Bulletin of the American Physical Society
4th Joint Meeting of the APS Division of Nuclear Physics and the Physical Society of Japan
Volume 59, Number 10
Tuesday–Saturday, October 7–11, 2014; Waikoloa, Hawaii
Session 1WG: Hadron Structure and Spectroscopy I |
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Chair: Bill Briscoe, George Washington University Room: King's 3 |
Tuesday, October 7, 2014 9:00AM - 9:30AM |
1WG.00001: Baryon Spectroscopy from Two-Pion Producton Data Invited Speaker: Kenneth Hicks Reaction models for extraction of baryon parameters from measured observables have made significant advances recently and have shown the importance of coupled-channels effects when extracting the masses of resonance poles from experimental data. These coupled-channels effects are not small. For example, the transition magnetic moment which governs the Electromagnetic decay rate of the Delta resonance is off by 30{\%} or more from predictions of the non-relativistic quark model, yet when coupled-channels effects of the nucleon's ``pion cloud'' are included, the decay rate is predicted correctly. Extraction of nucleon resonance poles using two-pion production data from Jefferson Lab is inextricably linked to the need for higher-precision ($\pi $,2$\pi )$ reaction from J-PARC. The world database for ($\pi $,2$\pi )$ data on the nucleon is paltry and a new experiment has been approved at J-PARC to remedy this situation. Together, new high-precision data from both JLab and J-PARC will work together to ensure that coupled-channels effects are properly constrained in the search for the spectrum of nucleon resonances. [Preview Abstract] |
Tuesday, October 7, 2014 9:30AM - 10:00AM |
1WG.00002: Hadron Spectroscopy: Providing the link between experiment and theory in the intermediate energy region at JLAB Invited Speaker: Diane Schott The study of hadronic properties and structure is an important part of understanding QCD. Measuring resonances predicted by the Quark Model as well as other complex states such as hybrids or glue balls can lead to insights on quark-confinement and the behavior of gluons. The CEBAF Large Acceptance Spectrometer (CLAS) at Jefferson Lab (JLab) offers a unique set of opportunities in meson and baryon spectroscopy using photon and electron production. This talk will give an update on the experimental results and coordinated efforts from the JLab Physics Analysis Center (JPAC) and George Washington University Data Analysis Center (GWDAC) who's common goals include using observed data to provide insights into the fundamental theory of strong interactions. [Preview Abstract] |
Tuesday, October 7, 2014 10:00AM - 10:30AM |
1WG.00003: Baryon spectroscopy at ELPH and LEPS2 Invited Speaker: Takatsugu Ishikawa Baryon spectroscopy is an important testing ground for understanding low energy QCD. Meson photoproduction is complementary to $\pi$ induced reactions for studying excited baryons. Among the meson photo-produced reactions, the neutron target, kaon photo-produced, and multi-meson photo-produced reactions are important to reveal the properties of baryon resonances. The photoproduction experiments at ELPH and the planned experiments at LEPS2 will be discussed. The nucleon and $\Delta$ resonances are studied with an electromagnetic calorimeter FOREST at ELPH, Tohoku University by using various photoproduction reactions. A narrow resonance observed at W-75 MeV in $\eta$ photoproduction on the neutron is of great interest. It would be attributed to a member of anti-decuplet pentaquark baryons with hidden strangeness since no signature corresponding to this bump has been observed so far in the proton channel. Multi-meson/kaon photoproduction is a good tool to study highly excited baryons. The results obtained at ELPH and planned experiments at LEPS2 will be presented. [Preview Abstract] |
Tuesday, October 7, 2014 10:30AM - 11:00AM |
1WG.00004: COFFEE BREAK |
Tuesday, October 7, 2014 11:00AM - 11:30AM |
1WG.00005: Baryon resonance physics and its application to neutrino interactions Invited Speaker: Satoshi Nakamura Recent breakthrough measurements of non-zero neutrino mixing angle $\theta_{13}$ indicated a possibility of the CP violation in the lepton sector. Now the main concern of the neutrino physics is the leptonic CP violation and mass hierarchy. For making a progress towards this direction by analyzing data from the next-generation long-baseline and atmospheric experiments, neutrino-nucleon and neutrino-nucleus scattering in a wide kinematical region need to be understood much better than what are available at present. Our effort of developing a dynamical coupled-channels (DCC) model for neutrino-nucleon interaction is for challenging this demanding problem. The DCC model is designed to work in the resonance region where single- and double-pion productions are dominant processes. The DCC model is based on meson-exchange non-resonant mechanisms, and excitations of nucleon resonances. The DCC model includes channels relevant to the resonance region of $W\le$ 2 GeV ($W$: total hadronic energy); they are $\pi N, \pi \pi N, \pi\Delta, \rho N, \sigma N, \eta N, K \Sigma$ and $K \Lambda$. By solving a scattering equation, we obtain unitary amplitudes for meson productions. The DCC model has been developed for the purpose of extracting baryon resonance properties. We have successfully done a DCC-based analysis of world data of $\pi N, \gamma N \rightarrow \pi N, \eta N, K \Sigma$ and $K \Lambda$, and extracted properties of the baryon resonances~[1]. The DCC model has thus been well tested by a large amount of data. We extend the DCC model to describe the neutrino processes. Non-resonant axial currents are derived from a chiral Lagrangian, while resonant axial currents are fixed by the PCAC relation to the pion couplings. We present results of our calculations for the neutrino-induced meson production cross sections. We discuss roles played by various mechanisms such as $\Delta$-, higher resonance-excitations, and non-resonant mechanisms.\\[4pt] [1] H. Kamano, S.X. Nakamura, T. -S. H. Lee, and T. Sato, Phys. Rev. C {\bf 88}, 035209 (2013). [Preview Abstract] |
Tuesday, October 7, 2014 11:30AM - 12:00PM |
1WG.00006: Inroads in meson spectroscopy Invited Speaker: Adam Szczepaniak Meson spectroscopy plays an important role in constraining models used to describe non-perturbative QCD phenomena. I will discuss recent developments in theory and phenomenology and the emerging opportunities and challenges given the high precision data forthcoming from the Jefferson Lab and other facilities. [Preview Abstract] |
Tuesday, October 7, 2014 12:00PM - 12:30PM |
1WG.00007: Role of scalar mesons moving in finite-volume \& PW mixing Invited Speaker: Michael Doring As quark masses come closer to their physical values in lattice simulations, finite volume effects dominate the level spectrum. Methods to extract excited mesons from the finite volume will be discussed, like moving frames in the presence of coupled channels. Effective field theory can be used to stabilize the determination of the resonance spectrum. [Preview Abstract] |
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