3,047 research outputs found

    Production of doubly-charged Δ\Delta baryon in e+ee^{+}e^{-} annihilation at energies from 2.3094 to 2.6464 GeV

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    The processes e+eΔ++Δˉe^{+}e^{-} \to \Delta^{++}\bar{\Delta}^{--} and e+eΔ++pˉπ+c.c.e^{+}e^{-}\to \Delta^{++} \bar{p} \pi^{-} + c.c. are studied for the first time with 179 pb1179~{\rm pb}^{-1} of e+ee^{+}e^{-} annihilation data collected with the BESIII detector at center-of-mass energies from 2.30942.3094 GeV to 2.64642.6464 GeV. No significant signal for the e+eΔ++Δˉe^{+}e^{-}\to \Delta^{++}\bar{\Delta}^{--} process is observed and the upper limit of the Born cross section is estimated at each energy point. For the process e+eΔ++pˉπ+c.c.e^{+}e^{-} \to \Delta^{++} \bar{p} \pi^{-} + c.c., a significant signal is observed at center-of-mass energies near 2.6454 GeV and the corresponding Born cross section is reported.Comment: 10 pages, 4 figure

    Surface waves and crustal structure on Mars

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    We detected surface waves from two meteorite impacts on Mars. By measuring group velocity dispersion along the impact-lander path, we obtained a direct constraint on crustal structure away from the InSight lander. The crust north of the equatorial dichotomy had a shear wave velocity of approximately 3.2 kilometers per second in the 5- to 30-kilometer depth range, with little depth variation. This implies a higher crustal density than inferred beneath the lander, suggesting either compositional differences or reduced porosity in the volcanic areas traversed by the surface waves. The lower velocities and the crustal layering observed beneath the landing site down to a 10-kilometer depth are not a global feature. Structural variations revealed by surface waves hold implications for models of the formation and thickness of the martian crust.D.K., S.C., D.G., J.C., C.D., A. K., S.C.S., N.D., and G.Z. were supported by the ETH+ funding scheme (ETH+02 19-1: “Planet Mars”). Marsquake Service operations at ETH Zürich were supported by ETH Research grant ETH-06 17-02. N.C.S. and V.L. were supported by NASA PSP grant no. 80NSSC18K1628. Q.H. and E.B. are funded by NASA grant 80NSSC18K1680. C.B. and J.L. were supported by NASA InSight PSP grant no. 80NSSC18K1679. S.D.K. was supported by NASA InSight PSP grant no. 80NSSC18K1623. P.L., E.B., M.D., H.S., E.S., M.W., Z.X., T.W., M.P., R.F.G. were supported by CNES and the Agence Nationale de la Recherche (ANR-19-CE31-0008-08 MAGIS) for SEIS operation and SEIS Science analysis. A.H., C.C. and W.T.P. were supported by the UKSA under grant nos. ST/R002096/1, ST/ W002523/1 and ST/V00638X/1. Numerical computations of McMC Approach 2 were performed on the S-CAPAD/DANTE platform (IPGP, France) and using the HPC resources of IDRIS under the allocation A0110413017 made by GENCI. A.H. was supported by the UKSA under grant nos. ST/R002096/1 and ST/W002523/1. F.N. was supported by InSight PSP 80NSSC18K1627. I.J.D. was supported by NASA InSight PSP grant no. 80NSSC20K0971. L.V.P. was funded by NASANNN12AA01C with subcontract JPL-1515835. The research was carried out in part by W.B.B., M.G. and M.P.P. at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration (80NM0018D0004)Peer reviewe

    Study of the decay J/ψϕπ0ηJ/\psi \to \phi \pi^{0}\eta

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    Based on (10.09±0.04)×109(10.09 \pm 0.04) \times 10^9 J/ψJ/\psi events collected with the BESIII detector operating at the BEPCII collider, a partial wave analysis of the decay J/ψϕπ0ηJ/\psi \to \phi \pi^{0}\eta is performed. We observe for the first time two new structures on the ϕη\phi\eta invariant mass distribution, with statistical significances of 24.0σ24.0\sigma and 16.9σ16.9\sigma; the first with JPCJ^{\rm PC} = 1+1^{+-}, mass M = (1911 ±\pm 6 (stat.) ±\pm 14 (sys.))~MeV/c2c^{2}, and width Γ=\Gamma = (149 ±\pm 12 (stat.) ±\pm 23 (sys.))~MeV, the second with JPCJ^{\rm PC} = 11^{--}, mass M = (1996 ±\pm 11 (stat.) ±\pm 30 (sys.))~MeV/c2c^{2}, and width Γ\Gamma = (148 ±\pm 16 (stat.) ±\pm 66 (sys.))~MeV. These measurements provide important input for the strangeonium spectrum. In addition, the f0(980)a0(980)0f_0(980)-a_0(980)^0 mixing signal in J/ψϕf0(980)ϕa0(980)0J/\psi \to \phi f_0(980) \to \phi a_0(980)^0 and the corresponding electromagnetic decay J/ψϕa0(980)0J/\psi \to \phi a_0(980)^0 are measured with improved precision, providing crucial information to understand the nature of a0(980)0a_0(980)^0 and f0(980)f_0(980)

    Study of Λc+→Λμ+νμ and test of lepton flavor universality with Λc+→Λℓ+νℓ decays

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    The study of the Cabibbo-favored semileptonic decay Λ+c → Λμ+νμ is reported using 4.5 fb−1 of e+e− annihilation data collected at center-of-mass energies ranging from 4.600 to 4.699 GeV. The branching fraction of the decay is measured to be B(Λ+c → Λμ+νμ) = (3.48 pm 0.14stat pm 0.10syst)%, 3 times more precise than the prior world average result. Tests of lepton flavor universality using Λ+c → Λl+νl (l = e, μ) decays are reported for the first time, based on measurements of the differential decay rates and the forward-backward asymmetries in separate four-momentum transfer regions. The results are compatible with Standard Model predictions. Furthermore, we improve the determination of the form-factor parameters in Λ+c → Λl+νl decays, which provide stringent tests and calibration for lattice quantum chromodynamics calculations

    Observation of the ψ(3686) decays into Σ+ Σ ̄ − ω and Σ+ Σ ̄ − φ

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    Based on (2712.4 pm 14.3) × 10^6 events recorded at the ψ(3686) nominal mass collected with the BESIII detector operating at the BEPCII collider, the ψ(3686)→Σ+Σ ̄−ω and Σ+Σ ̄−φ decays are observed for the first time with statistical significances of 13.8σ and 7.6σ, respectively. The corresponding branching fractions are measured to be B(ψ(3686) → Σ+Σ ̄−ω) = (1.89 pm 0.18 pm 0.21) × 10−5 and B(ψ(3686) → Σ+Σ ̄−φ) = (2.96 pm 0.54 pm 0.41) × 10−6, where the first uncertainties are statistical and the second systematic

    Search for the lepton flavor violating decay J/ψ → eμ

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    We present a search for the lepton flavor violating decay J/ψ → e±μ∓ using 8.998 × 109J/ψ events collected with the BESIII detector at the BEPCII e+e− storage ring. No excess of signal above background is observed; we therefore set an upper limit on the branching fraction of B(J/ψ → e±μ∓) < 4.5×10−9 at the 90% confidence level. Improving the previous best result by a factor of more than 30, this measurement places the most stringent limit to date on lepton flavor violation in the heavy quarkonium sector

    Amplitude analysis and branching fraction measurement of the decay D+ → K S 0 KS0 {\textrm{K}}_{\textrm{S}}^0 π + π 0 π 0

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    Abstract Using 2.93 fb −1 of e + e − collision data collected with the BESIII detector at the center-of-mass energy 3.773 GeV, we perform the first amplitude analysis of the decay D + → K S 0 KS0 {K}_S^0 π + π 0 π 0 and determine the relative magnitudes and phases of different intermediate processes. The absolute branching fraction of D + → K S 0 KS0 {K}_S^0 π + π 0 π 0 is measured to be (2.888 ± 0.058stat. ± 0.069syst. )%. The dominant intermediate processes are D + → K S 0 KS0 {K}_S^0 a 1(1260)+(→ ρ + π 0) and D + → K ¯ K \overline{K} *0 ρ +, with branching fractions of (8.66 ± 1.04stat. ± 1.39syst. ) × 10 −3 and (9.70 ± 0.81stat. ± 0.53syst. ) × 10 −3, respectively