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Photoproduction and Gluonic Excitations Meson 2002 Photoproduction and Gluonic Excitations QNP Photoproduction and Gluonic Excitations CAP Nov 2000 Feb 2001 References Design Report can be downloaded from the Hall D website. JLab whitepaper can also be linked to from the Hall D website. Sept/Oct 2000 Sept 2000 Cover story article on exotics and Hall D. Article on exotics and Hall D. Both can also be downloaded from the Hall D website. Flux Tubes and Confinement Color Field: Because of self interaction, confining flux tubes form between static color charges mesons Notion of flux tubes comes about from model-independent general considerations. Idea originated with Nambu in the ‘70s Flux Tubes and Confinement Color Field: Because of self interaction, confining flux tubes form between static color charges mesons Notion of flux tubes comes about from model-independent general considerations. Idea originated with Nambu in the ‘70s Lattice QCD Flux tubes realized From G. Bali Flux tube 2.0 forms Vo( r) [GeV] between qq 1.0 linear potential 0.0 0.4 0.8 1.2 r/fm 1.6 Hybrid Mesons Confinement arises from flux tubes and their excitation leads to a new spectrum of mesons Hybrid mesons 1 GeV mass difference (p/r) Normal mesons Normal Mesons Normal mesons occur when the flux tube is in its ground state Spin/angular momentum configurations & radial excitations generate our known spectrum of light quark mesons Nonets characterized by given JPC Not allowed: exotic combinations: JPC = 0-- 0+- 1-+ 2+- … Excited Flux Tubes How do we look for gluonic degrees of freedom in spectroscopy? First excited state of flux tube has J=1 and when combined with S=1 for quarks generates: JPC = 0-+ 0+- 1+- 1-+ 2-+ 2+- exotic Exotic mesons are not generated when S=0 Mass (GeV) Meson Map Each box corresponds to 4 nonets (2 for L=0) qq Mesons 2.5 Glueballs 2.0 1.5 0 ++ 1.0 L=0 1 2 3 4 (L = qq angular momentum) 2 +– 2 –+ 1 –– 1– + 1 +– 1 ++ 0 +– 0 –+ Hybrids 2 –+ 0 –+ 2 ++ Radial excitations exotic nonets Pion Production Quark spins anti-aligned Exotic hybrids suppressed Extensive search but little evidence Photoproduction Quark spins already aligned Production of exotic hybrids favored. Almost no data available E852 Results p pp p p p p p p p p At 18 GeV/c suggests 0 p p p p M(p pp ) GeV / c2 M(p p ) GeV / c2 to partial wave analysis p p p p dominates Results of Partial Wave Analysis a1 Benchmark resonances p2 a2 An Exotic Signal in E852 1 Leakage From Non-exotic Wave due to imperfectly understood acceptance Correlation of Phase & Intensity Exotic Signal M(p pp ) GeV / c2 Analysis in progress p System P-wave not consistent with B-W parameterization P-wave exotic reported at 1400 MeV/c2 Confirmed by Crystal Barrel p p p0 n a 2 1320 p p p p a 2 1320 p p a o 980 o Compare p p and p Data Compare statistics and shapes @ 18 GeV Events/50 MeV/c2 ca. 1998 BNL p p p p n p pp p p p ca. 1993 @ 19 GeV 28 SLAC SLAC 4 1.0 M(3p) GeV / c 2 1.5 2.0 2.5 What is Needed? PWA requires that the entire event be identified - all particles detected, measured and identified. The detector should be hermetic for neutral and charged particles, with excellent resolution and particle ID capability. The beam energy should be sufficiently high to produce mesons in the desired mass range with excellent acceptance. Too high an energy will introduce backgrounds, reduce cross-sections of interest and make it difficult to achieve above experimental goals. PWA also requires high statistics and linearly polarized photons. Linear polarization will be discussed. At 108 photons/sec and a 30-cm LH2 target a 1 µb cross section will yield 600M events/yr. We want sensitivity to sub-nanobarn production cross-sections. Linear Polarization Linear polarization is: Essential to isolate the production mechanism (M) if X is known A J filter if M is known (via a kinematic cut) PC Related to the fact that states of linear polarization are eigenstates of parity. States of circular polarization are not. M Optimal Photon Energy Figure of merit based on: 1. 2. 3. Beam flux and polarization Production yields Separation of meson/baryon production Optimum photon energy is about 9 GeV Coherent Bremsstrahlung flux This technique provides requisite energy, flux and polarization 12 GeV electrons Incoherent & coherent spectrum 40% polarization in peak photons out collimated electrons in spectrometer diamond crystal tagged with 0.1% resolution photon energy (GeV) JLab Facility Hall D will be located here Upgrade Plan Upgrade magnets and power supplies CHL-2 Detector http://dustbunny.physics.indiana.edu/HallD Barrel Calorimeter Lead Glass Detector Solenoid Coherent Bremsstrahlung Photon Beam Note that tagger is 80 m upstream of detector Tracking Target Electron Beam from CEBAF Time of Flight Cerenkov Counter Detector Solenoid & Lead Glass Array At LANL At SLAC Now at JLab -1 Acceptance Acceptance in Decay Angles -0.8 -0.6 -0.4 -0.2 -0 0.2 Cos ( GJ) p -> p pp 0.4 0.6 0.8 1 1 0.8 0.8 0.8 0.4 0.4 Gottfried-Jackson frame: 0 -1 0 -1 assuming 9 GeV photon beam 0.6 1.4 GeV frame of X InMass(X) the =rest Mass(X) = 1.4 GeV Mass(X) = 1.7 GeV the decay are Mass(X) = 1.7 angles GeV Mass(X) = 2.0 GeV theta, Mass(X)phi = 2.0 GeV -0.8 -0.6 -0.4 -0.2 -0 0.2 0.4 0.6 0.8 1 -0.8 -0.6 -0.4 Cos -0.2 ( -0 )0.2 0.4 0.6 0.8 CosGJ ( GJ) 0.2 0 0.6 0.6 0.6 3 Mass [X] = 1.7 GeV 0.2 Mass [X] = 2.0 GeV -3 0 -2 -1 -2 0 -1 GJ 1 0 GJ 2 1 3 2 3 2 1 3 2 3 1 0.8 Mass(X) = 1.4 GeV Mass(X) = 1.4 GeV Mass(X) = 1.7 GeV Mass(X) = 1.7 GeV Mass(X) = 2.0 GeV Mass(X) = 2.0 GeV 0.6 0.4 0.4 8 GeV 12 GeV 0.2 0.2 0 -0.8 -0.6 -0.4 -0.2 -0 0.2 0.4 0.6 0.8 1 -0.8 -0.6 -0.4 Cos -0.2 ( -0GJ)0.2 0.4 0.6 0.8 Cos ( GJ) -3 0 1 Acceptance is high and uniform 1 2 0.4 0 0 0.8 1 Mass [X] = 1.4 GeV p Xn p p n 0.8 0.8 0 -1 0 -1 0.6 -3 1 0.2 0.2 0 GJ 0.8 1 1 1 0.4 0.4 -1 1 0.4 58 GeV GeV 0.2 0.2 -2 p Xn p p p n 1 1 0.6 0.6 -3 1 -2 -3 -1 -2 0 -1GJ 1 0 GJ Finding an Exotic Wave An exotic wave (JPC = 1-+) was generated at level of 2.5 % with 7 other waves. Events were smeared, accepted, passed to PWA fitter. X(exotic ) p 3p Mass Input: 1600 MeV Output: 1598 +/- 3 MeV 5 00 500 events/20 MeV generated 4 00 400 PWA fit 3 00 300 Width Input: 170 MeV Output: 173 +/- 11 MeV 2 00 200 1 00 100 Statistics shown here correspond to a few days of running. Double-blind M. C. exercise 00 1 .2 1.2 1 .4 1.4 11.6 .6 Mass (3 pions) (GeV) 11.8 .8 Review Executive Summary Highlights: The experimental program proposed in the Hall D Project is well-suited for definitive searches of exotic states that are required according to our current understanding of QCD JLab is uniquely suited to carry out this program of searching for exotic states The basic approach advocated by the Hall D Collaboration is sound The Committee David Cassel Frank Close John Domingo Bill Dunwoodie Don Geesaman David Hitlin Martin Olsson Glenn Young Cornell (chair) Rutherford JLab SLAC Argonne Caltech Wisconsin ORNL Collaboration US Experimental Groups Carnegie Mellon University Catholic University of America A. Dzierba (Spokesperson) - IU C. Meyer (Deputy Spokesperson) - CMU E. Smith (JLab Hall D Group Leader) Collaboration Board L. Dennis (FSU) J. Kellie (Glasgow) G. Lolos (Regina) (chair) R. Jones (U Conn) A. Klein (ODU) A. Szczepaniak (IU) Christopher Newport University University of Connecticut Florida International University Florida State University Indiana University Jefferson Lab Los Alamos National Lab Norfolk State University Other Experimental Groups University of Glasgow Institute for HEP - Protvino Moscow State University Budker Institute - Novosibirsk University of Regina Theory Group CSSM & University of Adelaide Carleton University Carnegie Mellon University Insitute of Nuclear Physics - Cracow Hampton University Indiana University Old Dominion University Los Alamos Ohio University North Carolina Central University University of Pittsburgh Renssalaer Polytechnic Institute 90 collaborators 25 institutions University of Pittsburgh University of Tennessee/Oak Ridge www.nscl.msu.edu/future/lrp2002.html LRP NSAC Long Range Plan www.nscl.msu.edu/future/lrp2002.html LRP LRP Conclusion In the last decade we have seen much theoretical progress – especially in LGT Low energy data on gluonic excitations are needed to understand the nature of confinement in QCD. Recent data in hand provide hints of these excitations - but a detailed map of the hybrid spectrum is essential. Photoproduction promises to be rich in hybrids – starting with those possessing exotic quantum numbers – and little or no data exist. The energy-upgraded JLab will provide photon beams of the needed flux, duty factor, polarization along with a state-of-the-art detector to collect high-quality data of unprecedented statistics and precision. If exotic hybrids are there - we will find them. E852 Experiment at BNL p ppp After PWA: Conclusion: an exotic signal at A mass of 1400 MeV and width Of about 300 MeV Controversy E852 Experiment at BNL p ppp 18 GeV/c If p resonates in a P-wave - the resonance has exotic QN p0 Analysis - S & D Waves Robert Lindenbusch Maciej Swat p0 Analysis No P-wave Final state interactions P-wave exotic p0 Analysis Fixing D-wave (a2) and then fitting intensity and phase yields P-wave mass of 1.3 GeV and a width of 750 MeV (Exotic) Meson Spectroscopy : Role of Final State Interactions (IU experimentalists meet IU theorists) * • What is the nature of the P+ (JPC=1-+, p114 wave in p? p p1 •Quark based interactions, •Meson exchange, interactions (Isgur, Speth) vs Resonance such as (770) Rescattering such as s(400-1200) • 3pspectrum ( JPC=1-+, p116>p,E852 p p1 p p vs p1 •Dispersion relations •Feddeev equations (Ascoli, Wyld) • Study of P-wave mesons ( f0(980), a0(980), a2(1300) ) : E852 : amplitude analysis + production characteristics (t-dependence) Linear Polarization - I Suppose we produce a vector via exchange of spin 0 particle and then V SS V J=0 For circular polarization W, sin 2 For linear polarization x R L sin cos 2 y i R L sin sin 2 Px : W , sin 2 cos2 Py : W , sin 2 sin 2 Loss in degree of polarization requires corresponding increase in stats Linear Polarization - II V X Suppose we want to determine exchange: O+ from 0- or AN from AU L 0, 1, or 2 PV P PX 1 J=0– or 0+ L Parity conservation implies: With linear polarization which is sum or diff of R and L we can separate Linear Polarization Essential Pion-Induced Production a 2 1320 @ 18 GeV a 2 1320 1 From A. Szczepaniak Photoproduction a 2 1320 p p 0 n data @ 5 GeV theory 8 GeV a 2 1320 1 From A. Szczepaniak The Upgrade Plan Add Cryomodules More on Monday from Kees deJager from JLab Add Arc Add Cryomodules http://dustbunny.physics.indiana.edu/HallD Radphi @ JLab Rare radiative decays of the meson p p Complementary to factory measurements o o f p p o 5 o a o p Phi experiment Craig Steffen Phi decays Rare Radiative Decays of the meson data from Summer, 2000 200 Events/10 MeV p Vp 150 100 50 Cut-away of Radphi Detector located in Hall B 0 0.6 0.8 1.0 1.2 1.4 M() GeV 1.6 1.8 2.0 p b1 1235p Radphi @ JLab b1 1235 p0 p0 p0 5 p 0 p0 p 0 b1 1235 Craig Steffen Hall D at JLab $35M Strongly Recommended Build it Soon ! NSAC - March 2001 $50M $15M $12M $12M Construction start - 2006 Physics - 2009 Solenoid Before After February 2002