| 21. |
- 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
-
Ingår i: Physical Review D. - : AMER PHYSICAL SOC. - 2470-0010 .- 2470-0029. ; 97:3
-
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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| 22. |
- Ablikim, M., et al.
(författare)
-
Observation of h(1)(1380) in the J/psi -> eta ' K(K)over-bar pi decay
- 2018
-
Ingår i: Physical Review D. - : AMER PHYSICAL SOC. - 2470-0010 .- 2470-0029. ; 98:7
-
Tidskriftsartikel (refereegranskat)abstract
- Using 1.31 x 10(9) J/psi events collected by the BESIII detector at the BEPCII e(+)e(-) collider, we report the first observation of the h(1)(1380) in J/psi -> eta'h(1)(1380) with a significance of more than ten standard deviations. The mass and width of the possible axial-vector strangeonium candidate h(1)(1380) are measured to be M = (1423.2 +/- 2.1 +/- 7.3) MeV/c(2) and Gamma = (90.3 +/- 9.8 +/- 17.5) MeV. The product branching fractions, assuming no interference, are determined to be B(J/psi -> eta'h(1)(1380)) x B(h(1)(1380) -> K*(892)K-+(-)+c.c.) = (1.51 +/- 0.09 +/- 0.21) x 10(-4) in eta'K+K-pi(0) mode and B(J/psi -> eta'h(1)(1380)) x B(h(1)(1380) -> K*(892)(K) over bar +c.c.) =(2.16 +/- 0.12 +/- 0.29) x 10(-4) in eta'(KSK +/-)-K-0 pi(-/+) mode. The first uncertainties are statistical and the second are systematic. Isospin symmetry violation is observed in the decays h(1)(1380) K*(892)K-+(-) + c.c. and h(1)(1380) -> K*(892)(0)(K) over bar (0) + c.c.. Based on the measured h(1)(1380) mass, the mixing angle between the states h(1)(1170) and h(1)(1380) is determined to be (35.9 +/- 2.6)degrees, consistent with theoretical expectations.
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| 23. |
- Ablikim, M., et al.
(författare)
-
Observation of psi(3686) -> eta ' e(+)e(-)
- 2018
-
Ingår i: Physics Letters B. - : ELSEVIER SCIENCE BV. - 0370-2693 .- 1873-2445. ; 783, s. 452-458
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Tidskriftsartikel (refereegranskat)abstract
- Using a data sample of 448.1 x 10(6) psi(3686) events collected with the BESIII detector at the BEPCII collider, we report the first observation of the electromagnetic Dalitz decay psi(3686) -> eta'e(+)e(-), with significances of 7.0 sigma and 6.3 sigma when reconstructing the eta' meson via its decay modes eta' -> gamma pi(+)pi(-) and eta' -> pi(+)pi(-) eta (eta -> gamma gamma), respectively. The weighted average branching fraction is determined to be B(psi(3686) -> eta'e(+)e(-)) = (1.90 +/- 0.25 +/- 0.11) x 10(-6), where the first uncertainty is statistical and the second systematic.
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| 24. |
- Ablikim, M., et al.
(författare)
-
Observation of the Semileptonic Decay D-0 -> a(0)(980)(-)e(+)nu(e) and Evidence for D+ -> a(0)(980)(0)e(+)nu(e)
- 2018
-
Ingår i: Physical Review Letters. - : AMER PHYSICAL SOC. - 0031-9007 .- 1079-7114. ; 121:8
-
Tidskriftsartikel (refereegranskat)abstract
- Using an e(+)e(-) collision data sample of 2.93 fb(-1) collected at a center-of-mass energy of 3.773 GeV by the BESIII detector at BEPCII, we report the observation of D-0 -> a(0)(980)(-)e(+)nu(e) and evidence for D+ -> a(0)(980)(0)e(+)nu(e) with significances of 6.4 sigma and 2.9 sigma, respectively. The absolute branching fractions are determined to be B(D-0 -> a(0)(980)(-)e(+)nu(e)) x B(a(0)(980)(-) -> eta pi(-)) = [1.33(-0.29)(+0.33)(stat) +/- 0.09(syst)] x 10(-4) and B(D+ -> a(0)(980)(0)e(+)nu(e)) x B(a(0)(980)(0) -> eta pi(0)) = [1.66(-0.66)(+0.81)(stat) +/- 0.11(syst) x 10(-4). This is the first time the a(0)(980) meson has been measured in a D-0 semileptonic decay, which would open one more interesting page in the investigation of the nature of the puzzling a(0)(980) states.
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| 25. |
- Ablikim, M., et al.
(författare)
-
Observation of ψ(3686)→n¯n and improved measurement of ψ(3686)→p¯p
- 2018
-
Ingår i: Physical Review D. - : AMER PHYSICAL SOC. - 2470-0010 .- 2470-0029. ; 98:3
-
Tidskriftsartikel (refereegranskat)abstract
- We observe the decay psi (3686) -> n (n) over bar for the first time and measure psi (3686) -> p (p) over bar with improved accuracy by using 1.07 x 10(8) psi (3686) events collected with the BESIII detector. The measured branching fractions are B(psi(3686) -> n (n) over bar) = (3.06 +/- 0.06 +/- 0.14) x 10(-4) and B(psi(3686) -> p (p) over bar) = (3.05 +/- 0.02 +/- 0.12) x 10(-4). Here, the first uncertainties are statistical, and the second ones are systematic. With the hypothesis that the polar angular distributions of the neutron and proton in the center-of-mass system obey 1 + alpha cos(2) theta, we determine the a parameters to be alpha(n (n) over bar) = 0.68 +/- 0.12 +/- 0.11 and alpha(p (p) over bar) = 1.03 +/- 0.06 +/- 0.03 for psi(3686) -> n (n) over bar and psi(3686) -> p (p) over bar, respectively.
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| 26. |
- Ablikim, M., et al.
(författare)
-
Precision Measurement of the e(+)e(-) -> Lambda(+)(c)(Lambda)over-bar(c)(-) Cross Section Near Threshold
- 2018
-
Ingår i: Physical Review Letters. - : American Physical Society. - 0031-9007 .- 1079-7114. ; 120:13
-
Tidskriftsartikel (refereegranskat)abstract
- The cross section of the e(+)e(-) -> Lambda(+)(c)(Lambda) over bar (-)(c) process is measured with unprecedented precision using data collected with the BESIII detector at root s = 4574.5, 4580.0, 4590.0 and 4599.5 MeV. The nonzero cross section near the Lambda(+)(c)(Lambda) over bar (-)(c) production threshold is cleared. At center-of-mass energies root s = 4574.5 and 4599.5 MeV, the higher statistics data enable us to measure the Lambda(c) polar angle distributions. From these, the.c electric over magnetic form-factor ratios (vertical bar G(E)/G(M)vertical bar) are measured for the first time. They are found to be 1.14 +/- 0.14 +/- 0.07 and 1.23 +/- 0.05 +/- 0.03, respectively, where the first uncertainties are statistical and the second are systematic.
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| 27. |
- Ablikim, M., et al.
(författare)
-
Search for h(c) -> pi(+)pi(-) J/psi via psi(3686) -> pi(0)pi(+)pi(-) J/psi
- 2018
-
Ingår i: Physical Review D. - : American Physical Society. - 2470-0010 .- 2470-0029. ; 97:5
-
Tidskriftsartikel (refereegranskat)abstract
- Using a data sample of 448.1 x 10(6) psi(3686) events collected with the BESIII detector operating at the BEPCII, we perform search for the hadronic transition h(c)-> pi(+)pi(-) J/psi via psi (3686) -> pi(0)hc. No signals of the transition are observed, and the upper limit on the product branching fraction B(sigma(3686) -> pi(0)h(c))B(h(c) -> pi(+)pi(-) J/psi) at the 90% confidence level (C. L.) is determined to be 2.0 x 10(-6). This is the most stringent upper limit to date.
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| 28. |
- Ablikim, M., et al.
(författare)
-
Search for invisible decays of omega and phi with J/psi data at BESIII
- 2018
-
Ingår i: Physical Review D. - : American Physical Society. - 2470-0010 .- 2470-0029. ; 98:3
-
Tidskriftsartikel (refereegranskat)abstract
- Using a data sample of (1310.6 +/- 7.0) x 10(6) J/psi events collected with the BESIII detector operating at the BEPCII collider, we perform the first experimental search for invisible decays of a light vector meson (V = omega, phi) via J/psi -> V-eta decays. The decay of eta -> pi(+)pi(-)pi(0) is utilized to tag the V meson decaying into the invisible final state. No evidence for a significant invisible signal is observed, and the upper limits on the ratio of branching fractions at the 90% confidence level are determined to be B(omega -> invisible)/B(omega -> pi(+)pi(-)pi(0)) < 8.1 x 10(-5) and B(phi -> invisible)/B(phi -> K+K-) < 3.4 x 10(-4). By using the world average values of B(omega -> pi(+)pi(-)pi(0) and B(phi -> K+K-,) the upper limits on the decay branching fractions at the 90% confidence level are set as B(omega -> invisible) < 7.3 x 10(-5) and B(phi -> invisible) < 1.7 x 10(-4), respectively.
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| 29. |
- Ablikim, M., et al.
(författare)
-
Search for the rare decay of ψ(3686)→Λ+c¯pe+e−+c.c. at BESIII
- 2018
-
Ingår i: Physical Review D. - 2470-0010 .- 2470-0029. ; 97:9
-
Tidskriftsartikel (refereegranskat)abstract
- Based on a data sample of (448.1 +/- 2.9) x 10(6)Psi(3686) decays collected with the BESIII experiment, a search for the flavor changing neutral current transition Psi(3686) -> Lambda(+)(c) pe(+) e(-) + c.c. is performed for the first time. No signal candidates are observed and the upper limit on the branching fraction of Psi(3686) -> Lambda(+)(c) pe(+) e(-) is determined to be 1.7 x 10(-6) at the 90% confidence level. The result is consistent with expectations from the standard model, and no evidence for new physics is found.
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| 30. |
- Ablikim, M., et al.
(författare)
-
Search for the rare decays D -> h(h((')))e(+) e(-)
- 2018
-
Ingår i: Physical Review D. - : AMER PHYSICAL SOC. - 2470-0010 .- 2470-0029. ; 97:7
-
Tidskriftsartikel (refereegranskat)abstract
- We search for rare decays of D mesons to hadrons accompanied by an electron-positron pair (h(h((')))e(+)e(- )),using an e(+)e(-) collision sample corresponding to an integrated luminosity of 2.93 fb(-1) collected with the BESIII detector at root s = 3.773 GeV. No significant signals are observed, and the corresponding upper limits on the branching fractions at the 90% confidence level are determined. The sensitivities of the results are at the level of 10(-5)-10(-6), providing a large improvement over previous searches.
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