Title

Parity-violating electron scattering on hydrogen and helium and strangeness in the nucleon

Date of Award

2007

Degree Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Physics

Advisor(s)

Paul Souder

Keywords

Hydrogen, Helium, Parity violation, Strange form factors, Polarized electron scattering

Subject Categories

Physical Sciences and Mathematics | Physics

Abstract

The HAPPEX II measurement of the parity violating asymmetry A PV for longitudinally polarized 3 GeV electrons from both hydrogen and 4 He cryogenic targets, at a small scattering angle (6°), is reported in this thesis. The asymmetry for hydrogen is a function of a linear combination of [Special characters omitted.] and [Special characters omitted.] , the strange quark contributions to the electric and magnetic form factors of the nucleon respectively, and that for 4 He is a function solely of [Special characters omitted.] . The combination of the two measurements therefore allows [Special characters omitted.] and [Special characters omitted.] to be separately determined. The 4 He result is [Special characters omitted.] = +6.40 ± 0.23 (stat) ± 0.12 (syst) ppm. The hydrogen result is [Special characters omitted.] = -1.58 ± 0.12 (stat) ± 0.04 (syst) ppm. The strange quark form factors extracted from these asymmetries are [Special characters omitted.] = 0.002 ± 0.014 ± 0.007 at < Q 2 >= 0.077 GeV 2 , and [Special characters omitted.] + 0.09[Special characters omitted.] = 0.007 ± 0.011 ± 0.006 at < Q 2 >= 0.109 GeV 2 . These results significantly improve constraints on the electric and magnetic strange form factors with an unprecedented precision.

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