| 1. |
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| 2. |
- Ablikim, M., et al.
(författare)
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Measurement of azimuthal asymmetries in inclusive charged dipion production in $e^+e^-$ annihilations at $\sqrt{s}$ = 3.65 GeV
- 2016
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Ingår i: PHYSICAL REVIEW LETTERS. - 0031-9007 .- 1079-7114. ; 116:4
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Tidskriftsartikel (refereegranskat)abstract
- We present a measurement of the azimuthal asymmetries of two charged pions in the inclusive process $e^+e^-\rightarrow \pi\pi X$ based on a data set of 62 $\rm{pb}^{-1}$ at the center-of-mass energy $\sqrt{s}=3.65$ GeV collected with the BESIII detector. These asymmetries can be attributed to the Collins fragmentation function. We observe a nonzero asymmetry, which increases with increasing pion momentum. As our energy scale is close to that of the existing semi-inclusive deep inelastic scattering experimental data, the measured asymmetries are important inputs for the global analysis of extracting the quark transversity distribution inside the nucleon and are valuable to explore the energy evolution of the spin-dependent fragmentation function.
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| 3. |
- Ablikim, M., et al.
(författare)
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Measurement of the e(+)e(-) -> pi(+) pi(-) cross section between 600 and 900 MeV using initial state radiation
- 2016
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Ingår i: Physics Letters B. - : Elsevier BV. - 0370-2693 .- 1873-2445. ; 753, s. 629-638
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Tidskriftsartikel (refereegranskat)abstract
- We extract the e(+) e(-) -> pi(+) pi(-) cross section in the energy range between 600 and 900 MeV, exploiting the method of initial state radiation. A data set with an integrated luminosity of 2.93 fb(-1) taken at a center-of-mass energy of 3.773 GeV with the BESIII detector at the BEPCII collider is used. The cross section is measured with a systematic uncertainty of 0.9%. We extract the pion form factor vertical bar F pi vertical bar(2) as well as the contribution of the measured cross section to the leading-order hadronic vacuum polarization contribution to (g - 2)(mu). We find this value to be a(mu)(pi pi,LO) (600-900 MeV) = (368.2 +/- 2.5(stat)+/- 3.3(sys)).10(-10), which is between the corresponding values using the BaBar or KLOE data.
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| 4. |
- Ablikim, M., et al.
(författare)
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Measurement of the form factors in the decay D+ → ωe+νe and search for the decay D+ → ϕe+νe
- 2015
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Ingår i: Physical Review D. - : American Physical Society. - 1550-7998 .- 1550-2368. ; 92:7
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Tidskriftsartikel (refereegranskat)abstract
- Using 2.92 fb−1 of electron-positron annihilation data collected at a center-of-mass energy of √s=3.773 GeV with the BESIII detector, we present an improved measurement of the branching fraction B(D+ → ωe+νe)=(1.63±0.11±0.08)×10−3. The parameters defining the corresponding hadronic form factor ratios at zero momentum transfer are determined for the first time; we measure them to be rV=1.24±0.09±0.06 and r2=1.06±0.15±0.05. The first and second uncertainties are statistical and systematic, respectively. We also search for the decay D+ → ϕe+νe. An improved upper limit B(D+ → ϕe+νe)<1.3×10−5 is set at 90% confidence level.
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| 5. |
- Ablikim, M., et al.
(författare)
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Measurements of Absolute Hadronic Branching Fractions of the Lambda(+)(c) Baryon
- 2016
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Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 116:5
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Tidskriftsartikel (refereegranskat)abstract
- We report the first measurement of absolute hadronic branching fractions of Lambda(+)(c) baryon at the Lambda(+)(c)(Lambda) over bar (-)(c) production threshold, in the 30 years since the Lambda(+)(c) discovery. In total, 12 Cabibbo-favored Lambda(+)(c) hadronic decay modes are analyzed with a double-tag technique, based on a sample of 567 pb(-1) of e(+)e(-) collisions at root s = 4.599 GeV recorded with the BESIII detector. A global least-squares fitter is utilized to improve the measured precision. Among the measurements for twelve Lambda(+)(c) decay modes, the branching fraction for Lambda(+)(c) -> pK(-)pi(+) is determined to be (5.84 +/- 0.27 +/- 0.23)%, where the first uncertainty is statistical and the second is systematic. In addition, the measurements of the branching fractions of the other 11 Cabibbo-favored hadronic decay modes are significantly improved.
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| 6. |
- 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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| 7. |
- Ablikim, M., et al.
(författare)
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Observation of eta ' -> omega e(+)e(-)
- 2015
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Ingår i: Physical Review D. - 1550-7998 .- 1550-2368. ; 92:5
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Tidskriftsartikel (refereegranskat)abstract
- Based on a sample of eta' mesons produced in the radiative decay J/psi -> gamma eta' in 1.31 x 10(9) J/psi events collected with the BESIII detector, the decay eta' -> omega e(+)e(-) is observed for the first time, with a statistical significance of 8 sigma. The branching fraction is measured to be B(eta' -> omega e(+)e(-)) = (1.97 +/- 0.34(stat) +/- 0.17(syst)) x 10(-4), which is in agreement with theoretical predictions. The branching fraction of eta' -> omega gamma is also measured to be (2.55 +/- 0.03(stat) +/- 0.16(syst)) x 10(-2), which is the most precise measurement to date, and the relative branching fraction B(eta' -> omega e(+)e(-))/B(eta' -> omega gamma) is determined to be (7.71 +/- 1.34(stat) +/- 0.54(syst)) x 10(-3).
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| 8. |
- Ablikim, M., et al.
(författare)
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Study of dynamics of D-0 -> K(-)e(+)nu(e) and D-0 -> pi(-)e(+)nu(e) decays
- 2015
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Ingår i: Physical Review D. - 1550-7998 .- 1550-2368. ; 92:7
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Tidskriftsartikel (refereegranskat)abstract
- In an analysis of a 2.92 fb(-1) data sample taken at 3.773 GeV with the BESIII detector operated at the BEPCII collider, we measure the absolute decay branching fractions B(D-0 -> K(-)e(+)nu(e)) = (3.505 +/- 0.014 +/- 0.033)% and B(D-0 -> pi(-)e(+)nu(e)) = (0.295 +/- 0.004 +/- 0.003)%. From a study of the differential decay rates we obtain the products of hadronic form factor and the magnitude of the Cabibbo-Kobayashi-Maskawa (CKM) matrix element f(+)(K)(0)vertical bar V-cs vertical bar = 0.7172 +/- 0.0025 +/- 0.0035 and f(+)(pi)(0)vertical bar V-cd vertical bar = 0.1435 +/- 0.0018 +/- 0.0009. Combining these products with the values of vertical bar V-cs(d)vertical bar from the SM constraint fit, we extract the hadronic form factors f(+)(K)(0) = 0.7368 +/- 0.0026 +/- 0.0036 and f(+)(pi)(0) = 0.6372 +/- 0.0080 +/- 0.0044, and their ratio f(+)(pi)(0)/f(+)(K)(0) = 0.8649 +/- 0.0112 +/- 0.0073. These form factors and their ratio are used to test unquenched lattice QCD calculations of the form factors and a light cone sum rule (LCSR) calculation of their ratio. The measured value of f(+)(K(pi))(0)vertical bar V-cs(d)vertical bar and the lattice QCD value for f(+)(K(pi))(0) are used to extract values of the CKM matrix elements of vertical bar V-cs vertical bar = 0.9601 +/- 0.0033 +/- 0.0047 +/- 0.0239 and vertical bar V-cd vertical bar = 0.2155 +/- 0.0027 +/- 0.0014 +/- 0.0094, where the third errors are due to the uncertainties in lattice QCD calculations of the form factors. Using the LCSR value for f(+)(pi)(0)/f(+)(K)(0), we determine the ratio vertical bar V-cd vertical bar/vertical bar V-cs vertical bar = 0.238 +/- 0.004 +/- 0.002 +/- 0.011, where the third error is from the uncertainty in the LCSR normalization. In addition, we measure form factor parameters for three different theoretical models that describe the weak hadronic charged currents for these two semileptonic decays. All of these measurements are the most precise to date.
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| 9. |
- Ablikim, M., et al.
(författare)
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Amplitude analysis of the pi(0)pi(0) system produced in radiative J/psi decays
- 2015
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Ingår i: Physical Review D. - 1550-7998 .- 1550-2368. ; 92:5
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Tidskriftsartikel (refereegranskat)abstract
- An amplitude analysis of the pi(0)pi(0) system produced in radiative J/psi decays is presented. In particular, a piecewise function that describes the dynamics of the pi(0)pi(0) system is determined as a function of M pi(0)pi(0) from an analysis of the (1.311 +/- 0.011) x 10(9) J/psi decays collected by the BESIII detector. The goal of this analysis is to provide a description of the scalar and tensor components of the pi(0)pi(0) system while making minimal assumptions about the properties or number of poles in the amplitude. Such a model-independent description allows one to integrate these results with other related results from complementary reactions in the development of phenomenological models, which can then be used to directly fit experimental data to obtain parameters of interest. The branching fraction of J/psi -> pi(0)pi(0) is determined to be (1.15 +/- 0.05) x 10(-3), where the uncertainty is systematic only and the statistical uncertainty is negligible.
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| 10. |
- Ablikim, M., et al.
(författare)
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Dark photon search in the mass range between 1.5 and 3.4 GeV/c
- 2017
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Ingår i: Physics Letters B. - : Elsevier BV. - 0370-2693 .- 1873-2445. ; 774, s. 252-257
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Tidskriftsartikel (refereegranskat)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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