1,721,191 research outputs found
Extracting the femtometer structure of strange baryons using the vacuum polarization effect
No full textAbstract One of the fundamental goals of particle physics is to gain a microscopic understanding of the strong interaction. Electromagnetic form factors quantify the structure of hadrons in terms of charge and magnetization distributions. While the nucleon structure has been investigated extensively, data on hyperons are still scarce. It has recently been demonstrated that electron-positron annihilations into hyperon-antihyperon pairs provide a powerful tool to investigate their inner structure. We present a method useful for hyperon-antihyperon pairs of different types which exploits the cross section enhancement due to the effect of vacuum polarization at the J/ψ resonance. Using the 10 billion J/ψ events collected with the BESIII detector, this allows a precise determination of the hyperon structure function. The result is essentially a precise snapshot of the Λ ¯ Σ 0 ( Λ Σ ¯ 0 ) transition process, encoded in the transition form factor ratio and phase. Their values are measured to be R = 0.860 ± 0.029(stat.) ± 0.015(syst.), Δ Φ Λ ¯ Σ 0 = ( 1.011 ± 0.094 ( stat. ) ± 0.010 ( syst. ) ) r a d and Δ Φ Λ Σ ¯ 0 = ( 2.128 ± 0.094 ( stat. ) ± 0.010 ( syst. ) ) r a d . Furthermore, charge-parity (CP) breaking is investigated in this reaction and found to be consistent with CP symmetry
Measurement of B(psi(3770) -> gamma chi(c1)) and search for psi(3770) -> gamma chi(c2)
No full textKolcu, Onur Buğra (Arel Author)We report a measurement of the branching fraction for ?(3770)???c1 and search for the transition ?(3770)???c2 based on 2.92 fb-1 of e+e- data accumulated at s=3.773 GeV with the BESIII detector at the BEPCII collider. We measure B(?(3770)???c1)=(2.48±0.15±0.23)×10-3, which is the most precise measurement to date. The upper limit on the branching fraction of ?(3770)???c2 at a 90% confidence level is B(?(3770)???c2)<0.64×10-3. The corresponding partial widths are ?(?(3770)???c1)=(67.5±4.1±6.7) keV and ?(?(3770)???c2)<17.4 keV. © 2015 American Physical Society
Observation of a rare beta decay of the charmed baryon with a Graph Neural Network
No full textAbstract The beta decay of the lightest charmed baryon Λ c + provides unique insights into the fundamental mechanism of strong and electro-weak interactions, serving as a testbed for investigating non-perturbative quantum chromodynamics and constraining the Cabibbo-Kobayashi-Maskawa (CKM) matrix parameters. This article presents the first observation of the Cabibbo-suppressed decay Λ c + → n e + ν e , utilizing 4.5 fb−1 of electron-positron annihilation data collected with the BESIII detector. A novel Graph Neural Network based technique effectively separates signals from dominant backgrounds, notably Λ c + → Λ e + ν e , achieving a statistical significance exceeding 10σ. The absolute branching fraction is measured to be (3.57 ± 0.34stat. ± 0.14syst.) × 10−3. For the first time, the CKM matrix element V c d is extracted via a charmed baryon decay as 0.208 ± 0.01 1 exp. ± 0.00 7 LQCD ± 0.00 1 τ Λ c + . This work highlights a new approach to further understand fundamental interactions in the charmed baryon sector, and showcases the power of modern machine learning techniques in experimental high-energy physics
Precision Study of eta ' -> gamma pi(+) pi(-) Decay Dynamics
No full textUsing a low background data sample of 9.7×105 J/?????, ?????+?- events, which are 2 orders of magnitude larger than those from the previous experiments, recorded with the BESIII detector at BEPCII, the decay dynamics of ?????+?- are studied with both model-dependent and model-independent approaches. The contributions of ? and the ?(770)-? interference are observed for the first time in the decays ?????+?- in both approaches. Additionally, a contribution from the box anomaly or the ?(1450) resonance is required in the model-dependent approach, while the process specific part of the decay amplitude is determined in the model-independent approach. © 2018 authors. Published by the American Physical Society. Published by the American Physical Society under the terms of the »https://creativecommons.org/licenses/by/4.0/» Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI. Funded by SCOAP3
Partial wave analysis of + c.c.
No full textBased on a sample of (2712 . 4 ± 14 . 3) × 10 6 ψ (3686) events collected with the BESIII detector, a partial wave analysis of the decay + c . c . is performed to investigate Λ * and Σ * resonances in the and π 0 Λ invariant mass distributions. Significant contributions are found from the Λ(1405), Λ(1520), Λ(1600), Λ(1670), Λ(1690), Λ(1800), Λ(1890), Λ(2325), Σ(1385), Σ(1660), Σ(1670), Σ(1750), and Σ(1910). The masses, widths, and production branching fractions for each component are determined. In addition, the branching fraction of + c . c . is measured to be (1 . 544 ± 0 . 013 ± 0 . 071) × 10 − 4 for the first time, where the first uncertainty is statistical and the second systematic.LPHE-L
Measurement of the branching fraction of D + → τ + ν τ
No full textAbstract By analyzing e + e − collision data with an integrated luminosity of 7.9 fb −1 collected with the BESIII detector at the center-of-mass energy of 3.773 GeV, the branching fraction of D + → τ + ν τ is determined as B = (9.9 ± 1.1stat ± 0.5syst) × 10 −4. Using the most precise result B (D + → μ + ν μ ) = (3.981 ± 0.079stat ± 0.040syst) × 10 −4 [1], we determine R τ/μ = Γ(D + → τ + ν τ )/Γ(D + → μ + ν μ ) = 2.49 ± 0.31, achieving a factor of two improvement in precision compared to the previous BESIII result. This measurement is in agreement with the standard model prediction of lepton flavor universality within one standard deviation
Observation of ψ3686→K−Λ1520Ξ¯+ + c.c.
No full textBased on (2712.4 ± 14.3) × 106ψ(3686) events collected at the BESIII detector operating at the BEPCII collider, we present the first observation of the decay ψ3686→K−Λ1520Ξ¯+ + c.c. The product branching fraction Bψ3686→K−Λ1520Ξ¯++c.c.×BΛ1520→pK− is measured to be (9.47 ± 0.75 ± 0.97) × 10−7, where the first uncertainty is statistical and the second systematic.LPHE-L
Measurement of the branching fractions of doubly Cabibbo-suppressed D decays
No full textBy analyzing e + e − collision data collected at the center-of-mass energy of 3.773 GeV with the BESIII detector, corresponding to an integrated luminosity of 20.3 fb −1, we measure the branching fractions of the doubly Cabibbo-suppressed (DCS) decays D 0 → K + π − , D 0 → K + π − π − π +, D 0 → K + π − π 0, D 0 → K + π − π 0 π 0, D + → K + π + π − , and D + → K + K + K − . We also perform the first searches for D 0 → K + π − η, D 0 → K + π − π 0 η, D + → K + π + π − η, D + → K + (π + π − η)non−η′, and D + → K + ηη and report the first observations and evidence for some of these final states. Combining the measurements with the world averages of the corresponding Cabibbo-favored (CF) decays, the ratios of the DCS/CF branching fractions are obtained. For the D + → K + (π + π − η)non−η′ decay, the ratio is significantly larger than the corresponding ratios of the other DCS decays.LPHE-L
Search for the charmonium weak decays and
No full textBased on (10087 ± 44) × 10 6 J / ψ events recorded with the BESIII detector, we search for the rare charmonium weak decays and No signal is observed, and upper limits on the branching fractions at the 90% confidence level are set as and . Our results provide the most stringent experimental constraints on these decays.LPHE-L
Measurements of the absolute branching fractions of the doubly Cabibbo-suppressed decays D+ → K+π0, D+ → K+η and D+ → K+η′
Full text linkUsing 20.3 fb − 1 of e + e − collision data collected at a center-of-mass energy of 3.773 GeV with the BESIII detector, we present the measurements of the absolute branching fractions of the doubly Cabibbo-suppressed decays D + → K + π 0 , D + → K + η and D + → K + η′ with the double-tag method, with significantly improved precision compared to the previous measurements. The statistical significance of each signal decay exceeds 10 σ . The branching fractions are determined to be ℬ( D + → K + π 0 ) = (1.45 ± 0.06 ± 0.08) × 10 − 4 , ℬ( D + → K + η ) = (1.17 ± 0.10 ± 0.03) × 10 − 4 and ℬ( D + → K + η′ ) = (1.88 ± 0.15 ± 0.11) × 10 − 4 , where the first uncertainties are statistical and the second systematic. The branching fractions of D + → K + η and D + → K + η′ are consistent with the world average values. The reported branching fraction of D + → K + π 0 deviates with the world average value by 3 σ .LPHE-L
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