Vector analyzing power in elastic electron-proton scattering

Diaconescu, L.; Ramsey-Musolf, Michael J.

doi:10.1103/physrevc.70.054003

Cited by 29 publications

(28 citation statements)

References 33 publications

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“…[78] and (b) from Ref. [71]. Surprisingly, the Diaconescu & Musolf [71] (D&M) model using perturbation theory to estimate the elastic intermediate state contribution to second order in E e /M (the pions were integrated out) were able to predict a value for BNSSA at SAMPLE kinematics (see Figure 2.16b).…”

Section: Beam Normal Single Spin Asymmetry In Electron-nucleon Scattementioning

confidence: 95%

“…[71]. Surprisingly, the Diaconescu & Musolf [71] (D&M) model using perturbation theory to estimate the elastic intermediate state contribution to second order in E e /M (the pions were integrated out) were able to predict a value for BNSSA at SAMPLE kinematics (see Figure 2.16b). Since the SAMPLE measurement was carried out at the pion threshold, the inelastic states with the pions in the intermediate state should be accounted for in the full calculation of the BNSSA.…”

Section: Beam Normal Single Spin Asymmetry In Electron-nucleon Scattementioning

confidence: 99%

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A 3% Measurement of the Beam Normal Single Spin Asymmetry in Forward Angle Elastic Electron-Proton Scattering using the Qweak Setup

Waidyawansa

2013

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The beam normal single spin asymmetry generated in the scattering of transversely polarized electrons from unpolarized nucleons is an observable of the imaginary part of the two-photon exchange process. Moreover, it is a potential source of false asymmetry in parity violating electron scattering experiments. The Q weak experiment uses parity violating electron scattering to make a direct measurement of the weak charge of the proton. The targeted 4% measurement of the weak charge of the proton probes for parity violating new physics beyond the Standard Model. The beam normal single spin asymmetry at Q weak kinematics is at least three orders of magnitude larger than 5 ppb precision of the parity violating asymmetry. To better understand this parity conserving background, the Q weak Collaboration has performed elastic scattering measurements with fully transversely polarized electron beam on the proton and aluminum. This dissertation presents the analysis of the 3% measurement (1.3% statistical and 2.6% systematic) of beam normal single spin asymmetry in electronproton scattering at a Q 2 of 0.025 (GeV/c) 2 . It is the most precise existing measurement of beam normal single spin asymmetry available at the time. A measurement of this precision helps to improve the theoretical models on beam normal single spin asymmetry and thereby our understanding of the doubly virtual Compton scattering process.

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Section: Beam Normal Single Spin Asymmetry In Electron-nucleon Scattementioning

confidence: 95%

Section: Beam Normal Single Spin Asymmetry In Electron-nucleon Scattementioning

confidence: 99%

A 3% Measurement of the Beam Normal Single Spin Asymmetry in Forward Angle Elastic Electron-Proton Scattering using the Qweak Setup

Waidyawansa

2013

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“…[107], the beam normal spin asymmetry was studied at low energies in an effective theory of electrons, protons and photons. This calculation, in which pions are integrated out, effectively corresponds with the nucleon intermediate state contribution only, expanded to second order in E e /M.…”

Section: Threshold Regionmentioning

confidence: 99%

Two-Photon Physics in Hadronic Processes

Carlson

Vanderhaeghen

2007

Annu. Rev. Nucl. Part. Sci.

161

173

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Two-photon exchange contributions to elastic electron-scattering are reviewed. The apparent discrepancy in the extraction of elastic nucleon form factors between unpolarized Rosenbluth and polarization transfer experiments is discussed, as well as the understanding of this puzzle in terms of two-photon exchange corrections. Calculations of such corrections both within partonic and hadronic frameworks are reviewed. In view of recent spin-dependent electron scattering data, the relation of the two-photon exchange process to the hyperfine splitting in hydrogen is critically examined. The imaginary part of the two-photon exchange amplitude as can be accessed from the beam normal spin asymmetry in elastic electron-nucleon scattering is reviewed. Further extensions and open issues in this field are outlined.

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“…In another calculation of beam SSNA of Ref. [11], a low-momentum expansion was used for the TPE loop integral, which resulted in approximate analytic expressions valid for low electron beam energies. The main theoretical problem in description of the TPE amplitude on the proton at higher energies in the GeV range is a large uncertainty in the contribution of the inelastic hadronic intermediate states.…”

Section: Introductionmentioning

confidence: 99%

Large logarithms in the beam normal spin asymmetry of elastic electron-proton scattering

Afanasev

Merenkov

2004

Phys. Rev. D

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We study a parity-conserving single-spin beam asymmetry of elastic electron-proton scattering induced by an absorptive part of the two-photon exchange amplitude. It is demonstrated that excitation of inelastic hadronic intermediate states by the consecutive exchange of two photons leads to logarithmic and double-logarithmic enhancement due to contributions of hard collinear quasi-real photons. The asymmetry at small electron scattering angles is expressed in terms of the total photoproduction cross section on the proton, and is predicted to reach the magnitude of 20-30 parts per million. At these conditions and fixed 4-momentum transfers, the asymmetry is rising logarithmically with increasing electron beam energy, following the high-energy diffractive behavior of total photoproduction cross section on the proton.

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Vector analyzing power in elastic electron-proton scattering

Cited by 29 publications

References 33 publications

A 3% Measurement of the Beam Normal Single Spin Asymmetry in Forward Angle Elastic Electron-Proton Scattering using the Qweak Setup

A 3% Measurement of the Beam Normal Single Spin Asymmetry in Forward Angle Elastic Electron-Proton Scattering using the Qweak Setup

Two-Photon Physics in Hadronic Processes

Large logarithms in the beam normal spin asymmetry of elastic electron-proton scattering

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