skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Strange nucleon form-factors

Authors:
;
Publication Date:
Sponsoring Org.:
USDOE
OSTI Identifier:
1397392
Grant/Contract Number:
#DE-FG02-07ER41522
Resource Type:
Journal Article: Publisher's Accepted Manuscript
Journal Name:
Progress in Particle and Nuclear Physics
Additional Journal Information:
Journal Volume: 95; Journal Issue: C; Related Information: CHORUS Timestamp: 2017-10-04 21:27:45; Journal ID: ISSN 0146-6410
Publisher:
Elsevier
Country of Publication:
United Kingdom
Language:
English

Citation Formats

Maas, F. E., and Paschke, K. D. Strange nucleon form-factors. United Kingdom: N. p., 2017. Web. doi:10.1016/j.ppnp.2016.11.001.
Maas, F. E., & Paschke, K. D. Strange nucleon form-factors. United Kingdom. doi:10.1016/j.ppnp.2016.11.001.
Maas, F. E., and Paschke, K. D. 2017. "Strange nucleon form-factors". United Kingdom. doi:10.1016/j.ppnp.2016.11.001.
@article{osti_1397392,
title = {Strange nucleon form-factors},
author = {Maas, F. E. and Paschke, K. D.},
abstractNote = {},
doi = {10.1016/j.ppnp.2016.11.001},
journal = {Progress in Particle and Nuclear Physics},
number = C,
volume = 95,
place = {United Kingdom},
year = 2017,
month = 7
}

Journal Article:
Free Publicly Available Full Text
This content will become publicly available on May 17, 2018
Publisher's Accepted Manuscript

Save / Share:
  • We analyze the nucleon matrix element of the strange quark vector current in a nucleon-model-independent dispersive approach with input from the current world data set for the isoscalar electromagnetic form factors. The update of Jaffe{close_quote}s minimal three-pole {ital Ansatz} for the spectral functions yields a 40{percent} larger (Sachs) strangeness radius (r{sub s}{sup 2}){sub Sachs}=0.20 fm{sup 2} and a by 20{percent} reduced magnitude of the strangeness magnetic moment {mu}{sub s}={minus}0.26. In the pole approximation these values are shown to be upper bounds. After extending the {ital Ansatz} in order to implement the asymptotic QCD momentum dependence (which the three-pole form factorsmore » cannot reproduce), we find the magnitude of the three-pole results reduced by up to a factor of 2.5. The signs of the leading moments originate primarily from the large {phi}-meson couplings and are generic in the pole approximation. {copyright} {ital 1997} {ital The American Physical Society}« less
  • We report the most precise measurement to date of a parity-violating asymmetry in elastic electron-proton scattering. The measurement was carried out with a beam energy of 3.03 GeV and a scattering angle <{theta}{sub lab}> = 6.0 degrees, with the result A{sub PV} = -1.14 {+-} 0.24 (stat) {+-} 0.06 (syst) parts per million. From this we extract, at Q{sup 2} = 0.099 GeV{sup 2}, the strange form factor combination G{sub E}{sup s} + 0.080 G{sub M}{sup s} = 0.030 {+-} 0.025 (stat) {+-} 0.006 (syst) {+-} 0.012 (FF) where the first two errors are experimental and the last error ismore » due to the uncertainty in the neutron electromagnetic form factor. The measurement significantly improves existing constraints on G{sub E}{sup s} and G{sub M}{sup s} at Q{sup 2} {approx}0.1 GeV{sup 2}. A consistent picture emerges from all measurements at this Q{sup 2}. A combined fit shows that G{sub E}{sup s} is consistent with zero while G{sub M}{sup s} prefers positive values though G{sub E}{sup s} = G{sub M}{sup s} = 0 is compatible with the data at 95% C.L.« less
  • Using the complete world set of parity violating electron scattering data up to Q{sup 2} {approx} 0.3 GeV{sup 2}, we extract the current best determination of the strange electric and magnetic form factors of the proton, as well as the weak axial form factors of the proton and neutron at Q{sup 2} = 0.1 GeV{sup 2}. The results are consistent with state of the art calculations of all four form factors, with the latter including the anapole contribution.
  • We report new measurements of the parity-violating asymmetry A{sub PV} in elastic scattering of 3 GeV electrons off hydrogen and {sup 4}He targets with ({theta}{sub lab}) {approx} 6.0{sup o}. The {sup 4}He result is A{sub PV} = (+6.40 {+-} 0.23 (stat) {+-} 0.12 (syst)) x 10{sup -6}. The hydrogen result is A{sub PV} = (-1.58 {+-} 0.12 (stat) {+-} 0.04 (syst)) x 10{sup -6}. These results significantly improve constraints on the electric and magnetic strange form factors G{sub E}{sup s} and G{sub M}{sup s}. We extract G{sub E}{sup s} = 0.002 {+-} 0.014 {+-} 0.007 at (Q{sup 2}) = 0.077more » GeV{sup 2}, and G{sub E}{sup s} + 0.09 G{sub M}{sup s} = 0.007 {+-} 0.011 {+-} 0.006 at (Q{sup 2}) = 0.109 GeV{sup 2}, providing new limits on the role of strange quarks in the nucleon charge and magnetization distributions.« less
  • We report new measurements of the parity-violating asymmetry A{sub PV} in elastic scattering of 3 GeV electrons off hydrogen and {sup 4}He targets with {theta}{sub lab} {approx} 6.0{sup 0}. The {sup 4}He result is A{sub PV}=(+6.40 {+-} 0.23(stat) {+-} 0.12(syst)) x 10{sup -6}. The hydrogen result is A{sub PV}=(-1.58 {+-} 0.12(stat) {+-} 0.04(syst)) x 10{sup -6}. These results significantly improve constraints on the electric and magnetic strange form factors GE and GM. We extract GE = 0.002 {+-} 0.014 {+-} 0.007 at Q{sup 2} = 0.077 GeV{sup 2}, and GE + 0.09GM = 0.007 {+-} 0.011 {+-} 0.006 at Q{supmore » 2} = 0.109 GeV{sup 2}, providing new limits on the role of strange quarks in the nucleon charge and magnetization distributions.« less