1,170 research outputs found

    Amplitude Analysis of the Decays D0π+ππ+πD^0\to\pi^+\pi^-\pi^+\pi^- and π+ππ0π0\pi^+\pi^-\pi^0\pi^0

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    Using e+ee^+e^- annihilation data corresponding to an integrated luminosity of 2.93 fb1\rm fb^{-1} taken at the center-of-mass energy s=3.773\sqrt{s}=3.773~GeV with the BESIII detector, a joint amplitude analysis is performed on the decays D0π+ππ+πD^0\to\pi^+\pi^-\pi^+\pi^- and D0π+ππ0π0D^0\to\pi^+\pi^-\pi^0\pi^0(non-η\eta). The fit fractions of individual components are obtained, and large interferences among the dominant components of D0a1(1260)πD^{0}\to a_{1}(1260)\pi, D0π(1300)πD^{0}\to\pi(1300)\pi, D0ρ(770)ρ(770)D^{0}\to\rho(770)\rho(770) and D02(ππ)SD^{0}\to2(\pi\pi)_{S} are found in both channels. With the obtained amplitude model, the CPCP-even fractions of D0π+ππ+πD^0\to \pi^+\pi^-\pi^+\pi^- and D0π+ππ0π0D^0\to\pi^+\pi^-\pi^0\pi^0(non-η\eta) are determined to be (75.2±1.1stat.±1.5syst.)%(75.2\pm1.1_{\rm stat.}\pm1.5_{\rm syst.})\% and (68.9±1.5stat.±2.4syst.)%(68.9\pm1.5_{\rm stat.}\pm 2.4_{\rm syst.})\%, respectively. The branching fractions of D0π+ππ+πD^0\to \pi^+\pi^-\pi^+\pi^- and D0π+ππ0π0D^0\to\pi^+\pi^-\pi^0\pi^0(non-η\eta) are measured to be (0.688±0.010stat.±0.010syst.)%(0.688\pm0.010_{\rm stat.}\pm 0.010_{\rm syst.})\% and (0.951±0.025stat.±0.021syst.)%(0.951\pm0.025_{\rm stat.}\pm 0.021_{\rm syst.})\%, respectively. The amplitude analysis provides an important model for binning strategy in the measurements of the strong phase parameters of D04πD^0 \to 4\pi when used to determine the CKM angle γ(ϕ3)\gamma (\phi_{3}) via the BDKB^{-}\to D K^{-} decay

    Measurement of the Electromagnetic Transition Form-factors in the decays ηπ+πl+l\eta'\rightarrow\pi^+\pi^-l^+l^-

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    With a sample of (10087±44)×106(10087\pm44)\times10^{6} J/ψJ/\psi events accumulated with the BESIII detector, we analyze the decays ηπ+πl+l(l=e,\eta'\rightarrow\pi^+\pi^-l^+l^-(l=e, μ)\mu) via the process J/ψγηJ/\psi\rightarrow\gamma\eta'. The branching fractions are measured to be B(ηπ+πe+e)=(2.45±0.02(stat.)±0.08(syst.))×103\mathcal{B}(\eta'\rightarrow\pi^+\pi^-e^+e^-)=(2.45\pm0.02(\rm{stat.})\pm0.08(\rm{syst.})) \times10^{-3} and B(ηπ+πμ+μ)=(2.16±0.12(stat.)±0.06(syst.))×105\mathcal{B}(\eta'\rightarrow\pi^+\pi^-\mu^+\mu^-)=(2.16\pm0.12(\rm{stat.})\pm0.06(\rm{syst.}))\times10^{-5}, and the ratio is B(ηπ+πe+e)B(ηπ+πμ+μ)=113.4±0.9(stat.)±3.7(syst.)\frac{\mathcal{B}(\eta'\rightarrow\pi^{+}\pi^{-}e^{+}e^{-})}{\mathcal{B}(\eta'\rightarrow\pi^{+}\pi^{-}\mu^{+}\mu^{-})} = 113.4\pm0.9(\rm{stat.})\pm3.7(\rm{syst.}). In addition, by combining the ηπ+πe+e\eta'\rightarrow\pi^+\pi^-e^+e^- and ηπ+πμ+μ\eta'\rightarrow\pi^+\pi^-\mu^+\mu^- decays, the slope parameter of the electromagnetic transition form factor is measured to be bη=1.30±0.19 (GeV/c2)2b_{\eta'}=1.30\pm0.19\ (\mathrm{GeV}/c^{2})^{-2}, which is consistent with previous measurements from BESIII and theoretical predictions from the VMD model. The asymmetry in the angle between the π+π\pi^+\pi^- and l+ll^+l^- decay planes, which has the potential to reveal the CPCP-violation originating from an unconventional electric dipole transition, is also investigated. The asymmetry parameters are determined to be ACP(ηπ+πe+e)=(0.21±0.73(stat.)±0.01(syst.))%\mathcal{A}_{CP}(\eta'\rightarrow\pi^+\pi^-e^+e^-)=(-0.21\pm0.73(\rm{stat.})\pm0.01(\rm{syst.}))\% and ACP(ηπ+πμ+μ)=(0.62±4.71(stat.)±0.08(syst.))%\mathcal{A}_{CP}(\eta'\rightarrow\pi^+\pi^-\mu^+\mu^-)=(0.62\pm4.71(\rm{stat.})\pm0.08(\rm{syst.}))\%, implying that no evidence of CPCP-violation is observed at the present statistics. Finally, an axion-like particle is searched for via the decay ηπ+πa,ae+e\eta'\rightarrow\pi^+\pi^-a, a\rightarrow e^+e^-, and upper limits of the branching fractions are presented for the mass assumptions of the axion-like particle in the range of 0500 MeV/c20-500\ \mathrm{MeV}/c^{2}

    First Measurement of the Decay Asymmetry in the pure W-boson-exchange Decay Λc+Ξ0K+\Lambda_{c}^{+}\to\Xi^{0}K^{+}

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    Based on 4.4 fb14.4~\text{fb}^{-1} of e+ee^{+}e^{-} annihilation data collected at the center-of-mass energies between 4.604.60 and 4.70 GeV4.70~\text{GeV} with the BESIII detector at the BEPCII collider, the pure \textit{W}-boson-exchange decay Λc+Ξ0K+\Lambda_{c}^{+}\to\Xi^{0}K^{+} is studied with a full angular analysis. The corresponding decay asymmetry is measured for the first time to be αΞ0K+=0.01±0.16(stat.)±0.03(syst.)\alpha_{\Xi^{0}K^{+}}=0.01\pm0.16({\rm stat.})\pm0.03({\rm syst.}). This result reflects the non-interference effect between the SS- and PP-wave amplitudes. The phase shift between SS- and PP-wave amplitudes has two solutions, which are δpδs=1.55±0.25(stat.)±0.05(syst.) rad\delta_{p}-\delta_{s}=-1.55\pm0.25({\rm stat.})\pm0.05({\rm syst.})~\text{rad} or 1.59±0.25(stat.)±0.05(syst.) rad1.59\pm0.25({\rm stat.})\pm0.05({\rm syst.})~\text{rad}

    Improved measurements of the Dalitz decays η/ηγe+e\eta/\eta'\rightarrow\gamma e^{+}e^{-}

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    Based on a data sample of 10 billion J/ψJ/\psi events collected with the BESIII detector, improved measurements of the Dalitz decays η/ηγe+e\eta/\eta'\rightarrow\gamma e^+e^- are performed, where the η\eta and η\eta' are produced through the radiative decays J/ψγη/ηJ/\psi\rightarrow\gamma \eta/\eta'. The branching fractions of ηγe+e\eta\rightarrow\gamma e^+e^- and ηγe+e\eta'\rightarrow\gamma e^+e^- are measured to be (7.07±0.05±0.23)×103(7.07 \pm 0.05 \pm 0.23)\times10^{-3} and (4.83±0.07±0.14)×104(4.83\pm0.07\pm0.14)\times10^{-4}, respectively. Within the single pole model, the parameter of electromagnetic transition form factor for ηγe+e\eta\rightarrow\gamma e^+e^- is determined to be Λη=(0.749±0.027±0.007) GeV/c2\Lambda_{\eta}=(0.749 \pm 0.027 \pm 0.007)~ {\rm GeV}/c^{2}. Within the multi-pole model, we extract the electromagnetic transition form factors for ηγe+e\eta'\rightarrow\gamma e^+e^- to be Λη=(0.802±0.007±0.008) GeV/c2\Lambda_{\eta'} = (0.802 \pm 0.007\pm 0.008)~ {\rm GeV}/c^{2} and γη=(0.113±0.010±0.002) GeV/c2\gamma_{\eta'} = (0.113\pm0.010\pm0.002)~ {\rm GeV}/c^{2}. The results are consistent with both theoretical predictions and previous measurements. The characteristic sizes of the interaction regions for the η\eta and η\eta' are calculated to be (0.645±0.023±0.007) fm(0.645 \pm 0.023 \pm 0.007 )~ {\rm fm} and (0.596±0.005±0.006) fm(0.596 \pm 0.005 \pm 0.006)~ {\rm fm}, respectively. In addition, we search for the dark photon in η/ηγe+e\eta/\eta^\prime\rightarrow\gamma e^{+}e^{-}, and the upper limits of the branching fractions as a function of the dark photon are given at 90\% confidence level

    Study of e+eπ+ππ0e^{+}e^{-}\rightarrow\pi^{+}\pi^{-}\pi^{0} at s\sqrt{s} from 2.00 to 3.08 GeV at BESIII

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    With the data samples taken at center-of-mass energies from 2.00 to 3.08 GeV with the BESIII detector at the BEPCII collider, a partial wave analysis on the e+eπ+ππ0e^{+}e^{-}\rightarrow\pi^{+}\pi^{-}\pi^{0} process is performed. The Born cross sections for e+eπ+ππ0e^{+}e^{-}\rightarrow\pi^{+}\pi^{-}\pi^{0} and its intermediate processes e+eρπe^{+}e^{-}\rightarrow\rho\pi and ρ(1450)π\rho(1450)\pi are measured as functions of s\sqrt{s}. The results for e+eπ+ππ0e^{+}e^{-}\rightarrow\pi^{+}\pi^{-}\pi^{0} are consistent with previous results measured with the initial state radiation method within one standard deviation, and improve the uncertainty by a factor of ten. By fitting the line shapes of the Born cross sections for the e+eρπe^{+}e^{-}\rightarrow\rho\pi and ρ(1450)π\rho(1450)\pi, a structure with mass M=2119±11±15 MeV/c2M = 2119\pm11\pm15\ {\rm MeV}/c^2 and width Γ=69±30±5MeV\Gamma=69\pm30\pm5 {\rm MeV} is observed with a significance of 5.9σ5.9\sigma, where the first uncertainties are statistical and the second ones are systematic. This structure can be intepreteted as an excited ω\omega state

    Search for an invisible muon philic scalar X0X_{0} or vector X1X_{1} via J/ψμ+μ+invisibleJ/\psi\to\mu^+\mu^-+\rm{invisible} decay at BESIII

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    A light scalar X0X_{0} or vector X1X_{1} particles have been introduced as a possible explanation for the (g2)μ(g-2)_{\mu} anomaly and dark matter phenomena. Using (8.998±0.039)×109(8.998\pm 0.039)\times10^9 \jpsi events collected by the BESIII detector, we search for a light muon philic scalar X0X_{0} or vector X1X_{1} in the processes J/ψμ+μX0,1J/\psi\to\mu^+\mu^- X_{0,1} with X0,1X_{0,1} invisible decays. No obvious signal is found, and the upper limits on the coupling g0,1g_{0,1}' between the muon and the X0,1X_{0,1} particles are set to be between 1.1×1031.1\times10^{-3} and 1.0×1021.0\times10^{-2} for the X0,1X_{0,1} mass in the range of 1<M(X0,1)<10001<M(X_{0,1})<1000~MeV/c2/c^2 at 90%\% confidence level.Comment: 9 pages 7 figure

    First Observation of a Three-Resonance Structure in e+ee^+e^-\rightarrow{non-open} Charm Hadrons

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    We report the measurement of the cross sections for e+ee^+e^-\rightarrow{nOCH} (nOCH stands for non-open charm hadrons) with improved precision at center-of-mass energies from 3.645 to 3.871 GeV. We observe for the first time a three-resonance structure in the energy-dependent lineshape of the cross sections, which are R(3760)\mathcal R(3760), R(3780)\mathcal R(3780) and R(3810)\mathcal R(3810) with significances of 9.4σ9.4\sigma, 15.7σ15.7\sigma, and 9.8σ9.8\sigma, respectively. The R(3810)\mathcal R(3810) is observed for the first time. We found two solutions in analysis of the cross sections. For solution I [solution II], we measure the mass, the total width and the product of electronic width and nOCH decay branching fraction to be (3805.8±1.1±2.7)(3805.8 \pm 1.1 \pm 2.7) [(3805.8±1.1±2.7)(3805.8 \pm 1.1 \pm 2.7)] MeV/c2c^2, (11.6±2.6±1.9)(11.6 \pm 2.6 \pm 1.9) [(11.5±2.5±1.8)(11.5 \pm 2.5 \pm 1.8)] MeV, and (10.8±3.2±2.3)(10.8\pm 3.2\pm 2.3) [(11.0±2.9±2.4)(11.0\pm 2.9\pm 2.4)] eV for the R(3810)\mathcal R(3810), respectively. In addition, we measure the branching fractions B(R(3760){\mathcal B}({\mathcal R}(3760)\rightarrow{nOCH})=(24.5±13.4±27.4)%[(6.8±5.4±7.6)%])=(24.5 \pm 13.4 \pm 27.4)\% [(6.8 \pm 5.4 \pm 7.6)\%] for the first time, and B(R(3780){\mathcal B}(\mathcal R(3780)\rightarrow{nOCH})=(11.6±5.8±7.8)%[(10.3±4.5±6.9)%])=(11.6 \pm 5.8 \pm 7.8)\% [(10.3 \pm 4.5 \pm 6.9)\%]. Moreover, we determine the open-charm (OC) branching fraction B(R{\mathcal B}({\mathcal R}(3760)(3760)\rightarrow{OC})=(75.5±13.4±27.4)%[(93.2±5.4±7.6)%])=(75.5 \pm 13.4 \pm 27.4)\% [(93.2 \pm 5.4 \pm 7.6)\%], which supports the interpretation of R(3760)\mathcal R(3760) as an OC pair molecular state, but contained a simple four-quark state component. The first uncertainties are from fits to the cross sections, and the second are systematic

    A New Look at the Scalar Meson f0(500)f_0(500) via D+π+π+νD^+\to \pi^+\pi^-\ell^+\nu_\ell Decays

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    Using 2.93 fb12.93~\mathrm{fb}^{-1} of e+ee^+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+νD^+\to \pi^+\pi^- \ell^+\nu_\ell (=e\ell=e and μ\mu). The D+f0(500)μ+νμD^+\to f_0(500)\mu^+\nu_\mu decay is observed for the first time. By analyzing simultaneously the differential decay rates of D+f0(500)μ+νμD^+\to f_0(500) \mu^+\nu_\mu and D+f0(500)e+νeD^+\to f_0(500) e^+\nu_e in different +ν\ell^+\nu_\ell four-momentum transfer intervals, the product of the relevant hadronic form factor f+f0(0)f^{f_0}_{+}(0) and the magnitude of the cdc\to d Cabibbo-Kobayashi-Maskawa matrix element Vcd|V_{cd}| is determined to be f+f0(0)Vcd=0.0787±0.0060stat±0.0033systf_{+}^{f_0} (0)|V_{cd}|=0.0787\pm0.0060_{\rm stat}\pm0.0033_{\rm syst} for the first time. With the input of Vcd|V_{cd}| from the global fit in the standard model, we determine f+f0(0)=0.350±0.027stat±0.015systf_{+}^{f_0} (0)=0.350\pm0.027_{\rm stat}\pm0.015_{\rm syst}. The absolute branching fractions of D+f0(500)(π+π)μ+νμD^+\to f_0(500)_{(\pi^+\pi^-)}\mu^+\nu_\mu and D+ρ(π+π)0μ+νμD^+\to \rho^0_{(\pi^+\pi^-)} \mu^+\nu_\mu are determined as (0.72±0.13stat±0.10syst)×103(0.72\pm0.13_{\rm stat}\pm0.10_{\rm syst})\times10^{-3} and (1.64±0.13stat±0.11syst)×103(1.64\pm0.13_{\rm stat}\pm0.11_{\rm syst})\times 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{\mathcal B}_{D^+\to \rho^0 \mu^+\nu_\mu}/{\mathcal B}_{D^+\to \rho^0 e^+\nu_e}=0.88\pm0.10 and BD+f0(500)μ+νμ/BD+f0(500)e+νe=1.14±0.28{\mathcal B}_{D^+\to f_0(500) \mu^+\nu_\mu}/{\mathcal B}_{D^+\to f_0(500) e^+\nu_e}=1.14\pm0.28, which are compatible with the standard model expectation.Comment: Supplemental Materials added in this versio

    Updated measurements of the M1 transition ψ(3686)γηc(2S)\psi(3686) \to \gamma \eta_{c}(2S) with ηc(2S)KKˉπ\eta_{c}(2S) \to K \bar{K} \pi

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    Based on a data sample of (27.08±0.14)×108 ψ(3686)(27.08 \pm 0.14 ) \times 10^8~\psi(3686) events collected with the BESIII detector at the BEPCII collider, the M1 transition ψ(3686)γηc(2S)\psi(3686) \to \gamma \eta_{c}(2S) with ηc(2S)KKˉπ\eta_{c}(2S) \to K\bar{K}\pi is studied, where KKˉπK\bar{K}\pi is K+Kπ0K^{+} K^{-} \pi^{0} or KS0K±πK_{S}^{0}K^{\pm}\pi^{\mp}. The mass and width of the ηc(2S)\eta_{c}(2S) are measured to be (3637.8±0.8(stat)±0.2(syst))(3637.8 \pm 0.8 (\rm {stat}) \pm 0.2 (\rm {syst})) MeV/c2c^{2} and (10.5±1.7(stat)±3.5(syst))(10.5 \pm 1.7 (\rm {stat}) \pm 3.5 (\rm {syst})) MeV, respectively. The product branching fraction B(ψ(3686)γηc(2S))×B(ηc(2S)KKˉπ)\mathcal{B}\left(\psi(3686) \rightarrow \gamma \eta_{c}(2 S)\right) \times \mathcal{B}(\eta_{c}(2 S) \rightarrow K \bar{K} \pi) is determined to be (0.97±0.06(stat)±0.09(syst))×105(0.97 \pm 0.06 (\rm {stat}) \pm 0.09 (\rm {syst})) \times 10^{-5}. Using BR(ηc(2S)KKˉπ)=(1.860.49+0.68)%\mathcal{BR}(\eta_{c}(2S)\to K\bar{K}\pi)=(1.86^{+0.68}_{-0.49})\%, we obtain the branching fraction of the radiative transition to be BR(ψ(3686)γηc(2S))=(5.2±0.3(stat)±0.5(syst)1.4+1.9(extr))×104\mathcal{BR}(\psi(3686) \to \gamma \eta_{c}(2S)) = (5.2 \pm 0.3 (\rm {stat}) \pm 0.5 (\rm {syst}) ^{+1.9}_{-1.4} (extr)) \times 10^{-4}, where the third uncertainty is due to the quoted BR(ηc(2S)KKˉπ)\mathcal{BR}(\eta_{c}(2S) \to K\bar{K}\pi)

    Measurement of the e+eKS0KL0π0e^{+}e^{-} \to K_{S}^{0} K_{L}^{0} \pi^{0} cross sections from s=\sqrt{s}= 2.000 to 3.080 GeV

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    Based on e+ee^{+}e^{-} collision data collected at center-of-mass energies from 2.000 to 3.080 GeV by the BESIII detector at the BEPCII collider, a partial wave analysis is performed for the process e+eKS0KL0π0e^{+}e^{-}\to K_{S}^{0} K_{L}^{0} \pi^{0}. The results allow the Born cross sections of the process e+eKS0KL0π0e^{+}e^{-}\to K_{S}^{0} K_{L}^{0} \pi^{0}, as well as its subprocesses e+eK(892)0Kˉe^{+}e^{-}\to K^{*}(892)^{0}\bar{K} and K2(1430)0KˉK^{*}_{2}(1430)^{0}\bar{K} to be measured. The Born cross sections for e+eKS0KL0π0e^{+}e^{-}\to K_{S}^{0} K_{L}^{0}\pi^{0} are consistent with previous measurements by BaBar and SND, but with substantially improved precision. The Born cross section lineshape of the process e+eK(892)0Kˉe^{+}e^{-}\to K^{*}(892)^{0}\bar{K} is consistent with a vector meson state around 2.2 GeV with a statistical significance of 3.2σ\sigma. A Breit-Wigner fit determines its mass as MY=(2164.1±9.6±3.1) MeV/c2M_Y=(2164.1\pm9.6\pm3.1)~{\rm{MeV}}/c^{2} and its width as ΓY=(32.4±21.1±1.5) MeV\Gamma_{Y}=(32.4\pm21.1\pm1.5)~\rm{MeV}, where the first uncertainties are statistical and the second ones are systematic, respectively
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