Hybrids and Glueballs in the light of antiproton reactions pBar Workshop GSI, Klaus Peters Ruhr-Universität Bochum

Klaus Peters - pBar Workshop - GSI Light Mesons are complicated naive quark-antiquark- picture is wrong for light mesons “leading“ meson-term is only the simplest of many Fock-states exception: narrow states (small mixing of states) exotic quantum numbers (reduced density of states)

Klaus Peters - pBar Workshop - GSI Spectroscopy of Light Mesons No/small problem with statistics Interpretation biased by models (poles, couplings) Problem: interpretation of measured states less precise predictions density of states width of states mixing of states

Klaus Peters - pBar Workshop - GSI Exotic-Production via FSI

Klaus Peters - pBar Workshop - GSI LQCD-Potentials Comparison between quenched/unquenched shows compatibility for bbBar-Potentials  fD (stat) = 1% unquenched calc: 200 PCs for 3 months Vital field with large algorithmic improvements and improved systematic corrections

Klaus Peters - pBar Workshop - GSI Gluonic Degrees of Freedom - Hybrids Gluonic excitations of the quark-antiquark-potential may lead to bound states LQCD: m H ~ GeV Light charmed hybrids could be as narrow as  O(5-50 MeV) selection rules small # of charmed final states (Zweig-Rule)

Klaus Peters - pBar Workshop - GSI Charmed Hybrids Fluxtube  DD**, but if m H <4,29 GeV   H <50 MeV Some exotics can decay neither to DD nor to DD* e.g.: J PC (H)=0 +- fluxtube allowed J/f 2, J/() S,h 1c  fluxtube forbidden  c0 , c0 ,  c2 , c2 ,  c h 1 Small # of final states with small phasespace CLEO-II B  J/  K (S) (±)

Klaus Peters - pBar Workshop - GSI Density of states (e.g. for Vector Mesons) Light mesons have usually larger widths Since N Q =3 for (uds) combinatorics yields very many states Ideal: charm-Sector with a much reduced density of states

Klaus Peters - pBar Workshop - GSI Exotic Production in Proton-Antiproton High production yields for exotic mesons (or with a large fraction of it) f 0 (1500)  ~25 % in 3  f 0 (1500)  ~25 % in 2   1 (1400)  >10 % in      Interference with other (conventional) states is mandatory for the phase analysis Exotics are present !

Klaus Peters - pBar Workshop - GSI Hybrid Formation in in Proton-Antiproton Gluon rich process creates gluonic excitation directly since ccBar requires the quarks to annihilate (no rearrangement) yields comparable to production of excited charmonium 2 complementary techniques Formation (Broad- and Fine-Scans) Production (Fixed-Momentum) Momentum for an complete survey p~15 GeV

Klaus Peters - pBar Workshop - GSI Mass regions and p momentum Neccesary momentum span is driven by the charm-exotics Hybrids (H C ) H C non-exotic J PC Formation 10 GeV/c H C exotic J PC Production 15 GeV/c D (s) -Hybrids D s D s +1 GeV/c ~12 GeV/c Charmed Multiquarks (M C ) M C l + l - 15 GeV/c +Recoil-Particle +Phsp. Perfect Resolution

Klaus Peters - pBar Workshop - GSI Gluonic Degrees of Freedom - Glueballs Light gg/ggg-systems are complicated to identify Exotic heavy glueballs m(0 +- ) = 4140 (50)(200) MeV m(2 +- ) = 4740 (70)(230) MeV Width unknown, but! nature invests more likely in mass than in momentum Flavour-blindness predicts decays into charmed final states Same run period as hybrids In addition: scan m>2 GeV/c 2 Morningstar und Peardon, PRD60 (1999) Morningstar und Peardon, PRD56 (1997) 4043

Klaus Peters - pBar Workshop - GSI 4-Quark Formation with DiLepton-Tag Proton-Antiproton contains already a 4-Quark-System Idea: Dilepton-Tag from Drell-Yan-Production Advantages trigger less J PC -Ambiguities GeV/c GeV/c antiproton-Beam (for L=10 32 cm -2 s -1 )

Klaus Peters - pBar Workshop - GSI Lessons from LEAR Full solid angle no missing particles (photons!) Low threshold electromagnetic detector K S -Trigger Kaon high Energies EE 3030 E min cos 

Klaus Peters - pBar Workshop - GSI Annihilation in Flight – no longer a challenge! Crystal Barrel has prooven that the annihilation in flight can be analyzed unambiguously Formation: twobody decays, where at least one particle carries spin! Production: integration of the production process or small recoil momenta may reduce the available phsp. and the contributing waves dramatically Peters, NPA 692 (2001)295

Klaus Peters - pBar Workshop - GSI Channels, Signatures, Potential Problems “Leading charmonia” J/, ‘,  ( ‘ ) c,  cj [DDbar] a.o.m.? DiLeptons e + e - (Ecal,Trk) [ c.m.: usually fast, but slow for 4-Quark-Tag ]  +  - (Trk,Hcal) Photon-Pairs  from ccBar (Ecal,no-Trk) from  0 and (Ecal) ()-Tag  and recoil (Trk,Cherenkov) Most information needed on trigger level !

Klaus Peters - pBar Workshop - GSI Required Features “Usual” omni purpose features Forward spectrometry: cos1 for low multiplicity charged final states [low and medium energy scans] Mandatory! “Fast” particle id (guess) for trigger purposes [hard and/or soft] Threshold Cherenkov? In addition to a multi purpose device (DIRC)?

Klaus Peters - pBar Workshop - GSI Summary Exotics are present in proton-antiproton reactions Light exotics are complicated to measure and to classify Heavy exotics will show a clearer signature Charged and neutral tracking together with efficient particle id e ± / ± m ± / ± and  ± /K ± and V 0 -finder is mandatory Exclusiveness with flat efficieny for the full solid angle