Refine
Year of publication
Document Type
- Preprint (303)
- Article (255)
- Working Paper (1)
Language
- English (559)
Has Fulltext
- yes (559)
Is part of the Bibliography
- no (559)
Keywords
- BESIII (17)
- e +-e − Experiments (13)
- Branching fraction (9)
- Particle and Resonance Production (8)
- Hadron-Hadron Scattering (7)
- Quarkonium (7)
- Spectroscopy (6)
- Hadronic decays (5)
- Branching fractions (4)
- Charm Physics (4)
- Collective Flow (4)
- Exotics (4)
- Heavy Ion Experiments (4)
- Heavy-ion collisions (4)
- Lepton colliders (4)
- Quark-Gluon Plasma (4)
- Charmed mesons (3)
- Charmonium (3)
- Diffraction (3)
- Elastic scattering (3)
- Electroweak interaction (3)
- Initial state radiation (3)
- Jets (3)
- Jets and Jet Substructure (3)
- Polarization (3)
- QCD (3)
- e+-e− Experiments (3)
- Beam Energy Scan (2)
- Bhabha (2)
- Charm physics (2)
- Chiral Magnetic Effect (2)
- Collectivity (2)
- Correlation (2)
- Cross section (2)
- Electroweak Interaction (2)
- Hadronic cross section (2)
- Heavy Quark Production (2)
- Leptonic, semileptonic & radiative decays (2)
- Muon anomaly (2)
- Particle Correlations and Fluctuations (2)
- Particle decays (2)
- Pion form factor (2)
- RHIC (2)
- STAR (2)
- Shear viscosity (2)
- Absolute branching fraction (1)
- Alleles (1)
- Angular distribution (1)
- Annihilation (1)
- Aortic valve (1)
- Apoptosis (1)
- B-slope (1)
- BESIII detector (1)
- Beam energy scan (1)
- Boosted Jets (1)
- Born cross section measurement (1)
- CP violation (1)
- Cell proliferation (1)
- Charged-particle multiplicity (1)
- Charm quark spatial diffusion coefficient (1)
- Charmonia (1)
- Charmonium (-like) (1)
- Chiral magnetic effect (1)
- Coalescence (1)
- Cold nuclear matter effects (1)
- Collective Flow, (1)
- Covariance matrix (1)
- Critical point (1)
- Cross section measurements (1)
- D meson (1)
- D0 and D+ mesons (1)
- DNA barcode (1)
- Dalitz decay (1)
- Dark photon (1)
- Dark sector (1)
- Deuteron production (1)
- Di-hadron correlations (1)
- D⁰ meson (1)
- Electromagnetic amplitude (1)
- Electromagnetic form factor (1)
- Electromagnetic form factors (1)
- Electron-pion identification (1)
- Elliptic flow (1)
- Endothelial cells (1)
- Experimental nuclear physics (1)
- Experimental particle physics (1)
- FOS: Physical sciences (1)
- Fibre/foam sandwich radiator (1)
- Flavor changing neutral currents (1)
- Flavor symmetries (1)
- Flavour Physics (1)
- Flow (1)
- Form factors (1)
- Forward physics (1)
- Groomed jet radius (1)
- Hadron-Hadron Scattering Heavy (1)
- Hadron-Hadron scattering (experiments) (1)
- Hadrons (1)
- Hard Scattering (1)
- Heart (1)
- Heavy Ion Experiment (1)
- Heavy-Ion Collision (1)
- Heavy-flavor decay electron (1)
- Heavy-ion (1)
- High Energy Physics - Experiment (hep-ex) (1)
- Higher moments (1)
- Homeostasis (1)
- Hyperons (1)
- Immunostaining (1)
- Inclusive branching fraction (1)
- Interference fragmentation function (1)
- Invisible decays (1)
- Ionisation energy loss (1)
- J/ψ suppression (1)
- Jet Physics (1)
- Jet Substructure (1)
- Jet substructure (1)
- K0S (1)
- Macrothele (1)
- Material budget (1)
- Multi-Parton Interactions (1)
- Multi-wire proportional drift chamber (1)
- Multiple parton interactions (1)
- Neural network (1)
- Neutrinos (1)
- New species (1)
- Nonflow (1)
- Particle and resonance production (1)
- Particle phenomena (1)
- Phase (1)
- Properties of Hadrons (1)
- Proton (1)
- Proton-proton collisions (1)
- Proton–proton collisions (1)
- Quantum chromodynamics (1)
- Quark Deconfinement (1)
- Quark Production (1)
- R value (1)
- Radiative decay (1)
- Rare decays (1)
- Semi-leptonic decays (1)
- SoftDrop (1)
- Spin alignment (1)
- Splitting function (1)
- Strong amplitude (1)
- TR (1)
- Techniques Electromagnetic calorimeters (1)
- Thermal model (1)
- Tracking (1)
- Transition radiation detector (1)
- Transversity (1)
- Trigger (1)
- Triple quarkonia (1)
- Vector Boson Production (1)
- W-exchange (1)
- Xenon-based gas mixture (1)
- Y (4260) (1)
- Y states (1)
- Yunnan (1)
- active perception (1)
- branching fractions (1)
- center-of-mass energy (1)
- charmed baryon (1)
- charmonium-like states (1)
- dE/dx (1)
- decay (1)
- decays (1)
- detector (1)
- dimuon (1)
- diphoton (1)
- e+e − annihilation (1)
- e+e⁻ − Experiments (1)
- e+e− Experiments (1)
- e+e− annihilation (1)
- ectosomes (1)
- electron-positron collision (1)
- exosomes (1)
- experimental results (1)
- extracellular vesicles (1)
- guidelines (1)
- hadron spectroscopy (1)
- hadronic events (1)
- heavy-ion collisions (1)
- helicity amplitude analysis (1)
- inclusive J/ψ decays (1)
- luminosity (1)
- microparticles (1)
- microvesicles (1)
- minimal information requirements (1)
- number of J/ψ events (1)
- p+p collisions (1)
- reinforcement learning (1)
- reproducibility (1)
- rigor (1)
- robotics (1)
- robustness (1)
- sparse coding (1)
- standardization (1)
- stereo vision (1)
- tetraquark (1)
- trigger efficiency (1)
- vergence (1)
- Λ+c baryon (1)
- Λc⁺ (1)
- Σ hyperon (1)
- Υ suppression (1)
- ψ(3686) (1)
Institute
Improved measurement of the branching fraction of h_(c) → γη^(′)/η and search for h_(c) → γπ⁰
(2024)
The processes hc→γP(P=η′, η, π0)) are studied with a sample of (27.12±0.14)×108 ψ(3686) events collected by the BESIII detector at the BEPCII collider. The branching fractions of hc→γη′ and hc→γη are measured to be (1.40±0.11±0.04±0.10)×10−3 and (3.77±0.55±0.13±0.26)×10−4, respectively, where the first uncertainties are statistical, the second systematic, and the third from the branching fraction of ψ(3686)→π0hc. The ratio Rhc=B(hc→γη)B(hc→γη′) is calculated to be (27.0±4.4±1.0)%. The measurements are consistent with the previous results with improved precision by a factor of 2. The results are valuable for gaining a deeper understanding of η−η′ mixing, and its manifestation within quantum chromodynamics. No significant signal is found for the decay hc→γπ0, and an upper limit is placed on its branching fraction of B(hc→γπ0)<5.0×10−5, at the 90\% confidence level.
We perform the first investigation of the process e+e−→K+K−ψ(2S) and report its Born cross sections over a range of center-of-mass energies from 4.699 to 4.951~GeV. The measurements are carried out using several partial reconstruction techniques using data samples collected by the BESIII detector with a total integrated luminosity of 2.5~fb−1. We search for new tetraquark candidates Z±cs in the decays Z±cs→K±ψ(2S). No significant Z±cs signals are observed.
Using e+e− annihilation data sets corresponding to an integrated luminosity of 4.5 fb−1, collected with the BESIII detector at center-of-mass energies between 4.600 and 4.699 GeV, we report the first measurements of the absolute branching fractions B(Λ+c→pK0L)=(1.67±0.06±0.04)%, B(Λ+c→pK0Lπ+π−)=(1.69±0.10±0.05)%, and B(Λ+c→pK0Lπ0)=(2.02±0.13±0.05)%, where the first uncertainties are statistical and the second systematic. Combining with the known branching fractions of Λ+c→pK0S, Λ+c→pK0Sπ+π−, and Λ+c→pK0Sπ0, we present the first measurements of the K0S-K0L asymmetries R(Λ+c,K0S,LX)=B(Λ+c→K0SX)−B(Λ+c→K0LX)B(Λ+c→K0SX)+B(Λ+c→K0LX) in charmed baryon decays: R(Λ+c,pK0S,L)=−0.025±0.031, R(Λ+c,pK0S,Lπ+π−)=−0.027±0.048, and R(Λ+c,pK0S,Lπ0)=−0.015±0.046. No significant asymmetries within the uncertainties are observed.
Based on (2712.4±14.3)×106 ψ(3686) events, we investigate four hadronic decay modes of the P-wave charmonium spin-singlet state hc(1P1)→h+h−π0/η (h=π or K) via the process ψ(3686)→π0hc at BESIII. The hc→π+π−π0 decay is observed with a significance of 9.6σ after taking into account systematic uncertainties. Evidences for hc→K+K−π0 and hc→K+K−η are found with significances of 3.5σ and 3.3σ, respectively, after considering the systematic uncertainties. The branching fractions of these decays are measured to be B(hc→π+π−π0)=(1.36±0.16±0.14)×10−3, B(hc→K+K−π0)=(3.26±0.84±0.36)×10−4, and B(hc→K+K−η)=(3.13±1.08±0.38)×10−4, where the first uncertainties are statistical and the second are systematic. No significant signal of hc→π+π−η is found, and the upper limit of its decay branching fraction is determined to be B(hc→π+π−η)<4.0×10−4 at 90% confidence level.
The e+e−→D+sDs1(2536)− and e+e−→D+sD∗s2(2573)− processes are studied using data samples collected with the BESIII detector at center-of-mass energies from 4.530 to 4.946~GeV. The absolute branching fractions of Ds1(2536)−→D¯∗0K− and D∗s2(2573)−→D¯0K− are measured for the first time to be (35.9±4.8±3.5)% and (37.4±3.1±4.6)%, respectively. The measurements are in tension with predictions based on the assumption that the Ds1(2536) and D∗s2(2573) are dominated by a bare cs¯ component. The e+e−→D+sDs1(2536)− and e+e−→D+sD∗s2(2573)− cross sections are measured, and a resonant structure at around 4.6~GeV with a width of 50~MeV is observed for the first time with a statistical significance of 15σ in the e+e−→D+sD∗s2(2573)− process. It could be the Y(4626) found by the Belle collaboration in the D+sDs1(2536)− final state, since they have similar masses and widths. There is also evidence for a structure at around 4.75~GeV in both processes.
Using data samples collected with the BESIII detector operating at the BEPCII storage ring, the cross section of the inclusive process e+e−→η+X, normalized by the total cross section of e+e−→hadrons, is measured at eight center-of-mass energy points from 2.0000 GeV to 3.6710 GeV. These are the first measurements with momentum dependence in this energy region. Our measurement shows a significant discrepancy from calculations with the existing fragmentation functions. To address this discrepancy, a new QCD analysis is performed at the next-to-next-to-leading order with hadron mass corrections and higher twist effects, which can explain both the established high-energy data and our measurements reasonably well.
Using data samples with an integrated luminosity of 4.67 fb−1 collected by the BESIII detector operating at the BEPCII collider, we search for the process e+e−→η′ψ(2S) at center-of-mass energies from 4.66 to 4.95 GeV. No significant signal is observed, and upper limits for the Born cross sections σB(e+e−→η′ψ(2S)) at the 90\% confidence level are determined.
We report the first amplitude analysis of the decays D0→π+π−η and D+→π+π0η using a data sample taken with the BESIII detector at the center-of-mass energy of 3.773 GeV, corresponding to an integrated luminosity of 7.9 fb−1. The contribution from the process D0(+)→a0(980)+π−(0) is significantly larger than the D0(+)→a0(980)−(0)π+ contribution. The ratios B(D0→a0(980)+π−)/B(D0→a0(980)−π+) and B(D+→a0(980)+π0)/B(D+→a0(980)0π+) are measured to be 7.5+2.5−0.8stat.±1.7syst. and 2.6±0.6stat.±0.3syst., respectively. The measured D0 ratio disagrees with the theoretical predictions by orders of magnitudes, thus implying a substantial contribution from final-state interactions.
Six C-even states, denoted as X, with quantum numbers JPC=0−+, 1±+, or 2±+, are searched for via the e+e−→γD±sD∗∓s process using (1667.39±8.84) pb−1 of e+e− collision data collected with the BESIII detector operating at the BEPCII storage ring at center-of-mass energy of s√=(4681.92±0.30) MeV. No statistically significant signal is observed in the mass range from 4.08 to 4.32 GeV/c2. The upper limits of σ[e+e−→γX]⋅B[X→D±sD∗∓s] at a 90% confidence level are determined.
Observation of χcJ → 3(K⁺K⁻)
(2023)
By analyzing (27.12±0.14)×108 ψ(3686) events collected with the BESIII detector operating at the BEPCII collider, the decay processes χcJ→3(K+K−) (J=0,1,2) are observed for the first time with statistical significances of 8.2σ, 8.1σ, and 12.4σ, respectively. The product branching fractions of ψ(3686)→γχcJ, χcJ→3(K+K−) are presented and the branching fractions of χcJ→3(K+K−) decays are determined to be Bχc0→3(K+K−)=(10.7±1.8±1.1)×10−6, Bχc1→3(K+K−)=(4.2±0.9±0.5)×10−6, and Bχc2→3(K+K−)=(7.2±1.1±0.8)×10−6, where the first uncertainties are statistical and the second are systematic.
The process e+e−→pp¯π0 is studied at 20 center-of-mass energies ranging from 2.1000 to 3.0800 GeV using 636.8 pb−1 of data collected with the BESIII detector operating at the BEPCII collider. The Born cross sections for e+e−→pp¯π0 are measured with high precision. Since the lowest center-of-mass energy, 2.1000 GeV, is less than 90 MeV above the pp¯π0 energy threshold, we can probe the threshold behavior for this reaction. However, no anomalous threshold enhancement is found in the cross sections for e+e−→pp¯π0.
Using 9.0 fb−1 of e+e− collision data collected at center-of-mass energies from 4.178 to 4.278 GeV with the BESIII detector at the BEPCII collider, we perform the first search for the radiative transition χc1(3872)→γψ2(3823). No χc1(3872)→γψ2(3823) signal is observed. The upper limit on the ratio of branching fractions B(χc1(3872)→γψ2(3823),ψ2(3823)→γχc1)/B(χc1(3872)→π+π−J/ψ) is set as 0.075 at the 90\% confidence level. Our result contradicts theoretical predictions under the assumption that the χc1(3872) is the pure charmonium state χc1(2P).
Based on (2.712±0.014)×109 ψ(3686) events collected by the BESIII collaboration, evidence of the hadronic decay hc→K0SK+π−+c.c. is found with a significance of 4.3σ in the ψ(3686)→π0hc process. The branching fraction of hc→K0SK+π−+c.c. is measured to be (7.3±0.8±1.8)×10−4, where the first and second uncertainties are statistical and systematic, respectively. Combining with the exclusive decay width of ηc→KK¯π, our result indicates inconsistencies with both pQCD and NRQCD predictions.
Observation of η_(c)(1S, 2S) and χ_(cJ) decays to 2(π⁺π^(−))η via ψ(3686) radiative transitions
(2024)
Based on 2.7×109 ψ(3686) decays collected with the BESIII detector, the radiative decay ψ(3686)→γ2(π+π−)η is investigated to measure properties of S- and P-wave charmonium states. The branching fraction of the decay ηc(1S)→2(π+π−)η, which is found to have a strong dependence on the interference pattern between ηc(1S) and non-ηc(1S) processes, is measured in both destructive and constructive interference scenarios for the first time. The mass and width of the ηc(1S) are measured to be M=(2984.14±0.13±0.38) MeV/c2 and Γ=(28.82±0.11±0.82) MeV, respectively. Clear signals for the decays of the χcJ(J=0,1,2) and the ηc(2S) to 2(π+π−)η are also observed for the first time, and the corresponding branching fractions are measured. The ratio of the branching fractions between the ηc(2S) and ηc(1S) decays is significantly lower than the theoretical prediction, which might suggest different dynamics in their decays.
By analyzing (27.12±0.14)×108 ψ(3686) events accumulated with the BESIII detector, the decay ηc(2S)→K+K−η is observed for the first time with a significance of 6.2σ after considering systematic uncertainties. The product of the branching fractions of ψ(3686)→γηc(2S) and ηc(2S)→K+K−η is measured to be B(ψ(3686)→γηc(2S))×B(ηc(2S)→K+K−η)=(2.39±0.32±0.34)×10−6, where the first uncertainty is statistical, and the second one is systematic. The branching fraction of ηc(2S)→K+K−η is determined to be B(ηc(2S)→K+K−η)=(3.42±0.46±0.48±2.44)×10−3, where the third uncertainty is due to the branching fraction of ψ(3686)→γηc(2S). Using a recent BESIII measurement of B(ηc(2S)→K+K−π0), we also determine the ratio between the branching fractions of ηc(2S)→K+K−η and ηc(2S)→K+K−π0 to be 1.49±0.22±0.25, which is consistent with the previous result of BaBar at a comparable precision level.
Search for X(3872)→π⁰π⁰χc₁,₂
(2024)
Using 10.1 fb−1 of e+e− collision data collected by the BESIII detector with center-of-mass energies between 4.15 GeV and 4.30 GeV, we search for the decays X(3872)→π0π0χc1,2, where the X(3872) is produced in e+e−→γX(3872). No evidence above 3σ is found for either decay. Upper limits at the 90% C.L. on the branching fractions of X(3872)→π0π0χc1,2 normalized to the branching fraction of X(3872)→π+π−J/ψ are set to be B(X(3872)→π0π0χc1)/B(X(3872)→π+π−J/ψ)<1.1 and B(X(3872)→π0π0χc2)/B(X(3872)→π+π−J/ψ)<0.5, taking into account both statistical and systematic uncertainties.
Observation of χcJ → 3(K⁺K⁻)
(2024)
By analyzing (27.12±0.14)×108 𝜓(3686) events collected with the BESIII detector operating at the BEPCII collider, the decay processes 𝜒𝑐𝐽→3(𝐾+𝐾−) (𝐽=0, 1, 2) are observed for the first time with statistical significances of 8.2𝜎, 8.1𝜎, and 12.4𝜎, respectively. The product branching fractions of 𝜓(3686)→𝛾𝜒𝑐𝐽, 𝜒𝑐𝐽→3(𝐾+𝐾−) are presented and the branching fractions of 𝜒𝑐𝐽→3(𝐾+𝐾−) decays are determined to be ℬ𝜒𝑐0→3(𝐾+𝐾−)=(10.7±1.8±1.1)×10−6, ℬ𝜒𝑐1→3(𝐾+𝐾−)=(4.2±0.9±0.5)×10−6, and ℬ𝜒𝑐2→3(𝐾+𝐾−)=(7.2±1.1±0.8)×10−6, where the first uncertainties are statistical and the second are systematic.
Using (2.712±0.014)×109 ψ(3686) events collected with the BESIII detector operating at the BEPCII, we find an evidence of the ηc(2S)→K+K−η′ decay with a statistical significance of 3.1σ. Its decay branching fraction is measured to be (12.24±4.60(stat.)±2.37(syst.)±4.68(extr.))×10−4, where the first uncertainty is statistical, the second is systematic, and the third uncertainty is from the branching fraction of the ψ(3686)→γηc(2S) decay. The upper limit on the product branching fraction B[ψ(3686)→γηc(2S)]× B[ηc(2S)→K+K−η′] is set to be 1.14×10−6 at 90% confidence level. In addition, the branching fractions of χc1→K+K−η′ and χc2→K+K−η′ are updated to be (8.47±0.09(stat.)±0.47(syst.))×10−4 and (1.53±0.04(stat.)±0.08(syst.))×10−4, respectively. The precision is improved by twofold.
We measure the Born cross section for the reaction e+e−→ηhc from s√=4.129 to 4.600~GeV using data sets collected by the BESIII detector running at the BEPCII collider. A resonant structure in the cross section line shape near 4.200~GeV is observed with a statistical significance of 7σ. The parameters of this resonance are measured to be \MeasMass\ and \MeasWidth, where the first uncertainties are statistical and the second systematic.
The absolute branching fraction of the decay Λc(2625)+→Λ+cπ+π− is measured for the first time to be (50.7±5.0stat.±4.9syst.)% with 368.48 pb−1 of e+e− collision data collected by the BESIII detector at the center-of-mass energies of s√=4.918 and 4.950 GeV. This result is lower than the naive prediction of 67\%, obtained from isospin symmetry, by more than 2σ, thereby indicating that the novel mechanism referred to as the \textit{threshold effect}, proposed for the strong decays of Λc(2595)+, also applies to Λc(2625)+. This measurement is necessary to obtain the coupling constants for the transitions between s-wave and p-wave charmed baryons in heavy hadron chiral perturbation theory. In addition, we search for the decay Λc(2595)+→Λ+cπ+π−. No significant signal is observed, and the upper limit on its branching fraction is determined to be 80.8\% at the 90\% confidence level.
The Cabbibo-favored decay Λ+c→Ξ0K+π0 is studied for the first time using 6.1 fb−1 of e+e− collision data at center-of-mass energies between 4.600 and 4.840 GeV, collected with the BESIII detector at the BEPCII collider. With a double-tag method, the branching fraction of the three-body decay Λ+c→Ξ0K+π0 is measured to be (7.79±1.46±0.71)×10−3, where the first and second uncertainties are statistical and systematic, respectively. The branching fraction of the two-body decay Λ+c→Ξ(1530)0K+ is (5.99±1.04±0.29)×10−3, which is consistent with the previous result of (5.02±0.99±0.31)×10−3. In addition, the upper limit on the branching fraction of the doubly Cabbibo-suppressed decay Λ+c→nK+π0 is 7.1×10−4 at the 90% confidence level. The upper limits on the branching fractions of Λ+c→Σ0K+π0 and ΛK+π0 are also determined to be 1.8×10−3 and 2.0×10−3, respectively.
We search for the di-photon decay of a light pseudoscalar axion-like particle, a, in radiative decays of the J/ψ, using 10 billion J/ψ events collected with the BESIII detector. We find no evidence of a narrow resonance and set upper limits at the 95% confidence level on the product branching fraction B(J/ψ→γa)×B(a→γγ) and the axion-like particle photon coupling constant gaγγ in the ranges of (3.6−49.8)×10−8 and (2.2−103.8)×10−4 GeV−1, respectively, for 0.18≤ma≤2.85 GeV/c2. These are the most stringent limits to date in this mass region.
Based on 4.5 fb−1 of e+e− collision data accumulated at center-of-mass energies between 4599.53 MeV and 4698.82 MeV with the BESIII detector, the decay Λ+c→nK0Sπ+π0 is observed for the first time with a significance of 9.2σ. The branching fraction is measured to be (0.85±0.13±0.03)%, where the first uncertainty is statistical and the second systematic, which differs from the theoretical prediction based on isospin by 4.4σ. This indicates that there may be resonant contributions or some unknown dynamics in this decay.
The process e+e−→Σ+Σ¯− 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 Σ are measured in eleven Σ+Σ¯− 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/ψ→Σ+Σ¯− and ψ(3686)→Σ+Σ¯− are determined and the obtained results are consistent with the previous results of BESIII.
The Cabbibo-favored decay Λ+c→Ξ0K+π0 is studied for the first time using 6.1 fb−1 of e+e− collision data at center-of-mass energies between 4.600 and 4.840 GeV, collected with the BESIII detector at the BEPCII collider. With a double-tag method, the branching fraction of the three-body decay Λ+c→Ξ0K+π0 is measured to be (7.79±1.46±0.71)×10−3, where the first and second uncertainties are statistical and systematic, respectively. The branching fraction of the two-body decay Λ+c→Ξ(1530)0K+ is (5.99±1.04±0.29)×10−3, which is consistent with the previous result of (5.02±0.99±0.31)×10−3. In addition, the upper limit on the branching fraction of the doubly Cabbibo-suppressed decay Λ+c→nK+π0 is 7.1×10−4 at the 90% confidence level. The upper limits on the branching fractions of Λ+c→Σ0K+π0 and ΛK+π0 are also determined to be 1.8×10−3 and 2.0×10−3, respectively.
The Cabbibo-favored decay Λ+c→Ξ0K+π0 is studied for the first time using 6.1 fb−1 of e+e− collision data at center-of-mass energies between 4.600 and 4.840 GeV, collected with the BESIII detector at the BEPCII collider. With a double-tag method, the branching fraction of the three-body decay Λ+c→Ξ0K+π0 is measured to be (7.79±1.46±0.71)×10−3, where the first and second uncertainties are statistical and systematic, respectively. The branching fraction of the two-body decay Λ+c→Ξ(1530)0K+ is (5.99±1.04±0.29)×10−3, which is consistent with the previous result of (5.02±0.99±0.31)×10−3. In addition, the upper limit on the branching fraction of the doubly Cabbibo-suppressed decay Λ+c→nK+π0 is 7.1×10−4 at the 90% confidence level. The upper limits on the branching fractions of Λ+c→Σ0K+π0 and ΛK+π0 are also determined to be 1.8×10−3 and 2.0×10−3, respectively.
Using e+e− collision data, corresponding to an integrated luminosity of 892pb−1 collected at center-of-mass energies from 4.84 to 4.95\,GeV with the BESIII detector, we search for the process e+e−→K+K−ψ(3770) by reconstructing two charged kaons and one D meson from ψ(3770). No significant signal of e+e−→K+K−ψ(3770) is found and the upper limits of the Born cross sections are reported at 90\% confidence level.
Based on 4.5 fb−1 of e+e− collision data accumulated at center-of-mass energies between 4599.53 MeV and 4698.82 MeV with the BESIII detector, the decay Λ+c→nK0Sπ+π0 is observed for the first time with a significance of 9.2σ. The branching fraction is measured to be (0.85±0.13±0.03)%, where the first uncertainty is statistical and the second systematic, which differs from the theoretical prediction based on isospin by 4.4σ. This indicates that there may be resonant contributions or some unknown dynamics in this decay.
The process 𝑒+𝑒−→Σ+¯Σ− 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 Σ are measured in eleven Σ+¯Σ− 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/𝜓→Σ+¯Σ− and 𝜓(3686)→Σ+¯Σ− are determined and the obtained results are consistent with the previous results of BESIII.
We report a measurement of the observed cross sections of e+ e− → J/ψX based on 3.21 fb − 1 of data accumulated at energies from 3.645 to 3.891 GeV with the BESIII detector operated at the BEPCII collider. In analysis of the cross sections, we measured the decay branching fractions of B(ψ(3686) → J/ψX) = (64.4 ± 0.6 ± 1.6)% and B(ψ(3770) → J/ψX) = (0.5 ± 0.2 ± 0.1)% for the first time. The energy-dependent line shape of these cross sections cannot be well described by two Breit-Wigner (BW) amplitudes of the expected decays ψ (3686) → J/ψX and ψ(3770) → J/ψX. Instead, it can be better described with one more BW amplitude of the decay R(3760)→ J/ψX. Under this assumption, we extracted the R (3760) mass M R (3760 ) = 3766.2 ± 3.8 ± 0.4 MeV/c2, total width Γ tot R ( 3760 ) = 22.2 ± 5.9 ± 1.4 MeV, and product of leptonic width and decay branching fraction
ΓeeR(3760) B[R(3760) → J/ψX] = (79.4 ± 85.5 ± 11.7) eV. The significance of the R(3760) is 5.3σ. The first uncertainties of these measured quantities are from fits to the cross sections and second systematic.
The process 𝑒+𝑒−→𝜙𝜂′ has been studied for the first time in detail using data sample collected with the BESIII detector at the BEPCII collider at center of mass energies from 2.05 to 3.08 GeV. A resonance with quantum numbers 𝐽𝑃𝐶=1−− is observed with mass 𝑀=(2177.5±4.8(stat)±19.5(syst))MeV/𝑐2 and width Γ=(149.0±15.6(stat)±8.9(syst)) MeV with a statistical significance larger than 10𝜎, including systematic uncertainties. If the observed structure is identified with the 𝜙(2170), then the ratio of partial width between the 𝜙𝜂′ by BESIII and 𝜙𝜂 by BABAR is (ℬ𝑅𝜙𝜂Γ𝑅𝑒𝑒)/(ℬ𝑅𝜙𝜂′Γ𝑅𝑒𝑒)=0.23±0.10(stat)±0.18(syst), which is smaller than the prediction of the 𝑠¯𝑠𝑔 hybrid models by several orders of magnitude.
Using 10.1 × 109 J/ψ events produced by the Beijing Electron Positron Collider (BEPCII) at a center-of-mass energy √s = 3.097 GeV and collected with the BESIII detector, we present a search for the rare semi-leptonic decay J/ψ → D−e+νe + c.c. No excess of signal above background is observed, and an upper limit on the branching fraction ℬ(J/ψ → D−e+νe + c. c.) < 7.1 × 10−8 is obtained at 90% confidence level. This is an improvement of more than two orders of magnitude over the previous best limit.
The process e+e−→ϕη is studied at 22 center-of-mass energy points (√s) between 2.00 and 3.08 GeV using 715 pb−1 of data collected with the BESIII detector. The measured Born cross section of e+e−→ϕη is found to be consistent with BABAR measurements, but with improved precision. A resonant structure around 2.175 GeV is observed with a significance of 6.9σ with mass (2163.5±6.2±3.0) MeV/c2 and width (31.1+21.1−11.6±1.1) MeV, where the first uncertainties are statistical and the second are systematic.
Though immensely successful, the standard model of particle physics does not offer any explanation as to why our Universe contains so much more matter than antimatter. A key to a dynamically generated matter–antimatter asymmetry is the existence of processes that violate the combined charge conjugation and parity (CP) symmetry1. As such, precision tests of CP symmetry may be used to search for physics beyond the standard model. However, hadrons decay through an interplay of strong and weak processes, quantified in terms of relative phases between the amplitudes. Although previous experiments constructed CP observables that depend on both strong and weak phases, we present an approach where sequential two-body decays of entangled multi-strange baryon–antibaryon pairs provide a separation between these phases. Our method, exploiting spin entanglement between the double-strange Ξ− baryon and its antiparticle2 Ξ¯+
, has enabled a direct determination of the weak-phase difference, (ξP − ξS) = (1.2 ± 3.4 ± 0.8) × 10−2 rad. Furthermore, three independent CP observables can be constructed from our measured parameters. The precision in the estimated parameters for a given data sample size is several orders of magnitude greater than achieved with previous methods3. Finally, we provide an independent measurement of the recently debated Λ decay parameter αΛ (refs. 4,5). The ΛΛ¯
asymmetry is in agreement with and compatible in precision to the most precise previous measurement.
By analyzing 6.32 fb − 1 of e+ e− annihilation data collected at the center-of-mass energies between 4.178 and 4.226 GeV with the BESIII detector, we determine the branching fraction of the leptonic decay D + s → τ + ντ, with τ+ → π + π0¯ντ, to be B D + s → τ + ν τ = (5.29 ± 0.25 stat ± 0.20 syst) %. We estimate the product of the Cabibbo-Kobayashi-Maskawa matrix element |Vcs|and the D + s decay constant f D + s to be f D + s|Vcs| = (244.8 ± 5.8 stat ± 4.8syst) MeV, using the known values of the τ + and D + s masses as well as the D + s lifetime, together with our branching fraction measurement. Combining the value of |Vcs| obtained from a global fit in the standard model and f D + s from lattice quantum chromodynamics, we obtain f D + s = (251.6 ± 5.9 stat ± 4.9syst) MeV and |Vcs| = 0.980 ± 0.023 stat ± 0.019 syst. Using the branching fraction of B D + s → μ + νμ = (5.35±0.21)×10−3, we obtain the ratio of the branching fractions B D + s → τ + ντ/B D +s → μ+νμ = 9.89±0.71, which is consistent with the standard model prediction of lepton flavor universality.
Using a sample of (10.09±0.04)×109 J/ψ events collected with the BESIII detector, a partial wave analysis of J/ψ→γη′η′ is performed.The masses and widths of the observed resonances and their branching fractions are reported. The main contribution is from J/ψ→γf0(2020) with f0(2020)→η′η′, which is found with a significance of greater than 25σ. The product branching fraction B(J/ψ → γf0(2020))⋅B(f0(2020) → η′η′ is measured to be (2.63±0.06(stat.) + 0.31−0.46(syst.))×10−4.
We present the first experimental search for the rare charm decay D0→π0ν¯ν. It is based on an e+e− collision sample consisting of 10.6×10^6 pairs of D0¯D0 mesons collected by the BESIII detector at √s=3.773 GeV, corresponding to an integrated luminosity of 2.93 fb^−1. A data-driven method is used to ensure the reliability of the background modeling. No significant D0→π0ν¯ν signal is observed in data and an upper limit of the branching fraction is set to be 2.1×10^-4 at the 90% confidence level. This is the first experimental constraint on charmed-hadron decays into dineutrino final states.
Using data samples collected with the BESIII detector operating at the BEPCII storage ring at center-of-mass energies from 4.178 to 4.600 GeV, we study the process eþe− → π0Xð3872Þγ and search for Zcð4020Þ0 → Xð3872Þγ. We find no significant signal and set upper limits on σðeþe− → π0Xð3872ÞγÞ · BðXð3872Þ → πþπ−J=ψÞ and σðeþe− → π0Zcð4020Þ0Þ · BðZcð4020Þ0 → Xð3872ÞγÞ · BðXð3872Þ → πþπ−J=ψÞ for each energy point at 90% confidence level, which is of the order of several tenths pb.
We measure the inclusive semielectronic decay branching fraction of the D+s meson. A double-tag technique is applied to e+e− annihilation data collected by the BESIII experiment at the BEPCII collider, operating in the center-of-mass energy range 4.178–4.230 GeV. We select positrons fromD+s→Xe+νe with momenta greater than 200 MeV/c and determine the laboratory momentum spectrum, accounting for the effects of detector efficiency and resolution. The total positron yield and semielectronic branching fraction are determined by extrapolating this spectrum below the momentum cutoff. We measure the D+s semielectronic branching fraction to be(6.30±0.13(stat.)±0.09(syst.)±0.04(ext.))%, showing no evidence for unobserved exclusive semielectronic modes. We combine this result with external data taken from literature to determine the ratio of the D+s and D0 semielectronic widths, Γ(D+s→Xe+νe)Γ(D0→Xe+νe)=0.790±0.016(stat.)±0.011(syst.)±0.016(ext.). Our results are consistent with and more precise than previous measurements.
The electromagnetic process is studied with the initial-state-radiation technique using 7.5 fb−1 of data collected by the BESIII experiment at seven energy points from 3.773 to 4.600 GeV. The Born cross section and the effective form factor of the proton are measured from the production threshold to 3.0 GeV/ using the invariant-mass spectrum. The ratio of electric and magnetic form factors of the proton is determined from the analysis of the proton-helicity angular distribution.
Based on an e+e− collision data sample corresponding to an integrated luminosity of 2.93 fb−1 collected with the BESIII detector at √s=3.773 GeV, the first amplitude analysis of the singly Cabibbo-suppressed decay D+→K+K0Sπ0 is performed. From the amplitude analysis, the K∗(892)+K0S component is found to be dominant with a fraction of (57.1±2.6±4.2)%, where the first uncertainty is statistical and the second systematic. In combination with the absolute branching fraction B(D+→K+K0Sπ0) measured by BESIII, we obtain B(D+→K∗(892)+K0S)=(8.69±0.40±0.64±0.51)×10−3, where the third uncertainty is due to the branching fraction B(D+→K+K0Sπ0). The precision of this result is significantly improved compared to the previous measurement. This result also differs from most of theoretical predictions by about 4σ, which may help to improve the understanding of the dynamics behind.
Using 2.93 fb−1 of e+e− collision data collected with the BESIII detector at the center-of-mass energy of 3.773 GeV, we investigate the semileptonic decays D+→π+π−ℓ+νℓ (ℓ=e and μ). The D+→f0(500)μ+νμ decay is observed for the first time. By analyzing simultaneously the differential decay rates of D+→f0(500)μ+νμ and D+→f0(500)e+νe in different ℓ+νℓ four-momentum transfer intervals, the product of the relevant hadronic form factor ff0+(0) and the magnitude of the c→d Cabibbo-Kobayashi-Maskawa matrix element |Vcd| is determined to be ff0+(0)|Vcd|=0.0787±0.0060stat±0.0033syst for the first time. With the input of |Vcd| from the global fit in the standard model, we determine ff0+(0)=0.350±0.027stat±0.015syst. The absolute branching fractions of D+→f0(500)(π+π−)μ+νμ and D+→ρ0(π+π−)μ+νμ are determined as (0.72±0.13stat±0.10syst)×10−3 and (1.64±0.13stat±0.11syst)×10−3. Combining these results with those of previous BESIII measurements on their semielectronic counterparts from the same data sample, we test lepton flavor universality by measuring the branching fraction ratios BD+→ρ0μ+νμ/BD+→ρ0e+νe=0.88±0.10 and BD+→f0(500)μ+νμ/BD+→f0(500)e+νe = 1.14±0.28, which are compatible with the standard model expectation.
Using 2.93 fb−1 of e+e− collision data collected with the BESIII detector at the center-of-mass energy of 3.773 GeV, we investigate the semileptonic decays D+→π+π−ℓ+νℓ (ℓ=e and μ). The D+→f0(500)μ+νμ decay is observed for the first time. By analyzing simultaneously the differential decay rates of D+→f0(500)μ+νμ and D+→f0(500)e+νe in different ℓ+νℓ four-momentum transfer intervals, the product of the relevant hadronic form factor ff0+(0) and the magnitude of the c→d Cabibbo-Kobayashi-Maskawa matrix element |Vcd| is determined to be ff0+(0)|Vcd|=0.0787±0.0060stat±0.0033syst for the first time. With the input of |Vcd| from the global fit in the standard model, we determine ff0+(0)=0.350±0.027stat±0.015syst. The absolute branching fractions of D+→f0(500)(π+π−)μ+νμ and D+→ρ0(π+π−)μ+νμ are determined as (0.72±0.13stat±0.10syst)×10−3 and (1.64±0.13stat±0.11syst)×10−3. Combining these results with those of previous BESIII measurements on their semielectronic counterparts from the same data sample, we test lepton flavor universality by measuring the branching fraction ratios BD+→ρ0μ+νμ/BD+→ρ0e+νe = 0.88±0.10 and BD+→f0(500)μ+νμ/BD+→f0(500)e+νe = 1.14±0.28, which are compatible with the standard model expectation.
Using 7.33 fb−1 of e+e− collision data collected by the BESIII detector at center-of-mass energies between 4.128 and 4.226~GeV, we observe for the first time the decay D±s→ωπ±η with a statistical significance of 7.6σ. The measured branching fraction of this decay is (0.54±0.12±0.04)%, where the first uncertainty is statistical and the second is systematic.
We present cross sections for the reaction e+e−→K0SK0L at center-of-mass energies ranging from 3.51 GeV to 4.95 GeV using data samples collected in the BESIII experiment, corresponding to a total integrated luminosity of 26.5 fb−1. The ratio of neutral-to-charged kaon form factors at large momentum transfers (12 GeV2<Q2<25 GeV2) is determined to be 0.21±0.01, which indicates a small but significant effect of flavor-SU(3) breaking in the kaon wave function, and consequently excludes the possibility that flavor-SU(3) breaking is the primary reason for the strong experimental violation of the pQCD prediction |F(π±)|/|F(K±)|=f2π/f2K, where F(π±) and F(K±) are the form factors, and fπ and fK are the decay constants of charged pions and kaons, respectively. We also observe a significant signal for the charmless decay ψ(3770)→K0SK0L for the first time. Within a 1σ contour of the likelihood value, the the branching fraction for ψ(3770)→K0SK0L is determined to be B=(2.63+1.40−1.59)×10−5, and the relative phase between the continuum and ψ(3770) amplitudes is ϕ=(−0.39+0.05−0.10)π. The branching fraction is in good agreement with the S- and D-wave charmonia mixing scheme proposed in the interpretation of the "ρπ puzzle" between J/ψ and ψ(3686) decays.
A light scalar X0 or vector X1 particles have been introduced as a possible explanation for the (g−2)μ anomaly and dark matter phenomena.
Using (8.998±0.039)×109 $\jpsi$ events collected by the BESIII detector, we search for a light muon philic scalar X0 or vector X1 in the processes J/ψ→μ+μ−X0,1 with X0,1 invisible decays. No obvious signal is found, and the upper limits on the coupling g′0,1 between the muon and the X0,1 particles are set to be between 1.1×10−3 and 1.0×10−2 for the X0,1 mass in the range of 1<M(X0,1)<1000~MeV/c2 at 90% confidence level.
Using e+e− annihilation data corresponding to an integrated luminosity of 2.93 fb−1 taken at the center-of-mass energy s√=3.773~GeV with the BESIII detector, a joint amplitude analysis is performed on the decays D0→π+π−π+π− and D0→π+π−π0π0(non-η). The fit fractions of individual components are obtained, and large interferences among the dominant components of D0→a1(1260)π, D0→π(1300)π, D0→ρ(770)ρ(770) and D0→2(ππ)S are found in both channels. With the obtained amplitude model, the CP-even fractions of D0→π+π−π+π− and D0→π+π−π0π0(non-η) are determined to be (75.2±1.1stat.±1.5syst.)% and (68.9±1.5stat.±2.4syst.)%, respectively. The branching fractions of D0→π+π−π+π− and D0→π+π−π0π0(non-η) are measured to be (0.688±0.010stat.±0.010syst.)% and (0.951±0.025stat.±0.021syst.)%, respectively. The amplitude analysis provides an important model for binning strategy in the measurements of the strong phase parameters of D0→4π when used to determine the CKM angle γ(ϕ3) via the B−→DK− decay.
Using data samples with an integrated luminosity of 22.42 fb−1 collected by the BESIII detector operating at the BEPCII storage ring, we measure the cross sections of the $e^{+}e^{-}\rightarrow\etaJ/\psi$ process at center-of-mass energies from 3.808 to 4.951 GeV. Three structures are observed in the line shape of the measured cross sections. A maximum-likelihood fit with ψ(4040), two additional resonances, and a non-resonant component is performed. The mass and width of the first additional state are (4219.7±2.5±4.5)MeV/c2 and (80.7±4.4±1.4)MeV, respectively, consistent with the ψ(4230). For the second state, the mass and width are (4386±13±17)MeV/c2 and (177±32±13)MeV, respectively, consistent with the ψ(4360). The first uncertainties are statistical and the second ones are systematic. The statistical significance of ψ(4040) is 8.0σ and those for ψ(4230) and ψ(4360) are more than 10.0σ.
The cross sections of the 𝑒+𝑒−→𝜙𝜂′ process at center-of-mass energies from 3.508 to 4.951 GeV are measured with high precision using 26.1 fb−1 data collected with the BESIII detector operating at the BEPCII storage ring. The cross sections are of the order of a few picobarn and decrease as the center-of-mass energy increases as 𝑠−𝑛/2 with 𝑛=4.35±0.14. This result is in agreement with the Nambu-Jona-Lasinio model prediction of 𝑛=3.5±0.9. In addition, the charmless decay 𝜓(3770)→𝜙𝜂′ is searched for by fitting the measured cross sections, yet no significant signal is observed. The upper limit of ℬ(𝜓(3770)→𝜙𝜂′) at the 90% confidence level is determined to be 2.3×10−5.
Evidence for the singly Cabibbo suppressed decay Λ+c→pπ0 is reported for the first time with a statistical significance of 3.7σ based on 6.0 fb−1 of e+e− collision data collected at center-of-mass energies between 4.600 and 4.843 GeV with the BESIII detector at the BEPCII collider. The absolute branching fraction of Λ+c→pπ0 is measured to be (1.56+0.72−0.58±0.20)×10−4. Combining with the branching fraction of Λ+c→nπ+, (6.6±1.3)×10−4, the ratio of the branching fractions of Λ+c→nπ+ and Λ+c→pπ0 is calculated to be 3.2+2.2−1.2. As an important input for the theoretical models describing the decay mechanisms of charmed baryons, our result indicates that the non-factorizable contributions play an essential role and their interference with the factorizable contributions should not be significant. In addition, the absolute branching fraction of Λ+c→pη is measured to be (1.63±0.31stat±0.11syst)×10−3.