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Pert.
hard part
soft part
Successful factorization
@ Q2 ∞ , t << fixed
Nov. 25-26, 2010 Annual Meeting of GDR Nucleon - K. Park
Pert. 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. 25-26, 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, 111501 (2005)Pert. 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. 25-26, 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, 111501 (2005)Pert. 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. 25-26, 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, PRD75,074004 (2007)
GPD can not describe Non-perturbative part Baryon →π transition
Pert. Pert.
Amplitude = Meson almost stay at rest in the target(baryon) rest frame
Pert.Baryonic TDA
e’ n u << , t >> @ CLAS
at 180o @ Hall-C
e’p e’p o @ CLAS
JLAB 12GeV
*p pJ/ @ COMPASS
Nov. 25-26, 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. 25-26, 2010 Annual Meeting of GDR Nucleon - K. Park
Kinematical variables Unpol. CRS w/ one-photon exchange approx.
Nov. 25-26, 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. 25-26, 2010 Annual Meeting of GDR Nucleon - K. Park
Kinematical variables Unpol. CRS w/ one-photon exchange approx.
Nov. 25-26, 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. E0=5.754GeV, B =3375A, LH2
…….
Nov. 25-26, 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. 25-26, 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. 25-26, 2010 Annual Meeting of GDR Nucleon - K. Park
Requirement
W>2GeV
cos * <0.0
T2 <0.5GeV 2
TOF mass 3sigma cut
Nov. 25-26, 2010 Annual Meeting of GDR Nucleon - K. Park
Requirement
W>2GeV
cos * <0.0
T2 <0.5GeV 2
TOF mass 3sigma cut
: 2sigma cut
Nov. 25-26, 2010 Annual Meeting of GDR Nucleon - K. Park
Blue bullets : _T2 < 0.5GeV2 cut
Red hist. : _T2 < 1.0GeV2 cut
u
t
cos *
Nov. 25-26, 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. 25-26, 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. 25-26, 2010 Annual Meeting of GDR Nucleon - K. Park
1. Two event generators
were tested
2. cos cut was applied on
top of T2 cut
Nov. 25-26, 2010 Annual Meeting of GDR Nucleon - K. Park
1. Two event generators
were tested
2. cos cut was applied on
top of T2 cut
Nov. 12, 2010 DPWG K. Park
W>2GeV
T2 <1.0GeV 2
+ GPP+corr.
T2 <0.5GeV 2
MMx cut
Nov. 25-26, 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 Q2 bin
Nov. 25-26, 2010 Annual Meeting of GDR Nucleon - K. Park
σT+εσLσT+εσL
J.P. Lansberg, B. Pire, PRD75,074004 (2007)
But 0 – calculation for =0.8, =180o
Nov. 25-26, 2010 Annual Meeting of GDR Nucleon - K. Park
σT+εσLσT+εσL
< 1/2 < 1/2 ~1
- range is about 0.4-0.7
Nov. 25-26, 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. 25-26, 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. 25-26, 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. 25-26, 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. 25-26, 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. 25-26, 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. 25-26, 2010 Annual Meeting of GDR Nucleon - K. Park
W>2GeV
T2 <0.5GeV 2
+ 18 bins of
MMx cut
T2 <0.5GeV 2
+ 9 bins of
Nov. 25-26, 2010 Annual Meeting of GDR Nucleon - K. Park