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1. chinaXiv:201609.00628 [pdf]

Energy scan of the $e^+e^- \to h_b(nP)\pi^+\pi^-$ $(n=1,2)$ cross sections and evidence for $\Upsilon(11020)$ decays into charged bottomonium-like states

Abdesselam, A. and others
Subjects: Physics >> Nuclear Physics

Using data collected with the Belle detector at the KEKB asymmetric-energy?e+e??collider, we measure the energy dependence of the?e+e?→hb(nP)π+π??(n=1,2)?cross sections from thresholds up to?11.02GeV. We find clear?Υ(10860)?and?Υ(11020)?peaks with little or no continuum contribution. We study the resonant substructure of the?Υ(11020)→hb(nP)π+π??transitions and find evidence that they proceed entirely via the intermediate isovector states?Zb(10610)?and?Zb(10650). The relative fraction of these states is loosely constrained by the current data: the hypothesis that only?Zb(10610)?is produced is excluded at the level of 3.3 standard deviations, while the hypothesis that only?Zb(10650)?is produced is not excluded at a significant level.

submitted time 2016-09-10 Hits409Downloads260 Comment 0

2. chinaXiv:201609.00551 [pdf]

Measurement of Azimuthal Modulations in the Cross-Section of Di-Pion Pairs in Di-Jet Production from Electron-Positron Annihilation

Abdesselam, A. and others
Subjects: Physics >> Nuclear Physics

We present an extraction of azimuthal correlations between two pairs of charged pions detected in opposite jets from electron-positron annihilation. These correlations may arise from the dependence of the di-pion fragmentation on the polarization of the parent quark in the process?e+e?→qq?. Due to the correlation of the quark polarizations, the cross-section of di-pion pair production, in which the pion pairs are detected in opposite jets in a dijet event, exhibits a modulation in the azimuthal angles of the planes containing the hadron pairs with respect to the production plane. The measurement of this modulation allows access to combinations of fragmentation functions that are sensitive to the quark's transverse polarization and helicity. Within our uncertainties we do not observe a significant signal from the previously unmeasured helicity dependent fragmentation function?G⊥1. This measurement uses a dataset of 938~fb?1?collected by the Belle experiment at or near?s√≈10.58?GeV.

submitted time 2016-09-10 Hits415Downloads266 Comment 0

3. chinaXiv:201609.00543 [pdf]

First Observation of CP Violation in $\overlineB^0 \to D^(*)_\rm CP h^0$ Decays by a Combined Time-Dependent Analysis of BABAR and Belle Data

Abdesselam, A. and others
Subjects: Physics >> Nuclear Physics

We report a measurement of the time-dependent CP asymmetry of B0->D(*)CP h0 decays, where the light neutral hadron h0 is a pi0, eta or omega meson, and the neutral D meson is reconstructed in the CP eigenstates K+ K-, K0S pi0 or K0S omega. The measurement is performed combining the final data samples collected at the Y(4S) resonance by the BaBar and Belle experiments at the asymmetric-energy B factories PEP-II at SLAC and KEKB at KEK, respectively. The data samples contain ( 471 +/- 3 ) x 10^6 BB pairs recorded by the BaBar detector and ( 772 +/- 11 ) x 10^6, BB pairs recorded by the Belle detector. We measure the CP asymmetry parameters -eta_f S = +0.66 +/- 0.10 (stat.) +/- 0.06 (syst.) and C = -0.02 +/- 0.07 (stat.) +/- 0.03 (syst.). These results correspond to the first observation of CP violation in B0->D(*)CP h0 decays. The hypothesis of no mixing-induced CP violation is excluded in these decays at the level of 5.4 standard deviations.

submitted time 2016-09-10 Hits404Downloads258 Comment 0

4. chinaXiv:201609.00257 [pdf]

Measurement of the amplitude ratio of $B^0 \to D^0K^*0$ and $B^0 \to \bar{D}^0K^*0$ decays with a model-independent Dalitz plot analysis using $D\to K_S^0\pi^+\pi^-$ decays

Abdesselam, A. and others
Subjects: Physics >> Nuclear Physics

We report a measurement of the amplitude ratio rS of B0→D0K?0 and B0→D0?K?0 decays with a model-independent Dalitz plot analysis using D→K0Sπ+π? decays. Using the full data sample of 772×106 BB? pairs collected at the Υ(4S) resonance with the Belle detector at KEKB accelerator the upper limit is rS<0.87 at the 68 % confidence level. This result is the first measurement of rS with a model-independent Dalitz analysis, and is consistent with results from other analyses. The value of rS indicates the sensitivity of the decay to ?3 because the statistical uncertainty is proportional to 1/rS. The rS result is obtained from observables (x±, y±) x?y?x+y+,====+0.4+1.0+0.0?0.6?0.1±0.0?0.6+0.8+0.1?1.0?0.0±0.1+0.1+0.7+0.0?0.4?0.1±0.1+0.3+0.5+0.0?0.8?0.1±0.1 where x±=rScos(δS±?3), y±=rSsin(δS±?3) and ?3(δS) are the weak (strong) phase difference between B0→D0K?0 and B0→D0?K?0. The first uncertainty is statistical, the second is the experimental systematic and the third is the systematic due to the uncertainties on ci and si parameters measured by CLEO.

submitted time 2016-09-09 Hits438Downloads257 Comment 0

5. chinaXiv:201608.00166 [pdf]

Study of $\chi_bJ(1P)$ Properties in the Radiative $\Upsilon(2S)$ Decays

Abdesselam, A. and others
Subjects: Physics >> Nuclear Physics

We report a study of radiative decays of \chi_{bJ}(1P)(J=0,1,2) mesons into 74 hadronic final states comprising charged and neutral pions, kaons, protons; out of these, 41 modes are observed with at least 5 standard deviation significance. Our measurements not only improve the previous measurements by the CLEO Collaboration but also lead to first observations in many new modes. The large sample allows us to probe the total decay width of the \chi_{b0}(1P). In the absence of a statistically significant result, a 90% confidence-level upper limit is set on the width at \Gamma_{total}< 2.4 MeV. Our results are based on 24.7 fb^{-1} of e+e- collision data recorded by the Belle detector at the \Upsilon(2S) resonance, corresponding to (157.8\pm3.6)\times10^6 \Upsilon(2S) decays.

submitted time 2016-08-29 Hits401Downloads240 Comment 0

6. chinaXiv:201608.00117 [pdf]

Angular analysis of $B^0 \to K^\ast(892)^0 \ell^+ \ell^-$

Abdesselam, A. and others
Subjects: Physics >> Nuclear Physics

We present a measurement of angular observables,?P′4,?P′5,?P′6,?P′8, in the decay?B0→K?(892)0?+??, where??+???is either?e+e??or?μ+μ?. The analysis is performed on a data sample corresponding to an integrated luminosity of?711?fb?1?containing?772×106?BB??pairs, collected at the?Υ(4S)?resonance with the Belle detector at the asymmetric-energy?e+e??collider KEKB. Four angular observables,?P′4,5,6,8?are extracted in five bins of the invariant mass squared of the lepton system,?q2. We compare our results for?P′4,5,6,8?with Standard Model predictions including the?q2?region in which the LHCb collaboration reported the so-called?P′5?anomaly.

submitted time 2016-08-24 Hits433Downloads250 Comment 0

7. chinaXiv:201608.00101 [pdf]

Measurement of the branching ratio of $\barB^0 \rightarrow D^*+ \tau^- \bar\nu_\tau$ relative to $\barB^0 \rightarrow D^*+ \ell^- \bar\nu_\ell$ decays with a semileptonic tagging method

Abdesselam, A. and others
Subjects: Physics >> Nuclear Physics

We report a measurement of ratio R(D?)=B(B?0→D?+τ?ν?τ)/B(B?0→D?+??ν??), where ? denotes an electron or a muon. The results are based on a data sample containing 772×106 BB? pairs recorded at the Υ(4S) resonance with the Belle detector at the KEKB e+e? collider. We select a sample of B0B?0 pairs by reconstructing both B mesons in semileptonic decays to D???±. We measure R(D?)=0.302±0.030(stat)±0.011(syst), which is within 1.6σ of the Standard Model theoretical expectation, where σ is the standard deviation including systematic uncertainties.

submitted time 2016-08-23 Hits479Downloads275 Comment 0

8. chinaXiv:201608.00094 [pdf]

Measurement of the Branching Fraction and $CP$ Asymmetry in Radiative $D^0 \to V \gamma$ Decays

Abdesselam, A. and others
Subjects: Physics >> Nuclear Physics

We report a measurement of the branching fractions of the radiative decays?D0→Vγ, where?V=?,?K??????0?or?ρ0. This is the first observation of the decay?D0→ρ0γ. We measure preliminary branching fractions?B(D0→?γ)=(2.76±0.20±0.08)×10?5,?B(D0→K??????0γ)=(4.66±0.21±0.18)×10?4?and?B(D0→ρ0γ)=(1.77±0.30±0.08)×10?5, where the first uncertainty is statistical and the second systematic. We also present the first measurement of?CP?asymmetry in these decays. The preliminary values are?ACP(D0→?γ)=?(0.094±0.066±0.001),?ACP(D0→K??????0γ)=?(0.003±0.020±0.000)?and?ACP(D0→ρ0γ)=0.056±0.151±0.006. The analysis was conducted using 943 fb?1?of data collected by the Belle detector at the KEKB?e+e??collider.

submitted time 2016-08-23 Hits369Downloads234 Comment 0

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