HAPPEX: Strange Quarks in the Proton and He4

Conference · Mon Oct 02 04:00:00 EDT 2006

OSTI ID:897294

Michaels, Robert

HAPPEX results from our 2005 run for the parity-violating asymmetry A{sub PV} in elastic scattering of 3 GeV electrons off hydrogen and {sup 4}He targets at ({theta}{sub lab}) {approx} 6.0{sup o} are presented. 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}. The asymmetry for hydrogen is a linear combination of G{sub E}{sup s} and G{sub M}{sup s}, the strange quark contributions to the electric and magnetic form factors of the nucleon, respectively, and that for {sup 4}He is a function of G{sub E}{sup s} alone. The measurements imply 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} and G{sub E}{sup s} = 0.002 {+-} 0.014 {+-} 0.007 at <Q{sup 2}> = 0.077GeV{sup 2}.

• Research Organization: Thomas Jefferson National Accelerator Facility, Newport News, VA
• Sponsoring Organization: USDOE - Office of Energy Research (ER)
• DOE Contract Number: AC05-84ER40150
• OSTI ID: 897294
• Report Number(s): JLAB-PHY-06-584; DOE/ER/40150-4195
• Country of Publication: United States
• Language: English

Related Subjects

08 HYDROGEN
ASYMMETRY
ELASTIC SCATTERING
ELECTRONS
FORM FACTORS
HYDROGEN
PHYSICS
PROTONS
QUARKS
SPIN
TARGETS