Measurement of analyzing power for proton-carbon elastic scattering in the coulomb-nuclear interference region with a 22-GeV/c polarized proton beam

The analyzing power for proton-carbon elastic scattering in the Coulomb-nuclear interference region of momentum transfer, 9.0x10(-3)<-t<4.1x10(-2) (GeV/c)(2), was measured with a 21.7 GeV/c polarized proton beam at the Alternating Gradient Synchrotron of Brookhaven National Laboratory. The ratio of hadronic spin-flip to nonflip amplitude, r(5), was obtained from the analyzing power to be Rer(5)=0.088+/-0.058 and Imr(5)=-0.161+/-0.226.     

Excitation functions of the analyzing power in elastic proton-proton scattering from 0.45 to 2.5 GeV

Excitation functions A_N(p_lab,_c.m.) of the analyzing power in elastic proton-proton scattering have been measured in an internal target experiment at the Cooler Synchrotron COSY with an unpolarized proton beam and a polarized atomic hydrogen target. Data were taken continuously during the acceleration and deceleration for proton kinetic energies T_lab (momenta p_lab) between 0.45 and 2.5 GeV (1.0 and 3.3 GeV/c) and scattering angles 30 ^° _c.m. 90^°. The results provide excitation functions and angular distributions of high precision and internal consistency. The data can be used as calibration standard between 0.45 and 2.5 GeV. They have significant impact on phase shift solutions, in particular on the spin triplet phase shifts between 1.0 and 1.8 GeV.     

Polarization in proton-proton elastic scattering at 10, 14 and 17.5 GeV/c

Data on the polarization parameter in pp elastic scattering in the |t|-range from ∼0.1 to ∼ 2.9 (GeV/c)² and at 10, 14 and 17.5 GeV/c are presented.     

Measurement of the polarization parameter in small angle proton-proton elastic scattering at 6 GeV/c

The polarization parameter in pp elastic scattering was measured at 6 GeV/c with fine t resolution for 0.02 < ?t < 0.5 GeV² using a polarized proton beam with Effective Mass Spectrometer at the Zero Gradient Synchrotron. The polarization rises like √?t in the interval 0.02 < ?t < 0.1 GeV², No statistical significant structure was found in this region of momentum transfer.     

Parity non-conservation in proton-proton elastic scattering

The parity-non-conserving longitudinal asymmetry in proton-proton (p p) elastic scattering is calculated in the lab energy range 0-350 MeV using contemporary, realistic strong-interaction potentials combined with a weak-interaction potential comprised of - and -meson exchanges as exemplified by the DDH model. Values for the - and -meson coupling constants, and , are determined from comparison with the measured asymmetries at 13.6 MeV, 45 MeV, and 221 MeV.Received: 30 September 2002, Published online: 22 October 2003PACS: 21.30.-x Nuclear forces - 24.80. + y Nuclear tests of fundamental interactions and symmetries - 25.40.Cm Elastic proton scattering     

Vector analyzing power of polarized deuterons in elastic scattering

Isotope dependence of vector analyzing powers of polarized deuterons in elastic scattering off Se targets is discussed by optical-model and coupled-channel calculations. Attention is particularly directed to relations between analyzing power and imaginary potential.     

Measurement of the tensor analyzing power A yy in the inelastic scattering of 4.5-GeV/c deuterons on beryllium at an angle of 80 mrad

The tensor analyzing power A _yy and the vector analyzing power A _y for the inelastic scattering of 4.5-GeV/c deuterons on beryllium nuclei at angle of about 80 mrad are measured in the vicinity of baryon-resonance excitation. These new data, presented as a function of t, comply well with the results of previous 4.5-, 5.5-, and 9-GeV/c measurements at zero angle in overlapping regions of t; all available data are described by a unified dependence on |t| upto about 0.9 (GeV/c)². The experimental results are compared with the results of calculations performed within the multiple-scattering model and the model involving omega-meson exchange in the t channel.     

Upper limits on resonance contributions to proton-proton elastic scattering in the c.m. mass range 2.05-2.85 GeV/ c2

Recently published excitation functions in proton-proton (pp) elastic scattering observables in the laboratory energy range 0.5-2.5GeV provide an excellent data base to establish firm upper limits on the elasticities η_el = Γ_el/Γ_tot of possible isovector resonant contributions to the nucleon-nucleon (NN) system. Such contributions have been predicted to arise from dibaryonic states, with c.m. masses between 2.1-2.9GeV/c², but have not been confirmed experimentally. A method to determine quantitatively the maximum value of η_el compatible with experimental data is presented. We use energy-dependent phase shift fits to the pp data base to model the non-resonant interaction. Based upon the differential cross-section data measured by the EDDA Collaboration an unbiased statistical test is constructed to obtain upper limits on η_el, that exclude larger values with a 99% confidence level. Results in the c.m. mass range 2.05-2.85GeV/c² and total widths of 10-100MeV/c² in the partial waves ¹S₀, ¹D₂, ³P₀, ³P₁, and ³F₃ are presented and discussed.     

The use of fixed t analyticity in elastic proton-proton scattering

Several methods of exploiting fixed-t analyticity are described and compared with each other. For the forward amplitude the predictions of the real parts from the total cross section data — including the new NAL data — and dispersion relations are found to be in good agreement with the Coulomb interference data. It is also discussed how the results depend on the assumptions on the asymptotic behaviour of the cross section. Furthermore, the conventional dispersion relation approach is compared with the method of analytic parametrization and with the differential operator method. For the non-forward directions, information on the amplitude is extracted from a dispersion relation for the slopes and from a relation between the phase and the modulus of the amplitude.     

Spin effects in proton-proton elastic scattering near the forward direction

We have analysed the several sets of experimental data on pp elastic scattering in the Coulomb interference region in the range p_lab between 9 and 500 GeV/c, in order to estimate the size of the spin dependent part of the strong amplitude. Calling β the ratio of this spin-dependent part to the spin-dependent amplitude in the forward direction, we find all the data strongly suggest but do not conclusively prove a non-negligible β whose value is around 10% and approximately constant with energy. This result cannot be explained theoretically in terms of exchange of any simple factorising Regge pole. We suggest important pomeron cut contributions. Implications of our analysis for some experiments at ISR energies which appear to give rising total cross sections are discussed.     

Precision measurement of vector and tensor analyzing powers in elastic deuteron-proton scattering

High-precision vector and tensor analyzing powers of elastic deuteron-proton ( d + p) scattering have been measured at intermediate energies to investigate effects of three-nucleon forces. Angular distributions in the range of 70^°-120^° in the center-of mass frame for incident-deuteron energies E _d ^lab = 130 and 180 MeV were obtained using the RIKEN facility. The beam polarization was unambiguously determined by measuring the ^12C (d, α)^10B(2⁺) reaction at 0^°. Results of the measurements are compared with state-of-the-art three-nucleon calculations. The present modeling of nucleon-nucleon forces and its extension to the three-nucleon system is not sufficient to describe the high-precision data consistently and requires, therefore, further investigation.     

Proton-proton elastic scattering analyzing power in the 2.16 to 2.28 GeV energy region

We analyze the possibility of testing local Lorentz invariance from the observation of tau decays. Future prospects of probing distances below the electroweak characteristic scale are discussed.     

Polarization in the quasielastic scattering of 1-GeV/c protons on light nuclei

Polarization measurements in the A(p, 2p)B reactions on ⁶Li, ⁷Li, and ²⁸Si nuclei at a proton-beam energy of 1 GeV were performed in a kinematically complete experiment. By using a two-arm magnetic spectrometer, two secondary protons were recorded in coincidence at asymmetric scattering angles of θ₁=15°?26° and θ₂=58.6° for residual-nucleus momenta in the range K _B=0–150 MeV/c. Either arm of the spectrometer was equipped with polarimeters based on proportional chambers. The data coming from this experiment are analyzed within the distorted-wave impulse approximation. It is shown that the polarization of recoil protons formed at angle θ₂ in the interaction featuring a proton from the P shell of the ⁷Li nucleus can be described under the assumption of an effective intranuclear-proton polarization by using the single-particle shell-model wave function of the nucleus. Our data on the polarizations of the two protons from the reaction (p, 2p) on a ²⁸Si nucleus also suggest the effective polarization of the protons in the D shell of the ²⁸Si nucleus. It is found that, for high recoil-nucleus momenta of K _B≥90 MeV/c, the effective polarization of the protons in the P shell of the ⁶Li nucleus—this polarization was discovered in studying the polarization of recoil protons in the reaction ⁶Li(p, 2p)⁵He—cannot be described within the shell model assuming LS coupling. As might have been expected, the polarization of recoil protons knocked out from the S shells of the ⁶Li and ⁷Li nuclei comply well with the predictions obtained in the impulse approximation with allowance for the depolarization effect alone.