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1. chinaXiv:201609.00826 [pdf]

Observation of the Singly Cabibbo-Suppressed Decay $D^+\to\omega\pi^+$ and Evidence for $D^0\to\omega\pi^0$

Ablikim, M. and others
Subjects: Physics >> Nuclear Physics

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.

submitted time 2016-09-12 Hits379Downloads216 Comment 0

2. chinaXiv:201609.00799 [pdf]

Measurements of absolute hadronic branching fractions of the $\Lambda_c^+$ baryon

Ablikim, M. and others
Subjects: Physics >> Nuclear Physics

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.

submitted time 2016-09-12 Hits350Downloads201 Comment 0

3. chinaXiv:201609.00786 [pdf]

Measurement of the branching fraction for $\psi(3770) \to \gamma \chi_c0$

Ablikim, M. and others
Subjects: Physics >> Nuclear Physics

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.

submitted time 2016-09-12 Hits386Downloads203 Comment 0

4. chinaXiv:201609.00784 [pdf]

Measurement of the center-of-mass energies at BESIII via the di-muon process

Ablikim, M. and others
Subjects: Physics >> Nuclear Physics

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.

submitted time 2016-09-12 Hits380Downloads221 Comment 0

5. chinaXiv:201609.00765 [pdf]

Measurement of the absolute branching fraction for $\Lambda^+_c\to \Lambda e^+\nu_e$

Ablikim, M. and others
Subjects: Physics >> Nuclear Physics

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.

submitted time 2016-09-12 Hits392Downloads216 Comment 0

6. chinaXiv:201609.00759 [pdf]

Study of decay dynamics and $CP$ asymmetry in $D^+ \to K^0_L e^+ \nu_e$ decay

Ablikim, M. and others
Subjects: Physics >> Nuclear Physics

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).

submitted time 2016-09-12 Hits367Downloads213 Comment 0

7. chinaXiv:201609.00742 [pdf]

Observation of a Neutral Structure near the $D\barD^*$ Mass Threshold in $e^+e^− \to (D ¯D )0π0 at ps = 4.226 and 4.257 GeV

Ablikim, M. and others
Subjects: Physics >> Nuclear Physics

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¯∗.

submitted time 2016-09-12 Hits358Downloads180 Comment 0

8. chinaXiv:201609.00722 [pdf]

Confirmation of a charged charmoniumlike state $Z_c(3885)^\mp$ in $e^+e^-\to\pi^\pm(D\barD^*)^\mp$ with double $D$ tag

Ablikim, M. and others
Subjects: Physics >> Nuclear Physics

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)∓.

submitted time 2016-09-12 Hits376Downloads212 Comment 0

9. chinaXiv:201609.00711 [pdf]

Study of Dynamics of $D^0 \to K^- e^+ \nu_e$ and $D^0\to\pi^- e^+ \nu_e$ Decays

Ablikim, M. and others
Subjects: Physics >> Nuclear Physics

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.

submitted time 2016-09-12 Hits365Downloads177 Comment 0

10. chinaXiv:201609.00614 [pdf]

Measurement of the form factors in the decay $D^+ \to \omega e^+ \nu_e$ and search for the decay $D^+ \to \phi e^+ \nu_e$

Ablikim, M. and others
Subjects: Physics >> Nuclear Physics

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.

submitted time 2016-09-10 Hits349Downloads199 Comment 0

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