New Polarization Measurements in Deuteron Photodisintegration in the MeV range d( , p )n Adam J. Sarty Saint Mary’s University representing Jackie Glister (SMU & Dalhousie U., PhD student) Guy Ron (Tel Aviv U., PhD student) Ron Gilman (Rutgers U. & Jefferson Lab) Steffen Strauch (U. of South Carolina) Doug Higinbotham (Jefferson Lab) Byungwuek Lee (Seoul National U., PhD student) and the JLab Hall A “LEDEX Collaboration” (JLab experiments E and E05-004)

The Deuteron Key in Quark/Gluon  Nucleon/Meson connection A main focus at JLab: –understand the relation / connection between these 2 descriptive paradigms. Most basic “real nucleus” ( np ): –Simplicity offers hope of shedding light on the connection Simple reaction process:  d  High Energies (E   3 GeV): –both d  and Polarization appear to show evidence of tx to Quark/Gluon description via Dimensional Scaling (pQCD)

 cm = 90  K. Wijesooriya et al. (Hall A), PRL 2002 d( ,p)n : pQCD-type behaviour as E   PRC70 (2004), d  /dt  scale  s 11 P y  zero

d( ,p)n Quark/Gluon  Nucleon/Meson connection? Is displayed “scaling” behaviour truly a manifestation of quark/gluon d.o.f. (pQCD)? Lower in excitation energy than pQCD expected to be valid… perhaps can be modeled w/ “traditional” nucleon/meson framework? To understand: clearly need best understanding possible of nucleon/meson calculations at low E. Deuteron calculations at low E have been very successful … with one notable exception (30 yr problem!): inability to describe induced polarization at excitation of few hundred MeV

d( ,p)n State of Data/Theories at “Low E  ” (I) E  = 300 MeV: good description of d  and Polarization Hadronic (N / meson) theories are: Schwamb & Arenhoevel (solid line), Kang et al. (dashed) Schwamb & Arenhoevel “best”/most-realistic: modern NN potentials, relativistic corrections, channel coupling E  = 300 MeV

d( ,p)n State of Data/Theories at “Low E  ” (II)

d( ,p)n State of Data/Theories at “Low E  ” (III) E  = 450 MeV: clear disagreement for P y and still no data for P X C or P z C E  = 450 MeV

d( ,p)n State of Data/Theories at “Low E  ” (III) And by E  = 500 MeV: HUGE disagreement for P y at 90  cm-angle THUS - Our Goal: Measure high-precision Polarization obs. In MeV range Provide clues as to what hadronic theories are missing (evidenced by P y ) NEW Data taken summer 2006: JLab, Hall A LEDEX (Low Energy Deuteron Experiments)  cm = 90 

Goal of New d( ,p)n Measurements: Induced Polarization

Goal of New d( ,p)n Measurements: Transferred Polarization

d( , p )n Polarization Observable Definitions “C”  circular polarization of photon beam

d( , p )n Experimental Setup (“LEDEX” 2006)

d( , p )n Focal Plane Polarimeter (“FPP”) P z target from component-mixing in HRS spin-transport

d( , p )n Kinematics Table for LEDEX

d( , p )n Results Induced Polarization, P y Pre-existing world data shown in Blue. Our new results shown in Black (with statistical uncertainties); systematic uncertainty  black strip. Theory curves are Schwamb & Arenhövel: dashed is more recent (from Schwamb’s habilitation, to appear in Phys. Rep.) and treats interactions in propagating  NN system non-perturbatively (as opposed to approximately) LOWEST ENERGY: E  = 277  10 MeV Reasonable agreement w/ world-data + theory…theory slight over-predict’n

d( , p )n Results Induced Polarization, P y Pre-existing world data shown in Blue. Our new results shown in Black (with statistical uncertainties); systematic uncertainty  black strip. Theory curves are Schwamb & Arenhövel: dashed is more recent (from Schwamb’s habilitation, to appear in Phys. Rep.) and treats interactions in propagating  NN system non-perturbatively (as opposed to approximately) ENERGY BIN #2: E  = 297  10 MeV

d( , p )n Results Induced Polarization, P y Pre-existing world data shown in Blue. Our new results shown in Black (with statistical uncertainties); systematic uncertainty  black strip. Theory curves are Schwamb & Arenhövel: dashed is more recent (from Schwamb’s habilitation, to appear in Phys. Rep.) and treats interactions in propagating  NN system non-perturbatively (as opposed to approximately) ENERGY BIN #3: E  = 317  10 MeV

d( , p )n Results Induced Polarization, P y Pre-existing world data shown in Blue. Our new results shown in Black (with statistical uncertainties); systematic uncertainty  black strip. Theory curves are Schwamb & Arenhövel: dashed is more recent (from Schwamb’s habilitation, to appear in Phys. Rep.) and treats interactions in propagating  NN system non-perturbatively (as opposed to approximately) ENERGY BIN #4: E  = 337  10 MeV

d( , p )n Results Induced Polarization, P y Pre-existing world data shown in Blue. Our new results shown in Black (with statistical uncertainties); systematic uncertainty  black strip. Theory curves are Schwamb & Arenhövel: dashed is more recent (from Schwamb’s habilitation, to appear in Phys. Rep.) and treats interactions in propagating  NN system non-perturbatively (as opposed to approximately) HIGHEST ENERGY: E  = 357  10 MeV Agreement gone – data show clear evolution to “inverted shape” wrt theory; NOTE: large underestimate of theory for angles between 60  

d( , p )n Results Induced Polarization, P y ENERGY  cm = 90  Increase of polarization magnitude (away from theory) shows onset clearly by 337 MeV point Increase in polarization steeper as f(E  ) than older data Green line is theory by Kang et al.

d( , p )n Results Induced Polarization, P y ENERGY  cm = 90  When viewed on the larger “global” energy scale … Our data can be seen to confirm the “problem” seen in earlier data (and, in fact, show the “problem” to start at lower Energy!)

d( , p )n Results Transferred Polarizations, P x c and P z c LOWEST ENERGY: E  = 277 MeV Reasonable agreement with Schwamb & Arenhövel calculations at lower cm-angles (a little better agreement with older calculations) Data show “shape change” (relative to predictions) at angle above 50  (albeit this is regime where our systematic errors grow)

d( , p )n Results Transferred Polarizations, P x c and P z c HIGHEST ENERGY: E  = 357 MeV P x c clearly shows better agreement with Schwamb & Arenhövel’s older calculations (I’ll come back to this at end) P z c has a completely different angular- distribution “shape” than predicted (by either the old or new calculations)

d( , p )n Results Transferred Polarizations, P x c and P z c ENERGY  cm = 90  P x c approaches theory as E  increases … interesting since P x c and P y are the real and imaginary parts of the same amplitude- combination (and P y diverges from theory as E  increases!) P z c has same E  dependence as predicted, but it’s magnitude is consistently under-predicted.

d( , p )n Summary First : discussion/comparison of results to “old” (NPA 2001) vs. “new” (to appear Phys Rep). Schwamb & Arenhövel calculations: –“Old” calculations having following properties: parameters fixed/fit to NN-scattering and d( ,p)n data (as described earlier in talk)  NN dynamics treated approximately (with a resulting violation of unitarity) –“New” calculations having following properties: more rigorous “conceptually”: fulfills unitarity to leading order  NN dynamics treated non-perturbatively fewer parameters to be fixed/fit: parameters fit to simultaneously describe 7 reactions: d( ,p)n, d(e,e’p)n, d( ,  0 )d, d( ,  0 )pn,  d  NN, NN  NN, NN  NN SO…newer/better, but much less parameter “freedom”

d( , p )n Summary (continued) Confirmed steep increase in magnitude of induced normal polarization (beyond predictions of standard MB calculations) –rise in P y magnitude seen to start as low as ~330 MeV Standard MB calculations have rough agreement with new transferred polarizations at the lower energies (<300 MeV); –agreement deteriorates for P z c as energy goes > 300 MeV –interestingly, agreement improves for P x c as energy goes up (since P x c and P y are Im and Re part of same amplitude-combo) Conjecture for source of discrepancies between data and MB calculations: NN-potentials used are not well-calibrated/precise at the high energies of the FSI in our reaction …

Kinematics Overview (with e-beam polarization = 38-41%) : 5 bins in E  (20 MeV wide), 9  cm settings

d( , p )n Kinematics Overview for LEDEX

d( , p )n FPP Alignment

d( , p )n False Asymmetry

d( , p )n Measured Carbon Analyzing Power (A c )

New Parameterization Pubished: Glister et al., NIM A (2009)

d( , p )n Method of Extracting Polarizations (I)

d( , p )n Method of Extracting Polarizations (II)