Bulletin of the American Physical Society
2005 2nd Joint Meeting of the Nuclear Physics Divisions of the APS and The Physical Society of Japan
Sunday–Thursday, September 18–22, 2005; Maui, Hawaii
Session 2WD: Workshop 4B: Beyond qq-bar and qqq: Pentaquarks and More |
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Sponsoring Units: DNP JPS Chair: Ken Hicks, Ohio University Room: Ritz-Carlton Hotel Salon 1 |
Sunday, September 18, 2005 2:00PM - 2:30PM |
2WD.00001: Theory overview Invited Speaker: This talk will attempt an overview of the theory relevant to pentaquarks, with some emphasis on anticipated widths for the different parities, and on production rates for different circumstances and energies. [Preview Abstract] |
Sunday, September 18, 2005 2:30PM - 3:00PM |
2WD.00002: Spectroscopy of Pentaquark Baryons Invited Speaker: I summarize analyses of QCD-based approaches and constituent quark models of pentaquark baryon spectroscopy. QCD sum rules as well as lattice QCD simulations have been applied to the $S=+1$ pentaquark ($\Theta^+$) and its siblings. Their results do not completely agree with each other, but show interesting features which are not necessarily expected from naive constituent quark model pictures. On the other hand, quark models with various interaction models have predicted pentaquark baryons, but the predicted masses are generally much higher than the observed one. I will discuss possible solutions between the discrepancy between QCD and quark models, and most importantly with experiment. [Preview Abstract] |
Sunday, September 18, 2005 3:00PM - 3:30PM |
2WD.00003: Summary of Lattice Pentaquarks Invited Speaker: The status of lattice pentaquark studies will be reviewed. Claims in the literature are varied, with some calculations reporting evidence of a pentaquark state and others indicating nothing beyond a nucleon-kaon scattering state. The challenges in the identification of resonances and scattering states in lattice QCD will be discussed. I will identify the differences between various lattice pentaquark simulations and aim to provide a physical description of the results. [Preview Abstract] |
Sunday, September 18, 2005 3:30PM - 4:00PM |
2WD.00004: Production and decay of $\Theta^+$ Invited Speaker: In the first part we study the fall-apart decay of $\Theta^+$ within a non-relativistic quark model. Assuming $J^P$ of $\Theta^+$ are $1/2^{\pm}$, matrix elements and decay rates are computed in such way that the role of the overlap functions $\langle KN| \Theta^+\rangle$ for spin, flavor, color and orbital wave functions can be studied. We find that for $1/2^-$ of $(0s)^5$, the width is too large to be identified with a narrow resonance, while it is about a several tens MeV for $1/2^+$. By assuming strong diquark correlations, the width is reduced to be of order 10 MeV. It is then pointed out that within a quark model, strong suppression can occur if $J^P = 3/2^-$. Based on these observations, we study more on the possibility $J^P = 3/2^-$. We take a brief look at an analysis based on flavor SU(3), where we see that the present data seems to favor the $3/2^-$ quantum numbers. Then we reconsider photo-productions of $\Theta^+$ from the proton and neutron again but this time for $J = 3/2$. It is found that there is a large asymmetry between the production rates of the two targets; production from the proton is very much suppressed as compared with that from the neutron. The resulting cross section is only a few nb, which does not contradict the new CLAS result. [Preview Abstract] |
Sunday, September 18, 2005 4:00PM - 4:30PM |
2WD.00005: Chiral Structure of D Mesons in the Vector Manifestation Invited Speaker: Recently, BaBar, CLEO and Belle discovered the excited $D$ mesons with $J^P=0^+$ and $1^+$. There are several proposal of their constituents for explaining the mass splitting between the $D(0^+,1^+)$ mesons and the well-known $D(0^-,1^-)$ mesons which is much smaller than the one calculated in the constituent quark model: The 4-quark picture, the $D$-$K$ molecule picture, and so on. In this talk, I will introduce our work in which we consider the $D(0^+,1^+)$ mesons as the chiral partner to the $D(0^-,1^-) $ in the 2-quark picture. I will first introduce how to include the $D(0^+,1^+)$ mesons and the $D(0^-,1^-)$ mesons together with the pseudoscalar and vector mesons made from a light quark and a light anti-quark incorporating the heavy quark symmetry and the chiral symmetry. Then, starting with a hidden local symmetry Lagrangian at the vector manifestation fixed point and matching the bare theory to QCD, I will show that the mass splitting is well reproduced. I will also present our predictions on the hadronic decay processes of the excited $D(0^+,1^+)$ mesons. [Preview Abstract] |
Sunday, September 18, 2005 4:30PM - 5:00PM |
2WD.00006: Summary of Workshop Invited Speaker: I plan to discuss the experimental and theoretical talks and related publications that will be presented during the workshop. [Preview Abstract] |
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