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Exclusive Meson Production CLAS and CLAS11

Exclusive Meson Production CLAS and CLAS11. Paul Stoler-RPI. Goals of the DVMP Experimental Program. Measure electroproduction of mesons above the resonance region (W > 2 GeV ) over a large range of of Q 2 and t in the valence quark region of x.

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Exclusive Meson Production CLAS and CLAS11

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  1. Exclusive Meson ProductionCLAS and CLAS11 Paul Stoler-RPI

  2. Goals of the DVMP Experimental Program Measure electroproduction of mesons above the resonance region (W > 2 GeV) over a large range of of Q2 and t in the valence quark region of x

  3. Explore transition from “hadronic” to “partonic” regime by testing model-independent featuresof reaction mechanisms Obtain mapping of nucleon structure in terms of quarks and gluons through application of phenomenological models (e.g. handbag).

  4. Physics Issues Q2 : Size of interaction region probed by virtual photon. t: Size of interaction region for emission of meson (DVMP) or photon(DVCS) low Q2 high -t low Q2 low -t high -t high Q2

  5. Kinematic regions inelectroproduction

  6. Vector Pseudoscalar CLAS6: lots of data. CLAS12: Exp. # **** CLAS6: lots of data. CLAS12: New proposal being prepared for PAC 38 Strangeness No published CLAS6 papers Large program planned for CLAS12 by RICH group..

  7. Scaling of t slopes with Q2 Gluon GPD

  8. Dynamical Mass of Light Dressed Quarks DSE and LQCD Q2 ➙ 12 GeV2 p ➙1.15 GeV Q2 ~ 11 GeV LQCD per dressed quark Pq

  9. Q2 (GeV2) ___1.75 ___2.25 ___.752 ___3.25 ___4.75 ___5.25   epe’p Cross sections vs t for different Q2 ~0eBt B~1 GeV-2 0.2 fm rhot slope small for low Q2 –larger for large Q2 large size to small size eta same large for all Q2, therefore always small size ????? New experiment extend t Q2

  10. Structure Functions GM Laget Regge model -t

  11. GPD’s Flavor separation Access to polarized GPDs

  12. Pseudoscaler Meson Production (Analog to WACS) (Huang and Kroll) ds/dsdtdQ2 (nb/GeV6) -t (GeV2)

  13. Factorization of short range hard and long range soft only works for longitudinal photons.

  14. Large angle (high -t) relatively small Q2 (Analog to WACS where handbag works very well) ds/dsdtdQ2 (nb/GeV6) (Huang and Kroll) -t (GeV2)

  15. Vector mesons Separate Long Through angular distriburion of the decay products in helicity frame.

  16. Gluon and Quark GPDs

  17. VGG VGG+``D term” world data

  18. Comparef an r

  19. GPD n ≈ 2.0

  20. New PAC38 Proposal (August 2011) Vector Meson Deep Virtual Exclusive Electroproduction • Kinematics Q2 from 3 – 10 GeV2 • t from .5 to 10 Gev2 W from 2-4 GeV2 • W from 2-4 GeV2 • Run simultaneously with ******* • Simulations for f and r are beginning • (Isolating K’s over entire kinematic range.)

  21. We have a very rich program of pseudoscalar meson production which will provide unique information about the transition between soft long-range phenomena and hard short range. It will serve as a complementary component of the deep exclusive program at CLAS12, providing unique access to axial/spin distributions in the nucleon. The goal would then be to get a picture of the quark momentum and spin distributions of the nucleons. Conclusion

  22. Experiments Already Completed Electroproduction ofpπ+π- at 0.2<0.6, 1.3<1.57GeVFedotovPRC 79, 015204 (2009) Measurement of semi-inclusivep+electroproduction off the protonOsipenkoPRD 80, 032004 (2009) Exclusiveρ0electroproduction on the proton at CLAS,S.Morrow, EPJ A 39, 5 (2009) Electroproduction off(1020) mesons at 1.4<=Q2<=3.8 GeV^2 measured with the CLAS spectrometerSantoro PRC 78, 025210 (2008) Measurement of ep-->epp0 beam spin asymmetries above the resonance region De MasiPRC 77, 042201 (R) (2008) Separated Structure Functions for the Exclusive Electroproduction of K+ L and K+ S0 Final StatesAmbrozewiczPhys.Rev.C75:045203 Deeply virtual and exclusive electroproduction of omega mesonsMorandEPJA 24, 445 (2005) Exclusive rho0 meson electroproduction from hydrogen at CLASHadjidakisPLB 605, 256 (2005) First Measurement of Transferred Polarization in the Exclusive e(pol)p -> e'K+Lambda (pol) ReactionCarmanPRL 90, 131804 (2003) Measurement of ep -> e'pp+p- and baryon resonance analysisRipaniPRL 91, 022002, (2003) Exclusive electroproduction of F mesons at 4.2 GeVLukashinPRC 63, 065205 (2001); Err. 64, 059901 (2001) Electroproduction of the L(1520)HyperonBarrowPRC 64, 044601 (2001) Measurement of Single and Double Spin Asymmetries in Deep Inelastic PionElectroproduction with Longitudinally Polarized TargetAvakianPRL 105, 262002 (2010)

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