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QCD Exotics – Past, Present and Future Exotics as a Probe of Confinement Curtis A. Meyer Carnegie Mellon University 1 October 30, 2007 ODU Colloquium The beginning of time. Outline The strong force and QCD Color confinement Spectroscopy Lattice QCD Finding Gluonic Hadrons Confinement 2 October 30, 2007 ODU Colloquium The First Seconds of The Universe 3 October 30, 2007 ODU Colloquium Quark Gluon Plasma For a period from about 10-12 s to 10-6 s the universe contained a plasma of quarks, anti quarks and gluons. Relativistic Heavy Ion Collisions are trying to produce this state of matter in collisions 4 October 30, 2007 ODU Colloquium Confinement From about 10-6 s on, the quark and anti quarks became confined inside of Hadronic matter. At the age of 1s, only protons and neutrons remained. Flux tube forms between qq Mesons 5 October 30, 2007 The gluons produce the 16ton force that holds the hadrons together. ODU Colloquium Baryons The Formation of Nuclei By the old age of three minutes, the formation of low mass nuclei was essentially complete. Primordial hydrogen, deuterium, helium and a few other light nuclei now exist. It will be nearly a half a million years before neutral atoms will dominate matter. 6 October 30, 2007 ODU Colloquium Quantum Chromo Dynamics The rules that govern how the quarks froze out into hadrons are given by QCD. Just like atoms are electrically neutral, hadrons have to be neutral. Color Charge Three charges called RED, BLUE and GREEN, and three anti colors. The objects that form have to be color neutral: 7 October 30, 2007 ODU Colloquium Gluons Carry the Force The exchange of gluons is continually changing the Individual colors of the quarks, but the overall Color remains neutral G Meson G R G R Time R B B 8 October 30, 2007 R G G ODU Colloquium R Meson Gluons Carry the Force The exchange of gluons is continually changing the Individual colors of the quarks, but the overall Color remains neutral G Meson G R G R Time R B B 9 October 30, 2007 R G G ODU Colloquium R Meson Gluons Carry the Force The exchange of gluons is continually changing the Individual colors of the quarks, but the overall Color remains neutral G Meson R G R G R Meson Time R B B 10 October 30, 2007 R G G Gluons produce the forces that confine the quarks, but the gluons do not appear to be needed to understand normal hadrons ODU Colloquium Gluon Interactions R G R B G R 3 Colors 3 Anti Colors B October 30, 2007 R G B G B R G R 1 color neutral 8 colored objects 8 Gluons 11 R R G ODU Colloquium self-interaction of gluons leads to both interesting behavior of QCD, and its extreme complications. Flux Tubes 12 October 30, 2007 ODU Colloquium Flux Tubes Flux tube forms between qq Color Field: Because of self interaction, confining flux tubes form between static color charges 13 October 30, 2007 ODU Colloquium Confinement arises from flux tubes and their excitation leads to a new spectrum of mesons Quark Confinement • quarks can never be isolated • linearly rising potential – separation of quark from antiquark takes an infinite amount of energy – gluon flux breaks, new quark-antiquark pair produced 14 October 30, 2007 ODU Colloquium Strong QCD See qq and qqq systems. Color singlet objects observed in nature: Nominally, glue is not needed to describe hadrons. white white u u d d s s Focus on “light-quark mesons” quark-antiquark states Allowed systems: 15 October 30, 2007 glueballs hybrids gg, ggg , qq g , qq qq ODU Colloquium Spectroscopy A probe of QED Positronium e+ Spin: S=S1+S2=(0,1) e- Orbital Angular Momentum: L=0,1,2,… Total Spin: J=L+S L=0, S=0 : J=0 L=0, S=1 : J=1 L=1 , S=0 : J=1 L=1, S=1 : J=0,1,2 … … Reflection in a mirror: Parity: P=-(-1)(L) Notation: J(PC) (2S+1)L J 16 October 30, 2007 Particle<->Antiparticle: Charge Conjugation: C=(-1)(L+S) 0-+, 1--, 1+-, 0++, 1++, 2++ 1S , 3S , 1P , 3P , 3P , 3P ,… 0 1 1 0 1 2 ODU Colloquium Spectroscopy and QCD Quarkonium Mesons Consider the three lightest quarks 4++ ++ L=3 3 ++ 2 3+- u, d , s u, d , s 3-2-L=2 -1 2-+ L=1 2++ 1++ 0++ 1+- L=0 1-0-+ 17 October 30, 2007 q q 9 Combinations us ds 1 uu dd 2 du sd S=1 S=0 1 uu dd ss 3 ODU Colloquium ud su 1 uu dd 2ss 6 Spectroscopy an QCD Quarkonium Mesons q 4++ ++ L=3 3 ++ 2 3+- r,K*,w,f 3-2-L=2 -1 2-+ L=1 L=0 18 p,K,h,h’ 0-+ October 30, 2007 Mesons come in Nonets of the same JPC Quantum Numbers a,K,f,f’ 2++ 1++ 0++ 1+1-- q b,K,h,h’ S=1 S=0 r,K*,w,f p,K,h,h’ ODU Colloquium SU(3) is broken Last two members mix Quantum Mechanical Mixing States with the same quantum numbers mix: 1 1 uu dd ss 3 1 uu dd 2ss 8 6 cos sin 1 SU(3) f' sin cos 8 f physical states Ideal Mixing: 2 cos 3 1 sin 3 19 October 30, 2007 1 f uu dd 2 f' ss ODU Colloquium Spectroscopy an QCD Mesons Nothing to do with Glue! 4++ ++ L=3 3 ++ 2 3+- L=1 L=0 1-0-+ 20 October 30, 2007 q q Allowed JPC Quantum numbers: 3-2-L=2 -1 2-+ 2++ 1++ 0++ 1+- Quarkonium S=1 S=0 0-- 0++ 0-+ 0+1–- 1++ 1-+ 1+2-- 2++ 2-+ 2+3-- 3++ 3-+ 3+4-- 4++ 4-+ 4+5-- 5++ 5-+ 5+Exotic Quantum Numbers non quark-antiquark description ODU Colloquium Glueball Predictions Particles that only contain gluons qq Mesons 2.5 1.5 1.0 Glueballs 2.0 2 –+ 0 –+ 2 ++ 0 ++ L= 01 2 3 4 21 October 30, 2007 ODU Colloquium All of these are normal quark-antiquark quantum numbers. Lattice QCD Predictions Gluons can bind to form glueballs EM analogue: massive globs of pure light. Lattice QCD predicts masses The lightest glueballs have “normal” quantum numbers. Glueballs will Q.M. mix The observed states will be mixed with normal mesons. Strong experimental evidence For the lightest state. 22 October 30, 2007 ODU Colloquium Identification of Glueballs Lightest Glueball predicted near two states of same Q.N.. “Over population” Predict 2, see 3 states Glueballs should decay in a flavor-blind fashion. pp : KK : hh : h ' h ' : hh ' 3 : 4 : 1 : 1 : 0 Production Mechanisms: Certain are expected to by Glue-rich, others are Glue-poor. Where do you see them? Proton-antiproton Central Production J/y decays 23 October 30, 2007 ODU Colloquium Crystal Barrel Results: antiproton-proton annihilation at rest Crystal Barrel Results Discovery of the f0(1500) f0(1500) a pp, hh, hh’, KK, 4p Solidified the f0(1370) f0(1370) a 4p Establishes the scalar nonet Discovery of the a0(1450) 700,000 p0p0p0 Events f2(1565)+s 250,000 hhp0 Events f0(1500) f2(1270) f0(980) f0(1500) 24 October 30, 2007 ODU Colloquium Wa102 Results CERN experiment colliding p on a hydrogen target. Central Production Experiment f 0 (1370) pp 2.17 0.90 f 0 (1370) KK f 0 (1370) hh 0.35 0.21 f 0 (1370) KK f 0 (1500) pp 5.5 0.84 f 0 (1500) hh f 0 (1500) KK 0.32 0.07 f 0 (1500) pp f 0 (1500) hh ' 0.52 0.16 f 0 (1500) hh f 0 (1710) pp 0.20 0.03 f 0 (1710) KK Recent comprehensive data set and a coupled channel analysis. 25 October 30, 2007 ODU Colloquium f 0 (1710) hh 0.48 0.14 f 0 (1710) KK f 0 (1710) hh ' 0.05(90%cl ) f 0 (1710) hh A Model for Mixing meson meson meson meson Glueball meson meson Glueball meson G qq flavor blind? uu , dd , ss 1 r2 r3 r Solve for mixing scheme 26 F.Close: hep-ph/0103173 October 30, 2007 ODU Colloquium Experimental Evidence Glueballs Scalar (0++) Glueball and two nearby mesons are mixed. f0(1710) f0(1500) a0(1450) K*0(1430) f0(1370) Glueball spread over 3 mesons 27 October 30, 2007 ODU Colloquium a0(980) f0(980) Are there other glueballs? Higher Mass Glueballs? Part of the BES-III program will be to search for glueballs in radiative J/y decays. Lattice predicts that the 2++ and the 0-+ are the next two, with masses just above 2GeV/c2. Radial Excitations of the 2++ ground state L=3 2++ States + Radial excitations f2(1950), f2(2010), f2(2300), f2(2340)… 2’nd Radial Excitations of the h and h’, perhaps a bit cleaner environment! (I would Not count on it though….) I expect this to be very challenging. 28 October 30, 2007 ODU Colloquium Hybrid Meson Predictions Flux-tube model: 8 degenerate nonets 1++,1-- 0-+,0+-,1-+,1+-,2-+,2+- ~1.9 GeV/c2 S=0 qqg S=1 qq Mesons 2.0 1.5 2 +– 2 –+ 1 –– 1– + 1 +– 1 ++ 0 +– 0 –+ 1.0 L= 01 2 3 4 29 October 30, 2007 ODU Colloquium Hybrids 2.5 exotic nonets Start with S=0 1++ & 1-Start with S=1 0-+ & 0+1-+ & 1+2-+ & 2+- QCD Potential ground-state excited flux-tube flux-tube m=1 m=0 linear potential Gluonic Excitations provide an experimental measurement of the excited QCD potential. Observations of the nonets on the excited potentials are the best experimental signal of gluonic excitations. 30 October 30, 2007 ODU Colloquium Hybrid Predictions Flux-tube model: 8 degenerate nonets 1++,1-- 0-+,0+-,1-+,1+-,2-+,2+- ~1.9 GeV/c2 S=0 S=1 Lattice calculations --- 1-+ nonet is the lightest UKQCD (97) 1.87 0.20 MILC (97) 1.97 0.30 1-+ 1.9+/- 0.2 MILC (99) 2.11 0.10 2+- 2.0+/- 0.11 Lacock(99) 1.90 0.20 0+2.3+/- 0.6 Mei(02) 2.01 0.10 Bernard(04) 1.792§0.139 In the charmonium sector: 1-+ 4.39 0.08 Splitting = 0.20 +0 4.61 0.11 31 October 30, 2007 ODU Colloquium Fit n-D angular distributions Fit Models of production and decay of resonances. Lglue Meson Analysis Method Partial Wave Analysis Decay Predictions Meson Looking for Hybrids Angular momentum in the gluon flux stays confined. This leads to complicated multi-particle final states. Detector needs to be very good. 32 October 30, 2007 ODU Colloquium Experimental Evidence Hybrids Exotic Mesons 1-+ mass 1.4 E852 BNL ’97 CBAR CERN ’97 Too light Not Consistent Possible rescattering (?) Decays are wrong (?) Not a Hybrid 33 October 30, 2007 ODU Colloquium New York Times, Sept. 2, 1997 E852 Results p p p p p M(p pp ) GeV / c2 p pp p p p At 18 GeV/c M(p p ) GeV / c2 to partial wave analysis suggests 0 p pr p p p p p p 34 October 30, 2007 ODU Colloquium An Exotic Signal Correlation of Phase & Intensity 1 Exotic Signal p1(1600) Leakage From Non-exotic Wave due to imperfectly understood acceptance 35 October 30, 2007 M(p pp ) GeV / c2 3p m=1593+-8+28-47 G=168+-20+150-12 ph’ m=1597+-10+45-10 G=340+-40+-50 ODU Colloquium In Other Channels 1-+ in h’p p-p h’p-p at 18 GeV/c The p1(1600) is the Dominant signal in h’p. Mass = 1.5970.010 GeV Width = 0.3400.040 GeV p1(1600) h’p 36 October 30, 2007 E852 Results ODU Colloquium In Other Channels 1-+ in f1p and b1p p-p hp+p-p-p p-p wp0p-p E852 Results p1(1600) b1p p1(1600) f1p Mass=1.7090.024 GeV Width=0.4030.08 GeV In both b1p and f1p, observe Excess intensity at about 2GeV/c2. Mass ~ 2.00 GeV, Mass = 1.6870.011 GeV Width ~ 0.2 to 0.3 GeV Width = 0.2060.03 GeV 37 October 30, 2007 ODU Colloquium New Analysis Add Add Add Add Add p2(1670)->rp (L=3) p2(1670)->r3p p2(1670)-> (pp)Sp a3 decays a4(2040) No Evidence for the p1(1670) 38 October 30, 2007 ODU Colloquium Dzierba et. al. PRD 73 (2006) 10 times statistics in each of two channels. Get a better description of the data via moments comparison Exotic Signals p1(1400) Width ~ 0.3 GeV, Decays: only hp NOT A weak signal in pp production (scattering??) HYBRID strong signal in antiproton-deuterium. p1(1600) Width ~ 0.16 GeV, Decays rp,h’p,(b1p) Does this Only seen in pp production, (E852 + VES) exist? p1(2000) Weak evidence in preferred hybrid The right modes f1p and b1p place. Needs confirmation. p1 IG(JPC)=1-(1-+) K1 IG(JPC)= h1 IG(JPC)=0+(1-+) 39 October 30, 2007 ODU Colloquium ½ (1-) h’1 IG(JPC)=0+(1-+) Experimental Evidence Hybrid Nonets 1-+ Establish other Nonets: 0+- 1-+ New York Times, Sept. 2, 1997 2+- Levels Built on normal mesons us ds 1 uu dd 2 du sd 1 uu dd ss 3 40 October 30, 2007 ud su 1 uu dd 6 Identify other states in nonet 2 ss to establish hybrid ODU Colloquium Jefferson Lab Upgrade 41 October 30, 2007 ODU Colloquium Jefferson Lab Upgrade Upgrade magnets and power supplies CHL-2 42 October 30, 2007 ODU Colloquium The GlueX Experiment 43 October 30, 2007 ODU Colloquium How to Produce Hybrids Beams of photons may be a more natural way to create hybrid mesons. Simple QN counting leads to the exotic mesons There is almost no data for photon beams at these energies. GlueX will increase samples by 3-4 orders of magnitude. 44 October 30, 2007 ODU Colloquium This technique provides requisite energy, flux and polarization flux Coherent Bremsstrahlung 12 GeV electrons Incoherent & coherent spectrum 40% polarization in peak Linearly polarized photons out collimated electrons in spectrometer diamond crystal 45 October 30, 2007 tagged with 0.1% resolution ODU Colloquium photon energy (GeV) Exotics p1 In Photoproduction IG(JPC)=1-(1-+) 1-+ nonet K1 IG(JPC)= h1 IG(JPC)=0+(1-+) Need to establish nonet nature of exotics: p h h0 Need to establish more than one nonet: 0+- 1-+ 2+- 46 October 30, 2007 ODU Colloquium ½ (1-) h’1 IG(JPC)=0+(1-+) g N X e N g r,w,f Gluonic Hadrons and Confinement What are the light quark Potentials doing? DE Potentials corresponding To excited states of glue. Non-gluonic mesons – ground state glue. 47 October 30, 2007 ODU Colloquium Lattice QCD potentials Conclusions The quest to understand confinement and the strong force is about to make great leaps forward. Advances in theory and computing will soon allow us to solve QCD and understand the role of glue. The definitive experiments to confirm or refute our expectations are being built. The synchronized advances in both areas will allow us to finally understand QCD and confinement. 48 October 30, 2007 ODU Colloquium