Dispersion theory of parity non-conservation in pion-nucleon scattering at low energies

We examine the possibility for testing the weak parity non-conserving (pnc) interaction in pion-nucleon scattering at low energies. We start out analysis by assuming the existence of a pnc πNN coupling which conserves time reversal invariance and has the isospin selection rule ΔI = 1, and the existence of fixed-t dispersion relations obeyed by the pnc invariant amplitudes. By using the nonrelativistic expansion, we then derive dispersion relations for the partial-wave amplitudes.We calculate parity-odd observables in π^?p → π^?p and in π^?p → π⁰n, e.g., the up-down asymmetry α in the total cross section for a polarized target and the longitudinal polarization P of the recoil nucleon. In the conventional Cabibbo model for the weak interaction P and α are found to be of order 10^?7 to 10^?8.We have also examined the t-channel pnc ?-exchange process which has the isospin selection rule ΔI = 0, 2 and found it to contribute dominantly to P in the charge-exchange channel π^?p → π⁰n.     

Deep inelastic electron scattering from the deuteron

In the present lectures we discuss the role of nuclear structure effects in deep inelastic scattering of leptons on the deuteron. Also a problem of unfolding the neutron structure functions, spin-independent and spin-dependent, from the combined proton-deuteron data is considered.Lectures given (by the first author) at the Indian-Summer School on Electron Scattering of Nucleons and Nuclei, Prague (Czech Republic), September 1994.On leave from Bogoliubov's Laboratory of Physics, JINR, Dubna 141980, Russia.This work was supported in part by the Natural Sciences and Engineering Research Council of Canada. One of the author (LPK) wishes to thank NSERC for an international scientific exchange award that made it possible to visit the University of Alberta.     

Nuclear structure effects in parity non-conservation in heavy ions

We calculate the binding energy, charge radii in ¹²⁹Ba-¹⁴³Ba and ²¹⁴Ra-²²⁸Ra using the relativistic mean field theory which includes scalar and vector mesons. We then evaluate the nuclear structure corrections to the weak charges for a series of these isotopes using different parameters and estimate their uncertainty in the framework of this model. Our results will have important implication for the ongoing and planned parity nonconservation experiments and atomic structure calculations on Ba⁺ and Ra⁺.     

Deep inelastic electron scattering on light nuclei

Czechoslovak Journal of Physics -     

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     

Remark on the status of non-conservation of parity in nuclear beta-decay

Equality of β-decay coupling constants C′_A/C_A = C′_V/C_V = 1, implying V - A interaction, is less verified than commonly assumed. Deducing limits 0.52 < C′_V/C_V < 1.93 and 0.82 < C′_A/C_A < 1.22 we discuss a possible V+A admixture with a mass ratio m(W^V?A)/m(W^V+A) < 0.56 for intermediate bosons W^V±A.     

Polarized parity violating electron scattering on 3He

We calculate the asymmetry parameters, A, and figures-of-merit for polarized parity violating electron scattering from ³He via the reaction, e⁻ +³ He → e⁻ +³ He. We do this explicitly forv incident electron energies of 1.0 GeV and 4.0 GeV. We find a sharp and unexpected variation in A due to cancellations between the weak and electromagnetic form factors caused by the different q² dependences of these form factors. We find that at small angles, the asymmetry may be obtained to reasonably high accuracy for all energies considered and that the interesting region where the asymmetry has its first maximum and minimum is accessible for electron energies of 1 GeV or higher. In addition we find that the asymmetry and figures-of-merit are in the range of those for other proposed target nuclei. We also consider the possibility of strange quark contributions to the asymmetry and show that at the first maxima and minima, possible contributions of the strange quark current vector form factors cause large variations in the asymmetry which might be observed.     

Classical V-A theory and non-conservation of the dynamical parity

The V-A theory with and without cut-off is studied. The existence of finite-energy global solutions and scattered solutions is proved, for certain regularizations. The scattering operator turns out to be C^∞. Moreover, finite-charge global “solutions” are defined. The dynamical parity operator is discussed. Finally some remarks about the continuous spin modified V-A theory are made.     

Level shifts and inelastic electron scattering in dense plasmas

A completely quantum mechanical formalism has been developed to describe the high density plasma effects on fundamental atomic parameters. Both the bound and free electrons are treated by a method which in principle is similar to Hartree's self-consistent field method. The free plasma electrons' wavefunction is obtained from the Schrödinger equation with the effective pottential representing the spherically averaged Coulomb interaction with bound and free electrons. Results are given for level shifts, coefficients of transition probabilities, and electron collision cross sections of Ne⁺⁹ for temperatures of 200 and 500 eV for an electron density range of 1–6 × 10²⁴ cm^?3.     

Atomic parity non-conservation: Present status and future prospects

The general features of parity nonconservation (PNC) in atoms arising from neutral weak currents and the nuclear anapole moment are discussed. The theoretical approaches used to calculate PNC observables are briefly mentioned. A brief review of the present status of atomic PNC is presented and its potential as a probe of physics beyond the standard model is highlighted.     

Polarized deep inelastic scattering at high energies and parity violating structure functions

Zeitschrift für Physik C Particles and Fields - A comprehensive analysis of deep inelastic scattering of polarized charged leptons on polarized nucleons is presented; weak interaction...     

Transition probability functions for applications of inelastic electron scattering

In this work, the transition matrix elements for inelastic electron scattering are investigated which are the central quantity for interpreting experiments. The angular part is given by spherical harmonics. For the weighted radial wave function overlap, analytic expressions are derived in the Slater-type and the hydrogen-like orbital models. These expressions are shown to be composed of a finite sum of polynomials and elementary trigonometric functions. Hence, they are easy to use, require little computation time, and are significantly more accurate than commonly used approximations.     

Theory of adsorbate vibrational excitation by inelastic electron scattering

For electrons specularly reflected at a metal surface the differential cross-section for excitation of a single adsorbate vibration is calculated, with special application to the adsorbed CO group.     

Importance of longitudinal contributions to backward inelastic electron scattering

Coulomb contributions of multipolarity 2 are calculated for backward (θ = 180°) inelastic electron scattering by our improved DWBA code. General features are studied such as nuclear charge (Z) dependence, energy transfer dependence, momentum transfer dependence as well as the angle dependence near θ = 180°, with the help of a simple model for the transition charge density. We compare these features with PWBA and other simple approximations. We show, as a specific example, that the C2 contribution is comparable to the M1 and E2 multipole form factors for inelastic scattering to the rotational excited states of ¹⁸¹Ta.     

Nucleons produced in inelastic electron scattering with a deuterium target

We have measured at ?k² = 0.6 (GeV/c)² and W = 2.3 GeV the inclusive electroproduction cross sections for final-state neutrons and protons from a deuterium target. By comparison with previous data from a proton target, we present cross sections for inclusive nucleon production from neutrons which show great similarity to those from protons. There is evidence that ?⁰ production is present with essentially the same strength as with a proton target.