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Title: Recoil-proton polarization in high-energy deuteron photodisintegration with circularly plarized photons.

Abstract

We measured the angular dependence of the three recoil-proton polarization components in two-body photodisintegration of the deuteron at a photon energy of 2 GeV. These new data provide a benchmark for calculations based on quantum chromodynamics. Two of the five existing models have made predictions of polarization observables. Both explain the longitudinal polarization transfer satisfactorily. Transverse polarizations are not well described, but suggest isovector dominance.

Authors:
; ; ; ; ; ; ; ; ; ; ; ; ;
Publication Date:
Research Org.:
Argonne National Lab. (ANL), Argonne, IL (United States)
Sponsoring Org.:
USDOE Office of Science (SC); National Science Foundation (NSF)
OSTI Identifier:
949183
Report Number(s):
ANL/PHY/JA-58391
Journal ID: ISSN 0031-9007; PRLTAO; TRN: US0901775
DOE Contract Number:
DE-AC02-06CH11357
Resource Type:
Journal Article
Resource Relation:
Journal Name: Phys. Rev. Lett.; Journal Volume: 98; Journal Issue: May 1, 2007
Country of Publication:
United States
Language:
ENGLISH
Subject:
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; 71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; 73 NUCLEAR PHYSICS AND RADIATION PHYSICS; BENCHMARKS; DEUTERONS; ISOVECTORS; PHOTONS; PHOTONUCLEAR REACTIONS; POLARIZATION; QUANTUM CHROMODYNAMICS

Citation Formats

Jiang, X., Arrington, J., Benmokhtar, F., Camsonne, A., Chen, J. P., Holt, R. J., Qattan, I. A., Reimer, P. E., Schulte, E. C., Wijesooriya, K., Physics, Rutgers Univ., Univ. Blaise Pascal, and Thomas Jefferson National Accelerator Facility. Recoil-proton polarization in high-energy deuteron photodisintegration with circularly plarized photons.. United States: N. p., 2007. Web. doi:10.1103/PhysRevLett.98.182302.
Jiang, X., Arrington, J., Benmokhtar, F., Camsonne, A., Chen, J. P., Holt, R. J., Qattan, I. A., Reimer, P. E., Schulte, E. C., Wijesooriya, K., Physics, Rutgers Univ., Univ. Blaise Pascal, & Thomas Jefferson National Accelerator Facility. Recoil-proton polarization in high-energy deuteron photodisintegration with circularly plarized photons.. United States. doi:10.1103/PhysRevLett.98.182302.
Jiang, X., Arrington, J., Benmokhtar, F., Camsonne, A., Chen, J. P., Holt, R. J., Qattan, I. A., Reimer, P. E., Schulte, E. C., Wijesooriya, K., Physics, Rutgers Univ., Univ. Blaise Pascal, and Thomas Jefferson National Accelerator Facility. Tue . "Recoil-proton polarization in high-energy deuteron photodisintegration with circularly plarized photons.". United States. doi:10.1103/PhysRevLett.98.182302.
@article{osti_949183,
title = {Recoil-proton polarization in high-energy deuteron photodisintegration with circularly plarized photons.},
author = {Jiang, X. and Arrington, J. and Benmokhtar, F. and Camsonne, A. and Chen, J. P. and Holt, R. J. and Qattan, I. A. and Reimer, P. E. and Schulte, E. C. and Wijesooriya, K. and Physics and Rutgers Univ. and Univ. Blaise Pascal and Thomas Jefferson National Accelerator Facility},
abstractNote = {We measured the angular dependence of the three recoil-proton polarization components in two-body photodisintegration of the deuteron at a photon energy of 2 GeV. These new data provide a benchmark for calculations based on quantum chromodynamics. Two of the five existing models have made predictions of polarization observables. Both explain the longitudinal polarization transfer satisfactorily. Transverse polarizations are not well described, but suggest isovector dominance.},
doi = {10.1103/PhysRevLett.98.182302},
journal = {Phys. Rev. Lett.},
number = May 1, 2007,
volume = 98,
place = {United States},
year = {Tue May 01 00:00:00 EDT 2007},
month = {Tue May 01 00:00:00 EDT 2007}
}
  • We measured the angular dependence of the three recoil-proton polarization components in two-body photodisintegration of the deuteron at a photon energy of 2 GeV. These new data provide a benchmark for calculations based on quantum chromodynamics. Two of the five existing models have made predictions of polarization observables. Both explain the longitudinal polarization transfer satisfactorily. Transverse polarizations are not well described, but suggest isovector dominance.
  • We measured the angular dependence of the three recoil-proton polarization components in two-body photodisintegration of the deuteron at a photon energy of 2 GeV. These new data provide a benchmark for calculations based on quantum chromodynamics. Two of the five existing models have made predictions of polarization observables. Both explain the longitudinal polarization transfer satisfactorily. Transverse polarizations are not well described, but suggest isovector dominance.
  • We present measurements of the recoil proton polarization for the d(polarized y, polarized p)n reaction at thetac.m. = 90 degrees for photon energies up to 2.4 GeV. These are the first data in this reaction for polarization transfer with circularly polarized photons. The induced polarization py vanishes above 1 GeV, contrary to meson-baryon model expectations, in which resonances lead to large polarizations. However, the polarization transfer Cx does not vanish above 1 GeV, inconsistent with hadron helicity conservation. Thus, we show that the scaling behavior observed in the d(y,p)n cross sections is not a result of perturbative QCD. These datamore » should provide important tests of new nonperturbative calculations in the intermediate energy regime.« less
  • We present measurements of the recoil proton polarization for the d({rvec {gamma}},{rvec p})n reaction at {theta}{sub c.m.}=90{sup o} for photon energies up to 2.4 GeV. These are the first data in this reaction for polarization transfer with circularly polarized photons. The induced polarization p{sub y} vanishes above 1 GeV, contrary to meson-baryon model expectations, in which resonances lead to large polarizations. However, the polarization transfer C{sub x} does not vanish above 1 GeV, inconsistent with hadron helicity conservation. Thus, we show that the scaling behavior observed in the d({gamma},p)n cross sections is not a result of perturbative QCD. These datamore » should provide important tests of new nonperturbative calculations in the intermediate energy regime.« less
  • The proton polarization in deuteron photodisintegration by linearly polarized and unpolarized photons at theta = 90/sup 0/ (theta is the angle between the momenta of the proton and photon in the c.m.s.) has been measured in the photon-energy range 300--500 MeV. This permitted us to obtain under similar experimental conditions the observable polarization parameters: P-italic/sub Y-italic/: the proton polarization in the unpolarized beam; ..sigma..: the asymmetry of the cross section, and (for the first time) T-italic/sub 1/: the asymmetry of the proton polarization. Asymmetries arise from linear polarization of the photon. Comparison of the obtained polarization parameters with calculations accordingmore » to the gauge-invariant pole model (GIPM), which takes into account isobar-exchange currents and includes various numbers of dibaryon resonances (/sup 1/D/sub 2/, /sup 3/F/sub 3/, /sup 1/S/sub 0/, and /sup 3/P/sub 1/) with isospin 1, has shown that the best agreement is observed for the model which includes four dibaryons.« less