| 1. |
- Aad, G, et al.
(author)
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- 2015
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swepub:Mat__t
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| 2. |
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| 3. |
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| 4. |
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| 5. |
- Ablikim, M., et al.
(author)
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Observation of an Anomalous Line Shape of the eta 'pi(+)pi(-) Mass Spectrum near the p(p)over-bar Mass Threshold in J/psi -> gamma eta 'pi(+)pi(-)
- 2016
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In: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 117:4
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Journal article (peer-reviewed)abstract
- Using 1.09 x 10(9) J/psi events collected by the BESIII experiment in 2012, we study the J / psi -> gamma eta'pi(+)pi(-) process and observe a significant abrupt change in the slope of the eta'pi(+)pi(-) invariant mass distribution at the proton-antiproton (p (p) over bar) mass threshold. We use two models to characterize the eta'pi(+)pi(-) line shape around 1.85 GeV/c(2): one that explicitly incorporates the opening of a decay threshold in the mass spectrum (Flatte formula), and another that is the coherent sum of two resonant amplitudes. Both fits show almost equally good agreement with data, and suggest the existence of either a broad state around 1.85 GeV/c(2) with strong couplings to the c final states or a narrow state just below the p (p) over bar mass threshold. Although we cannot distinguish between the fits, either one supports the existence of a p (p) over bar moleculelike state or bound state with greater than 7 sigma significance.
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| 6. |
- Ablikim, M., et al.
(author)
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Amplitude analysis of D0 → K -π+π+π-
- 2017
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In: Physical Review D. - 2470-0010 .- 2470-0029. ; 95:7
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Journal article (peer-reviewed)abstract
- We present an amplitude analysis of the decay D0 → K -π+π+π- based on a data sample of 2.93 fb−1 acquired by the BESIII detector at the ψ(3770) resonance. With a nearly background free sample of about 16000 events, we investigate the substructure of the decay and determine the relative fractions and the phases among the different intermediate processes. Our amplitude model includes the two-body decays D0 → ¯K*0ρ0, D0 → K−a+1(1260) and D0 → K−1(1270)π+, the three-body decays D0 →¯K*0π+π− and D0 → K−π+ρ0, as well as the four-body nonresonant decay D0 → K−π+π+π−. The dominant intermediate process is D0 → K−a+1(1260), accounting for a fit fraction of 54.6%.
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| 7. |
- Ablikim, M., et al.
(author)
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Dark photon search in the mass range between 1.5 and 3.4 GeV/c
- 2017
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In: Physics Letters B. - : Elsevier BV. - 0370-2693 .- 1873-2445. ; 774, s. 252-257
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Journal article (peer-reviewed)abstract
- Using a data set of 2.93 fb taken at a center-of-mass energy root s = 3.773 GeV with the BESIII detector at the BEPCII collider, we perform a search for an extra U(1) gauge boson, also denoted as a dark photon. We examine the initial state radiation reactions e(+)e(-) -> e(+)e(-) gamma(ISR) and e(+)e(-) -> mu(+)mu(-) gamma(ISR) for this search, where the dark photon would appear as an enhancement in the invariant mass distribution of the leptonic pairs. We observe no obvious enhancement in the mass range between 1.5 and 3.4 GeV/c(2) and set a 90% confidence level upper limit on the mixing strength of the dark photon and the Standard Model photon. We obtain a competitive limit in the tested mass range.
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| 8. |
- Ablikim, M., et al.
(author)
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Measurement of the leptonic decay width of J/psi using initial state radiation
- 2016
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In: Physics Letters B. - : Elsevier BV. - 0370-2693 .- 1873-2445. ; 761, s. 98-103
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Journal article (peer-reviewed)abstract
- Using a data set of 2.93 fb(-1) taken at a center-of-mass energy of root s = 3.773 GeV with the BESIII detector at the BEPCII collider, we measure the process e(+) e(-) -> J/psi gamma -> mu(+)mu(-)gamma and determine the product of the branching fraction and the electronic width B-mu mu . Gamma(ee) = (333.4 +/- 2.5(stat) +/- 4.4(sys)) eV. Using the earlier-published BESIII result for B-mu mu = (5.973 +/- 0.007(stat) +/- 0.037(sys))%, we derive the J/psi electronic width Gamma(ee) = (5.58 +/- 0.05(stat) +/- 0.08(sys)) keV. (C) 2016 The Author(s). Published by Elsevier B.V.
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| 9. |
- Ablikim, M., et al.
(author)
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Observation of e(+)e(-) -> eta ' J/psi center-of-mass energies between 4.189 and 4.600 GeV
- 2016
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In: PHYSICAL REVIEW D. - 2470-0010. ; 94:3
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Journal article (peer-reviewed)abstract
- The process e(+)e(-) -> eta' J/psi is observed for the first time with a statistical significance of 8.6 sigma at center-of-mass energy root s = 4.226 GeV and 7.3 sigma at root s = 4.258 GeV using data samples collected with the BESIII detector. The Born cross sections are measured to be (3.7 +/- 0.7 +/- 0.3) and (3.9 +/- 0.8 +/- 0.3) pb at root s = 4.226 and 4.258 GeV, respectively, where the first errors are statistical and the second systematic. Upper limits at the 90% confidence level of the Born cross sections are also reported at other 12 energy points.
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| 10. |
- Ablikim, M., et al.
(author)
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Amplitude analysis of the chi(c1) -> eta pi(+)pi(-) decays
- 2017
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In: Physical Review D. - : AMER PHYSICAL SOC. - 2470-0010 .- 2470-0029. ; 95:3
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Journal article (peer-reviewed)abstract
- Using 448.0 x 10(6) psi(3686) events collected with the BESIII detector, an amplitude analysis is performed for psi(3686) -> gamma chi(c1), chi(c1) ->eta pi(+)pi(-) decays. The most dominant two- body structure observed is a(0)(980)(+/-) pi(-/+); a(0)(980)(+/-) -> eta pi(+/-.) line shape is modeled using a dispersion relation, and a significant nonzero a(0) (980) coupling to the eta'pi channel is measured. We observe chi(c1) -> a(2)(1700)pi production for the first time, with a significance larger than 17 sigma. The production of mesons with exotic quantum numbers, J(PC) = 1(-+), is investigated, and upper limits for the branching fractions chi(c1) -> pi(1)(1400)(+/-)pi(-/+) , chi(c1) -> pi(1)(1600)(+/-)pi(-/+) and chi(c1) -> pi 1(2015)(+/-)pi(-/+) with subsequent pi(1)(X)(+/-) -> eta pi(+/-) decay, are determined.
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