Measuring the Weak Charge of the Proton via Elastic Electron-Proton Scattering

Jones, D.

doi:10.2172/1227207

Cited by 7 publications

(8 citation statements)

References 66 publications

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“…Helicity-correlated beam-property correction (A beam ). Residual nonvanishing helicity correlations in the properties of the electron beam were measured and corrected through detector responses determined using a beam-modulation system (15). Kinematics (R Q 2 ).…”

Section: Determination Of a Epmentioning

confidence: 99%

Determination of the Proton's Weak Charge and Its Constraints on the Standard Model

Carlini

Oers

Pitt

et al. 2019

Annu. Rev. Nucl. Part. Sci.

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This article discusses some of the history of parity-violation experiments that culminated in the Qweak experiment, which provided the first determination of the proton's weak charge [Formula: see text]. The guiding principles necessary to the success of that experiment are outlined, followed by a brief description of the Qweak experiment. Several consistent methods used to determine [Formula: see text] from the asymmetry measured in the Qweak experiment are explained in detail. The weak mixing angle sin2θw determined from [Formula: see text] is compared with results from other experiments. A description of the procedure for using the [Formula: see text] result on the proton to set TeV-scale limits for new parity-violating semileptonic physics beyond the Standard Model (BSM) is presented. By also considering atomic parity-violation results on cesium, the article shows how this result can be generalized to set limits on BSM physics, which couples to any combination of valence quark flavors. Finally, the discovery space available to future weak-charge measurements is explored.

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Section: Determination Of a Epmentioning

confidence: 99%

Determination of the Proton's Weak Charge and Its Constraints on the Standard Model

Carlini

Oers

Pitt

et al. 2019

Annu. Rev. Nucl. Part. Sci.

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“…Details on the Compton polarimeter can be found in Ref. [5,6,10,11,12]. Since the electron detector provided the highest precision and most reliable measurements of the beam polarization from the Compton polarimeter, the results discussed here are from the electron detector only.…”

Section: The Hall-c Compton Polarimetermentioning

confidence: 99%

A novel comparison of Møller and Compton electron-beam polarimeters

et al. 2017

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We have performed a novel comparison between electron-beam polarimeters based on Møller and Compton scattering. A sequence of electron-beam polarization measurements were performed at low beam currents (< 5 µA) during the Q weak experiment in Hall C at Jefferson Lab. These low current measurements were bracketed by the regular high current (180 µA) operation of the Compton polarimeter. All measurements were found to be consistent within experimental uncertainties of 1% or less, demonstrating that electron polarization does not depend significantly on the beam current. This result lends confidence to the common practice of applying Møller measurements made at low beam currents to physics experiments performed at higher beam currents. The agreement between two polarimetry techniques based on independent physical processes sets an important benchmark for future precision asymmetry measurements that require sub-1% precision in polarimetry.

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“…The sensitivity of the asymmetry to such fluctuations was calibrated by a system that deliberately varied these beam properties periodically. More details on the beam asymmetries can be found in Josh Hoskins' [33] and Donald Jones' dissertations [58].…”

Section: Uncertainties On a Epmentioning

confidence: 99%

Determination of the Kinematics of the Qweak Experiment and Investigation of an Atomic Hydrogen Moller Polarimeter

Gray

2018

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The Q weak experiment has tested the Standard Model through making a precise measurement of the weak charge of the proton (Q p W ). This was done through measuring the parity-violating asymmetry for polarized electrons scattering off of unpolarized protons. The parity-violating asymmetry measured is directly proportional to the four-momentum transfer (Q 2 ) from the electron to the proton. The extraction of Q p W from the measured asymmetry requires a precise Q 2 determination. The Q weak experiment had a Q 2 = 24.8 ± 0.1 m(GeV 2 ) which achieved the goal of an uncertainty of ≤ 0.5%. From the measured asymmetry and Q 2 , Q p W was determined to be 0.0719 ± 0.0045, which is in good agreement with the Standard Model prediction. This puts a 7.5 TeV lower limit on possible "new physics". This dissertation describes the analysis of Q 2 for the Q weak experiment. Future parity-violating electron scattering experiments similar to the Q weak experiment will measure asymmetries to high precision in order to test the Standard Model. These measurements will require the beam polarization to be measured to sub-0.5% precision. Presently the electron beam polarization is measured through Møller scattering off of a ferromagnetic foil or through using Compton scattering, both of which can have issues reaching this precision. A novel Atomic Hydrogen Møller Polarimeter has been proposed as a non-invasive way to measure the polarization of an electron beam via Møller scattering off of polarized monatomic hydrogen gas. This dissertation describes the development and initial analysis of a Monte Carlo simulation of an Atomic Hydrogen Møller Polarimeter. Clearly good ol' Charlie Brown didn't know about graduate school because my dissertation is way more than a thousand words; but like him, there have been many people who have supported me. I would like to thank my adviser, David Armstrong, for all the help and guidance during my time at William & Mary. I am extremely grateful for all the time he has given to answering my questions and helping me through everything here. Thanks also to the members of my committee Dave Gaskell, Joshua Erlich, and Todd Avertt for help on various components of my work. I would also want to acknowledge my undergraduate teacher, adviser, and mentor, Michael Olson, without whom I would have never realized physics was interesting and pursued experimental nuclear physics. His advice and guidance at St. Norbert College and after has been invaluable and instrumental. I was given many opportunities for teaching, mentoring, and doing research and indispensable lab skills that I otherwise wouldn't have gotten. Also thanks for all the time dedicated to helping, working on research, and developing new labs for classes. I can't thank him enough for his amazing capacity for fostering confidence, giving perspective when needed, and the advice and support he has shared with me over the years and the ones to come. To the people whom I owe my existence, my parents David and Jola Gray. Thanks for all the unwavering support ov...

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Measuring the Weak Charge of the Proton via Elastic Electron-Proton Scattering

Abstract: Measuring the Weak Charge of the Proton via Elastic Electron-Proton ScatteringThe Qweak experiment which ran in Hall C at Jefferson Lab in Newport News, VA, and completed data taking in May 2012, measured the weak charge of the proton Q

Cited by 7 publications

References 66 publications

Determination of the Proton's Weak Charge and Its Constraints on the Standard Model

Determination of the Proton's Weak Charge and Its Constraints on the Standard Model

A novel comparison of Møller and Compton electron-beam polarimeters

Determination of the Kinematics of the Qweak Experiment and Investigation of an Atomic Hydrogen Moller Polarimeter

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