Radiative corrections to polarization observables in elastic electron-deuteron scattering in hadronic variables

Model-independent QED radiative corrections to polarization observables in the elastic scattering of unpolarized and longitudinally polarized electron beam by a deuteron target are calculated. Two experimental setups are considered: the deuteron target is arbitrarily polarized, or the vector and/or tensor polarization of the recoil deuteron is measured. The calculations are based on taking all essential Feynman diagrams into account and using the covariant parametrization of the deuteron polarization state. The radiative corrections are calculated for the hadronic variables using invariant integration of the leptonic tensor. Numerical estimates of the radiative corrections to the polarization observables are made for various values of the kinematical vari-ables.     

Weak neutral current effects in elastic electron deuteron scattering

We study the effect of weak neutral currents in elastic electron deuteron scattering on both unpolarized and polarized deuteron targets. Theoretical expressions have been derived for the polarized electron asymmetry, polarized target asymmetry and recoil deuteron vector polarization within the framework of impulse approximation. We show that these polarization parameters can give vital information on the space-time and isospin structure of the hadronic weak neutral current. In particular, our numerical estimates show that a measurement of polarized target asymmetry is sensitive to the isoscalar axial vector piece in the hadronic neutral current which, though zero in the Weinberg-Salam model, is not completely ruled out by the data.     

Radiative corrections to polarization observables in elastic electron-deuteron scattering in leptonic variables

The model-independent QED radiative corrections to polarization observables in elastic scattering of unpolarized and longitudinally polarized electron beams by a deuteron target are calculated in leptonic variables. The experimental setup when the deuteron target is arbitrarily polarized is considered and the procedure for applying the derived results to the vector or tensor polarization of the recoil deuteron is discussed. The calculation is based on taking all essential Feynman diagrams into account, which results in the form of the Drell-Yan representation for the cross section, and the use of the covariant parameterization of the deuteron polarization state. Numerical estimates of the radiative corrections are given in the case where event selection allows undetected particles (photons and electron-positron pairs) and the restriction on the lost invariant mass is used.     

Asymmetry in the scattering of protons on polarized deuterons at 1.21 GeV/c

By using a polarized deuteron target we have measured the asymmetry in the differential cross section for elastic scattering of protons on deuterons and for quasi-elastic scattering of protons on protons bound in deuterons between the two states of opposite polarization, normal to the scattering plane of the initial deuteron. The beam momentum was 1.21 GeV/c. It is checked that the neutrons bound in the deuterons are polarized to approximately 20%.     

Calculation of A x for the Proton–Deuteron Breakup Reaction at 135 MeV

Observables in proton–deuteron scattering are sensitive probes of the nucleon-nucleon interaction and three-nucleon force effects (3NF). Several facilities in the world, including Kernfysisch Versneller Instituut (KVI), allow a detailed study a few-nucleon interaction below the pion-production threshold exploiting polarized proton and deuteron beams. In this contribution we explored 3NF effects in the break-up scattering process by performing a measurement of differential cross section and the analyzing power, especially the x component of the analyzing power, using a 135 MeV polarized-proton beam impinging on a liquid-deuteron target. The proton–deuteron breakup reaction leads to a final state with three free particles and a rich phase space that allows us to study observables for continuous set of kinematical configurations of the outgoing nucleons. The results are interpreted with the help of state-of-the-art Faddeev calculations.     

Theoretical study of deuteron polarization in γ+d → π0+d

The state of polarization of the recoil deuteron in γ+d → π⁰+d on unpolarized and target polarized deuterons is analyzed in detail. A new set of statistical tensors is introduced to describe non-oriented systems, such as the recoil deuteron in γ+d → π⁰+d, and their relationships to the vector and tensor polarization parameters are established. The new statistical tensors reduce, in the case of oriented systems, to Fano's statistical tensors. Numerical results are computed using two different deuteron models for polarized photon asymmetry, polarized target asymmetry and the vector and tensor polarizations of the recoil deuteron, and these are presented at various c.m. pion production angles at different energies in the region of the first π-N resonance. The study of these parameters is suggested as a promising source of information on isoscalar pion photoproduction amplitudes.     

Spin-momentum correlations in quasielastic electron scattering from deuterium

The spin-momentum correlation parameter A(V)(ed) was measured for the 2H-->(e-->,e'p)n reaction for missing momenta up to 350 MeV/c at Q2 = 0.21 (GeV/c)(2) for quasielastic scattering of polarized electrons from vector-polarized deuterium. The data give detailed information about the deuteron spin structure and are in good agreement with the results of microscopic calculations based on realistic nucleon-nucleon potentials and including various spin-dependent reaction mechanism effects. The experiment reveals in a most direct manner the effects of the D state in the deuteron ground-state wave function and shows the importance of isobar configurations for this reaction.     

Measurement of the analysing powers iT11, T20, T21 and T22 in elastic deuteron-proton scattering

The analysing powers iT₁₁, T₂₀, T₂₁ and T₂₂ for the elastic scattering of polarized deuterons by protons have been measured at deuteron energies of 6, 8, 10 and 11.5 MeV with the polarized deuteron beam from a tandem accelerator. The measurements cover the c.m. angular range from 40° to 155° and show small but non-zero analysing powers at all energies.     

Variations on the deuteron theme

Several problems concerning the deuteron and having simple analytic solutions are considered. The relation between the electric quadrupole moment of the deuteron and the np scattering amplitude is established. The degree of the circular polarization of the photon emitted in the radiative capture of longitudinally polarized thermal neutrons is found. The anapole, electric dipole, and magnetic quadrupole moments of the deuteron are calculated.     

A polarized deuteron target in the d(e,e′)np reaction

Asymmetries for scattering of longitudinally polarized electrons from deuterons with a vector polarization as well as asymmetries for scattering of unpolarized electrons from deuterons with a tensor polarization have been considered for inclusive elastic ed scattering. The sensitivity of all asymmetries considered to the electric form factor of the neutron and to the spin structure of the deuteron wave function has been investigated.     

Complete Set of Deuteron Analyzing Powers for dp Elastic Scattering at Intermediate Energies and Three Nucleon Forces

With the aim of clarifying roles of the 3NFs in nuclei experimental programs with the polarized deuteron beam at intermediate energies are in progress at RIKEN RI Beam Factory. As the first step, we have measured a complete set of deuteron analyzing powers in deuteron–proton elastic scattering at 250 and 294 MeV/nucleon. The obtained data are compared with the Faddeev calculations based on the modern nucleon–nucleon forces together with the Tucson–Melbourne’99, and UrbanaIX three nucleon forces.     

Recent results on few-nucleon systems: Investigation from VBLHE-JINR

Recent results on the spin effects in deuteron inclusive breakup and deuteron-proton elastic scattering obtained at the Veksler and Baldin Laboratory of High Energies at JINR are reported. The experimental data have been obtained with the use of a high-energy polarized deuteron beam at the Synchrophasotron-Nuclotron Accelerator Complex. The covered energy range corresponds to the short internucleonic distances where the relativistic effects and non-nucleonic degrees of freedom can play a significant role.     

Manifestation of tensor magnetic polarizability of the deuteron in storage ring experiments

It was previously shown that the tensor magnetic polarizability of the deuteron causes the spin rotation with two frequencies and experiences beating for polarized deuteron beams in storage rings. We confirm an existence of this effect and derive general formulae describing deuteron spin dynamics. It is found that an initially tensor polarized deuteron beam can acquire a final horizontal vector polarization of order of 1%. This effect allows to measure the tensor magnetic polarizability of the deuteron in storage ring experiments.     

QED corrections to {\vec A}({\vec e},e'B)X and A({\vec e},e'{\vec B})X reactions: The case of tensor polarization

The model-independent leading radiative corrections to polarization observables in semi-inclusive longitudinally polarized electron-nucleus scattering with the registration of a produced hadron and scattered electron in coincidence were calculated using the Drell-Yan representation in electrodynamics. The cases of a tensor-polarized target or a produced hadron with tensor polarization were considered. The exclusive process of the electrodisintegration of a polarized deuteron was also studied.     

Inclusive hadron photoproduction from longitudinally polarized protons and deuterons

We report measurements of the asymmetry A₆ for inclusive hadron production on longitudinally polarized proton and deuteron targets by circularly polarized photons. The photons were produced via internal and external bremsstrahlung from an electron beam of 48.35 GeV. Asymmetries for both positive and negative signed hadrons, and a subset of identified pions, were measured in the momentum range 10<P<30 GeV at 2.75° and 5.5°. Small non-zero asymmetries are observed for the proton, while the deuteron results are consistent with zero. Recent calculations do not describe the data well.     

Coherent photo- and lepto-production of vector mesons from deuterium

We discuss the coherent photo- and lepto-production of vector mesons from deuterium at intermediate (virtual) photon energies, 3 GeV ≲ ν ≲ 30 GeV. These processes provide several options to explore the space-time evolution of small size quark-gluon configurations. Furthermore, we study the dependence of the production cross section on the energy and momentum transfer t due to variations of the finite longitudinal interaction length. Kinematic regions are determined where the production cross section is most sensitive to the final state interaction of the initially produced hadronic wave packet. For unpolarized deuteron targets this double scattering contribution can be investigated mainly at large values of the momentum transfer t. For polarized targets kinematic windows sensitive to double scattering are available also at moderate t. We suggest several methods for an investigation of color coherence effects at intermediate energies.     

Axial observables in d-->p--> breakup and the three-nucleon force

We have measured three axial polarization observables in d-->p--> breakup with a polarized 270 MeV deuteron beam on a polarized proton target. Axial observables are zero by parity conservation in elastic scattering but can be easily observed in the breakup channel at the present energy. Based on a symmetry argument, the sensitivity of these observables to the three-nucleon force might be enhanced. Calculations without three-nucleon force are in fair agreement with our measurement, indicating that the expected sensitivity of axial observables to the three-nucleon force is not confirmed. Including a three-nucleon force in the calculation does not improve the agreement with the data.     

Deep electroproduction of photons and mesons on the deuteron

We study deeply virtual Compton scattering and deep exclusive meson electroproduction on a deuteron target. We model the generalized quark distributions in the deuteron by using the impulse approximation for the lowest Fock-space state on the light cone. We study the properties of the resulting GPDs, and verify that sum rules violations are quite small in the impulse approximation. Numerical predictions are given for the unpolarized cross-sections and polarization asymmetries for the kinematical regimes relevant for JLab experiments and for HERMES at HERA. We conclude that the signal of coherent scattering on the deuteron is comparable to the one on the proton at least for low momentum transfer, providing support to the feasibility of the experiments. The short-distance structure of the deuteron may thus be scrutinized in the near future.Received: 21 July 2003, Revised: 9 September 2003, Published online: 5 February 2004PACS: 24.85. + p Quarks, gluons, and QCD in nuclei and nuclear processes - 12.38.Bx Perturbative calculations - 25.30.-c Lepton-induced reactions     

Nuclear binding and deep inelastic scattering

We examine deep inelastic scattering using methods which have been successfully applied to study inclusive scattering of GeV electrons by nuclei. We find that the consistent inclusion of the binding effects allows to describe much better the data on nuclear matter to deuteron cross section ratios in the region of large x where binding fully accounts for the deviation of the cross section ratio from one.