Charmonium Decays at BESIII

The BESIII Experiment at the Beijing Electron Positron Collider (BEPCII) has accumulated the largest [Formula: see text] collisions data sets in the [Formula: see text]-charm region in the world. Using the data sets of 448.1 million [Formula: see text] events and 1.3 billion [Formula: see text] events, the branching fractions and the angular distributions of [Formula: see text] and [Formula: see text] decay to [Formula: see text], [Formula: see text], [Formula: see text] and [Formula: see text] are measured. The branching fractions of [Formula: see text] are reported with improved precision. The higher-order multipole amplitudes in [Formula: see text] with [Formula: see text] are measured, as a byproduct the [Formula: see text] transition is searched. The Dalitz decays of [Formula: see text] and [Formula: see text] are observed and the branching fractions are measured. [Formula: see text] radiative decays [Formula: see text] are observed for the first time. Improved measurement of [Formula: see text] and search for [Formula: see text] are reported.

Statistical multipole formulations for shielding problems

A multipole-based method is presented for modelling an electromagnetic field with small statistical variations inside an arbitrary enclosure. The accurate computation of the statistics of the field components from the statistical moments of the multipole amplitudes is demonstrated for two- and three-dimensional examples. To obtain the statistics of quantities which depend non-linearly on the field components, higher-order statistical moments of the latter are required.

ANALYSIS OF PION WEAK-PRODUCTION NEAR THRESHOLD BY MULTIPOLE AMPLITUDES

By exploiting the chiral Ward identities based on the QCD Lagrangian for pion weak production, we derive a transition amplitude by the weak current and show analytical results of relevant multipole amplitudes without any expansion. Their physical implications and numerical results are also discussed.

STUDYING γ*N→Δ→πN WITH CROSS SECTIONS AND POLARIZATION OBSERVABLES

Preliminary results are presented of the reaction γ*N→Δ→πN that was studied at the Jefferson Laboratory for transferred four momentum of 1.0 (GeV/c)2. Angular distributions of the cross sections and polarizations were measured over much of the available phase space. Out of the eighteen response functions involved in this reaction, fourteen separate responses and two additional response combinations were extracted. All resonant and background multipole amplitudes were decomposed for s- and p-waves as well as several of the d-wave multipole amplitudes. The responses and multipoles were compared to model calculations. Significant differences were observed between the experimental values and those of the models for several of the responses and multipoles. The ratios of the electric and longitudinal quadrupole amplitudes to the magnetic dipole amplitude were extracted. These values are different from previously reported values.