Parity-violating electron scattering from 4He and the strange electric form factor of the nucleon.
نویسندگان
چکیده
We have measured the parity-violating electroweak asymmetry in the elastic scattering of polarized electrons from 4He at an average scattering angle = 5.7 degrees and a four-momentum transfer Q2 = 0.091 GeV2 . From these data, for the first time, the strange electric form factor of the nucleon G(E)s can be isolated. The measured asymmetry of A(PV) = (6.72 +/- 0.84(stat) +/- 0.21(syst) x 10(-6) yields a value of G(E)s = -0.038 +/- 0.042(stat) +/- 0.010(syst), consistent with zero.
منابع مشابه
Don ’ t forget to measure ∆ s
This talk explores our lack of knowledge of the strange quark contribution to the nucleon spin, ∆s. Data on ∆s from inclusive and semi-inclusive polarized deep-inelastic scattering will be reviewed, followed by a discussion of how the ongoing program of parity-violating elastic electron-nucleon scattering experiments, that seek out the strange electromagnetic form factors of the nucleon, need t...
متن کاملParity Violation with Electrons and Hadrons
A key question in understanding the structure of nucleons involves the role of sea quarks in their ground state electromagnetic properties such as charge and magnetism. Parity-violating electron scattering, when combined with determination of nucleon electromagnetic form factors from parity-conserving e-N scattering, provides another degree of freedom to separately determine the up, down and st...
متن کاملSample: Parity Violating Electron Scattering from Hydrogen and Deuterium
Recently, there has been considerable theoretical interest in determining strange quark contributions to hadronic matrix elements. Such matrix elements can be accessed through the nucleon’s neutral weak form factors as determined in parity violating electron scattering. The SAMPLE experiment will measure the strange magnetic form factor GM at low momentum transfer. By combining measurements fro...
متن کاملCan the meson cloud explain the nucleon strangeness?
We use a version of the meson cloud model, including the kaon and the K contributions, to estimate the electric and magnetic strange form factors of the nucleon. We compare our results with the recent measurements of the strange quark contribution to parity-violating asymmetries in the forward G0 electron-proton scattering experiment. We conclude that it is very important to determine experimen...
متن کامل2 3 Ju n 20 07 Global Analysis of Nucleon Strange Form Factors at Low Q 2
The existence of a “sea” of quarks and antiquarks in the nucleon has been firmly established in deep-inelastic lepton scattering experiments as well as in the production of dilepton pairs (the Drell-Yan process). However, demonstrating the role of these q̄q pairs in the static electromagnetic properties of the nucleon has been a more elusive and difficult task. As the lightest quark that contrib...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
عنوان ژورنال:
- Physical review letters
دوره 96 2 شماره
صفحات -
تاریخ انتشار 2006