| 1531. |
- Ablikim, M., et al.
(författare)
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Observation of e(+)e(-) -> gamma X(3872) at BESIII
- 2014
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Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 112:9, s. 092001-
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Tidskriftsartikel (refereegranskat)abstract
- With data samples collected with the BESIII detector operating at the BEPCII storage ring at center-of-mass energies from 4.009 to 4.420 GeV, the process e(+)e(-) -> gamma X(3872) is observed for the first time with a statistical significance of 6.3 sigma. The measured mass of the X(3872) is (3871.9 +/- 0.7(stat) +/- 0.2(syst)) MeV/c(2), in agreement with previous measurements. Measurements of the product of the cross section sigma[e(+)e(-) -> gamma X(3872)] and the branching fraction B [X(3872) -> pi(+)pi(-)J/psi] at center-of-mass energies 4.009, 4.229, 4.260, and 4.360 GeV are reported. Our measurements are consistent with expectations for the radiative transition process Y(4260) -> gamma X(3872).
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| 1532. |
- Ablikim, M., et al.
(författare)
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Observation of e(+)e(-) -> omega chi(c1,2) near root s=4.42 and 4.6 GeV
- 2016
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Ingår i: Physical Review D. - 1550-7998 .- 1550-2368. ; 93:1
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Tidskriftsartikel (refereegranskat)abstract
- Based on data samples collected with the BESIII detector operating at the BEPCII storage ring at center-of-mass energies root s > 4.4 GeV, the processes e(+)e(-) -> omega chi(c1,2) are observed for the first time. With an integrated luminosity of 1074 pb(-1) near root s = 4.42 GeV, a significant omega chi(c2) signal is found, and the cross section is measured to be (20.9 +/- 3.2 +/- 2.5) pb. With 567 pb(-1) near root s = 4.6 GeV, a clear omega chi(c2) signal is seen, and the cross section is measured to be (9.5 +/- 2.1 +/- 1.3) pb, while evidence is found for an omega chi(c2) signal. The first errors are statistical, and the second are systematic. Due to low luminosity or low cross section at other energies, no significant signals are observed. In the omega chi(c2) cross section, an enhancement is seen around root s = 4.42 GeV. Fitting the cross section with a coherent sum of the psi(4415) Breit-Wigner function and a phase-space term, the branching fraction B(psi(4415) -> omega chi(c2)) is obtained to be of the order of 10(-3).
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| 1533. |
- Ablikim, M., et al.
(författare)
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Observation of e(+)e(-) -> phi chi(c1) and phi chi(c2) at root s=4.600 GeV
- 2018
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Ingår i: Physical Review D. - : AMER PHYSICAL SOC. - 2470-0010 .- 2470-0029. ; 97:3
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Tidskriftsartikel (refereegranskat)abstract
- Using a data sample collected with the BESIII detector operating at the BEPCII storage ring at a center-of-mass energy of root s = 4.600 GeV, we search for the production of e(+)e(-) -> phi chi(c0,1,2). A search is also performed for the charmonium-like state X(4140) in the radiative transition e(+)e(-) -> gamma X(4140) with X(4140) subsequently decaying into phi J/psi The processes e(+)e(-) -> phi chi(c1) and phi chi(c2) are observed for the first time, each with a statistical significance of more than 10 sigma, and the Born cross sections are measured to be (4.2(-1.0)(+1.7) +/- 0.3) and (6.7(-1.7)(+3.4) +/- 0.5) pb, respectively, where the first uncertainties are statistical and the second systematic. No significant signals are observed for e(+)e(-) -> phi chi(c0) and e(+)e(-) -> gamma X(4140) and upper limits on the Born cross sections at 90% C. L. are provided at root s = 4.600 GeV.
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| 1534. |
- Ablikim, M., et al.
(författare)
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Observation of e(+)e(-) -> pi(0)pi(0)h(c) and a Neutral Charmoniumlike Structure Z(c)(4020)(0)
- 2014
-
Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 113:21, s. 212002-
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Tidskriftsartikel (refereegranskat)abstract
- Using data collected with the BESIII detector operating at the Beijing Electron Positron Collider at center-of-mass energies of root s = 4.23, 4.26, and 4.36 GeV, we observe e(+)e(-) -> pi(0)pi(0)h(c) for the first time. The Born cross sections are measured and found to be about half of those of e(+)e(-) -> pi(+)pi(-)h(c) within less than 2 sigma. In the pi(0)h(c) mass spectrum, a structure at 4.02 GeV/c(2) is found. It is most likely to be the neutral isospin partner of the Z(c)(4020)(+/-) observed in the process of e(+)e(-) -> pi(+)pi(-)h(c) being found. A fit to the pi(0)h(c) invariant mass spectrum, with the width of the Z(c)(4020)(0) fixed to that of its charged isospin partner and possible interferences with non-Z(c)(4020)(0) amplitudes neglected, gives a mass of (4023.9 +/- 2.2 +/- 3.8) MeV/c(2) for the Z(c)(4020)(0), where the first error is statistical and the second systematic.
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| 1535. |
- Ablikim, M., et al.
(författare)
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Observation of e(+)e(-) -> pi(+) pi(-)psi(3770) and D-1(2420)(0)(D)over-bar(0) + c.c
- 2019
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Ingår i: Physical Review D. - : AMER PHYSICAL SOC. - 2470-0010 .- 2470-0029. ; 100:3
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Tidskriftsartikel (refereegranskat)abstract
- Several intermediate states of the reaction channels e(+)e(-) -> pi(+)pi(-) D-0(D) over bar (0) and e(+)e(-) -> pi(+)pi-D+D- are studied using the data samples collected with the BESIII detector at center-of-mass energies above 4.08 GeV. For the first time in this final state, a psi(3770) signal is seen in the DD invariant mass spectrum, with a statistical significance of 5.2 sigma at root s = 4.42 GeV. There is also evidence for this resonance at root s = 4.26 and 4.36 GeV with statistical significance of 3.2 sigma and 3.3 sigma, respectively. In addition, the Born cross section of e(+)e(-) ->pi(+)pi(-)psi(3770) is measured. The proposed heavy-quark-spin-symmetry partner of the X(3872), the state X-2(4013), is also searched for in the D (D) over bar invariant mass spectra. No obvious signal is found. The upper limit of the Born cross section of the process e(+)e(-) -> rho X-0(2)(4013) combined with the branching fraction is measured. Also, the processes e(+)e(-) -> D-1(2420)(D) over bar c.c. are investigated. The neutral mode with D-1(2420)(0) -> D-0 pi(+)pi(-) is reported with statistical significance of 7.4 sigma at root s = 4.42 GeV for the first time, and evidence with statistical significance of 3.2 sigma and 3.3 sigma at root s = 4.36 and 4.60 GeV is seen, respectively. No evident signal for the process e(+)e(-) -> D-1(2420)(0)(D) over bar (0) + c.c., D-1(2420)(0) -> D*(+)pi(-) is reported. Evidence for e(+)e(-) -> D-1(2420)+D- + c.c., D-1(2420)(+) -> D+pi(+)pi(-) is reported with statistical significance of 3.1 sigma and 3.0 sigma at root s. = 4.36 and 4.42 GeV, respectively.
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| 1536. |
- Ablikim, M., et al.
(författare)
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Observation of e(+) e(-) -> pp(p)over-bar(p)over-bar pi(-) +c.c (*)
- 2023
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Ingår i: Chinese Physics C. - : IOP Publishing. - 1674-1137 .- 2058-6132. ; 47:4
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Tidskriftsartikel (refereegranskat)abstract
- Using data taken at 29 center-of-mass energies between 4.16 and 4.70 GeV with the BESIII detector at the Beijing Electron Positron Collider corresponding to a total integrated luminosity of approximately 18.8, the process e(+)e(-) -> pp (p) over bar(p) over bar pi(-) +c.c is observed for the first time with a statistical significance of 11.5 sigma. The average Born cross sections in the energy ranges of (4.160, 4.380) GeV, (4.400, 4.600) GeV and (4.610, 4.700) GeV are measured to be (21.5 +/- 5.7 +/- 1.2) fb, fb and (59.0 +/- 9.4 +/- 3.2)fb, respectively, where the first uncertainties are statistical and the second are systematic. The line shapes of the (p) over bar(n) over bar and pp pi(-) invariant mass spectra are consistent with phase space distributions, indicating that no hexaquark or di-baryon state is observed.
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| 1537. |
- Ablikim, M., et al.
(författare)
-
Observation of $e^+e^− → γX$(3872) at BESIII
- 2014
-
Ingår i: PHYSICAL REVIEW LETTERS. - 1079-7114. ; 112:9
-
Tidskriftsartikel (refereegranskat)abstract
- With data samples collected with the BESIII detector operating at the BEPCII storage ring at center-of-mass energies from 4.009 to 4.420 GeV, the process $e^{+} e^{-} \to \gamma X(3872)$ is observed for the first time with a statistical significance of $6.3\sigma$. The measured mass of the $X(3872)$ is ($3871.9\pm 0.7_{\rm stat.}\pm 0.2_{\rm sys.}$) MeV/$c^2$, in agreement with previous measurements. Measurements of the product of the cross section $\sigma[e^{+} e^{-} \to \gamma X(3872)]$ and the branching fraction $\mathcal{B}[X(3872) \to \pi^{+} \pi^{-} J/\psi]$ at center-of-mass energies 4.009, 4.229, 4.260, and 4.360 GeV are reported. Our measurements are consistent with expectations for the radiative transition process $Y(4260) \to \gamma X(3872)$.
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| 1538. |
- Ablikim, M., et al.
(författare)
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Observation of electromagnetic Dalitz decays J/\psi \to P e^+e^-
- 2014
-
Ingår i: PHYSICAL REVIEW D. - 2470-0010 .- 1550-7998 .- 1550-2368. ; 89:9
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Tidskriftsartikel (refereegranskat)abstract
- Based on a sample of (225.3\pm2.8)\times 10^{6} J/\psi events collected with the BESIII detector, the electromagnetic Dalitz decays of J/\psi \to P e^+e^-(P=\eta'/\eta/\pi^0) are studied. By reconstructing the pseudoscalar mesons in various decay modes, the decays J/\psi \to \eta' e^+e^-, J/\psi \to \eta e^+e^- and J/\psi \to \pi^0 e^+e^- are observed for the first time. The branching fractions are determined to be \mathcal{B}(J/\psi\to \eta' e^+e^-) = (5.81\pm0.16\pm0.31)\times10^{-5}, \mathcal{B}(J/\psi\to \eta e^+e^-) = (1.16\pm0.07\pm0.06)\times10^{-5}, and \mathcal{B}(J/\psi\to \pi^0 e^+e^-)=(7.56\pm1.32\pm0.50)\times10^{-7}, where the first errors are statistical and the second ones systematic.
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| 1539. |
- Ablikim, M., et al.
(författare)
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Observation of eta(c)(2S) -> 3(pi(+)pi(-)) and measurements of chi(cJ) -> 3(pi(+)pi(-)) in psi (3686) radiative transitions
- 2022
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Ingår i: Physical Review D. - : American Physical Society. - 2470-0010 .- 2470-0029. ; 106:3
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Tidskriftsartikel (refereegranskat)abstract
- The hadronic decay eta(c) (2S) -> 3 (pi(+)pi(-)) is observed with a statistical significance of 9.3 standard deviations using (448.1 +/- 2.9) x 10(6) psi(3686) events collected by the BESIII detector at the BEPCII collider. The measured mass and width of eta(c) (2S) are (3643.4 +/- 2.3 (stat) +/- 4.4 (syst)) MeV/c(2) and 19.8 +/- 3.9 (stat) +/- 3.1 (syst)) MeV, respectively, which are consistent with the world average values within two standard deviations. The product branching fraction B[psi(3686) -> gamma eta(c) (2S)] X B[eta(c)(2S) -> 3(pi(+)pi(-))] is measured to be (9.2 +/- 1.0(stat)+/- 1.2(syst)10(-6). Using B[psi(3686) -> gamma eta(c) (2S)] = (7.0(-2.5)(+3.4)) x 10(-4), we obtain B[eta(c)(2S) -> 3 (pi(+)pi(-))] = (1.31 +/- 0.15 (stat) +/- 0.17 (syst) ((+0.64)(-0.47)) (extr))x 10(-2), where the third uncertainty is from B [psi(3686)->gamma eta(c)(2S)]. We also measure the chi(cJ)-> 3(pi(+)pi(-)) (J = 0, 1, 2) decays via psi' -> gamma chi(cJ) transitions. The branching fractions are B[chi(c0) 3(pi(+)pi(-))] = (2.080 +/- 0.006(stat)+/- 0.068(syst))x10(-2), B [chi c(2) -> (pi(+)pi(-))]=1.092 x 0.004(stat)+/- 0.035(syst))x10(-2), and B[chi(C2) -> 3 (pi(+)pi(-))] = 1.565 +/- 0.005 (stat) +/- 0.048 (syst)) x 10(-2).
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| 1540. |
- Ablikim, M., et al.
(författare)
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Observation of eta(c) -> omega omega in J/psi -> gamma omega omega
- 2019
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Ingår i: Physical Review D. - : AMER PHYSICAL SOC. - 2470-0010 .- 2470-0029. ; 100:5
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Tidskriftsartikel (refereegranskat)abstract
- Using a sample of (1310.6 +/- 7.0) x 10(6) J/psi events recorded with the Beijing Spectrometer III detector at the Beijing Electron Positron Collider II, we report the observation of the decay of the (1(1)S(0)) charmonium state eta(c) into a pair of omega mesons in the process J/psi -> gamma omega omega. The branching fraction is measured for the first time to be B(eta(c) -> omega omega) = (2.88 +/- 0.10 +/- 0.46 +/- 0.68) x 10(-3), where the first uncertainty is statistical, the second systematic, and the third is from the uncertainty of B(J/psi -> gamma eta(c)). The mass and width of the eta(c) are determined as M = (2985.9 +/- 0.7 +/- 2.1) MeV/c(2) and Gamma = (33.8 +/- 1.6 +/- 4.1) MeV.
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