Download or read book Compton Scattering Polarimetry for the Determination of the Proton s Weak Charge Through Measurements of the Parity Violating Asymmetry of 1H e E p written by and published by . This book was released on 2016 with total page 240 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Standard Model has been a theory with the greatest success in describing the fundamental interactions of particles. As of the writing of this dissertation, the Standard Model has not been shown to make a false prediction. However, the limitations of the Standard Model have long been suspected by its lack of a description of gravity, nor dark matter. Its largest challenge to date, has been the observation of neutrino oscillations, and the implication that they may not be massless, as required by the Standard Model. The growing consensus is that the Standard Model is simply a lower energy effective field theory, and that new physics lies at much higher energies. The Qweak Experiment is testing the Electroweak theory of the Standard Model by making a precise determination of the weak charge of the proton (Qpw). Any signs of "new physics" will appear as a deviation to the Standard Model prediction. The weak charge is determined via a precise measurement of the parity-violating asymmetry of the electron-proton interaction via elastic scattering of a longitudinally polarized electron beam of an un-polarized proton target. The experiment required that the electron beam polarization be measured to an absolute uncertainty of 1%. At this level the electron beam polarization was projected to contribute the single largest experimental uncertainty to the parity-violating asymmetry measurement. This dissertation will detail the use of Compton scattering to determine the electron beam polarization via the detection of the scattered photon. I will conclude the remainder of the dissertation with an independent analysis of the blinded Qweak.
Download or read book Compton Scattering Polarimetry for the Determination of the Proton s Weak Charge Through Measurements of the Parity violating Asymmetry of 1H E e P written by Juan Carlos Cornejo and published by . This book was released on 2016 with total page 220 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Standard Model has been a theory with the greatest success in describing the fundamental interactions of particles. As of the writing of this dissertation, the Standard Model has not been shown to make a false prediction. However, the limitations of the Standard Model have long been suspected by its lack of a description of gravity, nor dark matter. Its largest challenge to date, has been the observation of neutrino oscillations, and the implication that they may not be massless, as required by the Standard Model. The growing consensus is that the Standard Model is simply a lower energy effective field theory, and that new physics lies at much higher energies. The Qweak Experiment is testing the Electroweak theory of the Standard Model by making a precise determination of the weak charge of the proton (Qpw). Any signs of 0́−new physics0́+ will appear as a deviation to the Standard Model prediction. The weak charge is determined via a precise measurement of the parity-violating asymmetry of the electron-proton interaction via elastic scattering of a longitudinally polarized electron beam of an un-polarized proton target. The experiment required that the electron beam polarization be measured to an absolute uncertainty of 1 %. At this level the electron beam polarization was projected to contribute the single largest experimental uncertainty to the parity-violating asymmetry measurement. This dissertation will detail the use of Compton scattering to determine the electron beam polarization via the detection of the scattered photon. I will conclude the remainder of the dissertation with an independent analysis of the blinded Qweak .
Download or read book The First Determination of the Proton s Weak Charge Through Parity Violating Asymmetry Measurements in Elastic e p and e Al Scattering written by Katherine E. Myers and published by . This book was released on 2012 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Determination of the Weak Charge of the Proton Through Parity Violating Asymmetry Measurements in the Elastic E p Scattering written by and published by . This book was released on 2014 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The Qweak experiment has taken data to make a 2.5% measurement of parity violating elastic e+p asymmetry in the four momentum transfer region of 0.0250 (GeV/c)^2. This asymmetry is proportional to the weak charge of the proton, which is related to the weak mixing angle, sin^2(theta_W). The final Qweak measurement will provide the most precise measurement of the weak mixing angle below the Z^0 pole to test the Standard Model prediction. A description of the experimental apparatus is provided in this dissertation. The experiment was carried out using a longitudinally polarized electron beam of up to 180 microampere on a 34.5 cm long unpolarized liquid hydrogen target. The Qweak target is not only the world's highest cryogenic target ever built for a parity experiment but also is the least noisy target. This dissertation provides a detailed description of this target and presents a thorough analysis of the target performance. Statistical analysis of Run 1 data, collected between Feb - May 2011, is done to extract a blinded parity violating asymmetry of size -299.7 " 13.4 (stat.) " 17.2 (syst.) " 68 (blinding) parts-per-billion. This resulted in a preliminary proton's weak charge of value 0.0865 " 0.0085, a 9% measurement. Based on this blinded asymmetry, the weak mixing angle was determined to be sin^2(theta_W) = 0.23429 " 0.00211.
Download or read book Parity Violation In Electron Scattering Proceedings Of The Workshop written by E J Beise and published by World Scientific. This book was released on 1990-08-23 with total page 246 pages. Available in PDF, EPUB and Kindle. Book excerpt: These proceedings cover the recent progress and future directions of parity violation in electron scattering. Both experimental and theoretical issues are discussed, such as those of hadronic structure, radiative corrections, and tests of the standard model. There are three sessions, the first of which serves as a general overview of theory and experiment. The second session deals with the technical aspects of making a measurement of the parity violating asymmetry in electron scattering, including not only detector design but polarized electron beams and beam polarimeters.. The remaining session covers the corrections to lowest order parity violating cross sections.
Download or read book New Measurement of Parity Violation in Elastic Electron Proton Scattering and Implications for Strange Form Factors written by and published by . This book was released on 2001 with total page 4 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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{sub lab} = 12.3 degrees and Q2 = 0.477 (GeV/c)2. The measurement implies that the value for the strange form factor (G{sub E}{sup s} + 0.392 G{sub M}{sup s})/(G{sub M}{sup p} [mu]{sub p}) = 0.069 +- 0.056 +- 0.039, where the first error is experimental and the second arises from the uncertainties in electromagnetic form factors. This measurement is the first fixed-target parity violation experiment that used either a ''strained'' GaAs photocathode to produce highly polarized electrons or a Compton polarimeter to continuously monitor the electron beam polarization.
Download or read book Parity violating Electroweak Asymmetry in rvec E P Scattering written by and published by . This book was released on 2004 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: We have measured the parity-violating electroweak asymmetry in the elastic scattering of polarized electrons from protons. Significant contributions to this asymmetry could arise from the contributions of strange form factors in the nucleon. The measured asymmetry is A = -15.05 ± 0.98(stat) ± 0.56(syst) ppm at the kinematic point [theta]{sub lab} = 12.3{sup o} and Q2 = 0.477 (GeV/c)2. Based on these data as well as data on electromagnetic form factors, we extract the linear combination of strange form factors G{sub E}{sup s} + 0.392G{sub M}{sup s} = 0.014 ± 0.020 ± 0.010 where the first error arises from this experiment and the second arises from the electromagnetic form factor data. This paper provides a full description of the special experimental techniques employed for precisely measuring the small asymmetry, including the first use of a strained GaAs crystal and a laser-Compton polarimeter in a fixed target parity-violation experiment.
Download or read book Measurement of the Proton s Weak Charge at the Qweak Experiment written by and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The Qweak experiment at Jefferson Laboratory measures the parity violating asymmetry of polarized electrons scattering from a proton target at very low momentum transfer. In the Standard Model, this asymmetry reveals the proton's coupling to the neutral vector current, the weak charge. This value, measured directly for the first time, will provide a precision test of the Standard Model and will constrain the possibility of relevant physics beyond the Standard Model. The planned precision will probe certain classes of new physics at the 2̃ TeV scale. In order to challenge the precise predictions, the asymmetry will be measured with a 2.5 percent accuracy. To achieve such a precision, great care has to be taken on many aspects of the experiment. The very low momentum transfer reduces the hadronic effects to the asymmetry and must be determined to half of a percent accuracy. Beam stability is controlled and monitored constantly and background events are carefully studied.
Download or read book Qweak written by and published by . This book was released on 2014 with total page 8 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Qweak experiment at Hall C of Thomas Jefferson National Accelerator Facility has made the first direct measurement of the weak charge of the proton, QWp, through a precision measurement of the parity-violating asymmetry in elastic e-p scattering at low momentum transfer Q2= 0.025 (GeV/c)2 with incident electron beam energy of 1.155 GeV. The Qweak experiment, along with earlier results of parity violating elastic scattering experiments, is expected to determine the most precise value of QWp which is suppressed in the Standard Model. If this result is further combined with the 133Cs atomic parity violation (APV) measurement, significant constraints on the weak charge of the up quark, down quark, and neutron can be extracted. This data will also be used to determine the weak-mixing angle, sin2?W, with a relative uncertainty of
Download or read book Parity Violating Electron Deuteron Scattering and the Proton s Neutral Axial Vector Form Factor written by and published by . This book was released on 2003 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The authors report on a new measurement of the parity-violating asymmetry in quasielastic electron scattering from the deuteron at the backward angles at electron beam energy of 125 MeV [Q2=0.038 (GeV/c)2]. This quantity provides a determination of the neutral weak axial vector form factor of the nucleon. In addition to the tree level amplitude associated with Z-exchange, the neutral weak axial vector form factor as measured in electron scattering can potentially receive large electroweak corrections, including the anapole moment, that are absent in neutrino scattering. The measured asymmetry A = -3.51 ± 0.57 (stat) ± 0.58 (sys) ppm is consistent with theoretical predictions. We also report on updated results of the previous experiment at 200 MeV [Q2 = 0.091 (GeV/c)2] on a deuterium target. The updated results are also consistent with theoretical predictions on the neutral weal axial vector form factor.
Download or read book Compton Scattering on Protons Project of Experimental Determination of Electric and Magnetic Polarizabilities of the Proton written by D. V. Balin and published by . This book was released on 1996 with total page 49 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Measurement of Deeply Virtual Compton Scattering with a Polarized Proton Target written by and published by . This book was released on 2006 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The longitudinal target-spin asymmetry A{sub UL} for the exclusive electroproduction of high energy photons was measured for the first time in p(e, e'p/gamma). The data have been accumulated at Jefferson Lab with the CLAS spectrometer using 5.7 GeV electrons and a longitudinally polarized NH3 target. A significant azimuthal angular dependence was observed, resulting from the interference of the Deeply Virtual Compton Scattering and Bethe-Heitler processes. The amplitude of the sin[phi] moment is 0.252 +/- 0.042(stat) +/- 0.020(sys). Theoretical calculations are in good agreement with the magnitude and the kinematic dependence of the target-spin asymmetry, which is sensitive to the generalized parton distributions H and H-tilde.
Download or read book Measurements of the Strangeness Content of the Proton Through Parity Violating Electron Scattering at JLAB written by and published by . This book was released on 2001 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The authors have measured the parity violating asymmetry in the cross section for elastic scattering of longitudinally polarized electrons from protons at 3.36 GeV incident energy and 0.48 GeV/c[sup 2] momentum transfer at Jefferson Lab. This asymmetry is[minus]14.5[+-] 2.3 ppm, consistent with the Standard Model with no contribution from strange quarks. They extract the combination of strange form factors G[sub E][sup s]+ 0.39G[sub M][sup s]= 0.023[+-] 0.034(stat)[+-] 0.022(syst)[+-] 0.026[delta]G[sub E][sup n], where the last error arises from the neutron electric form factor.
Download or read book The Measurement of Parity Violation in Proton proton Scattering at 221 MeV written by and published by . This book was released on 1998 with total page 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 Target spin Asymmetry Measurements for Deeply Virtual Compton Scattering on Longitudinally Polarized Protons written by Erin E. Seder and published by . This book was released on 2013 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Measurement of Parity Violation in Proton proton Scattering at 221 MeV written by Araz Alice Hamian and published by . This book was released on 1998 with total page 222 pages. Available in PDF, EPUB and Kindle. Book excerpt:
