Violation of P- and T-symmetries in polarized neutrino-proton elastic scattering

Analytical expressions are obtained and studied for the angular distributions of the recoil protons and spin asymmetries of elastic electroweak scattering of neutrinos on polarized/unpolarized proton targets with account of the C-, P- and T/CP-symmetries violating anapole and electric dipole moments, along with the neutral weak form factors of a proton and the neutrino charge radius and magnetic moment.     

On double polarization asymmetries in the elastic electron-proton scattering

Double polarization asymmetry D_p^(M) for the process of elastic electroweak scattering of the longitudinally polarized electrons by polarized proton target is considered with account of anapole G_1p and electric dipole moment (EDM) G_2p proton form factors. This asymmetry is only due to T-parity violating form factor G_2p, but does not directly depend on it, and having a significant value, allows to confirm the existence of the EDM of the proton.     

Two-photon exchange and elastic electron-proton scattering

Two-photon exchange contributions to elastic electron-proton scattering cross sections are evaluated in a simple hadronic model including the finite size of the proton. The corrections are found to be small in magnitude, but with a strong angular dependence at fixed Q2. This is significant for the Rosenbluth technique for determining the ratio of the electric and magnetic form factors of the proton at high Q2, and partly reconciles the apparent discrepancy with the results of the polarization transfer technique.     

Two-photon-exchange correction to parity-violating elastic electron-proton scattering

Higher-order QED effects play an important role in precision measurements of nucleon elastic form factors in electron scattering. Here we introduce a two-photon-exchange QED correction to the parity-violating polarization asymmetry of elastic electron-proton scattering. We calculate this correction in the parton model using the formalism of generalized parton distributions, and demonstrate that it can reach several percent in certain kinematics, becoming comparable in size with existing experimental measurements of strange-quark effects in the proton neutral weak current.     

Model-independent properties of two-photon exchange in elastic electron-proton scattering

We derive from general symmetry properties of the hadron electromagnetic interaction, such as C-invariance and crossing symmetry, the general characteristics of two-photon exchange in electron-proton elastic scattering. We show that the presence of this mechanism destroys the linearity of the Rosenbluth separation.PACS: 25.30.Bf Elastic electron scattering - 13.40.-f Electromagnetic processes and properties - 13.60.-r Photon and charged-lepton interactions with hadrons - 13.88. + e Polarization in interactions and scattering     

On radiative corrections for unpolarized electron-proton elastic scattering

A statistical analysis of the elastic unpolarized electron-proton scattering data shows that at large momentum transfer the size and the ε dependence of the radiative corrections, as traditionally calculated and applied, may induce large correlations of the parameters of the Rosenbluth fit, which prevent a correct extraction of the electric proton form factor. Using the electron QED structure (radiation) function approach, the cross section of elastic electron-proton scattering in leading and next-to-leading approximations is calculated and expressed as a correction to the Born cross section, which is different for the electric and magnetic contributions. When properly applied to the data, it may yield the solution to the problem of the discrepancy of the polarized and unpolarized results on electron-proton scattering. The text was submitted by the author in English.     

Two-photon-exchange and gammaZ-exchange corrections to parity-violating elastic electron-proton scattering

Leading electroweak corrections play an important role in precision measurements of the strange form factors. We calculate the two-photon-exchange (TPE) and gammaZ-exchange corrections to the parity-violating asymmetry of the elastic electron-proton scattering in a simple hadronic model including the finite size of the proton. We find both can reach a few percent and are comparable in size with the current experimental measurements of strange-quark effects in the proton neutral weak current. The effect of gammaZ exchange is in general larger than that of TPE, especially at low momentum transfer Q2相似文献   

Proton spin-spin asymmetries for large angle electron-proton elastic scattering

Using the proper-time technique we calculate the one-fermion-loop contributions in four and six derivatives to the effective Lagrangian for theSU(2)xSU(2) non-linear σ-model.     

The vanishing analyzing powers in electron-proton elastic scattering; symmetries and dynamics

In high energy electron-proton elastic scattering the two parity-conserving analyzing powers vanish in the one-photon-exchange approximation. The electron analyzing-power vanishes from electron helicity-conservation, but the underlying reason (s) for the vanishing of the proton analyzing-power is (are) not clear. Therefore, a more detailed examination of this question has been made and is reported here. It is then noted that the proton analyzing-power is an optimum experimental observable for the determination of higher order contributions to this basic electron-nucleon electromagnetic interaction.     

Radiative corrections to two-photon exchange in elastic electron-proton and positron-proton scattering

The radiative corrections to the differential elastic electron (positron)—proton scattering cross section is determined in the fourth order in perturbation theory by quantum electrodynamics methods. The contribution from two-photon exchange is determined in the static approximation with subsequent recalculation for the center of mass system and with allowance for recoil of the proton. The electromagnetic structure of the proton is taken into account.Kamsk Polytechnic Institute. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 6, pp. 87–94, June, 1993.     

Recent results of two-boson-exchange effects in the parity-violating elastic electron-proton scattering

The results of two-boson-exchange effects in the parity-violating elastic electron-proton scattering are reported based on a simple hadronic model. The corrections are calculated including the nucleon and △(1232) intermediate states. And the numerical results are also compared with the recent results reported by other group and other methods.     

Recent results of two-boson-exchange effects in the parity-violating elastic electron-proton scattering

The results of two-boson-exchange effects in the parity-violating elastic electron-proton scattering are reported based on a simple hadronic model. The corrections are calculated including the nucleon and △（1232） intermediate states. And the numerical results are also compared with the recent results reported by other group and other methods.     

Determination of two-photon exchange amplitudes from elastic electron-proton scattering data

Using the available cross-section and polarization data for elastic electron-proton scattering, we provide an extraction of the two-photon exchange amplitudes at a common value of four-momentum transfer, around Q ² = 2.5 GeV^2. This analysis also predicts the e ⁺ p/e ^- p elastic-scattering cross-section ratio, which will be measured by forthcoming experiments.     

Optimal positivity bounds to the up-down asymmetry in elastic electron-proton scattering

New positivity bounds on the up-down asymmetry in elastic electron-proton scattering are derived. The bounds are rigorous to order $\text{α ?}\text{1}\text{137}$, and optimal in the sense that they fully exploit the positivity restrictions of the off-shell absorptive Compton amplitudes which govern the asymmetry effect. We compare the results with existing experiments and discuss their relevance to future ones.     

Parity violation in elastic electron-proton scattering and the Proton's strange magnetic form factor

We report a new measurement of the parity-violating asymmetry in elastic electron scattering from the proton at backward scattering angles. This asymmetry is sensitive to the strange magnetic form factor of the proton as well as electroweak axial radiative corrections. The new measurement of A = -4.92+/-0.61+/-0.73 ppm provides a significant constraint on these quantities. The implications for the strange magnetic form factor are discussed in the context of theoretical estimates for the axial corrections.     

Spin rotation as an element of polarization experiments on elastic electron-proton scattering

The validity of some rules in the classical theory of spin, which are followed by the Bargmann-Michel-Telegdi formula for a relativistic particle spin rotation in a constant homogeneous magnetic field, is analyzed. In the framework of the quantum theory, we give examples where these rules are violated. Consequences for polarization experiments are discussed.     

Microscopic potentials for polarized triton elastic scattering

The double folding model is used to calculate real central and spin-orbit potentials for triton elastic scattering. These potentials are used to fit cross sections and analysing powers at 17 MeV for targets ranging from ²⁶Mg to ²⁰⁸Pb. For most targets the data are described as well as with phenomenological potentials. The real central potential can be used without any substantial renormalisation, but the spin-orbit potential needs to be increased in strength by a factor between 2 and 6. Comparisons are made with phenomenological studies of triton and ³He elastic scattering and with similar microscopic studies of ³He scattering.