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.     

Radiative corrections to deep inelastic electron-deuteron scattering: The case of tensor-polarized deuteron

Model-independent radiative corrections to deep inelastic scattering of an unpolarized electron beam off the tensor-polarized deuteron target are considered. The contribution to the radiative corrections due to the hard photon emission from the elastic electron-deuteron scattering (the so-called elastic radiative tail) is also investigated. The calculation is based on the covariant parametrization of the deuteron quadrupole polarization tensor. Radiative corrections to the polarization observables are estimated numerically for the kinematical conditions of the current experiment at HERA.     

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.     

QED corrections in deep-inelastic scattering from tensor-polarized deuteron target

The leading-log model-independent radiative corrections to deep-inelastic scattering of an unpolarized electron beam from the tensor-polarized deuteron target have been considered. The calculation is based on the covariant parameterization of the deuteron quadrupole polarization tensor and the use of the Drell-Yan-like representation in electrodynamics to describe the radiation of real and virtual particles by the initial and scattered electron.     

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 polarized inelastic scattering in the coincidence setup

We completely analyze the model-independent leading radiative corrections to the cross section and polarization observables in the semi-inclusive deep-inelastic electron-nucleus scattering with the detection of a proton and the scattered electron in coincidence. The calculations are based on representing the spin-independent and spin-dependent parts of the cross section in terms of the electron structure functions similarly to the Drell-Yan-like representation in electrodynamics. As the applications, we consider the polarization transfer effect from a longitudinally polarized electron beam to the detected proton and the scattering by a polarized target.     

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.     

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.     

Electron polarization in polarized muon decay: Radiative corrections

We calculate the first-order radiative corrections to the decay spectrum of polarized muons, for the case where the electron polarization is also observed. The significance of the results for further studies on muon decay is discussed.     

Electroweak radiative corrections to polarized Møller scattering at high energies

The cross section for with arbitrary electron polarizations is calculated within the Electroweak Standard Model for energies large compared to the electron mass, including the complete virtual and soft-photonic radiative corrections. The relevant analytical results are listed, and a numerical evaluation is presented for the unpolarized and polarized cross sections as well as for polarization asymmetries. The relative weak corrections are typically of the order of 10%. At low energies, the bulk of the corrections is due to the running of the electromagnetic coupling constant. For left-handed electrons, at high energies the vertex and box corrections involving virtual W bosons become very important. The polarization asymmetry is considerably reduced by the weak radiative corrections. Received: 22 July 1998 / Published online: 8 September 1998     

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%.     

Reactions p(d, p)d and p(d, p)pn as a tool for studying the short-range internal structure of the deuteron

In recent years, the deuteron structure at short distances has often been treated from the point of view of nonnucleonic degrees of freedom. In this study, measurements of T-odd polarization observables by using a tensorially polarized deuteron beam and a polarized proton target or a proton polarimeter are proposed as a means for seeking quark configurations inside the deuteron.     

Spin correlation coefficients for neutron-proton radiative capture

We use a theoretical model for deuteron photodisintegration below the pion production threshold, which has previously been used to calculate the observables for which experimental data is available, in order to calculate the spin correlation coefficients for radiative capture of a polarized neutron beam by a polarized proton target. We give results for the coefficients whose measurement is possible in the near future and explain how such experimental results could improve our understanding of the reaction mechanism. We also comment on exciting measurements of the neutron analyzing power at very low energies.     

Effects of polarization on radiation absorption in one-dimensional semitransparent slab exposed to collimated irradiation

The internal distribution of radiative absorption in one-dimensional semitransparent slab exposed to collimated irradiation is determined by the ray tracing method, and the detailed computation formulae for the distribution of radiative absorption are deduced. It is found that the ray will be polarized by specular reflection of slab boundaries even if the collimated irradiation is unpolarized, and the extent of polarization increases with the internal reflection times. The effects of polarization on the radiative absorption are analyzed and the radiative absorption distributions are compared with those obtained from the case in which the effects of polarization are omitted. The results show that the large differences between reflectances of perpendicular and parallel polarized components are the main causes resulting in errors of radiative absorption distribution. The polarization of incident beam has significant influences on the radiative absorption. Even for an unpolarized beam irradiated near Brewster's angle, omitting the effects of polarization will result in large errors, and the errors increase with the refractive index.     

Polarization transfer observables in π-d elastic scattering

Polarization transfer measurements in π⁺ elastic scattering have been performed at two incident pion energies, one below and one at the Δ(3, 3)-resonance. Using a vector polarized deuteron target four polarization transfer observables are determined. The results are compared to predictions from Faddeev calculations.     

Radiative corrections to very high energy electron-proton scattering

A “leading log” analysis of radiative corrections to inclusive ep scattering at HERA energies is presented. Neutral current weak interactions are considered at the level of the Born cross section as well as of the modifications of vertex and vacuum polarization parts. The leading log approximation has been also improved in the single hard and multiple soft photon emission by appropriate kinematical considerations. Some numerical results are presented for polarized electron and positron beams.     

Relativistically invariant analysis of -isobar production in deuteron electrodisintegration: : General analysis of polarization effects

The differential cross-section and the polarization observables for Δ-isobar production in the deuteron electrodisintegration process, e^-+d→e^-+Δ+N, are calculated in a general formalism based on structure functions. The obtained expressions have a general nature, hold for one-photon-exchange, assuming P-invariance of the electromagnetic interaction and the conservation of the hadron electromagnetic current. The dependence of the differential cross-section of the e^-+d→e^-+Δ+N reaction on the vector and tensor polarizations of the deuteron target with unpolarized and longitudinally polarized electrons is considered. The general dependence of the asymmetries on two of five kinematic variables, the azimuthal angle φ and (linear polarization of the virtual photon) is calculated. A similar analysis is performed for the polarization of the nucleon produced in γ^*d→ΔN reaction provided the electron beam is unpolarized or longitudinally polarized. Polarization effects, which are due to the strong ΔN-interaction in the final state are calculated. The photoproduction of the Δ-isobar on the deuteron target has been considered in detail, as a particular case. The differential cross-section and various polarization observables have been derived in terms of the reaction amplitudes. The polarization observables due to the linear and circular polarizations of the photon, when the deuteron target is arbitrarily polarized have been derived in terms of the reaction amplitudes. The polarization of the final nucleon is also considered.     

O(αs) corrections to polarized top quark decay into a charged Higgs boson: $t(\uparrow)\to{H}^+ + b$

We calculate the O(α_s) radiative corrections to polarized top quark decay into a charged Higgs boson and a massive bottom quark in two variants of the two-Higgs-doublet model. The radiative corrections to the polarization asymmetry of the decay may become as large as 25%. We provide analytical formulae for the unpolarized and polarized rates for m_b≠0 and for m_b=0. For m_b=0 our closed-form expressions for the unpolarized and polarized rates become rather compact. PACS 12.38.Bx; 13.88.+e; 14.65.Ha; 14.80.Cp     

Polar angle dependence of the longitudinal polarization of quarks produced in e+e−-annihilation

We calculate one-loop radiative QCD corrections to the three polarized and unpolarized structure functions that determine the beam-quark polar angle dependence of the longitudinal polarization of light and heavy quarks produced in e⁺e^?-annihilations. We present analytical and numerical results for the longitudinal polarization and its polar angle dependence. We discuss in some detail the zero-mass limit of our results and the role of the anomalous spin-flip contributions to the polarization observables in the zero-mass limit. Our discussion includes transverse and longitudinal beam polarization effects.