| 1. |
- Murari, A., et al.
(författare)
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A control oriented strategy of disruption prediction to avoid the configuration collapse of tokamak reactors
- 2024
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Ingår i: Nature Communications. - 2041-1723 .- 2041-1723. ; 15:1
-
Tidskriftsartikel (refereegranskat)abstract
- The objective of thermonuclear fusion consists of producing electricity from the coalescence of light nuclei in high temperature plasmas. The most promising route to fusion envisages the confinement of such plasmas with magnetic fields, whose most studied configuration is the tokamak. Disruptions are catastrophic collapses affecting all tokamak devices and one of the main potential showstoppers on the route to a commercial reactor. In this work we report how, deploying innovative analysis methods on thousands of JET experiments covering the isotopic compositions from hydrogen to full tritium and including the major D-T campaign, the nature of the various forms of collapse is investigated in all phases of the discharges. An original approach to proximity detection has been developed, which allows determining both the probability of and the time interval remaining before an incoming disruption, with adaptive, from scratch, real time compatible techniques. The results indicate that physics based prediction and control tools can be developed, to deploy realistic strategies of disruption avoidance and prevention, meeting the requirements of the next generation of devices.
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| 2. |
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| 3. |
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| 4. |
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| 5. |
- Labit, B., et al.
(författare)
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Dependence on plasma shape and plasma fueling for small edge-localized mode regimes in TCV and ASDEX Upgrade
- 2019
-
Ingår i: Nuclear Fusion. - : IOP Publishing. - 1741-4326 .- 0029-5515. ; 59:8
-
Tidskriftsartikel (refereegranskat)abstract
- © 2019 Institute of Physics Publishing. All rights reserved. Within the EUROfusion MST1 work package, a series of experiments has been conducted on AUG and TCV devices to disentangle the role of plasma fueling and plasma shape for the onset of small ELM regimes. On both devices, small ELM regimes with high confinement are achieved if and only if two conditions are fulfilled at the same time. Firstly, the plasma density at the separatrix must be large enough (ne,sep/nG ∼ 0.3), leading to a pressure profile flattening at the separatrix, which stabilizes type-I ELMs. Secondly, the magnetic configuration has to be close to a double null (DN), leading to a reduction of the magnetic shear in the extreme vicinity of the separatrix. As a consequence, its stabilizing effect on ballooning modes is weakened.
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| 6. |
- Meyer, H.F., et al.
(författare)
-
Overview of physics studies on ASDEX Upgrade
- 2019
-
Ingår i: Nuclear Fusion. - : IOP Publishing. - 1741-4326 .- 0029-5515. ; 59:11
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Forskningsöversikt (refereegranskat)abstract
- The ASDEX Upgrade (AUG) programme, jointly run with the EUROfusion MST1 task force, continues to significantly enhance the physics base of ITER and DEMO. Here, the full tungsten wall is a key asset for extrapolating to future devices. The high overall heating power, flexible heating mix and comprehensive diagnostic set allows studies ranging from mimicking the scrape-off-layer and divertor conditions of ITER and DEMO at high density to fully non-inductive operation (q 95 = 5.5, ) at low density. Higher installed electron cyclotron resonance heating power 6 MW, new diagnostics and improved analysis techniques have further enhanced the capabilities of AUG. Stable high-density H-modes with MW m-1 with fully detached strike-points have been demonstrated. The ballooning instability close to the separatrix has been identified as a potential cause leading to the H-mode density limit and is also found to play an important role for the access to small edge-localized modes (ELMs). Density limit disruptions have been successfully avoided using a path-oriented approach to disruption handling and progress has been made in understanding the dissipation and avoidance of runaway electron beams. ELM suppression with resonant magnetic perturbations is now routinely achieved reaching transiently . This gives new insight into the field penetration physics, in particular with respect to plasma flows. Modelling agrees well with plasma response measurements and a helically localised ballooning structure observed prior to the ELM is evidence for the changed edge stability due to the magnetic perturbations. The impact of 3D perturbations on heat load patterns and fast-ion losses have been further elaborated. Progress has also been made in understanding the ELM cycle itself. Here, new fast measurements of and E r allow for inter ELM transport analysis confirming that E r is dominated by the diamagnetic term even for fast timescales. New analysis techniques allow detailed comparison of the ELM crash and are in good agreement with nonlinear MHD modelling. The observation of accelerated ions during the ELM crash can be seen as evidence for the reconnection during the ELM. As type-I ELMs (even mitigated) are likely not a viable operational regime in DEMO studies of 'natural' no ELM regimes have been extended. Stable I-modes up to have been characterised using -feedback. Core physics has been advanced by more detailed characterisation of the turbulence with new measurements such as the eddy tilt angle - measured for the first time - or the cross-phase angle of and fluctuations. These new data put strong constraints on gyro-kinetic turbulence modelling. In addition, carefully executed studies in different main species (H, D and He) and with different heating mixes highlight the importance of the collisional energy exchange for interpreting energy confinement. A new regime with a hollow profile now gives access to regimes mimicking aspects of burning plasma conditions and lead to nonlinear interactions of energetic particle modes despite the sub-Alfvénic beam energy. This will help to validate the fast-ion codes for predicting ITER and DEMO.
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| 7. |
- Stroth, U., et al.
(författare)
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Progress from ASDEX Upgrade experiments in preparing the physics basis of ITER operation and DEMO scenario development
- 2022
-
Ingår i: Nuclear Fusion. - : IOP Publishing. - 1741-4326 .- 0029-5515. ; 62:4
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Tidskriftsartikel (refereegranskat)abstract
- An overview of recent results obtained at the tokamak ASDEX Upgrade (AUG) is given. A work flow for predictive profile modelling of AUG discharges was established which is able to reproduce experimental H-mode plasma profiles based on engineering parameters only. In the plasma center, theoretical predictions on plasma current redistribution by a dynamo effect were confirmed experimentally. For core transport, the stabilizing effect of fast ion distributions on turbulent transport is shown to be important to explain the core isotope effect and improves the description of hollow low-Z impurity profiles. The L-H power threshold of hydrogen plasmas is not affected by small helium admixtures and it increases continuously from the deuterium to the hydrogen level when the hydrogen concentration is raised from 0 to 100%. One focus of recent campaigns was the search for a fusion relevant integrated plasma scenario without large edge localised modes (ELMs). Results from six different ELM-free confinement regimes are compared with respect to reactor relevance: ELM suppression by magnetic perturbation coils could be attributed to toroidally asymmetric turbulent fluctuations in the vicinity of the separatrix. Stable improved confinement mode plasma phases with a detached inner divertor were obtained using a feedback control of the plasma β. The enhanced D α H-mode regime was extended to higher heating power by feedback controlled radiative cooling with argon. The quasi-coherent exhaust regime was developed into an integrated scenario at high heating power and energy confinement, with a detached divertor and without large ELMs. Small ELMs close to the separatrix lead to peeling-ballooning stability and quasi continuous power exhaust. Helium beam density fluctuation measurements confirm that transport close to the separatrix is important to achieve the different ELM-free regimes. Based on separatrix plasma parameters and interchange-drift-Alfvén turbulence, an analytic model was derived that reproduces the experimentally found important operational boundaries of the density limit and between L- and H-mode confinement. Feedback control for the X-point radiator (XPR) position was established as an important element for divertor detachment control. Stable and detached ELM-free phases with H-mode confinement quality were obtained when the XPR was moved 10 cm above the X-point. Investigations of the plasma in the future flexible snow-flake divertor of AUG by means of first SOLPS-ITER simulations with drifts activated predict beneficial detachment properties and the activation of an additional strike point by the drifts.
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| 8. |
- Coburn, J., et al.
(författare)
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Energy deposition and melt deformation on the ITER first wall due to disruptions and vertical displacement events
- 2022
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Ingår i: Nuclear Fusion. - : IOP Publishing. - 0029-5515 .- 1741-4326. ; 62:1
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Tidskriftsartikel (refereegranskat)abstract
- An analysis workflow has been developed to assess energy deposition and material damage for ITER vertical displacement events (VDEs) and major disruptions (MD). This paper describes the use of this workflow to assess the melt damage to be expected during unmitigated current quench (CQ) phases of VDEs and MDs at different points in the ITER research plan. The plasma scenarios are modeled using the DINA code with variations in plasma current I (p), disruption direction (upwards or downwards), Be impurity density n (Be), and diffusion coefficient chi. Magnetic field line tracing using SMITER calculates time-dependent, 3D maps of surface power density q (perpendicular to) on the Be-armored first wall panels (FWPs) throughout the CQ. MEMOS-U determines the temperature response, macroscopic melt motion, and final surface topology of each FWP. Effects of Be vapor shielding are included. Scenarios at the baseline combination of I (p) and toroidal field (15 MA/5.3 T) show the most extreme melt damage, with the assumed n (Be) having a strong impact on the disruption duration, peak q (perpendicular to) and total energy deposition to the first wall. The worst-cases are upward 15 MA VDEs and MDs at lower values of n (Be), with q (perpendicular to,max) = 307 MW m(-2) and maximum erosion losses of similar to 2 mm after timespans of similar to 400-500 ms. All scenarios at 5 MA avoided melt damage, and only one 7.5 MA scenario yields a notable erosion depth of 0.25 mm. These results imply that disruptions during 5 MA, and some 7.5 MA, operating scenarios will be acceptable during the pre-fusion power operation phases of ITER. Preliminary analysis shows that localized melt damage for the worst-case disruption should have a limited impact on subsequent stationary power handling capability.
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| 9. |
- Coburn, J., et al.
(författare)
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Reassessing energy deposition for the ITER 5 MA vertical displacement event with an improved DINA model
- 2021
-
Ingår i: Nuclear Materials and Energy. - : Elsevier BV. - 2352-1791. ; 28
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Tidskriftsartikel (refereegranskat)abstract
- The beryllium (Be) main chamber wall interaction during a 5 MA/1.8 T upward, unmitigated VDE scenario, first analysed in [J. Coburn et al., Phys. Scr. T171 (2020) 014076] for ITER, has been re-evaluated using the latest energy deposition analysis software. Updates to the DINA disruption model are summarized, including an improved numerical convergence for the OD power balance, limitations on the safety factor within the plasma core, and the choice to maintain a constant plasma + halo poloidal cross-section. Such updates result in a broad halo region and higher radiated power fractions compared to previous models. The new scenario lasts for similar to 75 ms and deposits similar to 29 MJ of energy, with the radial distribution of parallel heat flux q parallel to(r) resembling an exponential falloff with an effective lambda(q) = 75 -198 mm. A maximum halo width w(h) of 0.52 m at the outboard midplane is observed. SMITER field line tracing and energy deposition simulations calculate a q(perpendicular to,max) of similar to 83 MW/m(2) on the upper first wall panels (FWP). Heat transfer calculations with the MEMOS-U code show that the FWP surface temperature reaches similar to 1000 K, well below the Be melt threshold. Variations of this 5 MA scenario with Be impurity densities from 0 to 3.10(19) m(-3) also remain below the melt threshold despite differences in energy deposition and duration. These results are in contrast to the early study which predicted melt damage to the first wall [J. Coburn et al., Phys. Scr. T171 (2020) 014076], and emphasize the importance of accurate models for the halo width w(h) and the heat flux distribution q parallel to(r) within that halo width. The 2020 halo model in DINA has been compared with halo current experiments on COMPASS, JET, and Alcator C-Mod, and the preliminary results build confidence in the broad halo width predictions. Results for the 5 MA VDE are compared with those for a 15 MA equivalent, generated using the new DINA model. At the higher current, significant melting of the upper FWP is to be expected.
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| 10. |
- Krieger, K., et al.
(författare)
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Investigation of transient melting of tungsten by ELMs in ASDEX Upgrade
- 2017
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Ingår i: Physica Scripta. - : IOP PUBLISHING LTD. - 0031-8949 .- 1402-4896. ; T170
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Tidskriftsartikel (refereegranskat)abstract
- Repetitive melting of tungsten by power transients originating from edge localized modes (ELMs) has been studied in the tokamak experiment ASDEX Upgrade. Tungsten samples were exposed to H-mode discharges at the outer divertor target plate using the Divertor Manipulator II system. The exposed sample was designed with an elevated sloped surface inclined against the incident magnetic field to increase the projected parallel power flux to a level were transient melting by ELMs would occur. Sample exposure was controlled by moving the outer strike point to the sample location. As extension to previous melt studies in the new experiment both the current flow from the sample to vessel potential and the local surface temperature were measured with sufficient time resolution to resolve individual ELMs. The experiment provided for the first time a direct link of current flow and surface temperature during transient ELM events. This allows to further constrain the MEMOS melt motion code predictions and to improve the validation of its underlying model assumptions. Post exposure ex situ analysis of the retrieved samples confirms the decreased melt motion observed at shallower magnetic field line to surface angles compared to that at leading edges exposed to the parallel power flux.
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| 11. |
- Ratynskaia, Svetlana V., et al.
(författare)
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Tungsten dust remobilization under steady-state and transient plasma conditions
- 2017
-
Ingår i: NUCLEAR MATERIALS AND ENERGY. - : Elsevier. - 2352-1791. ; 12, s. 569-574
-
Tidskriftsartikel (refereegranskat)abstract
- Remobilization is one of the most prominent unresolved fusion dust-relevant issues, strongly related to the lifetime of dust in plasma-wetted regions, the survivability of dust on hot plasma-facing surfaces and the formation of dust accumulation sites. A systematic cross-machine study has been initiated to investigate the remobilization of tungsten micron-size dust from tungsten surfaces implementing a newly developed technique based on controlled pre-adhesion by gas dynamics methods. It has been utilized in a number of devices and has provided new insights on remobilization under steady-state and transient conditions. The experiments are interpreted with contact mechanics theory and heat conduction models.
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| 12. |
- Ablikim, M., et al.
(författare)
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Determination of spin and parity of D*ˆ—(s) mesons
- 2023
-
Ingår i: Physics Letters B. - : Elsevier. - 0370-2693 .- 1873-2445. ; 846
-
Tidskriftsartikel (refereegranskat)abstract
- The spin and parity of the charmed mesons D*s+, D*0 and D*+ are determined for the first time to be JP = 1- with significances greater than 10σ over other hypotheses of 2+ and 3-, using an e+e- collision data sample with an integrated luminosity of 3.19 fb-1 collected by the BESIII detector at a center-of-mass energy of 4.178 GeV. Different spin-parity hypotheses are tested via a helicity amplitude analysis of the processes e+e--→ D*s+ D-s, D*0D0 and D*+D-, with D∗+s → D*+s γ, D∗0 → D0π0 , and D∗+ → D+π0. The results confirm the quark model predictions
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| 13. |
- Ablikim, M., et al.
(författare)
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First observation of Λ+ c → ΛK+ π0 and evidence of Λ+ c → ΛK+ π + π -
- 2024
-
Ingår i: Physical Review D. - : American Physical Society. - 2470-0010 .- 2470-0029. ; 109:3
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Tidskriftsartikel (refereegranskat)abstract
- We present the first observation of the singly Cabibbo-suppressed decay Lambda thorn c ->Lambda K thorn pi 0with asignificance of5.7 sigma and the first evidence of Lambda thorn c ->Lambda K thorn pi thorn pi-decay with a significance of3.1 sigma,basedone thorn e-annihilation data recorded by the BESIII detector at the BEPCII collider. The data correspond to anintegrated luminosity of6.4fb-1, in the center-of-mass energy range from 4.600 to 4.950 GeV. Wedetermine the branching fractions of Lambda thorn c ->Lambda K thorn pi 0and Lambda thorn c ->Lambda K thorn pi thorn pi-relative to their Cabibbo-favored counterparts to beBo Lambda thorn c ->Lambda K thorn pi 0 thorn Bo Lambda thorn c ->Lambda pi thorn pi 0 thorn 1/4o2.090.39stat0.07syst thorn x10-2andBo Lambda thorn c ->Lambda K thorn pi thorn pi- thorn Bo Lambda thorn c ->Lambda pi thorn pi thorn pi- thorn 1/4o1.130.41stat0.06syst thorn x10-2, respectively. Moreover, by combining our measured result with theworld average ofBo Lambda thorn c ->Lambda pi thorn pi 0 thorn , we obtain the branching fractionBo Lambda thorn c ->Lambda K thorn pi 0 thorn 1/4o1.490.27stat0.05syst0.08ref thorn x10-3. This result significantly departs from theoretical predictionsbased on quarkSUo3 thorn flavor symmetry, which is underpinned by the presumption of meson pairS-waveamplitude dominance
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| 14. |
- Ablikim, M., et al.
(författare)
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Improved measurement of the branching fraction of Ds plus → Ό plus ΜΌ
- 2023
-
Ingår i: Physical Review D. - : American Physical Society. - 2470-0010 .- 2470-0029. ; 108:11
-
Tidskriftsartikel (refereegranskat)abstract
- Using e thorn e- collision data with an integrated luminosity of 7.33 fb-1 collected at center-of-mass energies between 4.128 and 4.226 GeV with the BESIII detector operating at the BEPCII collider, the branching fraction of the leptonic decay D thorn s -> mu thorn nu mu is measured to be o0.5294 0.0108stat 0.0085syst thorn %. Based on this, the product of the D thorn s decay constant fD thorn s and the magnitude of the c -> s quark mixing matrix element jVcsj is determined to be fD thorn s jVcsj 1/4 241.8 2.5stat 2.2syst MeV. Using the value of jVcsj given by the global standard model fit, fD thorn s is found to be 248.4 2.5stat 2.2syst MeV. Alternatively, using the value of fD thorn s from a recent lattice quantum chromodynamics calculation, jVcsj is determined to be 0.968 0.010stat 0.009syst.
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| 15. |
- Ablikim, M., et al.
(författare)
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Measurements of Σ electromagnetic form factors in the timelike region using the untagged initial-state radiation technique
- 2024
-
Ingår i: Physical Review D. - : American Physical Society. - 2470-0010 .- 2470-0029. ; 109:3
-
Tidskriftsartikel (refereegranskat)abstract
- The process e thorn e- -> sigma thorn sigma over bar - is studied from threshold up to 3.04 GeV=c2 via the initial -state radiation technique using data with an integrated luminosity of 12.0 fb-1, collected at center-of-mass energies between 3.773 and 4.258 GeV with the BESIII detector at the BEPCII collider. The pair production cross sections and the effective form factors of sigma are measured in eleven sigma thorn sigma over bar - invariant mass intervals from threshold to 3.04 GeV=c2. The results are consistent with the previous results from Belle and BESIII. Furthermore, the branching fractions of the decays J=psi ->sigma thorn sigma over bar - and psi o3686 thorn -> sigma thorn sigma over bar - are determined and the obtained results are consistent with the previous results of BESIII.
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| 16. |
- Ablikim, M., et al.
(författare)
-
Measurements of the absolute branching fractions of Ω- decays and test of the ΔI=1/2 rule
- 2023
-
Ingår i: Physical Review D. - : American Physical Society. - 2470-0010 .- 2470-0029. ; 108:9
-
Tidskriftsartikel (refereegranskat)abstract
- Based on a dataset of (27.12 +/- 0.10) x 10(8) psi(3686) events collected at the BESIII experiment, the absolute branching fractions of the three dominant Omega(-) decays are measured to be B Omega-->Xi 0 pi- = (25.03 +/- 0.44 +/- 0.53) %, B Omega-->Xi-pi 0 = (8.43 +/- 0.52 +/- 0.28) %, and B Omega-->Lambda K- = (66.3 +/- 0.8 +/- 2.0) %, where the first and second uncertainties are statistical and systematic, respectively. The ratio between B Omega-->Xi 0 pi- and B Omega-->Xi-pi 0 is determined to be 2.97 +/- 0.19 +/- 0.11, which is in good agreement with the PDG value of 2.74 +/- 0.15, but greater by more than four standard deviations than the theoretical prediction of 2 obtained from the Delta I = 1/2 rule.
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| 17. |
- Ablikim, M., et al.
(författare)
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Observation of the decay & chi;cJ & RARR; & omega;-& omega; over bar
- 2023
-
Ingår i: Physical Review D. - : American Physical Society (APS). - 2470-0010 .- 2470-0029. ; 107:9
-
Tidskriftsartikel (refereegranskat)abstract
- Using an e thorn e- collision data sample of o27.08 ⠂ 0.14 thorn x 108 & psi;o3686 thorn events collected by the BESIII detector, we report the first observation of & chi;cJ & RARR; & omega;- over bar & omega; thorn (J 1/4 0, 1, 2) decays with significances of 5.6 & sigma;, 6.4 & sigma;, and 18 & sigma;, respectively, where the & chi;cJ mesons are produced in the radiative & psi;o3686 thorn decays. The branching fractions are determined to be Bo & chi;c0 & RARR; & omega;- over bar & omega; thorn thorn 1/4 o3.51 ⠂ 0.54 ⠂ 0.29 thorn x 10-5, Bo & chi;c1 & RARR; & omega;- over bar & omega; thorn thorn 1/4 o1.49 ⠂ 0.23 ⠂ 0.10 thorn x 10-5, and Bo & chi;c2 & RARR; & omega;- over bar & omega; thorn thorn 1/4 o4.52 ⠂ 0.24 ⠂ 0.18 thorn x 10-5, where the first and second uncertainties are statistical and systematic, respectively.
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| 18. |
- Ablikim, M., et al.
(författare)
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Observation of the ψð3686ß decays into Σ+ Σ - ω and Σ+ Σ - φ
- 2023
-
Ingår i: Physical Review D. - : American Physical Society. - 2470-0010 .- 2470-0029. ; 108:9
-
Tidskriftsartikel (refereegranskat)abstract
- Based on (2712.4 +/- 14.3) x 106 events recorded at the psi(3686) nominal mass collected with the BESIII detector operating at the BEPCII collider, the psi(3686) -> E +/- E over bar -omega and E +/- E over bar -phi decays are observed for the first time with statistical significances of 13.8 sigma and 7.6 sigma, respectively. The corresponding branching fractions are measured to be B(psi (3686) -> E +/- E over bar -omega) = (1.89 +/- 0.18 +/- 0.21) x 10-5 and B(psi (3686) -> E +/- E over bar -phi) = (2.96 +/- 0.54 +/- 0.41) x 10-6, where the first uncertainties are statistical and the second systematic.
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| 19. |
- Ablikim, M., et al.
(författare)
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Observation of the Y(4230) and evidence for a new vector charmoniumlike state Y(4710) in e+ e- & RARR; K0SK0SJ/& psi
- 2023
-
Ingår i: Physical Review D. - : American Physical Society (APS). - 2470-0010 .- 2470-0029. ; 107:9
-
Tidskriftsartikel (refereegranskat)abstract
- Cross sections for the process e thorn e- & RARR; K0SK0SJ=& psi; at center-of-mass energies from 4.128 to 4.950 GeV are measured using data samples with a total integrated luminosity of 21.2 fb-1 collected by the BESIII detector operating at the BEPCII storage ring. The Yo4230 thorn state is observed in the energy dependence of the e thorn e- & RARR; K0SK0 SJ=& psi; cross section for the first time with a statistical significance of 26.0 & sigma;. In addition, an enhancement around 4.710 GeV, labeled as the Yo4710 thorn , is seen with a statistical significance of 4.2 & sigma;. There is no clear structure around 4.484 GeV. Using a fit with a coherent sum of three Breit-Wigner functions, we determine the mass and width of the Yo4230 thorn state to be 4226.9 ⠂ 6.6 ⠂ 22.0 MeV=c2 and 71.7 ⠂ 16.2 ⠂ 32.8 MeV, respectively, and the mass and width of the Yo4710 thorn state to be 4704.0 ⠂ 52.3 ⠂ 69.5 MeV=c2 and 183.2 ⠂ 114.0 ⠂ 96.1 MeV, respectively, where the first uncertainties are statistical and the second are systematic. In addition, the average Born cross section ratio & sigma;Bornoe thorn e-& RARR;K thorn K-J=& psi; thorn is measured to be 0.388 thorn 0.035 & sigma;Bornoe thorn e-& RARR;K0 SK0 SJ=& psi; thorn -0.028 ⠂0.016, or 0.426 thorn 0.038 -0.031 ⠂ 0.018 if three-body phase space is considered.
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| 20. |
- Ablikim, M., et al.
(författare)
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Precise Measurement of the e plus e- → D plus s D- s Cross Sections at Center-of-Mass Energies from Threshold to 4.95 GeV
- 2023
-
Ingår i: Physical Review Letters. - : American Physical Society. - 0031-9007 .- 1079-7114. ; 131:15
-
Tidskriftsartikel (refereegranskat)abstract
- The process e thorn e- -> D = thorn s D =- s is studied with a semi-inclusive method using data samples at center-of-mass energies from threshold to 4.95 GeV collected with the BESIII detector operating at the Beijing Electron Positron Collider. The Born cross sections of the process are measured for the first time with high precision in this energy region. Two resonance structures are observed in the energy-dependent cross sections around 4.2 and 4.4 GeV. By fitting the cross sections with a coherent sum of three Breit-Wigner amplitudes and one phase-space amplitude, the two significant structures are assigned masses of o4186.8  8.7  30 thorn and o4414.6  3.4  6.1 thorn MeV=c2, widths of o55  15  53 thorn and o122.5  7.5  8.1 thorn MeV, where the first errors are statistical and the second ones are systematic. The inclusion of a third Breit-Wigner amplitude is necessary to describe a structure around 4.79 GeV.
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| 21. |
- Ablikim, M., et al.
(författare)
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Precision measurement of the matrix elements for eta -> pi(+)pi(-)pi(0) and eta -> pi(0)pi(0)pi(0) decays
- 2023
-
Ingår i: Physical Review D. - : American Physical Society. - 2470-0010 .- 2470-0029. ; 107:9
-
Tidskriftsartikel (refereegranskat)abstract
- A precision measurement of the matrix elements for eta -> pi(+)pi(-)pi(0) and -> pi(0)pi(0)pi(0) decays is performed using a sample of (10087 +/- 44) x 10(6) J/psi decays collected with the BESIII detector. The decay J/psi -> gamma eta is used to select clean samples of 631, 686 eta -> pi(+)pi(-)pi(0) decays and 272, 322 eta -> pi(0)pi(0)pi(0) decays. The matrix elements for both channels are in reasonable agreement with previous measurements. The nonzero gX(2)Y term for the decay mode eta -> pi(+)pi(-)pi(0) is confirmed, as reported by the KLOE Collaboration, while the other higher-order terms are found to be insignificant. Dalitz plot asymmetries in the eta -> pi(+)pi(-)pi(0) decay are also explored and are found to be consistent with charge conjugation invariance. In addition, a cusp effect is investigated in the eta -> pi(0)pi(0)pi(0) decay, and no obvious structure around the pi(+)pi(-) mass threshold is observed.
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| 22. |
- Ablikim, M., et al.
(författare)
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Search for a scalar partner of the X(3872) via ψ(3770) decays into γηη' and γπ+ π- J/ψ
- 2023
-
Ingår i: Physical Review D. - : American Physical Society. - 2470-0010 .- 2470-0029. ; 108:5
-
Tidskriftsartikel (refereegranskat)abstract
- Using a data sample corresponding to an integrated luminosity of 2.93 fb(-1) collected at a center-of-mass energy of 3.773 GeV with the BESIII detector at the BEPCII collider, we search for a scalar partner of the X(3872), denoted as X(3700), via psi(3770) gamma eta eta' and gamma pi(+)pi(-)J/psi processes. No significant signals are observed and the upper limits of the product branching fractions B(psi(3770) ->gamma X(3700)) center dot B(X(3700)-> eta eta') and B(psi(3770) ->gamma X(3700)) center dot B(X(3700) -> pi(+)pi(-)J/psi) are determined at the 90% confidence level, for the narrow X(3700) with a mass ranging from 3710 to 3740 MeV/c(2), which are from 0.9 to 1.9(x10(-5)) and 0.9 to 3.4(x10(-5)), respectively.
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| 23. |
- Ablikim, M., et al.
(författare)
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Search for hyperon Delta S = Delta Q violating decay Xi(0) -> Sigma(-)e(+)nu(e)
- 2023
-
Ingår i: Physical Review D. - : American Physical Society. - 2470-0010 .- 2470-0029. ; 107:1
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Tidskriftsartikel (refereegranskat)abstract
- Using a data sample of (1.0087 +/- 0.0044) x 10(10) J/psi decay events collected with the BESIII detector at the center-of-mass energy of root s = 3.097 GeV, we present a search for the hyperon semileptonic decay Xi(0) -> Sigma(-)e(+)nu(e) which violates the Delta S = Delta Q rule. No significant signal is observed, and the upper limit on the branching fraction B(Xi(0) -> Sigma(-)e(+)nu(e)) is determined to be 1.6 x 10(-4) at the 90% confidence level. This result improves the previous upper limit result by about one order of magnitude.
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| 24. |
- Ablikim, M., et al.
(författare)
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Search for the light hadron decay χc1(3872) → π+π-η
- 2024
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Ingår i: Physical Review D. - : American Physical Society. - 2470-0010 .- 2470-0029. ; 109:1
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Tidskriftsartikel (refereegranskat)abstract
- With a data sample corresponding to an integrated luminosity of 11.5 fb(-1) collected with the BESIII detector operating at the BEPCII storage ring, for the first time the light hadron decay chi(c1()3872)->pi(+)pi(-)eta is searched for. While no significant signal is observed, the upper limits at the 90% confidence level for sigma[e(+)e(-)->gamma chi(c1)(3872)]B[chi(c1)(3872)->pi(+)pi(-)eta] at center of mass energies from 4.13 GeV to 4.34 GeV are determined. By normalizing to the chi(c1)(3872)->pi(+)pi(-)J/psi decay channel, a 90% confidence level upper limit for the branching fraction ratio R=B[chi(c1)(3872)->pi(+)pi(-)eta]/B[chi(c1)(3872)->pi(+)pi(-)J/psi]<0.12 is given. These measurements provide important inputs for understanding the internal structure of the chi(c1)(3872) resonance
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| 25. |
- Ablikim, M., et al.
(författare)
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Search for the semileptonic decays Ds+ → K1(1270)0e+Μe and Ds+ → b1(1235)0e+Μe
- 2023
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Ingår i: Physical Review D. - : American Physical Society. - 2470-0010 .- 2470-0029. ; 108:11
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Tidskriftsartikel (refereegranskat)abstract
- By analyzing 7.33 fb(-1) of e(+)e(-) collision data collected at center-of-mass energies between 4.128 and 4.226 GeV with the BESIII detector, we search for the semileptonic decays D-s(+)-> K-1(1270)(0)e(+)nu(e) and D-s(+)-> b(1)(1235)(0)e(+)nu(e) for the first time. No significant signals are observed for either decay mode. The upper limits on the (product) branching fractions are determined to be B[D-s(+)-> K-1(1270)(0)e(+)nu(e)] < 4.1x10(-4) and B[D-s(+)-> b(1)(1235)(0)e(+)nu(e)]center dot B[b(1)(1235)(0)->omega pi(0)] < 6.4x10(-4) at 90% confidence level.
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