seminars on Quark Condensate

                       FRASCATI GENERAL SEMINAR

         OGGI/TODAY June 22 - at 14.30 - Auditorio Bruno Touschek
            (note that we start 30' before than usual)

                         M. KNECHT - Marseille Univ.
                         S. PISLAK - Yale Univ.
                         G. COLANGELO - Zurich Univ.
                         N. GRION - Sez. INFN, Trieste
                         A. LANARO - INFN, LNF



       The quark condensate <0|qbar q|0> represents the most natural order
    parameter of chiral symmetry breaking, whence the push, in order to
    measure it. This parameter characterises the realisation of QCD at low
    energy, which is presently not yet strictly determined, providing a
    handle to understand the way chiral symmetry is broken.
       The quark condensate can be determined through a measurement of
    pion pion scattering lengths.
       There are different ways to access experimentally the
    pion pion -> pion pion scattering amplitude near threshold:
    1) the decay kaon -> pion pion electron neutrino, i.e. the so-called
       Ke4 decay;
    2) the pionic atom (pionium);
    3) the pion production reaction in nuclear matter
       pion nucleus -> pion pion nucleus'.
       Theoretical and experimental results and prospects, along the three
    lines above, will be discussed, with talks by members of EURODAPHNE
    Collaboration (theory), E865 Collaboration at BNL, DIRAC Collaboration
    at CERN, Chaos Collaboration at TRIUMF.


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