Meson2006 Summary: Theory

This is a summary of theoretical plenary contributions to the biennial hadron physics conference Meson2006, which was the ninth in this series. The topics covered in the meeting include low energy pion-pion and pion-nucleon interactions, photoproduction and hadronic production of light mesons and baryons,in-medium effects, recent developments in charmed mesons, charmonia and B mesons, the status of exotica, and some related topics such as final state interactions. In this contribution we review and summarize the plenary talks presented by theorists at the meeting, and emphasize some of the main points of their presentations. Where appropriate we will add brief comments on some aspects of QCD spectroscopy. Finally, following tradition, we conclude with a new Feynman story.Comment: 4 pages, 1 Feynman story. Invited summary talk (theory) at the 9th International Workshop on Meson Production, Properties and Interactions MESON2006 (Krakow, 9-13 June 2006

HADRON05 Summary: Heavy Quark Hadrons and Theory

This HADRON05 summary covers the topics of (1) mesons containing heavy quarks, and (2) theory. The new material discussed here is taken mainly from plenary presentations. We specifically emphasize new or recent results in spectroscopy that are likely to appear in future editions of the PDG. An exception is made for the pentaquark, which has now been withdrawn. We undoubtedly have something important to (re)learn about multiquarks from the pentaquark saga, and this merits a phrase in Portuguese. The three general areas we consider are: I. QQbar spectroscopy, II. Qqbar spectroscopy, and III. lessons from the pentaquark. Finally, in Section IIIb. we conclude with "Our moment of Zen".Comment: 14 pages, 10 eps figures. Presented at HADRON05 (Rio, 21-26 Aug. 2005

Photoproduction of Hybrid Mesons

In this contribution I discuss prospects for photoproducing hybrid mesons at CEBAF, based on recent model results and experimental indications of possible hybrids. One excellent opportunity appears to be a search for the I=1, JPC=2+-, neutral "(b2)o" hybrid in (a2 pi)o through diffractive photoproduction. Other notable possibilities accessible through pi+ or pio exchange photoproduction are I=1, JPC=1-+, charged "pi1+" in f1 pi+, (b1 pi)+ and (rho pi)+; piJ(1770)+ in f2 pi+ and (b1 pi)+; pi(1800)+ in f0 pi+, f2 pi+, omega rho+ and (rho pi)+; a1 in f1 pi+ and f2 pi+; and omega in (rho pi)o, omega eta and (K1 K)o.Comment: 5 pages, 3 postscript figures. Invited contribution to Confinement III, CEBAF (8-12 June 1998

MESON2000 Conference Summary

This short contribution is a {\it lite} MESON2000 conference summary. As appropriate for the 600th anniversary of the Jagellonian University, it begins with a brief summary of the last 600 years of European history and its place in hadron physics. Next a ``physicist chirality'' order parameter PC is introduced. When applied to MESON2000 plenary speakers this order parameter illustrates the separation of hadron physicists into disjoint communities. The individual plenary talks in MESON2000 are next sorted according to the subconference associated with each of the 36 plenary speakers. Finally, I conclude with a previously unreported Feynman story regarding the use of models in hadron physics.Comment: 11 pages, 3 figures, uses appolb.cps and epsfig. MESON2000 Conference Summary Tal

Update on Charmonium Theory

In this invited presentation I review some recent developments in the theory of charmonium that appear likely to be of importance for future experimental studies in this field. The specific areas considered are double charmonium production, LQCD studies of charmonium, recent results for hadron loops, c-cbar production cross sections at PANDA, charm molecules, and two recent developments, "charmiscelleny".Comment: 8 pp., 3 figures. Invited contribution to HADRON 2009 (XIIIth Internatl. Conf. on Hadron Spectroscopy, Tallahassee, FL, Nov.29 - Dec.4 2009)

Psi to N Nbar m

In this invited talk I discuss two recent applications of charmonium (Psi) decays to N Nbar m final states, where N is a nucleon and m is a light meson. There are several motivations for studying these decays: 1) They are useful for the study of N* spectroscopy; 2) they can be used to estimate cross sections for the associated charmonium production processes p pbar to Psi m, which PANDA plans to exploit in searches for charmonium hybrid exotics; and 3) they may allow the direct experimental measurement of NNm (meson-nucleon) strong couplings, which provide crucial input information for meson exchange models of the NN force. The latter two topics are considered in this talk, which will also compare results from a simple hadron pole model of these decays to recent experimental data.Comment: Invited contribution to Charm2010 (Fourth International Workshop on Charm Physics), Beijing, China, 21-24 Oct. 2010. 3 pages, 3 figures, uses epsfi

Radial Excitations

In this contribution I review recent experimental developments in the spectroscopy of higher-mass mesons, especially candidate radial excitations discussed at the WHS99 meeting in Frascati.Comment: Postscript, 14 pages, 1 fig, uses included frascatiphys.sty. Summary Report, Session on Radial Excitations, WHS99 (Frascati, 8-12 March 1999

Hybrid Baryons, a brief review

This contribution is a brief review of the status of hybrid baryons, which are hypothetical baryons that incorporate a gluonic excitation. We first summarize the status of hybrid mesons, since this closely related topic has seen considerable recent activity with the identification of two exotic candidates. Next we review theoretical expectations for the masses and quantum numbers of hybrid baryons, which have come from studies of the bag model, QCD sum rules and the flux tube model. Finally hybrid baryon experiment is discussed, including suggestions for experimenters at COSY.Comment: 11 pages, 5 figures. Invited contribution to the COSY Workshop on Baryon Excitations, Juelich, 2-3 May 200