Nov , 2010 Annual Meeting of GDR Nucleon - K. Park

Pert. hard part soft part Successful Q2  ∞, t << fixed Nov , 2010 Annual Meeting of GDR Nucleon - K. Park

Pert. hard part soft part What about u <<, DVCS ? Non-pert. Part does not describe the Hadron  Hadron transition Need a Transition DA (TDAs) ??? Nov , 2010 Annual Meeting of GDR Nucleon - K. Park

Non-pertubative transition between pion and baryon in backward angle Investigation of Transition Distribution Amplitude B. Pire, L. Szymanowski PRD71, (2005) Pert. Amplitude = Correlation between meson →  transition Mesonic TDA pp     GSI e+e- B-factories       Large Q2 would provide hard scale with pert. expansion pp  J/  GSI pp     t GSI Nov , 2010 Annual Meeting of GDR Nucleon - K. Park

Non-pertubative transition between pion and baryon in backward angle Investigation of Transition Distribution Amplitude B. Pire, L. Szymanowski PRD71, (2005) Pert. Amplitude = Correlation between meson →  transition Mesonic TDA pp     GSI e+e- B-factories       Large Q2 would provide hard scale with pert. expansion pp  J/  GSI pp     t GSI Nov , 2010 Annual Meeting of GDR Nucleon - K. Park

Non-pertubative transition between pion and baryon in backward angle Investigation of Transition Distribution Amplitude J.P. Lansberg, B. Pire, PRD75, (2007) GPD can not describe Non-perturbative part Baryon → π transition Pert. Amplitude = Meson almost stay at rest in the target(baryon) rest frame Pert. Baryonic TDA e’   n u CLAS   at 180 Hall-C e’p  e’p  CLAS JLAB 12GeV  *p  pJ/ COMPASS Nov , 2010 Annual Meeting of GDR Nucleon - K. Park

The kinematics imposes the exchange of 3 quarks in the u -channel Factorization in the generalized Bjorken limit: The object factorized from the hard part is a Transition Distribution Amplitude Interpretation at the amplitude Amplitude of probability to find a meson within the proton Baryonic TDA Nov , 2010 Annual Meeting of GDR Nucleon - K. Park

Kinematical variables Unpol. CRS w/ one-photon exchange approx. Nov , 2010 Annual Meeting of GDR Nucleon - K. Park

The CLAS Collaboration Old Dominion University, Norfolk, VA Rensselaer Polytechnic Institute, Troy, NY Rice University, Houston, TX University of Richmond, Richmond, VA University of Rome Tor Vergata, Italy University of South Carolina, Columbia, SC Thomas Jefferson National Accelerator Facility, Newport News, VA Union College, Schenectady, NY Virginia Polytechnic Institute, Blacksburg, VA University of Virginia, Charlottesville, VA College of William and Mary, Williamsburg, VA Yerevan Institute of Physics, Yerevan, Armenia Brazil, Germany, Morocco and Ukraine,, have individuals or groups involved with CLAS, but with no formal collaboration at this stage. Arizona State University, Tempe, AZ University Bari, Bari, Italy University of California, Los Angeles, CA California State University, Dominguez Hills, CA Carnegie Mellon University, Pittsburgh, PA Catholic University of America CEA-Saclay, Gif-sur-Yvette, France Christopher Newport University, Newport News, VA University of Connecticut, Storrs, CT Edinburgh University, Edinburgh, UK University Ferrara, Ferrara, Italy Florida International University, Miami, FL Florida State University, Tallahassee, FL George Washington University, Washington, DC University of Glasgow, Glasgow, UK University of Grenoble, Grenoble, France Idaho State University, Pocatello, Idaho INFN, Laboratori Nazionali di Frascati, Frascati, Italy INFN, Sezione di Genova, Genova, Italy Institut de Physique Nucléaire, Orsay, France ITEP, Moscow, Russia James Madison University, Harrisonburg, VA Kyungpook University, Daegu, South Korea University of Massachusetts, Amherst, MA Moscow State University, Moscow, Russia University of New Hampshire, Durham, NH Norfolk State University, Norfolk, VA Ohio University, Athens, OH Nov , 2010 Annual Meeting of GDR Nucleon - K. Park

CLAS E max 6 GeV I max 200  A Duty Factor 100%  E /E Beam P ~ 85% E g (tagged) ~ GeV

e-e- π+π+ e-e- Nov , 2010 Annual Meeting of GDR Nucleon - K. Park

Kinematical variables Unpol. CRS w/ one-photon exchange approx. Nov , 2010 Annual Meeting of GDR Nucleon - K. Park

Particle Identification Acceptance Calculation Radiative Correction Background Subtraction Kinematical Correction Extract CRS & structure functions Acceptance cross check after more simulation in backward angle with Modification of GENEV vs. FSGEN Bin corrections Systematic error studies E1-6 data set was used.E 0 =5.754GeV, B =3375A, LH2 ……. Nov , 2010 Annual Meeting of GDR Nucleon - K. Park

1.No (s-) resonance access (= no event below 2GeV of W) 2.No missing mass cut Nov , 2010 Annual Meeting of GDR Nucleon - K. Park

1.No (s-) resonance access (= no event below 2GeV of W) 2.No missing mass cut 3.Automatically, accessible small -u large –t u t Nov , 2010 Annual Meeting of GDR Nucleon - K. Park

Requirement W>2GeV Nov , 2010 Annual Meeting of GDR Nucleon - K. Park

Requirement W>2GeV cos  * <0.0  T 2 <0.5GeV 2 Nov , 2010 Annual Meeting of GDR Nucleon - K. Park

Requirement W>2GeV cos  * <0.0  T 2 <0.5GeV 2 TOF mass 3sigma cut Nov , 2010 Annual Meeting of GDR Nucleon - K. Park

Requirement W>2GeV cos  * <0.0  T 2 <0.5GeV 2 TOF mass 3sigma cut  : 2sigma cut Nov , 2010 Annual Meeting of GDR Nucleon - K. Park

Blue bullets :  _T2 < 0.5GeV2 cut Red hist. :  _T2 < 1.0GeV2 cut u t cos  * Nov , 2010 Annual Meeting of GDR Nucleon - K. Park

Black bullets : exp. Data before BG subtraction Red bullets : exp. Data before BG subtraction Blue solid lines : nominal MMx 3  cut Nov , 2010 Annual Meeting of GDR Nucleon - K. Park

Blue bullets : exp. Data after BG subtraction Red hist. : GPP + w/o (left) & with (right) correction applied MC Nov , 2010 Annual Meeting of GDR Nucleon - K. Park

1.Two event generators were tested 2.cos  cut was applied on top of  T 2 cut Nov , 2010 Annual Meeting of GDR Nucleon - K. Park

1.Two event generators were tested 2.cos  cut was applied on top of  T 2 cut Nov. 12, 2010 DPWG K. Park

W>2GeV MMx cut cos  * <0.0  T 2 <0.5GeV 2 Nov , 2010 Annual Meeting of GDR Nucleon - K. Park

W>2GeV  T 2 <1.0GeV 2 + GPP+corr.  T 2 <0.5GeV 2 MMx cut Nov , 2010 Annual Meeting of GDR Nucleon - K. Park

Blue square : data with stat. err. only Red triangle : fit with cos2  Average Chi2 ~ 1.74 except last Q 2 bin Nov , 2010 Annual Meeting of GDR Nucleon - K. Park

σ T +εσ L Nov , 2010 Annual Meeting of GDR Nucleon - K. Park

σ T +εσ L Nov , 2010 Annual Meeting of GDR Nucleon - K. Park

σ T +εσ L Nov , 2010 Annual Meeting of GDR Nucleon - K. Park

σ T +εσ L J.P. Lansberg, B. Pire, PRD75, (2007) But  0 – calculation for  =0.8,  =180 o Nov , 2010 Annual Meeting of GDR Nucleon - K. Park

σ T +εσ L < 1/2 ~1  - range is about Nov , 2010 Annual Meeting of GDR Nucleon - K. Park

Hard exclusive process of meson in the backward angle opens a new window in the understand of hadronic physics in the framework of the collinear-factorization approach of QCD. Measurement of cross sections and asymmetries are crucial to develop a realistic model for the TDAs. Careful study has been performed by communicating with theory group (kinematic binning, corrections, acceptance(GENEV/FSGEN), cuts, etc.) We measured the differential cross sections on backward angle in the kinematic range of W > 2GeV, high “t” and low “u”. We extracted the structure functions from differential cross sections,  TT has a similar amplitude of  LT  T +  L is ~2x larger than  TT and  LT.  Open questions ? Nov , 2010 Annual Meeting of GDR Nucleon - K. Park

Thank you ! Questions/comments ? Nov , 2010 Annual Meeting of GDR Nucleon - K. Park

Black bullets : exp. Data before BG subtraction Red bullets : exp. Data before BG subtraction Blue solid lines : nominal MMx 3sigma cut Nov , 2010 Annual Meeting of GDR Nucleon - K. Park

Black bullets : exp. Data before BG subtraction Red bullets : exp. Data before BG subtraction Blue solid lines : nominal MMx 3sigma cut Nov , 2010 Annual Meeting of GDR Nucleon - K. Park

Black bullets : exp. Data before BG subtraction Red bullets : exp. Data before BG subtraction Blue solid lines : nominal MMx 3sigma cut Nov , 2010 Annual Meeting of GDR Nucleon - K. Park

Black bullets : exp. Data before BG subtraction Red bullets : exp. Data before BG subtraction Blue solid lines : nominal MMx 3sigma cut Nov , 2010 Annual Meeting of GDR Nucleon - K. Park

Black bullets : exp. Data before BG subtraction Red bullets : exp. Data before BG subtraction Blue solid lines : nominal MMx 3sigma cut Nov , 2010 Annual Meeting of GDR Nucleon - K. Park

W>2GeV  T 2 <0.5GeV bins of  MMx cut  T 2 <0.5GeV bins of  Nov , 2010 Annual Meeting of GDR Nucleon - K. Park

W>2GeV  T 2 <0.5GeV 2 MMx : +/- 4  cut MMx : +/- 2  cut Nov , 2010 Annual Meeting of GDR Nucleon - K. Park