Hirschegg workshop

STRUCTURE OF HADRONS: Jan. 14 - 20, 2001

So far the following abstracts have been handed in:

QCD Exotica
Barnes, T. (ORNL and U.Tenn.)
Abstract: In this contribution I will review theoretical expectations and the current experimental status of meson spectroscopy, including both conventional qqbar states and exotica (glueballs and hybrids). The outstanding puzzles that have been raised by the recent f0(1500) glueball and pi1(1400) and pi1(1600) exotic candidates in particular will be considered, and the contributions that GSI might make to understanding the physics of glueballs and exotics with a pbar machine will be stressed.

New perspectives for the measurement of the nucleon timelike form factors
Bettoni, D (INFN - Ferrara), PEP-N Collaboration
Abstract: In this paper I will review the experimental situation of the electromagnetic form factors of the nucleon in the time-like region. Some unexpected features, such as the steep behaviour of the form factors near threshold and the fact that neutron form factor is bigger than that of the proton, remain unexplained and need further experimental study. I will then describe a new experiment being proposed at SLAC to carry out a high statistics measurement of the neutron and proton form factors from threshold to 2.5 GeV. The experiment will also be designed to perform a high precision measurement of the R ratio over the same energy range.

DAPHNE
T. Bressani, Dipartimento di Fisica Sperimentale, Universita' di Torino
Abstract: DAPHNE (acronym for Double Annular PHI-factory for Nice Experiments) is the PHI-factory complex recently assembled in Frascati and which is now continuing the commissioning stage. Maximum luminosity till now achieved is $10^31$ cm$^-2$ s$^-1$. Three experiments were approved: KLOE, aiming at a measurement of the ratio epsilon'/epsilon to a precision of $10^-4$, FINUDA, having the goal of a systematic and precise investi gation of the production and decay of Lambda-Hypernuclei, and DEAR, with the scope of measuring with high precision the X-ray spectrum from Kaonic Hydrogen. The FINUDA potentialities and physics program will be illustrated in details. The experiment take advantage from the unique features of the K- from phi decay ($\sim$16 MeV), that may be stopped in very thin targets ($\sim$200 mg cm$^-2$). Excitation spectra of the produced Hypernuclei could be measured with a precision of 700 keV FWHM as well as the products from the Hypernuclei decay, in coincidence with different regions of the Hypernucleus excitation spectrum. Answers to a possible violation of the DELTA I = 1/2 rule in non-mesonic weak decays are expected from experiment. Other interesting items within reach of the experiment are the production of neutron rich Lambda-hypernuclei and the identification of rare two-body non-mesonic decays of light hypernuclei.

Hadron Physics at Jefferson Lab - CLAS results
Burkert, V.D. (Jefferson Lab)
Abstract: Recent results of measurements of the N-Delta(1232) transition multipoles, the search for "missing" resonances in vector meson production, and on spin polarization asymmetries in the resonance region will be presented. Additional results on strangeness photo-and electroproduction,and on phi and rho photoproduction at high t may be discussed as time permits.

Current Status and Future Prospects for Exotic mesons
Suh-Urk Chung (Geneve)
Abstract: The current status and future prospects for exotic mesons are given. The emphasis will be on how one can gain further insight into the constituency of mesons through a new generation of high-flux pion and kaon beams at medium energies.

Charmonium spectroscopy in proton-antiproton annihilations
Roberto Calabrese - E835 Collaboration
Abstract: Fermilab experiment E835 studies the direct formation of charmonium states in proton-antiproton annihilations, obtained by intersecting the antiproton beam of the Fermilab Antiproton Accumulator with an internal hydrogen jet target. In this talk I will report the latest results of the experiment about mass, total width and partial widths of charmonium resonances.

Pontecorvo Reactions With Open Strangeness
W.Duennweber, Crystal Barrel Collaboration
Abstract: \def\circle{0} Annihilation reactions of antinucleons on nuclei that are kinematically not possible on a free nucleon were first envisaged by Pontecorvo. From experiments at LEAR a systematics of annihilation rates for antiproton + deuteron $\rightarrow$ meson + baryon Pontecorvo reactions emerges which lends support to a statistical (fireball) model. Of crucial importance are the open strangeness channels $K^{\circle}\Lambda$ and $K^{\circle}\Sigma^{\circle}$ discovered by the Crystal Barrel experiment.

The structure of the nucleon
Düren, M. (HERMES Collaboration)
Abstract: About 30 years ago deep inelastic scattering revealed the partonic substructure of the nucleon. Since then, deep inelastic scattering has been used extensively to study the quark and gluon content of proton and neutron, but we are still far away from understanding the "non-pertubative" substructure of the nucleon in detail. The talk will present some of the modern experimental techniques, and will focus on recent results about the flavor and spin structure of the nucleon and how this structure is modified in a nuclear environment.

Nuclear shadowing in photoabsorption at low energies
Falter, T., Leupold, S., Mosel, U.
Abstract:\def\gtrsim{>\hspace*{-4mm}^\sim} In [1] we showed that one can understand the early onset of nuclear shadowing in photoabsorption at photon energies $\gtrsim$ 1 GeV within simple Glauber theory if one takes the negative real part of the $\rho N$ scattering amplitude into account, corresponding to a higher effective mass of the $\rho$ meson in nuclear medium. However, some of the assumptions that enter the model become questionable at low energies. We examined how the consideration of diffractively produced pion pairs with invariant masses different from the physical $\rho$ mass influences our result and found no remarkable changes. We also investigated two other approximation that are usually made in Glauber theory namely the neglect of Fermi motion of the bound nucleons and the usage of the eikonal approximation. By choosing a multiple scattering approach one can avoid both approximations. We found that the eikonal approximation while working well at very high photon energies leads to an overestimation of the shadowing effect in the onset region. Furthermore does the possibility of scattering in non-forward directions allow for a new contribution to nuclear shadowing: The coherent production of neutral pions as intermediate hadronic states enhances the shadowing effect at very low energies and improves the agreement with experimental data. Work supported by BMBF and GSI. [1] T. Falter, S. Leupold and U. Mosel, Phys. Rev.C \textbf{62}, 031602 (2000).

Antinucleon-Nucleon elastic cross sections below 100 MeV/c
A. Feliciello, I.N.F.N. - Sezione di Torino, for the ELAPP Experiment
Abstract: Recent results from the OBELIX Collaboration have shown an anomalous behaviour of the elastic nbar-p cross section below 100 MeV/c, suggesting a dip-bump structure, not explained nor by present models nor by parameterizations of the antinucleon-nucleon interaction. Another conclusion inferred from the experimental data is that below 100 MeV/c the channel I = 0 dominates over the I = 1 one by at least a factor 2. Stimulated by the interest of these new data, we are investigating whether it is possible to perform some relevant measurement at the CERN AD machine. Clearly the investigation of the I = 1 channel (nbar-p system) is no longer feasible, but the above anomalous behaviour should manifest itself also in the pbar-p system elastic cross-section (mixture of I = 0 and I = 1 states) below 100 MeV/c, never measured. A way of measuring the pbar-p elastic cross section at AD in fast extraction mode is under study. We are investigating an experimental device based on the following options: a small target (radius $\sim$1.5 mm, thickness < 10 microns) made of CH2; a detector of reduced size, (essentially a box $\sim$ 6 x 6 x 6 cm3) with the four sides made by six layers of scintillanting fibers, with a section of $\sim$ 1 mm$^2$, viewed by multianode photomultipliers; a read-out system of the scintillating fibers based on 100 MHz FADCs; beam energy varied by absorbers of suitable thickness; a carefull studied and designed beam dump. Concerning the rates, we estimate to obtain $\sim$1 event/burst for pbar-p elastic scattering, by assuming 10$^6$ pbar/burst. pbar-p elastic cross section could be measured in 1-2 days at one energy settings and pbar-p annihilation cross section too, provided a background measurement with a C target of equivalent thickness is performed in the same amount of time.

Glueballs and Instantons
Hilmar Forkel
Abstract: The direct instanton contributions to the operator product expansion (OPE) of spin-0 glueball correlation functions are evaluated. These contributions are found to dominate those from perturbative fluctuations and from soft vacuum fields. Sum rules built on the instanton- improved OPE show a high degree of stability and are the first to be consistent with the low-energy theorem for the zero-momentum correlator. The predictions for the scalar glueball mass, $m_g = 1.53 \pm 0.2$ GeV, and the strongly enhanced decay constant, $f_G = 1.01 \pm 0.25$ GeV, are found to scale as powers of the average instanton size and density. The issue of gluonium-quarkonium mixing is also addressed.

Concept for an Antiproton Facility and the HESR at GSI.
Franzke, B. (GSI-Darmstadt)
Abstract: The proposal for the extension of the heavy ion accelerator facilities at GSI includes also high luminosity experiments with cooled antiproton beams in an High Energy Storage Ring HESR [1] at laboratory energies up to 14 GeV. The conceptual design of antiproton beam production and accumulation has to be based to a large extend on accelerators and storage rings, which either exist already (SIS 18) or are planned for other purpose (200 Tm-synchrotron SIS 200, 13 Tm-Collector Ring CR, new 13 Tm-Experimental Storage Ring). Besides the HESR a 50 MeV-proton linac and the antiptoton production target/separation area have to be designed especially for the preparation of antiproton beams. The contribution discusses major design characteristics as well as possible limitations due to the boundary conditions for the conceptual design of the antiproton beam facility and the HESR. [1] Construction of a Glue/Charm-Factory at GSI, Letter of Intend, edited by H. Koch, University of Bochum, Germany, October 1998

Cold Antihydrogen
Gabrielse, G., Harvard University, Department of Physics
Abstract: At CERN's new Antiproton Decelerator, our ATRAP Collaboration has trapped 4.2 K antiprotons, and 4.2 K positrons -- the first and only ingredients of cold antihydrogen realized at the new facility. We are now making these two species to interact in the hope of producing slow antihydrogen for the first time. Cold antihydrogen offers the possibility to trap the antihydrogen and use laser spectroscopy to probe for tiny differences between antihydrogen and hydrogen at a interesting level of precision.

Deeply Bound Pionic Atoms
A. Gillitzer, IKP, FZ Juelich
Abstract: will be sent later

The Structure of the Nucleon as seen with leptonic Probes
Dietrich Harrach
Abstract: The nonperturbative structure of hadrons can be studied by measuring structure functions and their dependence on momentum transfer. The determination of the spin and flavour structure including quarks and gluons is the goal of current experiments. The inclusion of semiinclusive and exclusive processes is underway experimentally and theoretically. Some speculations about the future possibilities to learn about chiral symmetry breaking, condensates and instantons are presented.

Photo Production of Charmonia
Huefner, J., Ivanov, Yu, Kopeliovich, B.Z., Tarasov, A.V., Heidelberg
Abstract: Elastic photo production cross sections (Gamma + proton > J/psi(Psiprime)are calculated without free parameter within the light-cone dipole formalism.

CP violation in the charm sector
Cecilia Jarlskog
Abstract: After a short review of the present situation concerning CP violation, I will focus on mixing and CP violation involving charmed particles.

Hadron structure functions in the next to leading order
Ali N. Khorramian
Abstract: We calculate the partonic structure of constituent quark in the Next-to-Leading Order. Using a convolution method, Structure function of proton is presented. While the constituent quark structure is generated purely perturbatively and accounts for the most part of the hadronic structure, there is a few percent contributions coming from the nonperturbative sector in the hadronic structure. This contribution plays the key role in explaining the $SU(2)$ symmetry breaking of the nucleon sea and the observed violation of Gottfried sum rule.

Reduction of the Chiral Order Parameter by a Nuclear Medium
P. Kienle and T. Yamazaki, TU München u. RIKEN Japan
Abstract: Model-independant procedures are discussed to deduce from spectra of deeply bound pionic states in heavy nuclei the isovector vector scattering length $b_1$ of the pion nucleus interaction, which is related to a possible modified pion decay constant, $f_\pi$, in a nuclear nuclear medium. Recently measured pion binding energies in $^{205}$Pb [1] indicate a $b_1$-scattering length of about -0.17 $m_\pi^{-1}$ compared with a vacuum value of $-(86.8 ± 1.4) x 10^{-3}$ [2]. This indicates a reduction of $f_{\pi}$ by about 30\% by a $^{205}$Pb nucleus, in agreement with expectations from chiral perturbation theory [3]. By comparing pion binding energies of two nuclei with different $(N-2)/A$ values such $^{205}$Pb and $^{115}$Sn or by isotope and isotone shift measurements of binding energies and widths, we hope to solve the in medium $b_1$-problem in a rather systematic fashion. [1]H. Geissel et al. to be published\\ [2]H. Ch. Schröder et al. Phys. Lett. B469 (1999) 469\\ [3]R. Leisbach, Diplomarbeit at W. Weise, Technische Universität München, August 2000

Future Physics Program at COSY
K. Kilian, Juelich
Abstract: The cooler synchrotron COSY produces data in the field of proton proton and proton nucleus interactions since 1994. With a first generation of detectors a growing number of new results is published year by year. Proton - proton interactions were studied from polarized elastic scattering down in cross section by 8 orders of magnitude to $K^+K^-$ production. Large acceptance detectors allow for kinematically complete information about multi particle events. First Dalitz plot analyses confirm that in threshold production experiments one can extract information via FSI about otherwise not easily accessible interactions of hadron pairs like nucleon-hyperon or various nucleon-meson combinations. For the next future provisions will be made to increase beam currents with polarized protons, to provide deuteron beams and to add detector systems which allow for precise and large acceptance tagging and tracking. This will especially allow for studies of multi particle channels higher above threshold. Selective excitations of nucleon resonances and hyperon resonances, their decays, polarization effects and decay branching ratios will be tried out. Studies of meson production in proton-proton, proton-neutron and proton-nucleus interactions will be extended. The interest here may focus on strangeness dissociation, medium modifications, reaction mechanisms and meson-meson interactions.

Physics with antiprotons: from antihydrogen to the top quark
Koch, Helmut, Ruhr Universitaet Bochum, Institut fuer Experimentalphysik I
Abstract: The talk gives a survey on experiments performed with antiprotons of different energies. The emphasis will be on results obtained at LEAR/CERN,but the very exciting investigations with higher energy antiprotons,leading to the discovery of the intermediate bosons W+,W-,Z0 and the top quark t, will also be discussed.

Phi Mesons from a Hadron Gas
E. Kolomeitsev, P. Filip (MPI, Muenchen)
Abstract: We suggest a possible explanation for a discrepancy in the $\phi$ meson yields measured by the NA49 ($\phi\to K^+K^-$) and NA50 ($\phi\to\mu^-\mu^+$) collaborations in Pb+Pb collision at SpS energies ($E_{\rm beam}=158~{\rm GeV}/A$). The rescattering of secondary kaons in the dense hadron gas explains only partially the relative decrease of a $\phi$ yield obtained by NA49. The increase of a $\phi$ meson width in medium can help to account for a full strength of the effect. We investigate also a possibility that the $\phi\to K\bar K$ decay branch is quenched in hadron gas due to the increase of kaon masses in pionic medium. We analyze the range of parameters of fireball evolution and of in-medium modification which are required for a quantitative agreement with experimental findings.

Magnetic Moment of the $\Delta(1232)$ Resonance
Martin Kotulla for the TAPS/A2 Collaboration
Abstract: Magnetic moments of baryons are a valuable testing ground for quark models. SU(6), e.g., predicts $\mu_{\Delta} = Q({\Delta}) \mu_{p}$ for the $\Delta$ isobars. So far only values with large uncertainties exist for the $\Delta^{++}(1232)$ resonance; the PDG quotes $\mu_{\Delta^{++}} = 3.7 - 7.5\mu_{N}$.\ We have measured the reaction $\gamma\;p\rightarrow\pi^\circ\gamma^\prime\,\;p$ which allows to extract the magnetic moment of the $\Delta^{+}(1232)$ resonance. The $\gamma^\prime$ transition within the $\Delta$ resonance is sensitive to the magnitude of $\mu_{\Delta^{+}}$. Previous measurements of $\mu_{\Delta^{++}}$ and the status of the current $\mu_{\Delta^{+}}$ measurement are summarized.

Photoexcitation of Baryon Resonances
Bernd Krusche
Abstract: The study of baryon resonances via meson photoproduction reactions on the free proton, nucleons bound in light nuclei and in the nuclear medium will be discussed. The topics thus range from the properties of resonances of the free nucleon via the isospin structure of the excitation of nucleon resoances to their in-medium properties. Special emphasis will be laid on the production of neutral mesons which due to suppression of non-resonant backgrounds are particularly well suited for the study of excited states of the nucleon.

Physics at H1 and ZEUS
E. Lohrmann (Desy)
Abstract: Invited talk

Hybrids and glueballs in lattice QCD
MICHAEL C. (University of Liverpool)
Abstract: QCD allows hadrons with a significant gluonic content: glueballs and hybrid mesons for example. I review lattice QCD results for these states. The mixing of scalar mesons and glueballs will be discussed too, because this is relevant to experimental identification of glueballs.

Structure of baryon resonances from hadronic and electromagnetic probes
H.P. Morsch and P. Zupranski
Abstract: The excitation of baryon resonances can be investigated with hadronic and electromagnetic probes, which yield complementary information on the structure of baryons. As an example the lowest N* resonances, the Roper resonance P11(1440) and D13(1510) are discussed which have been studied in alpha-p, pi-N and gamma-N. The information on excitation strengths and decay modes will be compared with predictions from baryon models. It turns out that alpha-p scattering, which is very selective, yields important information on the scalar structure of baryons which should be investigated further in exclusive experiments at COSY.

Aspects of dualities in Yang-Mills theory
Niemi, A (Uppsala), Faddeev, L. (St.Petersburg)
Abstract: We describe some recent developments towards understanding the dual structures in Yang-Mills theory, and how these could help in explaining confinement. In particular, we propose that the Yang-Mills field can be viewed as a dual to a field multiplet, with a Lagrangian that admits knotlike configurations as stable solitons. This leads to a particularly attractive desciption of the long distance Yang-Mills theory in terms of knotted solitons formed of the confining string.

Nucleon Properties in the Covariant Quark-Diquark Model
Oettel, M. (Tuebingen Univ.), Alkofer, R. (Tuebingen Univ.), v. Smekal, L. (Erlangen Univ.)
Abstract: In the covariant quark-diquark model the effective Bethe-Salpeter equations for the nucleon and the $\Delta$ are solved including scalar and axialvector diquark correlations. Their quark substructure is effectively taken into account in both, the interaction kernel of the BS equations and the currents employed to calculate nucleon observables. Electromagnetic current conservation is maintained. The electric form factors of proton and neutron match the data. Their magnetic moments improve considerably by including axialvector diquarks and photon induced scalar-axialvector transitions. The isoscalar magnetic moment can be reproduced, the isovector contribution is about 15\% too small. The ratio $\mu \,G_E/G_M$ and the axial and strong couplings $g_A$, $g_{\pi NN}$, provide an upper bound on the relative importance of axialvector diquarks confirming that scalar diquarks nevertheless describe the dominant 2-quark correlations inside nucleons.

Strangeness and Charm Production at COMPASS and HESR
Paul, S TU-Muenchen
Abstract: Physics with charm and strange quarks is reviewed in the framework of the COMPASS experiment at CERN and the HESR project at GSI. We describe the underlying production processes, cross sections and discuss different aspects of hadron physics which can and will be adressed.

Vector Meson Nucleon Production in the K-Matrix Approach
Penner, G., Mosel, U.
Abstract: Extending an unitary gauge invariant effective Lagrangian model [1,2], developped for the extraction of baryon properties through the comparison with pion and photon induced reactions on the nucleon, we add to the implemented $\gamma N$, $\pi N$, $\sigma N$, $\eta N$, $K \Lambda$, and $K \Sigma$ [3] final states vector meson nucleon states. We discuss the underlying formalism with special emphasis on the partial wave expansion and present the influence of the various channels on the extraction of the baryon properties. \newline Work supported by DFG and BMBF [1] T. Feuster and U. Mosel, Phys. Rev. C 58 (1998), 457 \newline [2] T. Feuster and U. Mosel, Phys. Rev. C 59 (1999), 460 \newline [3] A. Waluyo et al., Los Alamos Preprint, nucl-th/0008023

Physics at HESR
Peters, Klaus Ruhr-University Bochum
Abstract: Medium energy physicist in the forthcoming years are confronted with the problems of phasetransition from pertubative to non-pertubative QCD and the source of CP-violation. It is possible to address many of the questions in these fields with a multipurpose detector and a fixed target p$\bar{\mbox{p}}$ environment. As there is emerging evidence for the existence for gluonic degrees of freedom in hadronic reactions it is mandatory to extend the energy range to the charmonium region where ambiguities are easier to resolve. The second important topic to understand is the chiral aspect of QCD being explored for example by studying in-medium effects. CP-Violation is another very important topic. By the middle of this decade B-factories will have gathered a lot of information to constrain the CKM-Matrix. In these circumstances it is important to add complementary information from the D-Meson sector and from Hyperon decays.

Correlations between Identical Strange Baryons in 340 GeV/c $\Sigma^-$+Cu and 260 GeV/c n+Cu Interactions
J. Pochodzalla for the WA89 Collaboration
Abstract: We have measured the production of strange baryon and anti-baryon pairs in 340 GeV/c $\Sigma^-$+Cu and 260 GeV/c n+Cu interactions. $x_F$ correlations between two $\Lambda$'s indicate different distribution functions for {\it coincident} strange baryons. On the other hand two coincident $\overline{\Lambda}$ follow identical distribution functions. The effect of momentum conservation on the observed correlation will be discussed.

Gluon Bremsstrahlung and Elastic Scattering of Hadrons
Bogdan Povh, Max-Planck-Institut fuer Kernphysik, Heidelberg
Abstract: The differential and the total cross sections in high energy pp and pbarp interactions give a beautiful insight in the low $Q^2$ structure of the nucleon. The total cross section is composed of two parts. A large energy independent part corresponds to the interaction of the valence quarks with the target and an energy dependent part caused by gluon bremsstrahlung. The bremsstrahlung gluons are located at small transfer distances of about 0.3 fm from the valence quarks. The total cross section due to the gluon radiation is predicted to rise exponentially with energy as $s^{\Delta}$ with ${\Delta}=0.17+/-0.01$. A model with two scales, the size of the hadron ($R^2\sim 1$fm$^2$) and the size of the gluon cloud ($\rho\sim 0.1$ fm$^2$), correctly predicts the total cross sections and the slopes of the elastic scattering.

Antiproton Annihilation in Nuclei and the Charmonium Signals for the Quark-Gluon Plasma Formation in Heavy-ion Collisions
K. Seth (Evanston)
Abstract: Charmonium attenuation in presence of Quark-Gluon Plasma is considered to be the most promising signal for QGP formation in heavy ion collisions. In order to use it for this purpose, it is necessary to know attenuation due to charmonium-nucleon interaction in absence of QGP. Unfortunately, no direct measurements of charmonium nucleon cross sections exist. It is proposed that charmonium formation in antiproton annihilation with nuclear protons offers an unique opportunity to measure charmnium-nucleon cross sections unambiguously. Details of the experimental proposal will be presented.

The Status of Higher Twist in Hadron Structure Physics
Schäfer, A
Abstract: A detailed and systematic understanding of higher twist effects is crucial to push the applicability of QCD to medium hard and/or more exclusive reactions. Over the last years this was one of the main aims in particular in lepton-nucleon scattering. The status of these efforts is reviewed.

Strangeness and charm production in nucleus-nucleus collisions at beam energies near the thresholds
Senger, Peter (GSI)
Abstract: Experimental data on the production of kaons and antikaons in heavy ion collisions at SIS energies are reviewed with respect to in-medium effects. It was found that the $K^-/K^+$ ratios measured in C+C, Ni+Ni and Au+Au collisions are 1 - 2 orders of magnitude larger than in proton-proton collisions. The azimuthal angle distributions of $K^+$ mesons indicate a repulsive kaon-nucleon potential. The $K^+$ production excitation functions measured in light and heavy collision systems provide evidence for a soft nuclear equation-of-state. The future heavy ion synchrotron SIS200 offers the possibility to inclease baryonic densities in the fireball from twice (as now reached with SIS18) to about ten times nuclear matter density. The perspectives of exploring the high baryon density regime of the QCD phase diagram using charmed mesons as probes will be discussed.

Electron Cooling - An Option towards High Precision Experiments with Stored Relativistic Antiprotons
M.Steck (GSI Darmstadt)
Abstract: Electron Cooling has provided superb beam quality for stored beam of protons and heavy ions with velocities up to 75 % velocity of light. The basics of electron cooling will be discussed with particular emphasis on the difficulties arising at relativistic beam energies. Low energy cooling experiments have shown that the beam quality is determined by an equilibrium between intrabeam scattering and cooling. Based on the theoretical expression for the intrabeam scattering rate and on the experimental results at low energies the expected values for beam emittance and momentum spread of relativistic cooled antiprotons can be extrapolated. For a required beam quality the intensity of the antiproton beam will be limited either by the necessity to have strong cooling or by instabilities which are excited when the dense antiproton beam interacts with machine impedances. For experiments with internal target the cooling rate by the electron beam must exceed the heating rate originating from scattering and energy loss in the internal target. Possible solutions for the electron cooling device at relativistic energy will be presented.

Hadron-hadron Scattering: from pi-pi to pi-psi
Swanson, E.S. (Pitt) and Szczepaniak, A.P. (Indiana)
Abstract: In recent years the constituent quark model has proven remarkably accurate in describing a number of hadronic scattering reactions. These range from chiral pi-pi scattering to heavy-light systems, which may be tested on the lattice. After a review of the formalism, applications to pi-pi, K-pi ,rho-rho, pi-rho,K-N, N-N, B-B, and pi-J/psi reactions are presented. Extensions of the quark model to account for the chiral nature of the pion, coupled channel effects, and annihilation are also discussed.

Hypernuclear studies at KEK and BNL
Tamura, H (Dept. of Physics, Tohoku University)
Abstract: A breakthrough has recently been made in hypernuclear physics by gamma-ray spectroscopy with germanium detectors. I will summarize recent results at KEK and BNL on spectroscopy of $\Lambda$ hypernuclei, particularly on gamma-ray spectroscopy, and discuss $\Lambda$-N interactions based on those experimental results. We constructed a germanium detector array dedicated to hypernuclear studies (Hyperball) and started a series of experiments. At KEK we successfully observed gamma transitions in $^7_\Lambda$Li and obtained unambiguous information on strength of the $\Lambda$-N spin-spin interaction from the observed spin-flip M1 transition. In the next experiment at BNL we observed two E2 transitions in $^9_\Lambda$Be and confirmed a very small spin-orbit interaction of $\Lambda$. I will also briefly mention recent other experiments at KEK and BNL in view of $\Lambda$-N interactions.

Crystal Barrel measurements, hadron physics at ELSA
Abstract: After seven years of successful operation at the Low Energy Antiproton Ring (LEAR) at CERN the Crystal Barrel detector has been moved to Bonn to investigate the photo- and electroproduction of neutral mesons at the Electron Stretcher Ring ELSA. In this talk the goals of the experiment as well as its actual status will be discussed.

Towards Laser-Cooling and Laser-Spectroscopy of Antihydrogen
J.\ Walz, B.\ Schatz, A.\ Pahl, K.S.E.\ Eikema, and T.W.\ H\"ansch
Abstract: The new Antiproton Decelerator (AD) at CERN opens the possibility for intriguing experiments with antihydrogen. A direct comparison between antihydrogen and ordinary hydrogen would make very stringent tests of the fundamental CPT symmetry possible. The extremely narrow 1S--2S two-photon transition seems to be an excellent candidate for that purpose. Equally exciting is the prospect of experiments on the gravitational acceleration of antihydrogen. For both types of experiment it is of great importance to have antihydrogen as cold as possible. When low energy antihydrogen atoms are eventually produced, the next milestones will be to store them in a magnetic trap and to perform laser cooling of magnetically trapped antihydrogen. The strong 1S--2S transition in (anti)hydrogen at 121.6$\,$nm is the only transition that allows for efficient laser cooling. The highest efficiency, lowest temperature, and best magnetic sub-level selectivity is achieved for a continuous coherent source of Lyman-$\alpha$. We have developed the first source of this kind based on nonlinear optical four-wave mixing in mercury vapor.

Hadrons with Charmed Quarks in the Nuclear Medium
Weise, W. , Morath, Ph. (Physics Department, TU Munich), Lee, S.H., (Yonsei University, Seoul, Korea)
Abstract: We summarize and discuss the masses of charmonium systems and D-mesons in nuclear matter. the calculations are based on in-medium QCD sum rule techniques. Possible observable implications will be elaborated.