Download or read book Measurement of the Two Photon Exchange Asymmetry in the Quasielastic Scattering of Transversely Polarized Electrons of Unpolarized Deuterium written by David Balaguer Ríos and published by . This book was released on 2008 with total page 157 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Two Photon Exchange Correction to Parity Violating Elastic Electron Proton Scattering written by and published by . This book was released on 2005 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: 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 per cent in certain kinematics, becoming comparable in size with existing experimental measurements of strange-quark effects in the proton neutral weak current.

Download or read book The Two Photon Exchange Contribution to Elastic Electron Nucleon Scattering at Large Momentum Transfer written by and published by . This book was released on 2005 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: We estimate the two-photon exchange contribution to elastic electron-proton scattering at large momentum transfer by using a quark-parton representation of virtual Compton scattering. We thus can relate the two-photon exchange amplitude to the generalized parton distributions which also enter in other wide angle scattering processes. We find that the interference of one- and two-photon exchange contribution is able to substantially resolve the difference between electric form factor measurements from Rosenbluth and polarization transfer experiments. Two-photon exchange has additional consequences which could be experimentally observed, including nonzero polarization effects and a positron-proton/electron-proton scattering asymmetry. The predicted Rosenbluth plot is no longer precisely linear; it acquires a measurable curvature, particularly at large laboratory angle.

Download or read book Two Photon Exchange in Elastic Electron nucleon Scattering written by and published by . This book was released on 2005 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: A detailed study of two-photon exchange in unpolarized and polarized elastic electron-nucleon scattering is presented, taking particular account of nucleon finite size effects. Contributions from nucleon elastic intermediate states are found to have a strong angular dependence, which leads to a partial resolution of the discrepancy between the Rosenbluth and polarization transfer measurements of the proton electric to magnetic form factor ratio. The two-photon exchange contribution to the longitudinal polarization transfer ratio P{sub L} is small, whereas the contribution to the transverse polarization transfer ratio P{sub T} is enhanced at backward angles by several percent, increasing with Q2. This gives rise to a several percent enhancement of the polarization transfer ratio P{sub T}/P{sub l} at large Q2 and backward angles. We compare the two-photon exchange effects with data on the ratio of e{sup +p} to e{sup -p} cross sections, which is predicted to be enhanced at backward angles. Finally, we evaluate the corrections to the form factors of the neutron, and estimate the elastic intermediate state contribution to the 3He form factors.

Download or read book Demonstration of a Novel Technique to Measure Two photon Exchange Effects in Elastic E p Scattering written by and published by . This book was released on 2013 with total page 13 pages. Available in PDF, EPUB and Kindle. Book excerpt: The discrepancy between proton electromagnetic form factors extracted using unpolarized and polarized scattering data is believed to be a consequence of two-photon exchange (TPE) effects. However, the calculations of TPE corrections have significant model dependence, and there is limited direct experimental evidence for such corrections. The TPE contributions depend on the sign of the lepton charge in e"p scattering, but the luminosities of secondary positron beams limited past measurement at large scattering angles, where the TPE effects are believe to be most significant. We present the results of a new experimental technique for making direct e"p comparisons, which has the potential to make precise measurements over a broad range in Q2 and scattering angles. We use the Jefferson Laboratory electron beam and the Hall B photon tagger to generate a clean but untagged photon beam. The photon beam impinges on a converter foil to generate a mixed beam of electrons, positrons, and photons. A chicane is used to separate and recombine the electron and positron beams while the photon beam is stopped by a photon blocker. This provides a combined electron and positron beam, with energies from 0.5 to 3.2 GeV, which impinges on a liquid hydrogen target. The large acceptance CLAS detector is used to identify and reconstruct elastic scattering events, determining both the initial lepton energy and the sign of the scattered lepton. The data were collected in two days with a primary electron beam energy of only 3.3 GeV, limiting the data from this run to smaller values of Q2 and scattering angle. Nonetheless, this measurement yields a data sample for e"p with statistics comparable to those of the best previous measurements. We have shown that we can cleanly identify elastic scattering events and correct for the difference in acceptance for electron and positron scattering. Because we ran with only one polarity for the chicane, we are unable to study the difference between the incoming electron and positron beams. This systematic effect leads to the largest uncertainty in the final ratio of positron to electron scattering: R=1.027"0.005"0.05 for Q2=0.206 GeV2 and 0.830 d"[epsilon] d"0.943. We have demonstrated that the tertiary e" beam generated using this technique provides the opportunity for dramatically improved comparisons of e"p scattering, covering a significant range in both Q2 and scattering angle. Combining data with different chicane polarities will allow for detailed studies of the difference between the incoming e+ and e- beams.

Download or read book A Measurement of the Spin dependent Asymmetry in Quasielastic Scattering of Polarized Electrons from Polarized supercript 3He written by Cathleen Elaine Jones and published by . This book was released on 1992 with total page 396 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book TWO PHOTON EXCHANGE IN ELECTRON PROTON ELASTIC SCATTERING written by and published by . This book was released on 2007 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: 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 experimental measurements of the proton electric form factor at momentum transfers of several GeV$^2$. This mechanism predicts measurable effects that are currently studied experimentally.

Download or read book Electromagnetic Probes and the Structure of Hadrons and Nuclei written by Amand Faessler and published by Elsevier Science & Technology. This book was released on 1995 with total page 448 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Measurement of the Target normal Single spin Asymmetry in Quasielastic Scattering from the Reaction math Display written by and published by . This book was released on 2015 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: We report the first measurement of the target single-spin asymmetry, Ay, in quasi-elastic scattering from the inclusive reaction 3He1!(e, e') on a 3He gas target polarized normal to the lepton scattering plane. Assuming time-reversal invariance, this asymmetry is strictly zero for one-photon exchange. A non-zero Ay can arise from the interference between the one- and two-photon exchange processes which is sensitive to the details of the sub-structure of the nucleon. An experiment recently completed at Jefferson Lab yielded asymmetries with high statistical precision at Q2= 0.13, 0.46 and 0.97 GeV2. These measurements demonstrate, for the first time, that the 3He asymmetry is clearly non-zero and negative with a statistical significance of (8-10)[sigma]. Using measured proton-to-3He cross-section ratios and the effective polarization approximation, neutron asymmetries of -(1-3)% were obtained. The neutron asymmetry at high Q2 is related to moments of the Generalized Parton Distributions (GPDs). Our measured neutron asymmetry at Q2=0.97 GeV2 agrees well with a prediction based on two-photon exchange using a GPD model and in addition provides a new independent constraint on these distributions.

Download or read book Measurement of Asymmetries in Inclusive Quasi elastic Scattering of Polarized Electrons from Polarized 3He written by Alan Keith Thompson and published by . This book was released on 1991 with total page 234 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Measurement of Parity violating Asymmetry in Electron deuteron Inelastic Scattering written by and published by . This book was released on 2015 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The parity-violating asymmetries between a longitudinally-polarized electron beam and an unpolarized deuterium target have been measured recently. The measurement covered two kinematic points in the deep inelastic scattering region and five in the nucleon resonance region. We provide here details of the experimental setup, data analysis, and results on all asymmetry measurements including parity-violating electron asymmetries and those of inclusive pion production and beam-normal asymmetries. The parity-violating deep-inelastic asymmetries were used to extract the electron-quark weak effective couplings, and the resonance asymmetries provided the first evidence for quark-hadron duality in electroweak observables. These electron asymmetries and their interpretation were published earlier, but are presented here in more detail.

Download or read book A Measurement of Spin dependent Asymmetries in Quasielastic Scattering of Polarized Electrons from Polarized Helium 3 written by Jens-Ole Hansen and published by . This book was released on 1995 with total page 145 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Measurement of the Helicity dependent Asymmetry in sup 3 H e E Quasielastic Scattering written by and published by . This book was released on 1995 with total page 123 pages. Available in PDF, EPUB and Kindle. Book excerpt: The analysis of the data from the MIT-Bates experiment in June 1993 to measure the helicity-dependent asymmetry in quasielastic scattering of polarized electrons from polarized 3He was completed. The neutron magnetic form factor was extracted from data on polarized 3He for the first time and is found to be in very good agreement with the dipole form at Q2 = 0. 19 (GeV/c)2. A paper reporting the transverse asymmetry and the extracted value of the neutron magnetic form factor was published, and papers reporting the transverse-longitudinal asymmetries at the quasielastic peak and on the low energy-transfer side of the quasielastic peak were submitted for publication.

Download or read book Physics With Gev particle Beams Proceedings Of The International Conference written by Hartmut Machner and published by World Scientific. This book was released on 1995-05-31 with total page 618 pages. Available in PDF, EPUB and Kindle. Book excerpt: The investigation of hadronic and nuclear probes with protons and electrons in the energy range of a few GeV is of great importance for the understanding of the properties of nucleons and mesons as well as of their interaction. Experimental results from studies with these beams provide the basis for the development and the tests of theoretical approaches in the energy regime of non-perturbative QCD. They can also clarify the effect of the nuclear medium on elementary reactions. The conference has reviewed the present status of this field of research. The topics have beenThe conference topics comprised investigations near energy thresholds in the tradition of the conferences on Particle Production near Threshold in Nashville, IN, USA, 1990, and Uppsala, Sweden, 1992.

Download or read book Single spin Asymmetries from Two photon Exchange in Elastic Electron Proton Scattering written by N. P. Merenkov and published by . This book was released on 2005 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The parity-conserving single-spin beam asymmetry of elastic electron-proton scattering is induced by an absorptive part of the two-photon exchange amplitude. We demonstrate that this asymmetry has logarithmic and double-logarithmic enhancement due to contributions of hard collinear quasi-real photons. An optical theorem is used to evaluate the asymmetry in terms of the total photoproduction cross section on the proton.

Download or read book Progress in Particle and Nuclear Physics written by and published by . This book was released on 1995 with total page 448 pages. Available in PDF, EPUB and Kindle. Book excerpt: Vols. 1, 6, 8-9, 11, 13- consist of Proceedings of the International School of Nuclear Physics.

Download or read book Measurement of the Polarization in Elastic Electron ProtonScattering written by and published by . This book was released on 1970 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: We have measured the (illegible) scattering (?-illegible) of electrons (?-illegible) from a polarized proton target. (illegible) between (?-illegible) imaginary part of the two-photon-(illegible) (illegible) photon-exchange amplitude could produce (?-illegible) (illegible) results indicate no asymmetry within (illegible) 1 to 2% at four(?-illegible)-momentum transfer (illegible) (illegible) 0.98 (GeV/c)2.