Off-campus UMass Amherst users: To download dissertations, please use the following link to log into our proxy server with your UMass Amherst user name and password.

Non-UMass Amherst users, please click the view more button below to purchase a copy of this dissertation from Proquest.

(Some titles may also be available free of charge in our Open Access Dissertation Collection, so please check there first.)

Precision measurement of the proton neutral weak form factors at squared momentum transfer ~ 0.1 GeV(2)

Lisa J Kaufman, University of Massachusetts Amherst


This thesis reports the HAPPEX measurement of the parity-violating asymmetry for longitudinally polarized electrons elastically scattered from protons in a liquid hydrogen target. The measurement was carried out in Hall A at Thomas Jefferson National Accelerator Facility using a beam energy E = 3 GeV and scattering angle ⟨&thetas;lab⟩ = 6°. The asymmetry is sensitive to the weak neutral form factors from which we extract the strange quark electric and magnetic form factors ([special characters omitted] and [special characters omitted]) of the proton. The measurement was conducted during two data-taking periods in 2004 and 2005. This thesis describes the methods for controlling the helicity-correlated beam asymmetries and the analysis of the raw asymmetry. The parity-violating asymmetry has been measured to be APV = -1.14 ± 0.24 (stat) ± 0.06 (syst) ppm at ⟨Q 2⟩ = 0.099 GeV2 (2004), and APV = -1.58 ± 0.12 (stat) ± 0.04 (syst) ppm at ⟨Q 2⟩ = 0.109 GeV2 (2005). The strange quark form factors extracted from the asymmetry are [special characters omitted] + 0.080[special characters omitted] = 0.030 ± 0.025 (stat) ± 0.006 (syst) ± 0.012 (FF) (2004) and [special characters omitted] + 0.088[special characters omitted] = 0.007 ± 0.011 (stat) ± 0.004 (syst) ± 0.005 (FF) (2005). These results place the most precise constraints on the strange quark form factors and indicate little strange dynamics in the proton.

Subject Area

Nuclear physics

Recommended Citation

Kaufman, Lisa J, "Precision measurement of the proton neutral weak form factors at squared momentum transfer ~ 0.1 GeV(2)" (2007). Doctoral Dissertations Available from Proquest. AAI3254934.