Test of Time-Reversal Invariance in Electroproduction Interactions Using a Polarized Proton Target

Chen, J. R.; Sanderson, J.; Appel, J. A.; Gladding, G.; Goitein, Michael; Hanson, K.; Imrie, D. C.; Kirk, T.; Madaras, R. J.; Pound, R. V.; Price, L. E.; Wilson, Richard; Zajde, C.

doi:10.1103/physrevlett.21.1279

Cited by 40 publications

(14 citation statements)

References 13 publications

(6 reference statements)

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“…On the other hand, the SSAs are proportional to the electromagnetic fine structure constant α em ≈ 1/137 which may lead to relatively small effects. Indeed, the results of early measurements of the transverse target SSA at the Cambridge Electron Accelerator [5] and at the Stanford Linear Accelerator [6] were compatible with zero within the error bars. However, present experiments with their higher precision should be able to observe such effects.…”

mentioning

confidence: 71%

Transverse single spin asymmetries in inclusive deep-inelastic scattering

Metz¹,

Schlegel²,

Goeke³

2006

Physics Letters B

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In inclusive deep-inelastic lepton-hadron scattering multi-photon exchange between the leptonic and the hadronic part of the process causes single spin asymmetries. The asymmetries exist for a polarized target as well as a polarized incoming or outgoing lepton, if the polarization vector has a component transverse with respect to the reaction plane. The spin dependent parts of the single polarized cross sections are suppressed like α em m pol /Q -where m pol denotes the mass of the polarized particle -compared to the leading terms of the cross section for unpolarized or double-polarized deep-inelastic scattering. Both the target and the beam spin asymmetry are evaluated in the parton model. In the calculation only quark-quark correlators are included. While this approximation turns out to be justified for the lepton spin asymmetries, it is not sufficient for the target asymmetry.

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confidence: 71%

Transverse single spin asymmetries in inclusive deep-inelastic scattering

Metz¹,

Schlegel²,

Goeke³

2006

Physics Letters B

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“…Experimentally, the single-spin asymmetry (SSA) for a transversely polarized nucleon, denoted by A UT , was already measured in 1970 in the resonance region [2]. A result consistent with zero within an error of about 10 À2 was obtained.…”

Section: Introductionmentioning

confidence: 90%

“…The relation (2) implies that the single spindependent cross section d UT in the first line of Eq. (4) vanishes-as it should according to Ref.…”

Section: Perturbative Calculationsmentioning

confidence: 99%

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Partonic description of the transverse target single-spin asymmetry in inclusive deep-inelastic scattering

Schlegel

2013

Phys. Rev. D

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The single-spin asymmetry of unpolarized leptons scattering deep-inelastically off transversely polarized nucleons is studied in a partonic picture within a collinear twist-3 framework. Since this observable is generated by multiphoton exchanges between a lepton and nucleon a partonic description of the asymmetry contains essential elements of a full next-to-leading order calculation for single-spin asymmetries in perturbative quantum chromodynamics. In particular, it is shown how nontrivial cancellations between kinematical and dynamical twist-3 contributions lead to a well-behaved and finite formula. This final result can be expressed in terms of multipartonic quark-gluon and quark-photon correlation functions. Hence, a measurement of the transverse target single-spin asymmetry may provide new constraints on these multipartonic correlations.

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“…Since this is also a unique combination of new form factors, a measurement of A n would provide new constraints on TPE. Previous measurements of A n with electron scattering have either been made with inelastic scattering [35][36][37][38][39], or in quasielastic scattering from polarized 3 He [40]. There are currently no published results from elastic electron scattering from polarized hydrogen.…”

Section: Target-normal Single Spin Asymmetriesmentioning

confidence: 99%

Polarization observables using positron beams

Schmidt¹

2018

AIP Conference Proceedings

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The discrepancy between polarized and unpolarized measurements of the proton's electromagnetic form factors is striking, and suggests that two-photon exchange (TPE) may be playing a larger role in elastic electron-proton scattering than is estimated in standard radiative corrections formulae. While TPE is difficult to calculate in a model-independent way, it can be determined experimentally from asymmetries between electron-proton and positron-proton scattering. The possibility of a polarized positron beam at Jefferson Lab would open the door to measurements of TPE using polarization observables. In these proceedings, I examine the feasibility of measuring three such observables with positron scattering. Polarization-transfer, specifically the -dependence for fixed Q 2 , is an excellent test of TPE, and the ability to compare electrons and positrons would lead to a drastic reduction of systematics. However, such a measurement would be severely statistically limited. Normal single-spin asymmetries (SSAs) probe the imaginary part of the TPE amplitude and can be improved by simultaneous measurements with electron and positron beams. Beam-normal SSAs are too small to be measured with the proposed polarized positron beam, but target-normal SSAs could be feasibly measured with unpolarized positrons in the spectrometer halls. This technique should be included in the physics case for developing a positron source for Jefferson Lab.

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Test of Time-Reversal Invariance in Electroproduction Interactions Using a Polarized Proton Target

Cited by 40 publications

References 13 publications

Transverse single spin asymmetries in inclusive deep-inelastic scattering

Transverse single spin asymmetries in inclusive deep-inelastic scattering

Partonic description of the transverse target single-spin asymmetry in inclusive deep-inelastic scattering

Polarization observables using positron beams

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