜏∓ with 𝜏∓→𝜋∓𝜋0𝜈𝜏 is performed with about 10×109 𝐽/𝜓 events collected with the BESIII detector at the BEPCII. No significant signal is observed, and an upper limit is set on the branching fraction ℬ(𝐽/𝜓→𝑒±𝜏∓)<7.5×10−8 at the 90% confidence level. This improves the previously published limit by two orders of magnitude.
Based on a sample of (10.09±0.04)×109 J/ψ events collected with the BESIII detector operating at the BEPCII storage ring, a partial wave analysis of the decay J/ψ→γηη′ is performed. An isoscalar state with exotic quantum numbers JPC=1−+, denoted as η1(1855), has been observed for the first time with statistical significance larger than 19σ. Its mass and width are measured to be (1855±9+6−1)~MeV/c2 and (188±18+3−8)~MeV, respectively. The product branching fraction B(J/ψ→γη1(1855)→γηη′) is measured to be (2.70±0.41+0.16−0.35)×10−6. The first uncertainties are statistical and the second are systematic. In addition, an upper limit on the branching ratio B(f0(1710)→ηη′)/B(f0(1710)→ππ) is determined to be 1.61×10−3 at 90\% confidence level, which lends support to the hypothesis that the f0(1710) has a large glueball component.
In Ref. [1] the BESIII collaboration published a cross section measurement of the process e+e− → π+π− in the energy range between 600 and 900 MeV. In this corrigendum, we report a corrected evaluation of the statistical errors in terms of a fully propagated covariance matrix. The correction also yields a reduced statistical uncertainty for the hadronic vacuum polarization contribution to the anomalous magnetic moment of the muon, which now reads as aππ,LO μ (600 − 900 MeV) = (368.2 ± 1.5stat ± 3.3syst) × 10−10. The central values of the cross section measurement and of aππ,LO μ , as well as the systematic uncertainties remain unchanged.
We report the measurement of the cross sections for e+e−→hadrons at center-of-mass (c.m.) energies from 3.645 to 3.871 GeV. We observe a new resonance R(3810) in the cross sections for the first time, and observe the R(3760) resonance with high significance in the cross sections. The R(3810) has a mass of (3804.5±0.9±0.9) ~MeV/c2, a total width of (5.4±3.5±3.2)~MeV, and an electronic partial width of (19.4±7.4±12.1)~eV. Its significance is 7.7σ. The R(3810) could be interpreted as a hadro-charmonium resonance predicted by Quantum Chromodynamics (QCD). In addition, we measure the mass (3751.9±3.8±2.8) ~MeV/c2, the total width (32.8±5.8±8.7)~MeV, and the electronic partial width (184±75±86)~eV with improved precision for the R(3760). Furthermore, for the R(3780) we measure the mass (3778.7±0.5±0.3) ~MeV/c2 and total width (20.3±0.8±1.7)~MeV with improved precision, and the electronic partial width (265±69±83)~eV. The R(3780) can be interpreted as the 13D1 state of charmonium. Its mass and total width differ significantly from the corresponding fitted values given by the Particle Data Group in 2022 by 7.1 and 3.2 times the uncertainties for ψ(3770), respectively. ψ(3770) has been interpreted as the 13D1 state for 45 years.
We search for an axion-like particle (ALP) a through the process ψ(3686)→π+π−J/ψ, J/ψ→γa, a→γγ in a data sample of (2.71±0.01)×109 ψ(3686) events collected by the BESIII detector. No significant ALP signal is observed over the expected background, and the upper limits on the branching fraction of the decay J/ψ→γa and the ALP-photon coupling constant gaγγ are set at 95% confidence level in the mass range of 0.165≤ma≤2.84GeV/c2. The limits on B(J/ψ→γa) range from 8.3×10−8 to 1.8×10−6 over the search region, and the constraints on the ALP-photon coupling are the most stringent to date for 0.165≤ma≤1.468GeV/c2.
We search for an axion-like particle (ALP) a through the process ψ(3686)→π+π−J/ψ, J/ψ→γa, a→γγ in a data sample of (2.71±0.01)×109 ψ(3686) events collected by the BESIII detector. No significant ALP signal is observed over the expected background, and the upper limits on the branching fraction of the decay J/ψ→γa and the ALP-photon coupling constant gaγγ are set at 95% confidence level in the mass range of 0.165≤ma≤2.84GeV/c2. The limits on B(J/ψ→γa) range from 8.3×10−8 to 1.8×10−6 over the search region, and the constraints on the ALP-photon coupling are the most stringent to date for 0.165 ≤ ma ≤ 1.468GeV/c2.
We report on the first search for ¯Λ−Λ oscillations in the decay 𝐽/𝜓→𝑝𝐾−¯Λ+c.c. by analyzing 1.31×109 𝐽/𝜓 events accumulated with the BESIII detector at the BEPCII collider. The 𝐽/𝜓 events are produced using 𝑒+𝑒− collisions at a center of mass energy √𝑠=3.097 GeV. No evidence for hyperon oscillations is observed. The upper limit for the oscillation rate of ¯Λ to Λ hyperons is determined to be 𝒫(Λ)=[ℬ(𝐽/𝜓→𝑝𝐾−Λ+c.c.)/ℬ(𝐽/𝜓→𝑝𝐾−¯Λ+c.c.)]<4.4×10−6 corresponding to an oscillation parameter 𝛿𝑚Λ¯Λ of less than 3.8×10−18 GeV at the 90% confidence level.
Based on a data sample of (1.0087±0.0044)×1010 𝐽/𝜓 events collected by the BESIII detector at the BEPCII accelerator, the absolute branching fraction (BF) of the decay 𝐽/𝜓→𝛾𝜂 is measured with high precision using events in which the radiative photon converts to 𝑒+𝑒−. Using the measured absolute BF of 𝐽/𝜓→𝛾𝜂, the absolute BFs of four dominant 𝜂 decay modes are measured for the first time. The results are ℬ(𝐽/𝜓→𝛾𝜂)=(1.067±0.005±0.023)×10−3, ℬ(𝜂→𝛾𝛾)=(39.86±0.04±0.99)%, ℬ(𝜂→𝜋0𝜋0𝜋0)=(31.96±0.07±0.84)%, ℬ(𝜂→𝜋+𝜋−𝜋0)=(23.04±0.03±0.54)%, and ℬ(𝜂→𝜋+𝜋−𝛾)=(4.38±0.02±0.10)%, where the first and second uncertainties are statistical and systematic, respectively. The results are consistent with the world average values within two standard deviations.
Using J/ψ radiative decays from 9.0 billion J/ψ events collected by the BESIII detector, we search for di-muon decays of a CP-odd light Higgs boson (A0), predicted by many new physics models beyond the Standard Model, including the Next-to-Minimal Supersymmetric Standard Model. No evidence for the CP-odd light Higgs production is found, and we set 90% confidence level upper limits on the product branching fraction B(J/ψ→γA0)×B(A0→μ+μ−) in the range of (1.2−778.0)×10−9 for 0.212≤mA0≤3.0 GeV/c2. The new measurement is a 6-7 times improvement over our previous measurement, and is also slightly better than the BaBar measurement in the low-mass region for tanβ=1.
Based on a data sample of (1.0087+-0.0044)x10^10 Jpsi events collected by the BESIII detector at the BEPCII accelerator, the absolute branching fraction (BF) of the decay Jpsi->gamma eta is measured with high precision using events in which the radiative photon converts to e+e-. Using the measured absolute BF of Jpsi->gamma eta, the absolute BFs of four dominant eta decay modes are measured for the first time. The results are B(Jpsi->gamma eta) = (1.067+-0.005+-0.023)x10^-3, B(eta->gamma gamma) = (39.86+-0.04+-0.99)%, B(eta->pi0pi0pi0) = (31.96+-0.07+-0.84)%, B(eta->pi+pi-pi0) = (23.04+-0.03+-0.54)%, and B(eta->pi+pi-gamma) = (4.38+-0.02+-0.10)%, where the first and second uncertainties are statistical and systematic, respectively. The results are consistent with the world average values within two standard deviations.
Using e+e− annihilation data corresponding to a total integrated luminosity of 6.32 fb−1 collected at center-of-mass energies between 4.178 and 4.226 GeV with the BESIII detector, we perform an amplitude analysis of the decay D+s→K0SK0Sπ+ for the first time. An enhancement is observed in the K0SK0S mass spectrum near 1.7 GeV/c2, which was not seen in D+s→K+K−π+ in an earlier work, implying the existence of an isospin one partner of the f0(1710). The branching fraction of the decay D+s→K0SK0Sπ+ is determined to be B(D+s→K0SK0Sπ+)=(0.68±0.04stat±0.01syst)%.
Using J/ψ radiative decays from 9.0 billion J/ψ events collected by the BESIII detector, we search for di-muon decays of a CP-odd light Higgs boson (A0), predicted by many new physics models beyond the Standard Model, including the Next-to-Minimal Supersymmetric Standard Model. No evidence for the CP-odd light Higgs production is found, and we set 90% confidence level upper limits on the product branching fraction B(J/ψ→γA0)×B(A0→μ+μ−) in the range of (1.2−778.0)×10−9 for 0.212≤mA0≤3.0 GeV/c2. The new measurement is a 6-7 times improvement over our previous measurement, and is also slightly better than the BaBar measurement in the low-mass region for tanβ=1.
Using J/ψ radiative decays from 9.0 billion J/ψ events collected by the BESIII detector, we search for di-muon decays of a CP-odd light Higgs boson (A0), predicted by many new physics models beyond the Standard Model, including the Next-to-Minimal Supersymmetric Standard Model. No evidence for the CP-odd light Higgs production is found, and we set 90% confidence level upper limits on the product branching fraction B(J/ψ→γA0)×B(A0→μ+μ−) in the range of (1.2−778.0)×10−9 for 0.212≤mA0≤3.0 GeV/c2. The new measurement is a 6-7 times improvement over our previous measurement, and is also slightly better than the BaBar measurement in the low-mass region for tanβ=1.
Based on 3.19 fb−1 of e+e− collision data accumulated at the center-of-mass energy 4.178 GeV with the BESIII detector operating at the BEPCII collider, the electromagnetic Dalitz decay D∗0→D0e+e− is observed for the first time with a statistical significance of 13.2σ. The ratio of the branching fraction of D∗0→D0e+e− to that of D∗0→D0γ is measured to be (11.08±0.76±0.49)×10−3. By using the world average value of the branching fraction of D∗0→D0γ, the branching fraction of D∗0→D0e+e− is determined to be (3.91±0.27±0.17±0.10)×10−3, where the first uncertainty is statistical, the second systematic and the third external branching fractions.
The Born cross section of the process e+e−→ΛΛ¯ is measured at 33 center-of-mass energies between 3.51 and 4.60 GeV using data corresponding to the total integrated luminosity of 20.0 fb−1 collected with the BESIII detector at the BEPCII collider. Describing the energy dependence of the cross section requires a contribution from the ψ(3770)→ΛΛ¯ decay, which is fitted with a significance of 4.6-4.9σ including the systematic uncertainty. The lower bound on its branching fraction is 2.4×10−6 at the 90% confidence level (C.L.), at least an order of magnitude larger than expected from predictions using a scaling based on observed electronic widths. This result indicates the importance of effects from vector charmonium(-like) states when interpreting data in terms of e.g., electromagnetic structure observables. The data do not allow for definite conclusions on the interplay with other vector charmonium(-like) states, and we set 90% C.L.upper limits for the products of their electronic widths and the branching fractions.
Using (448.1±2.9)×106 ψ(3686) events collected with the BESIII detector and a single-baryon tagging technique, we present the first observation of the decays ψ(3686)→Ξ(1530)0Ξ¯(1530)0 and Ξ(1530)0Ξ¯0. The branching fractions are measured to be B(ψ(3686)→Ξ(1530)0Ξ¯(1530)0)=(6.77±0.14±0.39)×10−5 and B(ψ(3686)→Ξ(1530)0Ξ¯0)=(0.53±0.04±0.03)×10−5. Here, the first and second uncertainties are statistical and systematic, respectively. In addition, the parameter associated with the angular distribution for the decay ψ(3686)→Ξ(1530)0Ξ¯(1530)0 is determined to be α=0.32±0.19±0.07, in agreement with theoretical predictions within one standard deviation.
The Born cross section of the process e+e−→ΛΛ¯ is measured at 33 center-of-mass energies between 3.51 and 4.60 GeV using data corresponding to the total integrated luminosity of 20.0 fb−1 collected with the BESIII detector at the BEPCII collider. Describing the energy dependence of the cross section requires a justification from the ψ(3770)→ΛΛ¯ decay, which is fitted with a significance of 4.9σ with the systematic uncertainty included. The lower bound on its branching fraction is 2.4×10−6 at the 90\% confidence level (C.L.), at least five times larger than expected from predictions using a simple scaling approach. This result indicates the importance of effects from vector charmonium(-like) when interpreting data in terms of {\it e.g.}, electromagnetic structure observables. There are no definite conclusions about the interplay with other vector charmonium(-like), and we set 90\% C.L.upper limits for the products of the electronic widths and the branching fractions.
In 2002 wurden im ca. 55 ha großen Langelt, einem der letzten historisch alten Laubwälder des Emslandes, die Brutvogelbestände mittels Revierkartierung erhoben. Der vorwiegend aus Trauben- und Stieleichenmit einzelnen Hudebuchen durchsetzteWaldkomplex ist Teil des wesentlich größeren Arenberger Eleonorenwaldes (ca. 2.000 ha). Die Kartierung erbrachte 28 Brutvogelarten mit insgesamt 122 Revieren. Rund die Hälfte aller Arten und Individuen wurde von Höhlenund Halbhöhlenbrütern gestellt. Auch Kronendach- und Baumbrüter (ohne Bodenbrüter) waren zahlreich vertreten, wobei der Buchfink die individuenstärksten Bestände aufwies. Gebüschbrüter wie Mönchsgrasmücke und Zaunkönig traten kaum in Erscheinung. Die gefundenen Ergebnisse werden mit der aktuellen Waldstruktur in Verbindung gebracht. Sie wiederum ist das Ergebnis einer extensiven forstlichen Nutzung sowie einer langen Beweidungstradition. Bis in die jüngste Vergangenheit hinein lebte im eingegatterten Teil des Arenberger Eleonorenwaldes (ca. 1.000 ha) neben Rothirsch, Damhirsch, Reh und Wildschwein auch eine ca. 120 Tiere umfassende, verwilderte Rinderherde. Es wird vermutet, dass diese Pflanzenfresser-Gemeinschaft, die vom Konzentratselektierer (browser) bis hin zum reinen Grasfresser (grazer) alle Ernährungstypen in z. T. hoher Dichte umfaßte, ganz wesentlich an der derzeit fast völlig fehlenden Ausbildung einer Strauchschicht im Langelt beteiligt war.
In 2001 wurden an 9 ausgewählten Kleingewässern im ca. 2.000 ha großen Arenberger Eleonorenwald bei Vrees (Landkreis Emsland, Niedersachsen) qualitative Untersuchungen zum Vorkommen und zur Verbreitung von Amphibien durchgeführt. Die untersuchten Gewässer unterschieden sich in Größe und pflanzlichem Bewuchs. Insgesamt konnten 9 Amphibienarten nachgewiesen werden, von denen 4 Arten (Erdkröte, Grasfrosch, Teichfrosch, Teichmolch) an fast allen Gewässern auftraten. Die Vorkommen von Kreuz- und Knoblauchkröte beschränkten sich auf zwei, z. T. stark temporäre Gewässer, die von größeren Offenlandbiotopen innerhalb des Eleonorenwaldes umgeben waren. Ebenfalls nachgewiesen werden konnten Kamm- und Bergmolch. Beim Bergmolch handelt es sich um den ersten Nachweis für den Landkreis Emsland. Das Vorkommen befindet sich in einem historisch alten Laubwaldrest. Der Kammmolch trat an einem kleinen, wasserpflanzenreichen Stillgewässer auf, das in Waldrandnähe lag. Moorfrösche wurden in nur wenigen Exemplaren festgestellt. Ihre Fundorte lagen im östlichen Teil des Eleonorenwaldes im Übergang zur Marka-Niederung. Die Ergebnisse der vorliegenden Untersuchung werden mit anderen Arbeiten zum Vorkommen von Amphibien im Weser-Ems-Raum verglichen.