Subjects: Physics >> Nuclear Physics submitted time 2016-09-12
Abstract： Based on 2.93 fb−1 e+e− collision data taken at center-of-mass energy of 3.773 GeV by the BESIII detector, we report searches for the singly Cabibbo-suppressed decays D+→ωπ+ and D0→ωπ0. A double tag technique is used to measure the absolute branching fractions B(D+→ωπ+)=(2.79±0.57±0.16)×10−4 and B(D0→ωπ0)=(1.17±0.34±0.07)×10−4, with statistical significances of 5.5σ and 4.1σ, respectively. We also present measurements of the absolute branching fractions for the related ηπ decay modes. We find B(D+→ηπ+)=(3.07±0.22±0.13)×10−3 and B(D0→ηπ0)=(0.65±0.09±0.04)×10−3, which are consistent with the current world averages. The first and second uncertainties are statistical and systematic, respectively.
Peer Review Status:
Awaiting Review
Subjects: Physics >> Nuclear Physics submitted time 2016-09-12
Abstract： Using 567pb−1 of e+e− collisions recorded at s√=4.599GeV with the BESIII detector, we report first measurements of absolute hadronic branching fractions of Cabibbo-favored decays of the Λ+c baryon with a double-tag technique. A global least-square fitter is utilized to improve the measured precision. Among the measurements for twelve Λ+c decay modes, the branching fraction for Λ+c→pK−π+ 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 eleven Cabbibo-favored hadronic decay modes are significantly improved.
Peer Review Status:Awaiting Review
Subjects: Physics >> Nuclear Physics submitted time 2016-09-12
Abstract： By analyzing a data set of 2.92 fb−1 of e+e− collision data taken at s√=3.773 GeV and 106.41×106 ψ(3686) decays taken at s√=3.686 GeV with the BESIII detector at the BEPCII collider, we measure the branching fraction and the partial decay width for ψ(3770)→γχc0 to be B(ψ(3770)→γχc0)=(6.88±0.28±0.67)×10−3 and Γ[ψ(3770)→γχc0]=(187±8±19) keV, respectively. These are the most precise measurements to date.
Peer Review Status:Awaiting Review
Subjects: Physics >> Nuclear Physics submitted time 2016-09-12
Abstract： From 2011 to 2014, the BESIII experiment collected about 5 fb−1 data at center-of-mass energies around 4 GeV for the studies of the charmonium-like and higher excited charmonium states. By analyzing the di-muon process e+e−→γISR/FSRμ+μ−, the center-of-mass energies of the data samples are measured with a precision of 0.8 MeV. The center-of-mass energy is found to be stable for most of time during the data taking.
Peer Review Status:Awaiting Review
Subjects: Physics >> Nuclear Physics submitted time 2016-09-12
Abstract： We report the first absolute measurement of the branching fraction of Λ+c→Λe+νe. This measurement is based on 567 pb−1 of e+e− annihilation data produced at s√=4.599 GeV, which is just above the Λ+cΛ¯−cthreshold. The data were collected with the BESIII detector at the BEPCII storage rings. The branching fraction is determined to be B(Λ+c→Λe+νe)=(3.63±0.38(stat)±0.20(syst))%, representing a more than twofold improvement in precision upon previously published results. As the branching fraction for Λ+c→Λe+νeis the benchmark for those of other Λ+c semileptonic channels, our result provides a unique test of different theoretical models, which is the most stringent to date.
Peer Review Status:Awaiting Review
Subjects: Physics >> Nuclear Physics submitted time 2016-09-12
Abstract： Using 2.92~fb−1 of electron-positron annihilation data collected at s√=3.773~GeV with the BESIII detector, we obtain the first measurements of the absolute branching fraction B(D+→K0Le+νe)=(4.481±0.027(stat.)±0.103(sys.))% and the CP asymmetry AD+→K0Le+νeCP=(−0.59±0.60(stat.)±1.48(sys.))%. From the D+→K0Le+νe differential decay rate distribution, the product of the hadronic form factor and the magnitude of the CKM matrix element, fK+(0)|Vcs|, is determined to be 0.728±0.006(stat.)±0.011(sys.). Using |Vcs| from the SM constrained fit with the measured fK+(0)|Vcs|, fK+(0)=0.748±0.007(stat.)±0.012(sys.) is obtained, and utilizing the unquenched LQCD calculation for fK+(0), |Vcs|=0.975±0.008(stat.)±0.015(sys.)±0.025(LQCD).
Peer Review Status:Awaiting Review
Subjects: Physics >> Nuclear Physics submitted time 2016-09-12
Abstract： A neutral structure in the DD¯∗ system around the DD¯∗ mass threshold is observed with a statistical significance greater than 10σ in the processes e+e−→D+D∗−π0+c.c. and e+e−→D0D¯∗0π0+c.c. at s√ = 4.226 and 4.257 GeV in the BESIII experiment. The structure is denoted as Zc(3885)0. Assuming the presence of a resonance, its pole mass and width are determined to be (3885.7+4.3−5.7(stat)±8.4(syst)) MeV/c2 and (35+11−12(stat)±15(syst)) MeV, respectively. The Born cross sections are measured to be σ(e+e−→Zc(3885)0π0,Zc(3885)0→DD¯∗)=(77±13(stat)±17(syst)) pb at 4.226 GeV and (47±9(stat)±10(syst)) pb at 4.257 GeV. The ratio of decay rates B(Zc(3885)0→D+D∗−+c.c.)B(Zc(3885)0→D0D¯∗0+c.c.) is determined to be0.96±0.18(stat)±0.12(syst), consistent with no isospin violation in the process Zc(3885)0→DD¯∗.
Peer Review Status:Awaiting Review
Subjects: Physics >> Nuclear Physics submitted time 2016-09-12
Abstract： We present a study of the process e+e−→π±(DD¯∗)∓ using data samples of 1092~pb−1 at s√=4.23~GeV and 826~pb−1 at s√=4.26~GeV collected with the BESIII detector at the BEPCII storage ring. With full reconstruction of the D meson pair and the bachelor π± in the final state, we confirm the existence of the charged structure Zc(3885)∓ in the (DD¯∗)∓ system in the two isospin processes e+e−→π+D0D∗− and e+e−→π+D−D∗0. By performing a simultaneous fit, the statistical significance of Zc(3885)∓ signal is determined to be greater than 10σ, and its pole mass and width are measured to be Mpole=(3881.7±1.6(stat.)±1.6(syst.))~MeV/c2 and Γpole=(26.6±2.0(stat.)±2.1(syst.))~MeV, respectively. The Born cross section times the (DD¯∗)∓ branching fraction (σ(e+e−→π±Zc(3885)∓)×Br(Zc(3885)∓→(DD¯∗)∓)) is measured to be (141.6±7.9(stat.)±12.3(syst.)) pb at s√=4.23~GeV and (108.4±6.9(stat.)±8.8(syst.)) pb at s√=4.26~GeV. The polar angular distribution of the π±-Zc(3885)∓ system is consistent with the expectation of a quantum number assignment of JP=1+ for Zc(3885)∓.
Peer Review Status:Awaiting Review
Subjects: Physics >> Nuclear Physics submitted time 2016-09-12
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 to be B(D0→K−e+νe)=(3.505±0.014±0.033)% and B(D0→π−e+νe)=(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 CKM matrix element fK+(0)|Vcs|=0.7172±0.0025±0.0035 and fπ+(0)|Vcd|=0.1435±0.0018±0.0009. Combining these products with the values of |Vcs(d)| from the SM constraint fit, we extract the hadronic form factors fK+(0)=0.7368±0.0026±0.0036 and fπ+(0)=0.6372±0.0080±0.0044, and their ratio fπ+(0)/fK+(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 fK(π)+(0)|Vcs(d)| and the lattice QCD value for fK(π)+(0) are used to extract values of the CKM matrix elements of |Vcs|=0.9601±0.0033±0.0047±0.0239 and |Vcd|=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 fπ+(0)/fK+(0), we determine the ratio |Vcd|/|Vcs|=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.
Peer Review Status:Awaiting Review
Subjects: Physics >> Nuclear Physics submitted time 2016-09-10
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.
Peer Review Status:Awaiting Review
Subjects: Physics >> Nuclear Physics submitted time 2016-09-10
Abstract： We extract the e+e−→π+π− 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 |Fπ|2 as well as the contribution of the measured cross section to the leading order hadronic vacuum polarization contribution to (g−2)μ. We find this value to be aππ,LOμ(600−900MeV)=(368.2±2.5stat±3.3sys)⋅10−10.
Peer Review Status:Awaiting Review
Subjects: Physics >> Nuclear Physics submitted time 2016-09-10
Abstract： We present a measurement of the azimuthal asymmetries of two charged pions in the inclusive process e+e−→ππX based on a data set of 62 pb−1 at the center-of-mass energy 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.
Peer Review Status:Awaiting Review
Subjects: Physics >> Nuclear Physics submitted time 2016-09-10
Abstract： Based on a sample of \etapr mesons produced in the radiative decay J/ψ→γη′ in 1.31×109 J/ψ events collected with the BESIII detector, the decay η′→ωe+e− is observed for the first time, with a statistical significance of 8σ. The branching fraction is measured to be B(η′→ωe+e−)=(1.97±0.34(stat)±0.17(syst))×10−4, which is in agreement with theoretical predictions. The branching fraction of η′→ωγ is also measured to be (2.55±0.03(stat)±0.16(syst))×10−2, which is the most precise measurement to date, and the relative branching fraction B(η′→ωe+e−)B(η′→ωγ) is determined to be (7.71±1.34(stat)±0.54(syst))×10−3.
Peer Review Status:Awaiting Review
Subjects: Physics >> Nuclear Physics submitted time 2016-09-10
Abstract： We report a study of the process e+e−→(D∗D¯∗)0π0 using e+e− collision data samples with integrated luminosities of 1092pb−1 at s√=4.23GeV and 826pb−1 at s√=4.26GeV collected with the BESIII detector at the BEPCII storage ring. We observe a new neutral structure near the (D∗D¯∗)0 mass threshold in the π0 recoil mass spectrum, which we denote as Zc(4025)0. Assuming a Breit-Wigner line shape, its pole mass and pole width are determined to be (4025.5+2.0−4.7±3.1)MeV/c2 and (23.0±6.0±1.0)MeV, respectively. The Born cross sections of e+e−→Zc(4025)0π0→(D∗D¯∗)0π0 are measured to be (61.6±8.2±9.0)pb at s√=4.23GeV and (43.4±8.0±5.4)pb at s√=4.26GeV. The first uncertainties are statistical and the second are systematic.
Peer Review Status:Awaiting Review
Subjects: Physics >> Nuclear Physics submitted time 2016-09-10
Abstract： The decay Zc(3900)±→ωπ± is searched for using data samples collected with the BESIII detector operating at the BEPCII storage ring at center-of-mass energies s√=4.23 and 4.26~GeV. No significant signal for the Zc(3900)± is found, and upper limits at the 90\% confidence level on the Born cross section for the process e+e−→Zc(3900)±π∓→ωπ+π− are determined to be 0.26 and 0.18 pb at s√=4.23 and 4.26 GeV, respectively.
Peer Review Status:Awaiting Review
Subjects: Physics >> Nuclear Physics submitted time 2016-09-10
Abstract： We study D+s decays to final states involving the η′ with a 482pb−1 data sample collected at s√ = 4.009GeV with the \mbox{BESIII} detector at the BEPCII collider. We measure the branching fractions B(D+s→η′X) = (8.8±1.8±0.5)% and B(D+s→η′ρ+) = (5.8±1.4±0.4)% where the first uncertainty is statistical and the second is systematic. In addition, we estimate an upper limit on the non-resonant branching ratio B(D+s→η′π+π0)<5.1% at the 90% confidence level. Our results are consistent with CLEO's recent measurements and help to resolve the disagreement between the theoretical prediction and CLEO's previous measurement of B(D+s→η′ρ+).
Peer Review Status:Awaiting Review
Subjects: Physics >> Nuclear Physics submitted time 2016-09-10
Abstract： Using a data sample collected with the BESIII detector operating at the BEPCII storage ring, we observe a new neutral state Zc(3900)0 with a significance of 10.4σ. The mass and width are measured to be 3894.8±2.3±3.2MeV/c2 and 29.6±8.2±8.2~MeV, respectively, where the first error is statistical and the second systematic. The Born cross section for e+e−→π0π0J/ψ and the fraction of it attributable to π0Zc(3900)0→π0π0J/ψ in the range Ecm=4.19−4.42 GeV are also determined. We interpret this state as the neutral partner of the four-quark candidate Zc(3900)±.
Peer Review Status:Awaiting Review
Subjects: Physics >> Nuclear Physics submitted time 2016-09-10
Abstract： Based on a sample of 1.31×109 J/ψ events collected with the BESIII detector at the BEPCII collider, Dalitz plot analyses of selected 79,625 η→π+π−π0 events, 33,908 η→π0π0π0 events and 1,888 η′→π0π0π0events are performed. The measured matrix elements of η→π+π−π0 are in reasonable agreement with previous measurements. The Dalitz plot slope parameters of η→π0π0π0 and η′→π0π0π0 are determined to be −0.055±0.014±0.004 and −0.640±0.046±0.047, respectively, where the first uncertainties are statistical and the second systematic. Both values are consistent with previous measurements, while the precision of the latter one is improved by a factor of three. Final state interactions are found to have an important role in those decays.
Peer Review Status:Awaiting Review
Subjects: Physics >> Nuclear Physics submitted time 2016-09-10
Abstract： We report an observation of the process J/ψ→γX(1835)→γK0SK0Sη at low K0SK0S mass with a statistical significance larger than 12.9σ using a data sample of 1.31×109 J/ψ events collected with the BESIII detector. In this region of phase space the K0SK0S system is dominantly produced through the f0(980). By performing a partial wave analysis, we determine the spin-parity of the X(1835) to be JPC=0−+. The mass and width of the observed X(1835) are 1844±9(stat)+16−25(syst)~\MeV~and 192+20−17(stat)+62−43(syst)~MeV, respectively, which are consistent with the results obtained by BESIII in the channel J/ψ→γπ+π−η′.
Peer Review Status:Awaiting Review
Subjects: Physics >> Nuclear Physics submitted time 2016-09-10
Abstract： An amplitude analysis of the π0π0 system produced in radiative J/ψ decays is presented. In particular, a piecewise function that describes the dynamics of the π0π0 system is determined as a function of Mπ0π0 from an analysis of the (1.311±0.011)×109 J/ψ decays collected by the BESIII detector. The goal of this analysis is to provide a description of the scalar and tensor components of the π0π0 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/ψ→γπ0π0 is determined to be (1.15±0.05)×10−3, where the uncertainty is systematic only and the statistical uncertainty is negligible.
Peer Review Status:Awaiting Review
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