We study the e^{+}e^{-}→γωJ/ψ process using 11.6 fb^{-1} e^{+}e^{-} annihilation data taken at center-of-mass energies from sqrts=4.008 GeV to 4.600 GeV with the BESIII detector at the BEPCII ...storage ring. The X(3872) resonance is observed for the first time in the ωJ/ψ system with a significance of more than 5σ. The relative decay ratio of X(3872)→ωJ/ψ and π^{+}π^{-}J/ψ is measured to be R=1.6_{-0.3}^{+0.4}±0.2, where the first uncertainty is statistical and the second systematic (the same hereafter). The sqrts-dependent cross section of e^{+}e^{-}→γX(3872) is also measured and investigated, and it can be described by a single Breit-Wigner resonance, referred to as the Y(4200), with a mass of 4200.6_{-13.3}^{+7.9}±3.0 MeV/c^{2} and a width of 115_{-26}^{+38}±12 MeV. In addition, to describe the ωJ/ψ mass distribution above 3.9 GeV/c^{2}, we need at least one additional Breit-Wigner resonance, labeled as X(3915), in the fit. The mass and width of the X(3915) are determined. The resonant parameters of the X(3915) agree with those of the Y(3940) in B→KωJ/ψ and of the X(3915) in γγ→ωJ/ψ observed by the Belle and BABAR experiments within errors.
Using a data sample corresponding to an integrated luminosity of 2.93 fb−1 taken at a center-of-mass energy of 3.773 GeV with the BESIII detector operated at the BEPCII collider, we perform an ...analysis of the semileptonic decays D0(+)→π−(0)μ+νμ. The branching fractions of D0→π−μ+νμ and D+→π0μ+νμ are measured to be (0.272±0.008stat±0.006syst)% and (0.350±0.011stat±0.010syst)%, respectively, where the former is of much improved precision compared to previous results and the latter is determined for the first time. Using these results along with previous BESIII measurements of D0(+)→π−(0)e+νe, we calculate the branching fraction ratios to be R0≡BD0→π−μ+νμ/BD0→π−e+νe=0.922±0.030stat±0.022syst and R+≡BD+→π0μ+νμ/BD+→π0e+νe=0.964±0.037stat±0.026syst, which are compatible with the theoretical expectation of lepton flavor universality within 1.7σ and 0.5σ, respectively. We also examine the branching fraction ratios in different four-momentum transfer square regions, and find no significant deviations from the standard model predictions.
Cross sections of the process e+e− → π0 π0 J / ψ at center-of-mass energies between 3.808 and 4.600 GeV are measured with high precision by using 12.4 fb−1 of data samples collected with the BESIII ...detector operating at the BEPCII collider facility. A fit to the measured energy-dependent cross sections confirms the existence of the charmoniumlike state Y ( 4220 ) . The mass and width of the Y ( 4220 ) are determined to be ( 4220.4 ± 2.4 ± 2.3 ) MeV / c2 and ( 46.2 ± 4.7 ± 2.1 ) MeV , respectively, where the first uncertainties are statistical and the second systematic. The mass and width are consistent with those measured in the process e+e− → π+π− J / ψ. The neutral charmonium-like state Zc ( 3900 )0 is observed prominently in the π 0 J / ψ invariant-mass spectrum, and, for the first time, an amplitude analysis is performed to study its properties. The spin-parity of Zc ( 3900 )0 is determined to be JP = 1+, and the pole position is ( 3893.1 ± 2.2 ± 3.0 ) − i ( 22.2 ± 2.6 ± 7.0 ) MeV / c2, which is consistent with previous studies of electrically charged Zc ( 3900 )±. In addition, cross sections of e+e− → π0Zc ( 3900 )0 → π0π0 J / ψ are extracted, and the corresponding line shape is found to agree with that of the Y ( 4220 ).
Particles directly produced at electron–positron colliders, such as the J/ψ meson, decay with relatively high probability into a baryon–antibaryon pair1. For spin-1/2 baryons, the pair can have the ...same or opposite helicites. A non-vanishing phase ΔΦ between the transition amplitudes to these helicity states results in a transverse polarization of the baryons2–4. From the joint angular distribution of the decay products of the baryons, this phase as well as the parameters characterizing the baryon and the antibaryon decays can be determined. Here, we report the measurement of ΔΦ = 42.4 ± 0.6 ± 0.5° using Λ → pπ− and Λ¯→p¯π+,n¯π0 decays at BESIII. We find a value for the Λ → pπ− decay parameter of α− = 0.750 ± 0.009 ± 0.004, 17 ± 3% higher than the current world average, which has been used as input for all Λ polarization measurements since 19785,6. For Λ¯→p¯π+ we find α+ = −0.758 ± 0.010 ± 0.007, giving ACP = (α− + α+)/(α− − α+) = −0.006 ± 0.012 ± 0.007, a precise direct test of charge–parity symmetry (CP) violation in Λ decays.The decay asymmetry and helicity phase of polarized baryon–antibaryon pairs are measured at the BESIII experiment, testing charge–parity symmetry and revealing a discrepancy of the Λ → pπ− decay asymmetry with respect to the current world average.
The exclusive process e+e−→ΛΛ¯, with Λ→pπ− and Λ¯→p¯π+, has been studied at s=2.396 GeV for measurement of the timelike Λ electric and magnetic form factors, GE and GM. A data sample, corresponding ...to an integrated luminosity of 66.9 pb−1, was collected with the BESIII detector for this purpose. A multidimensional analysis with a complete decomposition of the spin structure of the reaction enables a determination of the modulus of the ratio R=|GE/GM| and, for the first time for any baryon, the relative phase ΔΦ=ΦE−ΦM. The resulting values are R=0.96±0.14(stat)±0.02(syst) and ΔΦ=37°±12°(stat)±6°(syst), respectively. These are obtained using the recently established and most precise value of the asymmetry parameter αΛ=0.750±0.010 measured by BESIII. In addition, the cross section is measured with unprecedented precision to be σ=118.7±5.3(stat)±5.1(syst) pb, which corresponds to an effective form factor of |G|=0.123±0.003(stat)±0.003(syst). The contribution from two-photon exchange is found to be negligible. Our result enables the first complete determination of baryon timelike electromagnetic form factors.
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•LSP was combined with LC to realize the hybrid additive remanufacturing.•MLSPT generated compressive residual stress in surface layer of LCed coating.•The wear resistance of LCed ...coating was obviously improved by MLSPT.•MLSPT-induced wear mechanisms of LCed coating were proposed.
H13 tool steel is often damaged by wear, erosion and thermal fatigue, and laser hybrid additive remanufacturing is an effective method to repair damaged locations to extend their service lives. In this study, the Fe-based layer with Ni-based transitional layer is fabricated in the surface layer of H13 tool steel by laser cladding (LC). Subsequently, massive laser shock peening treatment (MLSPT) is applied to improve the mechanical properties of the LCed coating. Meanwhile, the effects of MLSPT on the residual stress, micro-hardness, microstructure and wear performance are systematically investigated. Results indicate that after MLSPT, the residual stress is transformed from tensile to compressive state, and high-density dislocations and a large number of mechanical twins are generated in the coating. MLSPT-induced surface nanocrystallization contributes to the improvement of micro-hardness and wear resistance of the LCed Ni25/Fe104 coating, and the grain refinement and wear property enhancement mechanisms are also revealed.
Topological semimetals with different types of band crossings provide a rich platform to realize novel fermionic excitations, known as topological fermions. In particular, some fermionic excitations ...can be direct analogs of elementary particles in quantum field theory when both obey the same laws of physics in the low-energy limit. Examples include Dirac and Weyl fermions, whose solid-state realizations have provided new insights into long-sought phenomena in high-energy physics. Recently, theorists predicted new types of fermionic excitations in condensed-matter systems without any high-energy counterpart, and their existence is protected by crystalline symmetries. By studying the topology of the electronic structure in PdBiSe using density functional theory calculations and bulk-sensitive soft x-ray angle-resolved photoemission spectroscopy, we demonstrate a coexistence of four different types of topological fermions: Weyl, Rarita-Schwinger-Weyl, double class-II three-component, and charge-2 fourfold fermions. Our discovery provides a remarkable platform to realize multiple fermions in a single solid, charting the way forward to studies of their potentially exotic properties as well as their interplay.
Using a data sample corresponding to an integrated luminosity of 2.93 fb−1 recorded by the BESIII detector at a center-of-mass energy of 3.773 GeV, we present an analysis of the decays D0 → π−π0e+νe ...and D+ → π−π+e+νe. By performing a partial wave analysis, the π+π− S-wave contribution to D+ → π−π+e+νe is observed to be (25.7 ± 1.6 ± 1.1)% with a statistical significance greater than 10σ, besides the dominant P-wave contribution. This is the first observation of the S-wave contribution. We measure the branching fractions B(D0 → ρ−e+νe) = (1.445 ± 0.058 ± 0.039) × 10−3, B(D+ → ρ0e+νe) = (1.860 ± 0.070 ± 0.061) × 10−3, and B(D+ → f0(500)e+νe, f0(500) → π+π−) = (6.30 ± 0.43 ± 0.32) × 10−4. An upper limit of B(D+ → f0(980)e+νe, f0(980) → π+π−) < 2.8 × 10−5 is set at the 90% confidence level. We also obtain the hadronic form factor ratios of D → ρe+νe at q2 = 0 assuming the single-pole dominance parametrization: rV = {V(0)/A1(0)} = 1.695 ± 0.083 ± 0.051, r2 = {A2(0)/A1(0)} = 0.845 ± 0.056 ± 0.039.
EIF5A2, eukaryotic translation initiation factor 5A2, is associated with several human cancers. In this study, we investigated the role of EIF5A2 in the metastatic potential of localised invasive ...bladder cancer (BC) and its underlying molecular mechanisms were explored.
The expression pattern of EIF5A2 in localised invasive BC was determined by immunohistochemistry. In addition, the function of EIF5A2 in BC and its underlying mechanisms were elucidated with a series of in vitro and in vivo assays.
Overexpression of EIF5A2 was an independent predictor for poor metastasis-free survival of localised invasive BC patients treated with radical cystectomy. Knockdown of EIF5A2 inhibited BC cell migratory and invasive capacities in vitro and metastatic potential in vivo and reversed epithelial-mesenchymal transition (EMT), whereas overexpression of EIF5A2 promoted BC cells motility and invasiveness in vitro and metastatic potential in vivo and induced EMT. In addition, we found that EIF5A2 might activate TGF-β1 expression to induce EMT and drive aggressiveness in BC cells. EIF5A2 stabilized STAT3 and stimulated nuclear localisation of STAT3, which resulted in increasing enrichment of STAT3 onto TGF-β1 promoter to enhance the transcription of TGF-β1.
EIF5A2 overexpression predicts tumour metastatic potential in patients with localised invasive BC treated with radical cystectomy. Furthermore, EIF5A2 elevated TGF-β1 expression through STAT3 to induce EMT and promotes aggressiveness in BC.
Using e+e− annihilation data corresponding to an integrated luminosity of 3.19 fb−1 collected at a center-of-mass energy of 4.178 GeV with the BESIII detector, we measure the absolute branching ...fractions BDs+→ηe+νe = (2.323±0.063stat ± 0.063syst)% and BDs+→η′e+νe = (0.824±0.073stat ± 0.027syst)% via a tagged analysis technique, where one Ds is fully reconstructed in a hadronic mode. Combining these measurements with previous BESIII measurements of BD+→η(′)e+νe, the η−η′ mixing angle in the quark flavor basis is determined to be ϕP = (40.1±2.1stat ± 0.7syst)°. From the first measurements of the dynamics of Ds+ → η(′)e+νe decays, the products of the hadronic form factors f+η(′)(0) and the Cabibbo-Kobayashi-Maskawa matrix element |Vcs| are determined with different form factor parametrizations. For the two-parameter series expansion, the results are f+η(0)|Vcs| = 0.4455±0.0053stat±0.0044syst and f+η′(0)|Vcs|=0.477±0.049stat±0.011syst.
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