g/ JLab Users Group Meeting Curtis A. Meyer Poster

g/ JLab Users Group Meeting Curtis A. Meyer The GlueX Experiment Curtis A. Meyer Carnegie Mellon University Jefferson Lab HallD q q

g/ JLab Users Group Meeting Curtis A. Meyer Outline  Glue and Confinement  Normal and Hybrid Mesons  Photoproduction  Evidence for Exotic Mesons  Partial Wave Analysis  Summary

g/ JLab Users Group Meeting Curtis A. Meyer Flux Tubes Color Field: Because of self interaction, confining flux tubes form between static color charges Notion of flux tubes comes about from model-independent general considerations. Idea originated with Nambu in the ‘70s and Confinement

g/ JLab Users Group Meeting Curtis A. Meyer linear potential From G. Bali Lattice QCD Flux tubes realized Confinement arises from flux tubes and their excitation leads to a new spectrum of mesons Hybrid mesons Normal mesons 1 GeV mass difference

g/ JLab Users Group Meeting Curtis A. Meyer What role do gluons play in the meson spectrum? Lattice calculations predict a spectrum of glueballs. The lightest 3 have J PC Quantum numbers of 0 ++, 2 ++ and The lightest is about 1.6 GeV /c 2 Glueball Mass Spectrum Morningstar et al. f 0 (980) f 0 (1500) f 0 (1370) f 0 (1710) a 0 (980) a 0 (1450) K* 0 (1430) QCD A Theory of Quarks and Gluons mixing!

g/ JLab Users Group Meeting Curtis A. Meyer quark-antiquark pairs u d s u d s J=L+S P=(-1) L+1 C=(-1) L+S G=C (-1) I (2S+1) L J 1 S 0 = S 1 = 1 -- ,K*  ’,K L= a 2,f 2,f’ 2,K 2 a 1,f 1,f’ 1,K 1 a 0,f 0,f’ 0,K 0 b 1,h 1,h’ 1,K 1 L=  3,  3,  3,K 3  2,  2,  2,K 2  1,  1,  1,K 1  2,  2,  ’ 2,K 2 L= radial orbital Non-quark-antiquark … Normal Mesons

g/ JLab Users Group Meeting Curtis A. Meyer Hybrid Mesons m=0 CP=(-1) S+1 m=1 CP=(-1) S Flux-tube Model ground-state flux-tube m=0 excited flux-tube m=1 built on quark-model mesons CP={(-1) L+S }{(-1) L+1 } ={(-1) S+1 } S=0,L=0,m=1 J=1 CP=+ J PC =1 ++,1 -- (not exotic) S=1,L=0,m=1 J=1 CP=- J PC =0 -+, , ,2 +- exotic normal mesons

g/ JLab Users Group Meeting Curtis A. Meyer linear potential QCD Potential ground-state flux-tube m=0 excited flux-tube m=1 Gluonic Excitations provide an experimental measurement of the excited QCD potential. Observations of exotic quantum number nonets are the best experimental signal of gluonic excitations.

g/ JLab Users Group Meeting Curtis A. Meyer qq Mesons L = Spectrum Each box corresponds to 4 nonets (2 for L=0) Radial excitations (L = qq angular momentum) exotic nonets 0 – – – 1 – + 1 – – 2 – – – + 2 – Glueballs Hybrids Lattice GeV GeV GeV

g/ JLab Users Group Meeting Curtis A. Meyer Why Photoproduction A pion or kaon beam, when scattering occurs, can have its flux tube excited  or  beam Quark spins anti-aligned Much data in hand with some evidence for gluonic excitations (tiny part of cross section) q q before q q after q q q q before  beam Almost no data in hand in the mass region where we expect to find exotic hybrids when flux tube is excited Quark spins aligned _ _ _ _

g/ JLab Users Group Meeting Curtis A. Meyer Very little photoproduction data exist. What little there is hint at a different resonance structure than what is seen in pion production. In one year of initial running, expect 100 times pion statistics In one year of initial running, expect 100 times pion statistics Existing Data

g/ JLab Users Group Meeting Curtis A. Meyer Exotics NN  e X  , ,   1 I G (J PC )=1 - (1 -+ )  ’ 1 I G (J PC )=0 + (1 -+ )  1 I G (J PC )=0 + (1 -+ ) K 1 I G (J PC )= ½ (1 - )  1    1   b 1,   ’ 1   Couple to V.M + e in Photoproduction 1 -+ nonet

g/ JLab Users Group Meeting Curtis A. Meyer data 5 GeV 8 GeV From A. Szczepaniak Photoproduction

g/ JLab Users Group Meeting Curtis A. Meyer From A. 18 GeV Pion-Induced Production

g/ JLab Users Group Meeting Curtis A. Meyer 0 +- and 2 +- Exotics NN  e X b 0 I G (J PC )=1 + (0 +- ) h 0 I G (J PC )=0 - (0 +- ) h’ 0 I G (J PC )=0 - (0 +- ) K 0 I(J P )=½(0 + ) b 2 I G (J PC )=1 + (2 +- ) h 2 I G (J PC )=0 - (2 +- ) h’ 2 I G (J PC )=0 - (2 +- ) K 2 I(J P )= ½(2 + ) a1,f0,f1a1,f0,f1 f0,f1,a1f0,f1,a1 f0,f1,a1f0,f1,a1 ,  a 1,  f 0,  f 1  f 0,  f 1,  a 1  f 0,  f 1,  a 1 In photoproduction, couple to ,  or  ? “Similar to  1 ”

g/ JLab Users Group Meeting Curtis A. Meyer   p    p (18 GeV) The a 2 (1320) is the dominant signal. There is a small (few %) exotic wave. Interference effects show a resonant structure in  . (Assumption of flat background phase as shown as 3.)    Mass = MeV/c 2 Width= MeV/c 2 a2a2  E852 Results

g/ JLab Users Group Meeting Curtis A. Meyer   (1400) antiproton-neutron annihilation Mass = MeV/c 2 Width= MeV/c 2 Same strength as the a 2. Produced from states with one unit of angular momentum. Without  1  2 /ndf = 3, with = 1.29     Crystal Barrel Results

g/ JLab Users Group Meeting Curtis A. Meyer At 18 GeV/c suggeststo partial wave analysis E852 Results

g/ JLab Users Group Meeting Curtis A. Meyer Leakage From Non-exotic Wave due to imperfectly understood acceptance Exotic Signal Correlation of Phase & Intensity  1 (1600) 3  m=  =  ’ m=  = An Exotic Signal in E852

g/ JLab Users Group Meeting Curtis A. Meyer Detector designed to do Double blind studies of 3  final states  p n    X  Linear Polarization m  [GeV/c 2 ]  GJ a2a2    Partial Wave Analysis

g/ JLab Users Group Meeting Curtis A. Meyer GlueX will be sensitive to a wide variety of decay modes - the measurements of which will be compared against theory predictions. To certify PWA - consistency checks will be made among different final states for the same decay mode, for example: Should give same results Gluonic excitations transfer angular momentum in their decays to the internal angular momentum of quark pairs not to the relative angular momentum of daughter meson pairs - this needs testing. For example, for hybrids: favored not-favored Measure many decay modes! Hybrid Decays

g/ JLab Users Group Meeting Curtis A. Meyer Acceptance Acceptance in Decay Angles Gottfried-Jackson frame: In the rest frame of X the decay angles are theta, phi assuming 9 GeV photon beam Mass [X] = 1.4 GeV Mass [X] = 1.7 GeV Mass [X] = 2.0 GeV Acceptance is high and uniform

g/ JLab Users Group Meeting Curtis A. Meyer Leakage An imperfect understanding of the detector can lead to “leakage” of strength from a strong partial wave into a weak one. STRONG: a 1 (1260) (J PC =1 ++ ) Break the GlueX Detector (in MC). Look for Signal strength in Exotic 1 -+ Under extreme distortions, ~1% leakage!

g/ JLab Users Group Meeting Curtis A. Meyer Three Day Workshop on partial wave analysis held at Carnegie Mellon University last week. 35 Participants from Europe and North America, about 50% theorists and 50% Experimentalists. About equal numbers of “Baryon” and “Meson” people. Proceedings will be published late this year. PWA Workshop

g/ JLab Users Group Meeting Curtis A. Meyer CLAS PWA  p  p  +  - (~5GeV Photons) PRELIMINARY g6c Results m  +  - ) [GeV/c 2 ] Presented by Paul Eugenio m  +  - ) [GeV/c 2 ] PWA  0 (770) f 2 (1270) J P =1 - (m=+-1) J P =1 - (m=0) (10% of exclusive events)

g/ JLab Users Group Meeting Curtis A. Meyer Other Physics 4  detector built to do PWA  Normal Meson Spectroscopy come for free.  Strangonium states (ss) are not well known.  Non-exotic Hybrids states (mixed).  Threshold KK physics (lower beam energy).  Baryons, particularly Hyperons (lower beam energy)  For 5GeV photons, can achieve ~70% polarization.  …

g/ JLab Users Group Meeting Curtis A. Meyer Summary QCD predicts a spectrum of states directly associated with the gluonic degree of freedom and confinement. Exotic Quantum numbers are a definitive signature. Experiments have started to observe states with exotic quantum numbers, but the observations are few, and not in agreement with theoretical expectations. Photoproduction is expected (vector meson beams) are expected be a very good, yet unexplored way to produce these states. GlueX will be able to map out a detailed picture of these states and their decays with statistics 100 times better than current pion experiments. Such information will yield important data on the dynamics of glue and its role in QCD.

g/ JLab Users Group Meeting Curtis A. MeyerCHL-2 Upgrade magnets and power supplies

g/ JLab Users Group Meeting Curtis A. Meyer CHL-2 Upgrade magnets and power supplies