Michael Dugger Arizona State University

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S = 0 pseudoscalar meson photoproduction from the proton: γ p → π 0 p, γ p → π + n γ p → η p, γ p → η " p Michael Dugger* Arizona State University *Work at ASU is upheld by the U.S. National Science Foundation 1

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Outline Motivations – Theoretical & Practical Experimental Facilities New and Existing Data Brief Look At Models Conclusions/What's Next *Work at ASU is bolstered by the U.S. National Science Foundation 2

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Motivations Theoretical Practical *Work at ASU is upheld by the U.S. National Science Foundation 3

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Motivations (Theoretical) Pions are the lightest mesons and are abundantly created in the solid cooperation. The η and η " mesons have isospin ½ and restrict one stage energized conditions of the proton to likewise be isospin ½. The η and η " go about as isospin channels to the reverberation range. This may be valuable for find "missing" resonances The η and η " have unusual substance yet no net oddness: May be helpful in deciding contrasting interesting quark substance of the proton The η " is the main isosinglet. This can be utilized to in a roundabout way test gluonic coupling to the proton *Work at ASU is upheld by the U.S. National Science Foundation 4

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Motivations (Practical) Photoproduction: Electromagnetic collaborations are surely knew Real photons are especially straightforward: Only 2 polarization states. Non-abnormality responses: The active proton is anything but difficult to recognize and has generally little pollution *Work at ASU is bolstered by the U.S. National Science Foundation 5

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Experimental Facilities: SAPHIR (Spectrometer Arrangement for Photon instigated Reactions. ELSA) CLAS (CEBAF Large Acceptance Spectrometer. JLab) CB-ELSA (Crystal Barrel at ELSA) GRAAL (at the ESRF in Grenoble) *Work at ASU is upheld by the U.S. National Science Foundation 6

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SAPHIR at Bonn Electron Stretcher Photon energies up to 3.0 GeV Good for charged particles Small acknowledgment Drift chamber Electrocalorimeter Time of flight Magnet *Work at ASU is upheld by the U.S. National Science Foundation 7

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CLAS Photon energies up to 5.7 GeV Good for charged particles Large acknowledgment *Work at ASU is upheld by the U.S. National Science Foundation 8

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CB-ELSA Photon energies up to 3.2 GeV Good for nonpartisan particles Large acknowledgment TAPS Crystal Barrel *Work at ASU is upheld by the U.S. National Science Foundation 9

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GRAAL Photon energies up to 1.1 GeV Good for impartial particles Large acknowledgment Variable collimator Fixed collimator Plastic scintillator barrel Cleaning magnet Target Cylindrical wire chambers BGO calorimeter Vacuum framework Shielding divider Scintillator and lead sandwich *Work at ASU is bolstered by the U.S. National Science Foundation 10

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New γ p → π 0 p Results New results from GRAAL: d σ/d Ω and Σ New results from CLAS: d σ/d Ω *Work at ASU is upheld by the U.S. National Science Foundation 11

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New GRAAL γ p → π 0 p Results SAID BONN-PNPI (Anisivich, Klempt) d σ/d Ω from 555 to 1021 MeV MAID *Work at ASU is bolstered by the U.S. National Science Foundation 12

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New GRAAL γ p → π 0 p Results SAID BONN-PNPI (Anisivich, Klempt) d σ/d Ω from 1036 to 1496 MeV MAID *Work at ASU is bolstered by the U.S. National Science Foundation 13

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New GRAAL γ p → π 0 p Results SAID BONN-PNPI (Anisivich, Klempt) Σ from 1036 to 1496 MeV MAID *Work at ASU is upheld by the U.S. National Science Foundation 14

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Preliminary CLAS γ p → π 0 p Results d σ/d Ω from 0.675 to 1.425 GeV SAID ( Blue line) Mainz ( Blue focuses) CB-ELSA ( Red focuses) CLAS (Black focuses) *Work at ASU is upheld by the U.S. National Science Foundation 15

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Preliminary CLAS γ p → π 0 p Results d σ/d Ω from 1.475 to 2.125 GeV SAID ( Blue lines) CLAS ( Black focuses) CB-ELSA ( Red focuses) *Work at ASU is bolstered by the U.S. National Science Foundation 16

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γ p → π 0 p Polarization Observables Beam polarization Target asymmetry Recoil polarization Double polarization *Work at ASU is upheld by the U.S. National Science Foundation 17

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Status: γ p → π 0 p Database World information set turning out to be very intensive Cross Section New bar asymmetry and d σ/d Ω estimations from GRAAL New d σ/d Ω from CLAS try (g8b) simply completed with information taking for bar asymmetry CLAS twofold polarization (target & bar) slated for 2007 *Work at ASU is upheld by the U.S. National Science Foundation 18

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New γ p → π + n Results New results from CLAS: d σ/d Ω *Work at ASU is bolstered by the U.S. National Science Foundation 19

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Preliminary CLAS γ p → π + n Results Differential cross segments E γ from 0.625 to 1.625 GeV SAID ( Blue lines ) CLAS ( Black focuses) *Work at ASU is bolstered by the U.S. National Science Foundation 20

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Preliminary CLAS γ p → π + n Results Differential Cross areas E γ from 1.675 to 2.275 GeV SAID ( Blue lines) CLAS ( Black focuses) *Work at ASU is upheld by the U.S. National Science Foundation 21

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γ p → π + n Polarization Observables Beam polarization Recoil polarization Target asymmetry Target asymmetry Double polarization *Work at ASU is bolstered by the U.S. National Science Foundation 22

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γ p → π + n World database has great scope for bar polarization, pull back polarization, and target asymmetry between 20 ° and 120 ° and up to E γ = 2300 MeV Cross Section Double polarization information for G and H between 40 ° and 100° and up to E γ = 1900 MeV New CLAS information to cover d σ/d Ω up to E γ = 2275 MeV Cross segment *Work at ASU is upheld by the U.S. National Science Foundation 23

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γ p → η p Data turning out to be very careful More polarization estimations coming More d σ/d Ω estimations with supreme photon flux assurance coming d σ/d Ω Beam polarization Target polarization *Work at ASU is upheld by the U.S. National Science Foundation 24

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New CLAS γ p → η " p Results SAPHIR ( Blue focuses) CLAS ( Black focuses) SAPHIR utilized aberrant technique for photon flux SAPHIR utilized a branch to decide η " and had just ~1% acknowledgment CLAS η " results were gotten in comparative way as the CLAS π 0 comes about *Work at ASU is upheld by the U.S. National Science Foundation 25

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New CLAS γ p → η " p Results Solid line: Nakayama and Haberzettl Dashed line: Model motivated by A. Sibertsev Solid line → Nakayama, Haberzettl: Relativistic meson-trade demonstrate s-channel j=1/2 and j=3/2 resonances t-channel ρ , ω trade Nucleon trade in s-and u-channels Contact current to make gage-invariant Dashed line → Sibertsev/Dugger: Relativistic meson-trade display s-channel j=1/2 resonances t-channel ρ , ω trade Nucleon trade in s-and u-channels *Work at ASU is bolstered by the U.S. National Science Foundation 26

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Some π and η Photoproduction Models γ MAID: Isobar resonances Born terms t-station ρ , ω trade Newly Reggeized for higher vitality information γ Anisivich, Klempt: Resonances are Breit-Wigner aside from two station K lattice for S 11 (1535) and S 11 (1650) Reggeized t-and u-station Coupled stations (d σ/d Ω and Σ : π + n, π 0 p, η p, K Λ ,K Σ ) Li, Saghi: Chiral constituent quark display SU(6) x O(3) symmetry broken by gluon trade γ 27

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Red : π + n and π 0 p Blue : η p LS: Li, Saghi AK: Anisovich, Klempt S 11 (1650) bringing on trouble in deciding width for the S 11 (1535)? Missing reverberation D 15 (2070) found? Intriguing at 1800 MeV? 28

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Conclusions/What's Next π 0 , π + , η , and η " photoproduction off the proton World database incredibly upgraded amid recent years Evidence that a missing D 15 (2070) reverberation may have been discovered Need for more polarization observables and coupled channel examinations to oblige the hypothetical models More information coming, including twofold polarization observables from CLAS in 2007 *Work at ASU is upheld by the U.S. National Science Foundation 29

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Acknowledgments NSF ASU Group Members J. Ball P. Collins E. Pasyuk B. Ritchie CLAS Collaboration Theoretical bends for η " Kanzo Nakayama Helmut Haberzettl New information from GRAAL Annalisa D'Angelo Dominique Rebreyand Carlo Schaerf *Work at ASU is upheld by the U.S. National Science Foundation 30

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