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Strange Summary of AGS Program and List of Questions

Explore key observations from E917, E895 programs at Columbia University. Analyze strangeness enhancement, excitation functions, centrality dependence, and more in the context of a global picture and deconfinement implications.

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Strange Summary of AGS Program and List of Questions

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  1. Strange Summary of AGS Program and List of Questions Strangeness 2000 Jamie Nagle Columbia University

  2. Key Observations • Overall strangeness enhancement (E917, E895) • Excitation function (E917/E866, E895) • Phi enhancement and centrality dependence (E917) • L flow (E895) • Anti- L / Anti-p enhancement (E864,E878,E917) • L polarization (E896) • L-p correlations (E895) How do these observations fit into a more global picture? What do they imply about deconfinement?

  3. CERN Press Statement “A particularly striking aspect of this apparent ‘chemical equilibrium’ at the quark-hadron transition temperature is the observed enhancement, relative to proton-induced collisions, of hadrons containing strange quarks. Since the hadron abundances appear to be frozen in at the point of hadron formation, this enhancement signals a new and faster strangeness-producing process before or during hadronization, involving intense rescattering among quarks and gluons.” “Experimentally [strangeness enhancement] is found not only in lead-lead collisions, but even in sulfur-nucleus collisions. This is consistent with estimates of the initial energy densities above the critical value of 1 GeV/fm3 even in those collisions.” U.Heinz

  4. Excellent data from E917 shows that strangeness enhancement is observed in Au + Au collisions down to threshold. Au+Au Pb+Pb p+p J.C. Dunlop and C.A. Ogilvie, Phys. Rev. C61:031901 (2000)

  5. Is there a phase transition at the AGS as well?Are these completely different mechanisms?Are the extraction of these parameters reliable? F. Becattini et al., EPJ C5 (1998) 143

  6. Proton-Nucleus Studies Experiments E910 and NA49 are making major contributions that show strangeness enhancement starts in proton induced collisions. Does a mechanism that starts in p-A collisions, imply that a steady increase in that mechanism is not possible as a signature for deconfined matter? p-A is the beginning of multiple parton level interactions before hadronization….? But not “intense rescattering amongst quarks and gluons.”

  7. Strange Antibaryons at AGS Escape path Calculations indicate antiproton losses on the order of 90-95% Extreme calculation with no annihilation for strange antibaryons in RQMD yield Y/p ~ 3 This has a dramatic effect of Pt distribution

  8. Key question AGS data shows many of the features of strangeness enhancement all the way down to the strangeness production threshold. The mechanism for strangeness enhancement is starting to be understood in terms of multiply stuck nucleons/partons in proton-nucleus studies. How do we put this information into a global picture with the conclusions coming from the exciting CERN results?

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