Related papers: Polarization Observables using Positron Beams
We report on a new measurement of the beam transverse single spin asymmetry in electron-proton elastic scattering, $A^{ep}_{\perp}$, at five beam energies from 315.1 MeV to 1508.4 MeV and at a scattering angle of $30^{\circ} < \theta <…
We have measured the beam-normal single-spin asymmetry $A_n$ in the elastic scattering of 1-3 GeV transversely polarized electrons from $^1$H and for the first time from $^4$He, $^{12}$C, and $^{208}$Pb. For $^1$H, $^4$He and $^{12}$C, the…
Positron beams, both polarized and unpolarized, are identified as essential ingredients for the experimental programs at the next generation of lepton accelerators. In the context of the hadronic physics program at Jefferson Lab (JLab),…
One of the most surprising discoveries made at Jefferson Lab has been the discrepancy in the determinations of the proton's form factor ratio $\mu_p G_E^p/G_M^p$ between unpolarized cross section measurements and the polarization transfer…
We have measured the parity-violating electroweak asymmetry in the elastic scattering of polarized electrons from the proton. The result is A = -15.05 +- 0.98(stat) +- 0.56(syst) ppm at the kinematic point theta_lab = 12.3 degrees and Q^2 =…
Recent theoretical developments in the studies of two-photon exchange effects in elastic electron-proton scattering are reviewed. Two-photon exchange mechanism is considered a likely source of discrepancy between polarized and unpolarized…
J-PET is a detector optimized for registration of photons from the electron-positron annihilation via plastic scintillators where photons interact predominantly via Compton scattering. Registration of both primary and scattered photons…
The cross section which addresses the spin-flip transitions of a proton (antiproton) interacting with a polarized non-relativistic electron or positron is calculated analytically. In the case of attraction, this cross section is greatly…
The proton elastic form factor ratio can be measured either via Rosenbluth separation in an unpolarized beam and target experiment, or via the use of polarization degrees of freedom. However, data produced by these two approaches show a…
As part of the spin physics program at Jefferson Laboratory (JLab), a M\o ller polarimeter was developed to measure the polarization of electron beam of energies 0.8 to 5.0 GeV. A unique signature for M\o ller scattering is obtained using a…
The paper describes a precise measurement of electron scattering off the proton at momentum transfers of $0.003 \lesssim Q^2 \lesssim 1$\ GeV$^2$. The average point-to-point error of the cross sections in this experiment is $\sim$ 0.37%.…
At the Cooler Synchrotron COSY/J\"ulich spin correlation parameters in elastic proton-proton (pp) scattering have been measured with a 2.11 GeV polarized proton beam and a polarized hydrogen atomic beam target. We report results for…
After recalling the arguments for possible excess of two-photon contribution over $\alpha$-counting, model independent statements about the consequences on the observables will be given. The relevant experimental data are discussed:…
We propose to extend the investigations of the eta meson production in nucleon-nucleon collisions by studying single and double polarization observables. Over the last years, the eta meson has been studied at several different experiments…
Polarisation observables are measured with the Crystal Barrel/TAPS experiment at ELSA for photoproduction reactions with various final states, using a circularly or linearly polarised photon beam and a longitudinally or transversely…
Several important and unique measurements, within the standard model and of possible physics beyond it, could be made with {\em polarized HERA} in which both the proton and the electron beams are polarized. With a $\sim$820 GeV proton beam…
In the one-photon exchange approximation, we analyze polarization effects in the elastic $\vec e \vec p \to e p$ and $ e \vec p \to \vec e p$ processes in the case when the spin quantization axes of a target proton at rest and an incident…
Systematic differences in the the proton's charge radius, as determined by ordinary atoms and muonic atoms, have caused a resurgence of interest in elastic lepton scattering measurements. The proton's charge radius, defined as the slope of…
We analyze polarization phenomena for elastic lepton-nucleon scattering, parametrizing the $2\gamma$-exchange contribution, as the product of lepton and nucleon axial vector currents, that correspond to $C=+1$ exchange in the annihilation…
Measurements of polarized electron-nucleon scattering can be realized at the TESLA linear collider facility with projected luminosities that are about two orders of magnitude higher than those expected of other experiments at comparable…