| 1. |
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| 2. |
- Khatri, C, et al.
(författare)
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Outcomes after perioperative SARS-CoV-2 infection in patients with proximal femoral fractures: an international cohort study
- 2021
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Ingår i: BMJ open. - : BMJ. - 2044-6055. ; 11:11, s. e050830-
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Tidskriftsartikel (refereegranskat)abstract
- Studies have demonstrated high rates of mortality in people with proximal femoral fracture and SARS-CoV-2, but there is limited published data on the factors that influence mortality for clinicians to make informed treatment decisions. This study aims to report the 30-day mortality associated with perioperative infection of patients undergoing surgery for proximal femoral fractures and to examine the factors that influence mortality in a multivariate analysis.SettingProspective, international, multicentre, observational cohort study.ParticipantsPatients undergoing any operation for a proximal femoral fracture from 1 February to 30 April 2020 and with perioperative SARS-CoV-2 infection (either 7 days prior or 30-day postoperative).Primary outcome30-day mortality. Multivariate modelling was performed to identify factors associated with 30-day mortality.ResultsThis study reports included 1063 patients from 174 hospitals in 19 countries. Overall 30-day mortality was 29.4% (313/1063). In an adjusted model, 30-day mortality was associated with male gender (OR 2.29, 95% CI 1.68 to 3.13, p<0.001), age >80 years (OR 1.60, 95% CI 1.1 to 2.31, p=0.013), preoperative diagnosis of dementia (OR 1.57, 95% CI 1.15 to 2.16, p=0.005), kidney disease (OR 1.73, 95% CI 1.18 to 2.55, p=0.005) and congestive heart failure (OR 1.62, 95% CI 1.06 to 2.48, p=0.025). Mortality at 30 days was lower in patients with a preoperative diagnosis of SARS-CoV-2 (OR 0.6, 95% CI 0.6 (0.42 to 0.85), p=0.004). There was no difference in mortality in patients with an increase to delay in surgery (p=0.220) or type of anaesthetic given (p=0.787).ConclusionsPatients undergoing surgery for a proximal femoral fracture with a perioperative infection of SARS-CoV-2 have a high rate of mortality. This study would support the need for providing these patients with individualised medical and anaesthetic care, including medical optimisation before theatre. Careful preoperative counselling is needed for those with a proximal femoral fracture and SARS-CoV-2, especially those in the highest risk groups.Trial registration numberNCT04323644
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| 3. |
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| 4. |
- Ablikim, M., et al.
(författare)
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Search for invisible decays of omega and phi with J/psi data at BESIII
- 2018
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Ingår i: Physical Review D. - : American Physical Society. - 2470-0010 .- 2470-0029. ; 98:3
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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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| 5. |
- Ablikim, M., et al.
(författare)
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First measurement of e(+)e(-) -> pK(S)(0)(n)over-barK(-) + c.c. above open charm threshold
- 2018
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Ingår i: Physical Review D. - 2470-0010 .- 2470-0029. ; 98:3
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Tidskriftsartikel (refereegranskat)abstract
- The process e(+)e(-) -> pK(S)(0)(n) over barK(-) + c.c. and its intermediate processes are studied for the first time, using data samples collected with the BESIII detector at BEPCII at center-of-mass energies of 3.773, 4.008, 4.226, 4.258, 4.358, 4.416, and 4.600 GeV, with a total integrated luminosity of 7.4 fb(-1). The Born cross section of e(+)e(-) -> pK(S)(0)(n) over barK(-) + c.c. is measured at each center-of-mass energy, but no significant resonant structure in the measured cross-section line shape between 3.773 and 4.600 GeV is observed. No evident structure is detected in the pK(-), nK(S)(0), pK(S)(0), nK(+), p (n) over bar, or (KSK-)-K-0 invariant mass distributions except for Lambda(1520). The Born cross sections of e(+)e(-) -> Lambda(1520)(n) over barK(S)(0) + c.c. and e(+)e(-) -> Lambda(1520)(p) over barK(+) + c.c. are measured, and the 90% confidence level upper limits on the Born cross sections of e(+)e(-) -> Lambda(1520)(Lambda) over bar (1520) are determined at the seven center-of-mass energies. There is an evident difference in line shape and magnitude of the measured cross sections between e(+)e(-) -> Lambda(1520)(-> pK(-))(n) over barK(S)(0) and e(+)e(-) -> pK-(Lambda) over bar (1520)(-> (n) over barK(S)(0)).
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| 6. |
- Ablikim, M., et al.
(författare)
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Measurement of e(+)e(-) -> D(D)over-bar cross sections at the psi(3770) resonance
- 2018
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Ingår i: Chinese Physics C. - : IOP PUBLISHING LTD. - 1674-1137 .- 2058-6132. ; 42:8
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Tidskriftsartikel (refereegranskat)abstract
- We report new measurements of the cross sections for the production of D (D) over bar final states at the psi(3770) resonance. Our data sample consists of an integrated luminosity of 2.93 fb(-1) of e(+)e(-) annihilation data produced by the BEPCII collider and collected and analyzed with the BESIII detector. We exclusively reconstruct three D-0 and six D+ hadronic decay modes and use the ratio of the yield of fully reconstructed D (D) over bar events ("double tags") to the yield of all reconstructed D or (D) over bar mesons ("single tags") to determine the number of D-0(D) over bar (0) and D+D- events, benefiting from the cancellation of many systematic uncertainties. Combining these yields with an independent determination of the integrated luminosity of the data sample, we find the cross sections to be sigma(e(+)e(-) -> D-0(D) over bar (0)(-) )=(3.615 +/- 0.010 +/- 0.038) nb and sigma(e(+)e(-) -> D+D-)=(2.830 +/- 0.011 +/- 0.026) nb, where the uncertainties are statistical and systematic, respectively.
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| 7. |
- Ablikim, M., et al.
(författare)
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Measurement of the integrated Luminosities of cross-section scan data samples around the psi(3770) mass region
- 2018
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Ingår i: Chinese Physics C. - : SCIENCE PRESS. - 1674-1137 .- 2058-6132. ; 42:6
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Tidskriftsartikel (refereegranskat)abstract
- To investigate the nature of the psi(3770) resonance and to measure the cross section for e(+)e(-) -> D (D) over bar, a cross-section scan data sample, distributed among 41 center-of-mass energy points from 3.73 to 3.89 GeV, was taken with the BESIII detector operated at the BEPCII collider in the year 2010. By analyzing the large angle Bhabha scattering events, we measure the integrated luminosity of the data sample at each center-of-mass energy point. The total integrated luminosity of the data sample is 76.16 +/- 0.04 +/- 0.61 pb(-1), where the first uncertainty is statistical and the second systematic.
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| 8. |
- Ablikim, M., et al.
(författare)
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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
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Ingår i: Physical Review Letters. - : AMER PHYSICAL SOC. - 0031-9007 .- 1079-7114. ; 121:8
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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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| 9. |
- Ablikim, M., et al.
(författare)
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Amplitude analysis of the KSKS system produced in radiative J /psi decays
- 2018
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Ingår i: Physical Review D. - : AMER PHYSICAL SOC. - 2470-0010 .- 2470-0029. ; 98:7
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Tidskriftsartikel (refereegranskat)abstract
- An amplitude analysis of the KSKS system produced in radiative J/psi decays is performed using the (1310.6 +/- 7.0) x 10(6) nip decays collected by the BESIII detector. Two approaches are presented. A mass-dependent analysis is performed by parametrizing the KSKS invariant mass spectrum as a sum of Breit-aligner line shapes. Additionally, a mass-independent analysis is performed to extract a piecewise function that describes the dynamics of the KSKS system while making minimal assumptions about the properties and number of poles in the amplitude. The dominant amplitudes in the mass-dependent analysis include the f(0)(1710), f(0)(2200), and f(2)'(1525). The mass-independent results, which are made available as input for further studies, are consistent with those of the mass-dependent analysis and are useful for a systematic study of hadronic interactions. The branching fraction of radiative J/psi decays to KSKS is measured to be (8.1 +/- 0.4) x 10(-4), where the uncertainty is systematic and the statistical uncertainty is negligible.
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| 10. |
- Ablikim, M., et al.
(författare)
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Branching fraction measurement of J/ψ→KSKL and search for J/ψ→KSKS
- 2017
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Ingår i: Physical Review D. - 2470-0010 .- 2470-0029. ; 96:11
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Tidskriftsartikel (refereegranskat)abstract
- Using a sample of 1.31 x 10(9) J/Psi events collected with the BESIII detector at the BEPCII collider, we study the decays of J/Psi -> KSKL and KSKS. The branching fraction of J/Psi -> KSKL is determined to be B(J/Psi -> KSKL) = (1.93 +/- 0.01 (stat) +/- 0.05 (syst)) x 10(-4), which significantly improves on previous measurements. No clear signal is observed for the J/Psi -> KSKS process, and the upper limit at the 95% confidence level for its branching fraction is determined to be B(J/Psi -> KSKS) < 1.4 x 10(-8), which improves on the previous searches by 2 orders in magnitude and reaches the order of the Einstein-Podolsky-Rosen expectation.
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| 11. |
- Ablikim, M., et al.
(författare)
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Evidence for e+e−→γηc(1S) at center-of-mass energies between 4.01 and 4.60 GeV
- 2017
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Ingår i: Physical Review D. - 2470-0010 .- 2470-0029. ; 96:5
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Tidskriftsartikel (refereegranskat)abstract
- We present first evidence for the process e(+)e(-) -> gamma eta(c)(1S) at six center-of-mass energies between 4.01 and 4.60 GeV using data collected by the BESIII experiment operating at BEPCII. We measure the Born cross section at each energy using a combination of twelve eta(c)(1S) decay channels. We also combine all six energies under various assumptions for the energy-dependence of the cross section. If the process is assumed to proceed via the Y(4260), we measure a peak Born cross section sigma(peak)(e(+)e(-) -> gamma eta(c)(1S)) = 2.11 +/- 0.49 (stat.) +/- 0.36 (syst.) pb with a statistical significance of 4.2 sigma.
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| 12. |
- Ablikim, M., et al.
(författare)
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Improved measurements of X-cJ -> Sigma(+) (Sigma)over-bar(-) and Sigma(0)(Sigma)over-bar(0) decays
- 2018
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Ingår i: Physical Review D. - : American Physical Society. - 2470-0010 .- 2470-0029. ; 97:5
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Tidskriftsartikel (refereegranskat)abstract
- Using a data sample of (448.1 +/- 2.9) x 10(6) psi (3686) events collected with the BESIII detector at the BEPCII collider, we present measurements of branching fractions for the decays X-cJ -> Sigma(+) (Sigma) over bar (-) and Sigma(0) (Sigma) over bar (0) The decays X-c1.2 -> Sigma(+) (Sigma) over bar (-) and Sigma (Sigma) over bar (0) are observed for the first time, and the branching fractions for X-c0 -> Sigma(+) (Sigma) over bar (-) and Sigma(0) (Sigma) over bar (0) decays are measured with improved precision. The branching fraction ratios between the charged and neutral modes are consistent with the prediction of isospin symmetry.
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| 13. |
- Ablikim, M., et al.
(författare)
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Measurement of e(+)e(-) -> K(K)over-barJ/psi cross sections at center-of-mass energies from 4.189 to 4.600 GeV
- 2018
-
Ingår i: Physical Review D. - : AMER PHYSICAL SOC. - 2470-0010 .- 2470-0029. ; 97:7
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Tidskriftsartikel (refereegranskat)abstract
- We investigate the process e(+)e(-) -> K (K) over barJ/psi at center-of-mass energies from 4.189 to 4.600 GeV using 4.7 fb(-1) of data collected by the BESIII detector at the BEPCII collider. The Born cross sections for the reactions e(+)e(-) -> K(+)K(-)J/psi and K(S)(0)K(S)(0)J/psi are measured as a function of center-of-mass energy. The energy dependence of the cross section for e(+)e(-) -> K(+)K(-)J/psi is shown to differ from that for pi(+)pi(-)J/psi in the region around the Y(4260). In addition, there is evidence for a structure around 4.5 GeV in the e(+)e(-) -> K(+)K(-)J/psi cross section that is not present in pi(+)pi(-)J/psi.
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| 14. |
- Ablikim, M., et al.
(författare)
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Measurement of the absolute branching fraction of D*(s0) (2317)(+/-) -> pi D-0(s)+/-
- 2018
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Ingår i: Physical Review D. - : American Physical Society. - 2470-0010 .- 2470-0029. ; 97:5
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Tidskriftsartikel (refereegranskat)abstract
- The process e(+)e(-) -> D*D-+(s)*(s0) (2317)(-) + c.c. is observed for the first time with the data sample of 567 pb(-1) collected with the BESIII detector operating at the BEPCII collider at a center-of-mass energy root s = 4.6 GeV. The statistical significance of the D*(s0) (2317)(+/-) signal is 5.8 sigma and the mass is measured to be (2318.3 +/- 1.2 +/- 1.2) MeV/c(2). The absolute branching fraction B(D*(s0) (2317)(+/-) -> pi D-0(s)+/-) is measured as 1.00(-0.14)(+0.00) (stat)(-0.14)(+0.00) (syst) for the first time. The uncertainties are statistical and systematic, respectively.
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| 15. |
- Ablikim, M., et al.
(författare)
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Measurement of the Absolute Branching Fraction of the Inclusive Decay Lambda(+)(c) -> Lambda plus X
- 2018
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Ingår i: Physical Review Letters. - : AMER PHYSICAL SOC. - 0031-9007 .- 1079-7114. ; 121:6
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Tidskriftsartikel (refereegranskat)abstract
- Based on an e(+)e(-) collision data sample corresponding to an integrated luminosity of 567 pb(-1) taken at the center-of-mass energy of root s = 4.6 GeV with the BESIII detector, we measure the absolute branching fraction of the inclusive decay Lambda(+)(c) -> Lambda + X to be B(Lambda(+)(c) -> Lambda + X) = (38.2(-2.2)(+2.8) +/- 0.9)% using the double-tag method, where X refers to any possible final state particles. In addition, we search for direct CP violation in the charge asymmetry of this inclusive decay for the first time, and obtain A(CP) [B(Lambda(+)(c) -> Lambda + X) - B((Lambda) over bar (-)(c) -> (Lambda) over bar + X)]/[B(Lambda(+)(c) -> Lambda + X) + B((Lambda) over bar (-)(c) -> (Lambda) over bar + X)] = (2.1(-6.6)(+7.0) +/- 1.6)%, a statistically limited result with no evidence of CP violation.
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| 16. |
- Ablikim, M., et al.
(författare)
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Measurement of the matrix elements for the decays eta' -> eta pi(+) pi(-) and eta' -> eta pi(0)pi(0)
- 2018
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Ingår i: Physical Review D. - : AMER PHYSICAL SOC. - 2470-0010 .- 2470-0029. ; 97:1
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Tidskriftsartikel (refereegranskat)abstract
- Based on a sample of 1.31 x 10(9) J/psi events collected with the BESIII detector, the matrix elements for the decays eta' -> eta pi(+) pi(-) and eta' -> eta pi(0)pi(0) are determined using 351,016 eta' -> (eta -> gamma gamma)pi' pi(-) and 56,249 eta' -> (eta -> gamma gamma)pi(0) pi(0) events with background levels less than 1%. Two commonly used representations are used to describe the Dalitz plot density. We find that an assumption of a linear amplitude does not describe the data well. A small deviation of the obtained matrix elements between eta' -> eta pi(+) pi(-) and eta' -> eta pi(0)pi(0) is probably caused by the mass difference between charged and neutral pions or radiative corrections. No cusp structure in eta' -> eta pi(0)pi(0) is observed.
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| 17. |
- Ablikim, M., et al.
(författare)
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Measurements of the branching fractions for the semileptonic decays D-s(+) -> phi e(+)v(e), phi mu(+)v(mu), eta mu(+)v(mu) and eta 'mu(+)v(mu)
- 2018
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Ingår i: Physical Review D. - : American Physical Society. - 2470-0010 .- 2470-0029. ; 97:1
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Tidskriftsartikel (refereegranskat)abstract
- By analyzing 482 pb(-1) of e(+) e(-) collision data collected at the center-of-mass energy root s = 4.009 GeV with the BESIII detector, we measure the branching fractions for the semi-leptonic decays D-s(+) -> phi e(+)v(e), phi mu(+)v(mu), eta mu(+)v(mu) and eta'mu(+)v(mu) to be B(D-s(+) -> phi e(+)v(e)) = (2.26 +/- 0.45 +/- 0.09)%, B(D-s(+) -> phi mu+v(mu)) = (1.94 +/- 0.53 +/- 0.09)%, B(D-s(+) -> eta mu(+)v(mu)) = (2.42 +/- 0.46 +/- 011)% and B(D-s(+) -> eta'mu(+)v(mu)) = (1.06 +/- 0.54 +/- 0.07)%, where the first and second uncertainties are statistical and systematic, respectively. The branching fractions for the three semi-muonic decays D-s(+) -> phi mu(+)v(mu), eta mu(+)v(mu) and eta'mu(+)v(mu) are determined for the first time and that of D-s(+) -> phi e(+)v(e) is consistent with the world average value within uncertainties.
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| 18. |
- Ablikim, M., et al.
(författare)
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Observation of a(0)(0)(980)-f(0)(980) Mixing
- 2018
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Ingår i: Physical Review Letters. - : AMER PHYSICAL SOC. - 0031-9007 .- 1079-7114. ; 121:2
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Tidskriftsartikel (refereegranskat)abstract
- We report the first observation of a(0)(0)(980)-f(0)(980) mixing in the decays of J/psi -> phi f(0)(980) -> phi a(0)(0)(980) -> phi eta pi(0) and chi(c1) -> a(0)(0)(980)pi(0) -> f(0)(980)pi(0)->pi(+)pi(-)pi(0), using data samples of 1.31 x 10(9) J/psi events and 4.48 x 10(8) psi (3686) events accumulated with the BESIII detector. The signals of f(0)(980) -> a(0)(0)(980) and a(0)(0)(980) -> f(0)(980) mixing are observed at levels of statistical significance of 7.4 sigma and 5.5 sigma, respectively. The corresponding branching fractions and mixing intensities are measured and the constraint regions on the coupling constants, g(a0K+K-) and g(f0K+K-), are estimated. The results improve the understanding of the nature of a(0)(0)(980) and f(0)(980).
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| 19. |
- Ablikim, M., et al.
(författare)
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Study of the decays D+-> eta(('))e(+)nu(e)
- 2018
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Ingår i: Physical Review D. - : AMER PHYSICAL SOC. - 2470-0010 .- 2470-0029. ; 97:9
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Tidskriftsartikel (refereegranskat)abstract
- The charm semileptonic decays D+ -> eta e(+)nu(e) and D+ -> eta'e(+)nu(e) are studied with a sample of e(+)e(-) collision data corresponding to an integrated luminosity of 2.93 fb(-1) collected at root s = 3.773 GeV with the BESIII detector. We measure the branching fractions for D+ -> eta e(+)upsilon(e) to be (10.74 +/- 0.81 +/- 0.51)x10(-4), and for D+ -> eta'e(+)nu(e) to be (1.91 +/- 0.51 +/- 0.13) x 10(-4), where the uncertainties are statistical and systematic, respectively. In addition, we perform a measurement of the form factor in the decay D+ -> eta e(+)nu(e) . All the results are consistent with those obtained by the CLEO-c experiment.
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| 20. |
- Ablikim, M., et al.
(författare)
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Branching fraction measurements of psi (3686) -> gamma chi(cJ)
- 2017
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Ingår i: Physical Review D. - 2470-0010 .- 2470-0029. ; 96:3
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Tidskriftsartikel (refereegranskat)abstract
- Using a sample of 106 million psi(3686) decays, the branching fractions of psi(3686) -> gamma chi(c0), psi(3686) -> gamma chi(c1), and psi(3686) -> gamma chi(c2) are measured with improved precision to be (9.389 +/- 0.014 +/- 0.332) %, (9.905 +/- 0.011 +/- 0.353) %, and (9.621 +/- 0.013 +/- 0.272) %, respectively, where the first uncertainties are statistical and the second ones are systematic. The product branching fractions of (psi 3686) -> gamma chi(c1), chi(c1) -> gamma J/psi (3686) -> gamma chi(c2), chi(c2) -> gamma J/psi and the branching fractions of chi(c1) -> gamma J/psi and chi(c2) -> gamma J/psi are also presented.
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| 21. |
- Ablikim, M., et al.
(författare)
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Improved measurements of two-photon widths of the chi(cJ) states and helicity analysis for chi(c2) -> gamma gamma
- 2017
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Ingår i: Physical Review D. - : AMER PHYSICAL SOC. - 2470-0010 .- 2470-0029. ; 96:9
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Tidskriftsartikel (refereegranskat)abstract
- Based on 448.1 x 10(6) Psi(3686) events collected with the BESIII detector, the decays Psi(3686) -> gamma chi(cJ), chi(cJ) -> gamma gamma(J = 0, 1, 2) are studied. The decay branching fractions of chi(c0,2) -> gamma gamma are measured to be B(chi(c0) -> gamma gamma) = (1.93 +/- 0.08 +/- 0.05 +/- 0.05) x 10(-4) and B(chi(c2) -> gamma gamma) = (3.10 +/- 0.09 +/- 0.07 +/- 0.11) x 10(-4) which correspond to two-photon decay widths of Gamma(gamma gamma)(chi(c0)) = 2.03 +/- 0.08 +/- 0.06 +/- 0.13 keV and Gamma(gamma gamma)(chi(c2)) = 0.60 +/- 0.02 +/- 0.01 +/- 0.04 keV with a ratio of R = Gamma(gamma gamma)(chi(c2))/Gamma(gamma gamma)(chi(c0)) = 0.295 +/- 0.014 +/- 0.007 +/- 0.027, where the uncertainties are statistical, systematic and associated with the uncertainties of B(Psi(3686) -> gamma chi(c0,2)) and the total widths Gamma(chi(c0,2)), respectively. For the forbidden decay of chi(c1) -> gamma gamma, no signal is observed, and an upper limit on the two-photon width is obtained to be Gamma(gamma gamma)(chi(c1)) < 5.3 eV at the 90% confidence level. The ratio of the two-photon widths between helicity-zero and helicity-two components in the decay chi(c2) -> gamma gamma is also measured to be f(0/2) = Gamma(lambda=0)(gamma gamma) (chi(c2))/Gamma(lambda=2)(gamma gamma) (chi(c2)) = (0.0 +/- 0.6 +/- 1.2) x 10(-2), where the uncertainties are statistical and systematic, respectively.
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| 22. |
- Ablikim, M., et al.
(författare)
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Measurement of e+e−→π0π0ψ(3686) at √s from 4.009 to 4.600 GeV and observation of a neutral charmoniumlike structure
- 2018
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Ingår i: Physical Review D. - 2470-0010 .- 2470-0029. ; 97:5
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Tidskriftsartikel (refereegranskat)abstract
- Using ethorne-collision data collected with the BESIII detector at the BEPCII collider corresponding to an integrated luminosity of 5.2 fb(-1) at center-of-mass energies (root s) from 4.009 to 4.600 GeV, the process e(+)e(-) -> pi(0)pi(0)psi(3686) is studied for the first time. The corresponding Born cross sections are measured and found to be half of those of the reaction e(+)e(-) -> pi(0)pi(0)psi(3686). This is consistent with the expectation from isospin symmetry. Furthermore, the Dalitz plots for pi(0)pi(0)psi(3686) are accordant with those of pi(0)pi(0)psi(3686) at all energy points, and a neutral analog to the structure in pi(+/-)psi(3686) around 4040 MeV/c(2) first observed at root s = 4.416 GeV is observed in the isospin neutral mode at the same energy.
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| 23. |
- Ablikim, M., et al.
(författare)
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Measurements of the branching fractions of the singly Cabibbo-suppressed decays D0→ωη, η(')π0 and η(')η
- 2018
-
Ingår i: Physical Review D. - : AMER PHYSICAL SOC. - 2470-0010 .- 2470-0029. ; 97:5
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Tidskriftsartikel (refereegranskat)abstract
- By analyzing a data sample of 2.93 fb(-1) collected at root s = 3.773 GeV with the BESIII detector operated at the BEPCII storage rings, we measure the branching fractions B(D-0 -> omega eta) = (2.15 +/- 0.17(stat) +/- 0.15(sys)) x 10(-3), B(D-0 ->eta pi(0)) = (0.58 +/- 0.05(stat) +/- 0.05(sys)) x 10(-3), B(D-0 ->eta'pi(0)) = (0.93 +/- 0.11(stat) +/- 0.09(sys)) x 10(-3), B(D-0 -> eta eta) = (2.20 +/- 0.07(stat) +/- 0.06(sys)) x 10(-3) and B(D-0 -> eta'eta) = (0.94 degrees +/- 0.25(stat) +/- 0.11(sys)) x 10(-3). We note that B(D-0 -> omega eta) is measured for the first time and that B(D-0 -> eta eta) is measured with much improved precision.
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| 24. |
- Ablikim, M., et al.
(författare)
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Observation of J/psi -> gamma eta pi(0)
- 2016
-
Ingår i: PHYSICAL REVIEW D. - 2470-0010. ; 94:7
-
Tidskriftsartikel (refereegranskat)abstract
- We present the first study of the process J/psi -> gamma eta pi(0) using (223.7 +/- 1.4) x 10(6) J/psi events accumulated with the BESIII detector at the BEPCII facility. The branching fraction for J/psi -> gamma eta pi(0) is measured to be B(J/psi -> gamma eta pi(0)) = (2.14 +/- 0.18(stat) +/- 0.25(syst)) x 10(-5). With a Bayesian approach, the upper limits of the branching fractions B(J/psi -> gamma a(0)(980), a(0)(980) -> eta pi(0)) and B(J/psi -> gamma a(2)(1320), a(2)(1320) -> eta pi(0)) are determined to be 2.5 x 10(-6) and 6.6 x 10(-6) at the 95% confidence level, respectively. All of these measurements are given for the first time.
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| 25. |
- Ablikim, M., et al.
(författare)
-
Observation of the decay Lambda(+)(c) -> Sigma(-)pi(+)pi(+)pi(0)
- 2017
-
Ingår i: Physics Letters B. - : Elsevier BV. - 0370-2693 .- 1873-2445. ; 772, s. 388-393
-
Tidskriftsartikel (refereegranskat)abstract
- We report the first observation of the decay Lambda(+)(c) -> Sigma(-)pi(+)pi(+)pi(0), based on data obtained in e(+)e(-) annihilations with an integrated luminosity of 567 pb(-1) at vs = 4.6 GeV. The data were collected with the BESIII detector at the BEPCII storage rings. The absolute branching fraction B(Lambda(+)(c) -> Sigma(-)pi(+)pi(+)pi(0)) is determined to be (2.11 +/- 0.33(stat.) +/- 0.14(syst.))%. In addition, an improved measurement of B(Lambda(+)(c) -> Sigma(-)pi(+)pi(+)pi(0)) is determined as (1.81 +/- 0.17(stat.) +/- 0.09(syst.))%.
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| 26. |
- Ablikim, M., et al.
(författare)
-
Observation of χc2→η′η′ and χc0,2→ηη′
- 2017
-
Ingår i: Physical Review D. - 2470-0010 .- 2470-0029. ; 96:11
-
Tidskriftsartikel (refereegranskat)abstract
- Using a sample of 448.1×106 ψ(3686) events collected with the BESIII detector in 2009 and 2012, we study the decays χc0,2→η′η′ and ηη′. The decays χc2→η′η′, χc0→ηη′ and χc2→ηη′ are observed for the first time with statistical significances of 9.6σ, 13.4σ and 7.5σ, respectively. The branching fractions are determined to be B(χc0→η′η′)=(2.19±0.03±0.14)×10−3, B(χc2→η′η′)=(4.76±0.56±0.38)×10−5, B(χc0→ηη′)=(8.92±0.84±0.65)×10−5 and B(χc2→ηη′)=(2.27±0.43±0.25)×10−5, where the first uncertainties are statistical and the second are systematic. The precision for the measurement of B(χc0→η′η′) is significantly improved compared to previous measurements. Based on the measured branching fractions, the role played by the doubly and singly Okubo-Zweig-Iizuka disconnected transition amplitudes for χc0,2 decays into pseudoscalar meson pairs can be clarified.
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| 27. |
- 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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| 28. |
- 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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| 29. |
- 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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| 30. |
- Ablikim, M., et al.
(författare)
-
Search for the rare decays J/ψ→D0e+e−+c.c. and ψ(3686)→D0e+e−+c.c.
- 2017
-
Ingår i: Physical Review D. - 2470-0010 .- 2470-0029. ; 96:11
-
Tidskriftsartikel (refereegranskat)abstract
- Using the data samples of (1310.6 +/- 7.2) x 10(6) J/psi events and (448.1 +/- 2.9) x 10(6) psi(3686) events collected with the BESIII detector, we search for the rare decays J/psi -> D(0)e(+) e(-) + c.c. and psi(3686) -> D(0)e(+) e(-) + c.c. No significant signals are observed and the corresponding upper limits on the branching fractions at the 90% confidence level are determined to be B(J/psi -> D(0)e(+) e(-) + c.c.) < 8.5 x 10(-8) and B(psi(3686) -> D(0)e(+) e(-) + c.c.) < 1.4 x 10(-7), respectively. Our limit on B(J/psi -> D(0)e(+) e(-) + c.c.) is more stringent by 2 orders of magnitude than the previous results, and B(psi(3686) -> D(0)e(+) e(-) + c.c.) is measured for the first time.
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| 31. |
- Ablikim, M., et al.
(författare)
-
Search for ψ(3686)→γηc(η(1405))→γπ+π−π0
- 2017
-
Ingår i: Physical Review D. - 2470-0010 .- 2470-0029. ; 96:11
-
Tidskriftsartikel (refereegranskat)abstract
- Using a sample of 448.1×106 ψ(3686) events collected with the BESIII detector, a search for the isospin violating decay ηc→π+π−π0 via ψ(3686)→γηc is presented. No signal is observed, and the upper limit on B(ψ(3686)→γηc)×B(ηc→π+π−π0) is determined to be 1.6×10−6 at the 90% confidence level. In addition, a search for η(1405)→f0(980)π0 in ψ(3686) radiative decays is performed. No signal is observed, and the branching fraction B(ψ(3686)→γη(1405))×B(η(1405)→f0(980)π0)×B(f0(980)→π+π−) is calculated to be less than 5.0×10−7 at the 90% confidence level.
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| 32. |
- Ablikim, M., et al.
(författare)
-
Study of eta(1475) and X(1835) in radiative J/psi decays to gamma phi
- 2018
-
Ingår i: Physical Review D. - : AMER PHYSICAL SOC. - 2470-0010 .- 2470-0029. ; 97:5
-
Tidskriftsartikel (refereegranskat)abstract
- The decay J/psi -> gamma gamma phi is studied using a sample of 1.31 x 10(9) J/psi events collected with the BESIII detector. Two structures around 1475 MeV/c(2) and 1835 MeV/c(2) are observed in the gamma phi invariant mass spectrum for the first time. With a fit on the gamma phi invariant mass, which takes into account the interference between the two structures, and a simple analysis of the angular distribution, the structure around 1475 MeV/c(2) is found to favor an assignment as the eta(1475) and the mass and width for the structure around 1835 MeV/c(2) are consistent with the X(1835). The statistical significances of the two structures are 13.5 sigma and 6.3 sigma, respectively. The results indicate that both eta(1475) and X(1835) contain a sizeable s (s) over bar component.
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| 33. |
- Ablikim, M., et al.
(författare)
-
Study of J/ψ and ψ(3686) decays to π+π−η′
- 2017
-
Ingår i: Physical Review D. - 2470-0010 .- 2470-0029. ; 96:11
-
Tidskriftsartikel (refereegranskat)abstract
- Using the data samples of 1.31×109 J/ψ events and 4.48×108 ψ(3686) events collected with the BESIII detector, partial wave analyses on the decays J/ψ and ψ(3686)→π+π−η′ are performed with a relativistic covariant tensor amplitude approach. The dominant contribution is found to be J/ψ and ψ(3686) decays to ρη′. In the J/ψ decay, the branching fraction B(J/ψ→ρη′) is determined to be (7.90±0.19(stat)±0.49(sys))×10−5. Two solutions are found in the ψ(3686) decay, and the corresponding branching fraction B(ψ(3686)→ρη′) is (1.02±0.11(stat)±0.24(sys))×10−5 for the case of destructive interference, and (5.69±1.28(stat)±2.36(sys))×10−6 for constructive interference. As a consequence, the ratios of branching fractions between ψ(3686) and J/ψ decays to ρη′ are calculated to be (12.9±1.4(stat)±3.1(sys))% and (7.2±1.6(stat)±3.0(sys))%, respectively. We also determine the inclusive branching fractions of J/ψ and ψ(3686) decays to π+π−η′ to be (1.36±0.02(stat)±0.08(sys))×10−4 and (1.51±0.14(stat)±0.23(sys))×10−5, respectively
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| 34. |
- Ablikim, M., et al.
(författare)
-
Study of J/ψ and ψ(3686) decay to Λ¯Λ and Σ0¯Σ0 final states
- 2017
-
Ingår i: Physical Review D. - 2470-0010 .- 2470-0029. ; 95:5
-
Tidskriftsartikel (refereegranskat)abstract
- Using 1310.6 x 10(6) J/psi and 447.9 x 10(6) psi (3686) events collected with the BESIII detector at the BEPCII e(+)e(-) collider, the branching fractions and the angular distributions of J/psi and psi (3686) decays to Lambda(Lambda) over bar and Sigma(0)(Sigma) over tilde (0) final states are measured. The branching fractions are determined, with much improved precision, to be 19.43 +/- 0.03 +/- 0.33, 11.64 +/- 0.04 +/- 0.23, 3.97 +/- 0.02 +/- 0.12 and 2.44 +/- 0.03 +/- 0.11 for J/psi -> Lambda(Lambda) over bar -> Sigma(0)(Sigma) over tilde (0) , psi (3686) -> Lambda(Lambda) over bar and psi (3686) -> Sigma(0)(Sigma) over tilde (0), respectively. The polar angular distributions of psi (3686) decays are measured for the first time, while those of J/psi decays are measured with much improved precision. In addition, the ratios of branching fractions B(psi(3686)->Lambda(Lambda) over bar)/B(J/psi -> Lambda(Lambda) over bar) and B(psi(3686)->Sigma(0)(Sigma) over tilde (0))/B(J/psi ->Sigma(0)(Sigma) over tilde (0)) are determined to test the "12% rule."
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| 35. |
- Ablikim, M., et al.
(författare)
-
Measurement of singly Cabibbo-suppressed decays D-0 → π0π0π0, π0π0η, π0ηη and ηηη
- 2018
-
Ingår i: Physics Letters B. - : ELSEVIER SCIENCE BV. - 0370-2693 .- 1873-2445. ; 781, s. 368-375
-
Tidskriftsartikel (refereegranskat)abstract
- Using a data sample of e(+)e(-) collision data corresponding to an integrated luminosity of 2.93 fb(-1) collected with the BESIII detector at a center-of-mass energy of root s = 3.773 GeV, we search for the singly Cabibbo-suppressed decays D-0 -> pi(0)pi(0)pi(0), pi(0)pi(0)eta, pi(0)eta eta and eta eta eta using the double tag method. The absolute branching fractions are measured to be B(D-0 -> pi(0)pi(0)pi(0)) = (2.0 +/- 0.4 +/- 0.3) x 10(-4), B(D-0 -> pi(0)pi(0)eta) = (3.8 +/- 1.1 +/- 0.7) x 10(-4) and B(D-0 -> pi(0)eta eta) = (7.3 +/- 1.6 +/- 1.5) x 10(-4) with the statistical significances of 4.8 sigma, 3.8 sigma and 5.5 sigma, respectively, where the first uncertainties are statistical and the second ones systematic. No significant signal of D-0 -> eta eta eta is found, and the upper limit on its decay branching fraction is set to be B(D-0 -> eta eta eta) < 1.3 x 10(-4) at the 90% confidence level.
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| 36. |
- Ablikim, M., et al.
(författare)
-
Measurements of absolute branching fractions for D mesons decays into two pseudoscalar mesons
- 2018
-
Ingår i: Physical Review D. - : AMER PHYSICAL SOC. - 2470-0010 .- 2470-0029. ; 97:7
-
Tidskriftsartikel (refereegranskat)abstract
- Using a data sample of e(+)e(-) collision data with an integrated luminosity of 2.93 fb(-1) taken at the center-of-mass energy root s = 3.773 GeV with the BESIII detector operating at the BEPCII storage rings, we measure the absolute branching fractions of the two-body hadronic decays D+ -> pi(+)pi(0), K+pi(0), pi(+)eta., K+eta., pi(+)eta', K+eta', K-S(0)pi(+), (KSK+)-K-0, and D-0 -> pi(+)pi(-), K+ K-, K--/+pi(+/-), K-S(0)pi(0), K-S(0)eta, K-S(0)eta' Our results are consistent with previous measurements within uncertainties. Among them, the branching fractions for D+-> pi(+)pi(0), K+pi(0), pi(+)eta, pi(+)eta', (KSK+)-K-0, (KSK+)-K-0 and D-0 -> K-S(0)pi(0), K-S(0)eta, K-S(0)eta' are determined with improved precision compared to the world average values.
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| 37. |
- Ablikim, M., et al.
(författare)
-
Measurements of absolute branching fractions for Lambda(+)(c) -> Xi K-0(+) and Xi(1530)K-0(+)
- 2018
-
Ingår i: Physics Letters B. - : ELSEVIER SCIENCE BV. - 0370-2693 .- 1873-2445. ; 783, s. 200-206
-
Tidskriftsartikel (refereegranskat)abstract
- We report the first measurements of absolute branching fractions for the W-exchange-only processes Lambda(+)(c) -> Xi K-0(+) and Lambda(+)(c)-> Xi(1530)K-0(+) with the double-tag technique, by analyzing an e(+)e(-) collision data sample, that corresponds to an integrated luminosity of 567 pb(-1) collected at a center-of-mass energy of 4.6 GeV by the BESIII detector. The branching fractions are measured to be B(Lambda(+)(c)-> Xi K-0(+)) = (5.90 +/- 0.86 +/- 0.39) x 10(-3) and B(Lambda(+)(c)-> Xi(1530)K-0(+)) = (5.02 +/- 0.99 +/- 0.31) x 10(-3), where the first uncertainties are statistical and the second systematic. Our results are more precise than the previous relative measurements.
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| 38. |
- Ablikim, M., et al.
(författare)
-
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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| 39. |
- 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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| 40. |
- 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
-
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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| 41. |
- 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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| 42. |
- Ablikim, M., et al.
(författare)
-
Study of two-photon decays of pseudoscalar mesons via J/Psi radiative decays
- 2018
-
Ingår i: Physical Review D. - 2470-0010 .- 2470-0029. ; 97:7
-
Tidskriftsartikel (refereegranskat)abstract
- Using a sample of 4.48 x 10(8) Psi(3686) events collected with the BESIII detector at the BEPCII collider, we study the two-photon decays of the pseudoscalar mesons pi(0,) eta , eta' , eta(1405), eta(1475), eta(1760), and X(1835) in J/Psi radiative decays using Psi(3686) -> pi(+) pi(-) J/Psi events. The pi(0), eta, and eta' mesons are clearly observed in the two-photon mass spectra, and the branching fractions are determined to be B(J/Psi -> gamma pi(0) -> 3 gamma) = (3.57 +/- 0.12 +/- 0.16) x 10(-5), B(J/Psi -> gamma eta -> 3 gamma) = (4.42 +/- 0.04 +/- 0.18) x 10(-4), and B(J/Psi -> gamma eta' -> 2 gamma) = (1.26 +/- 0.02 +/- 0.05) x 10(-4), where the first error is statistical and the second is systematic. No clear signal for eta(1405), eta(1475), eta(1760) or X(1835) is observed in the two- photon mass spectra, and upper limits at the 90% confidence level on the product branching fractions are obtained.
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| 43. |
- Aaron, F. D., et al.
(författare)
-
Combined measurement and QCD analysis of the inclusive e(+/-)p scattering cross sections at HERA
- 2010
-
Ingår i: Journal of High Energy Physics. - 1029-8479. ; :1
-
Tidskriftsartikel (refereegranskat)abstract
- A combination is presented of the inclusive deep inelastic cross sections measured by the H1 and ZEUS Collaborations in neutral and charged current unpolarised e(+/-)p scattering at HERA during the period 1994-2000. The data span six orders of magnitude in negative four-momentum-transfer squared, Q(2), and in Bjorken x. The combination method used takes the correlations of systematic uncertainties into account, resulting in an improved accuracy. The combined data are the sole input in a NLO QCD analysis which determines a new set of parton distributions, HERAPDF1.0, with small experimental uncertainties. This set includes an estimate of the model and parametrisation uncertainties of the fit result.
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| 44. |
- Aaron, F. D., et al.
(författare)
-
Events with an isolated lepton and missing transverse momentum and measurement of W production at HERA
- 2010
-
Ingår i: Journal of High Energy Physics. - 1029-8479. ; 2010:3, s. 1-19
-
Tidskriftsartikel (refereegranskat)abstract
- A search for events containing an isolated electron or muon and missing trans verse momentum produced in e(+/-)p collisions is performed with the H1 and ZEUS detectors at HERA. The data were taken in the period 1994-2007 and correspond to an integrated luminosity of 0.98 fb(-1). The observed event yields are in good overall agreement with the Standard Model prediction, which is dominated by single W production. In the e(+)p data, at large hadronic transverse momentum P-T(X) > 25GeV, a total of 23 events are observed compared to a prediction of 14.0 +/- 1.9. The total single W boson production cross section is measured as 1.06 +/- 0.16 (stat.) +/- 0.07 (sys.) pb, in agreement with an Standard Model (SM) expectation of 1.26 +/- 0.19 pb.
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| 45. |
- Aaron, F. D., et al.
(författare)
-
Multi-leptons with high transverse momentum at HERA
- 2009
-
Ingår i: Journal of High Energy Physics. - : Springer Science and Business Media LLC. - 1029-8479. ; :10
-
Tidskriftsartikel (refereegranskat)abstract
- Events with at least two high transverse momentum leptons (electrons or muons) are studied using the H1 and ZEUS detectors at HERA with an integrated luminosity of 0.94 fb(-1). The observed numbers of events are in general agreement with the Standard Model predictions. Seven di- and tri-lepton events are observed in e(+)p collision data with a scalar sum of the lepton transverse momenta above 100 GeV while 1.94 +/- 0.17 events are expected. Such events are not observed in e(-)p collisions for which 1.19 +/- 0.12 are predicted. Total visible and differential di-electron and di-muon photoproduction cross sections are extracted in a restricted phase space dominated by photon-photon collisions.
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| 46. |
- Adrian-Martinez, S., et al.
(författare)
-
The First Combined Search For Neutrino Point-Sources In The Southern Hemisphere With The Antares And Icecube Neutrino Telescopes
- 2016
-
Ingår i: Astrophysical Journal. - 0004-637X .- 1538-4357. ; 823:1
-
Tidskriftsartikel (refereegranskat)abstract
- We present the results of searches for point-like sources of neutrinos based on the first combined analysis of data from both the ANTARES and IceCube neutrino telescopes. The combination of both detectors, which differ in size and location, forms a window in the southern sky where the sensitivity to point sources improves by up to a factor of 2 compared with individual analyses. Using data recorded by ANTARES from 2007 to 2012, and by IceCube from 2008 to 2011, we search for sources of neutrino emission both across the southern sky and from a preselected list of candidate objects. No significant excess over background has been found in these searches, and flux upper limits for the candidate sources are presented for E-2.5 and E-2 power-law spectra with different energy cut-offs.
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| 47. |
- Petroff, E., et al.
(författare)
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A polarized fast radio burst at low Galactic latitude
- 2017
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Ingår i: Monthly notices of the Royal Astronomical Society. - : Oxford Academic. - 0035-8711 .- 1365-2966. ; 469:4, s. 4465-4482
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Tidskriftsartikel (refereegranskat)abstract
- We report on the discovery of a new fast radio burst (FRB), FRB 150215, with the Parkes radio telescope on 2015 February 15. The burst was detected in real time with a dispersion measure (DM) of 1105.6 +/- 0.8 pc cm(-3), a pulse duration of 2.8(-0.5)(+1.2) ms, and a measured peak flux density assuming that the burst was at beam centre of 0.7(-0.1)(+0.2) Jy. The FRB originated at a Galactic longitude and latitude of 24.66 degrees, 5.28 degrees and 25 degrees away from the Galactic Center. The burst was found to be 43 +/- 5 per cent linearly polarized with a rotation measure (RM) in the range -9 < RM < 12 rad m(-2) (95 per cent confidence level), consistent with zero. The burst was followed up with 11 telescopes to search for radio, optical, X-ray, gamma-ray and neutrino emission. Neither transient nor variable emission was found to be associated with the burst and no repeat pulses have been observed in 17.25 h of observing. The sightline to the burst is close to the Galactic plane and the observed physical properties of FRB 150215 demonstrate the existence of sight lines of anomalously low RM for a given electron column density. The Galactic RM foreground may approach a null value due to magnetic field reversals along the line of sight, a decreased total electron column density from the Milky Way, or some combination of these effects. A lower Galactic DM contribution might explain why this burst was detectable whereas previous searches at low latitude have had lower detection rates than those out of the plane.
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| 48. |
- Aaron, F. D., et al.
(författare)
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Combined inclusive diffractive cross sections measured with forward proton spectrometers in deep inelastic ep scattering at HERA
- 2012
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Ingår i: European Physical Journal C. Particles and Fields. - : Springer Science and Business Media LLC. - 1434-6044. ; 72:10
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Tidskriftsartikel (refereegranskat)abstract
- A combination of the inclusive diffractive cross section measurements made by the H1 and ZEUS Collaborations at HERA is presented. The analysis uses samples of diffractive deep inelastic ep scattering data at a centre-of-mass energy root s = 318 GeV where leading protons are detected by dedicated spectrometers. Correlations of systematic uncertainties are taken into account, resulting in an improved precision of the cross section measurement which reaches 6 % for the most precise points. The combined data cover the range 2.5 < Q(2) < 200 GeV2 in photon virtuality, 0.00035 < x(P) < 0.09 in proton fractional momentum loss, 0.09 < vertical bar t vertical bar < 0.55 GeV2 in squared four-momentum transfer at the proton vertex and 0.0018 < beta < 0.816 in beta = x/x(P), where x is the Bjorken scaling variable.
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| 49. |
- Abramowicz, H., et al.
(författare)
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Combination and QCD analysis of charm production cross section measurements in deep-inelastic ep scattering at HERA
- 2013
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Ingår i: European Physical Journal C. Particles and Fields. - : Springer Science and Business Media LLC. - 1434-6044. ; 73:2
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Tidskriftsartikel (refereegranskat)abstract
- Measurements of open charm production cross sections in deep-inelastic ep scattering at HERA from the H1 and ZEUS Collaborations are combined. Reduced cross sections sigma(c (c) over bar)(red) for charm production are obtained in the kinematic range of photon virtuality 2.5 <= Q(2) <= 2000 GeV2 and Bjorken scaling variable 3 . 10(-5) <= x <= 5 . 10(-2). The combination method accounts for the correlations of the systematic uncertainties among the different data sets. The combined charm data together with the combined inclusive deep-inelastic scattering cross sections from HERA are used as input for a detailed NLO QCD analysis to study the influence of different heavy flavour schemes on the parton distribution functions. The optimal values of the charm mass as a parameter in these different schemes are obtained. The implications on the NLO predictions for W-+/- and Z production cross sections at the LHC are investigated. Using the fixed flavour number scheme, the running mass of the charm quark is determined.
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| 50. |
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