Strange Quarks in the Nucleon Sea

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Strange Quarks in the Nucleon Sea Results from
Happex II
Konrad A. Aniol, CSULA
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Recent Talks by the HAPPEX Collaboration
See these talks for greater detail
http//hallaweb.jlab.org/experiment/HAPPEX/pubsand
talks.html
APS Meeting Parity-Violation Electron Scattering
on Hydrogen and Helium and Strangeness in the
Nucleon, 23 April 2006 - Paul Souder (PPT)
TJNAF Seminar Results from the 2005 HAPPEX-II
Run, 21 April 2006 - Kent Paschke (PPT)
Kent Paschke, University of Massachusetts,
Amherst, Mass Thesis Students Lisa Kaufman,
University of Massachusetts, Amherst, Mass Bryan
Moffit, College of William and Mary,
Williamsburg, VA Hachemi Benaoum, Syracuse
University, Syracuse, NY Ryan Snyder, University
of Virginia, Charlottesville, VA
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Strange Quarks in the Nucleon
Strange Sea measured in nN scattering
Strange sea is well-known, but contributions to
nucleon matrix elements are somewhat unsettled
Spin polarized DIS Inclusive Ds -0.10 0.06
uncertainties from SU(3), extrapolation Semi-inc
lusive Ds 0.03 0.03 fragmentation function
Strange mass pN scattering 0-30
Strange vector FF
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Neutral Currents andWeak-Electromagnetic
Interference
Electron Scattering off Nucleons Nuclei
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Parts of the Lagrangian responsible for neutral
current scattering
photon
Z boson
Electroweak coupling of charged fundamental
particles
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Detailed Formulae Clean Probe of
StrangenessInside the Nucleon
Hydrogen

• Measurement of APV yields linear combination of
  GsE, GsM

4He

• Sensitive only to GsE

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HAPPEX-II
Q20.091 GeV2
Q20.099 GeV2
Q20.077 GeV2
Q20.109 GeV2
Example The window pair statistical error is 620
ppm for 2004 HAPPEX-H.
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Recent Happex Publications 2004 runs
Phys.Rev. Lett. 96, 022003 (2006)
Parity-Violating Electron Scattering from 4He and
the Strange Electric Form Factor fo the Nucleon
                             GEs -0.038
0.042(stat) 0.010(syst)                      
            
Phys. Lett. B635 (2006) 275
Constraints on the Nucleon Strange Form Factors
at Q2 0.1 GeV2
GEs 0.080GMs 0.030 0.025(stat)
0.006(syst) 0.012(FF)
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Theory Calculations
16. Skyrme Model - N.W. Park and H. Weigel, Nucl.
Phys. A 451, 453 (1992). 17. Dispersion Relation
- H.W. Hammer, U.G. Meissner, D. Drechsel, Phys.
Lett. B 367, 323 (1996). 18. Dispersion Relation
- H.-W. Hammer and Ramsey-Musolf, Phys. Rev. C
60, 045204 (1999). 19. Chiral Quark Soliton
Model - A. Sliva et al., Phys. Rev. D 65, 014015
(2001). 20. Perturbative Chiral Quark Model - V.
Lyubovitskij et al., Phys. Rev. C 66, 055204
(2002). 21. Lattice - R. Lewis et al., Phys.
Rev. D 67, 013003 (2003). 22. Lattice charge
symmetry -Leinweber et al, Phys. Rev. Lett. 94,
212001 (2005) hep-lat/0601025
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HAPPEX-II 2005 Preliminary Results
HAPPEX-4He
Q2 0.0772 0.0007 (GeV/c)2 APV 6.43 ? 0.23
(stat) ? 0.22 (syst) ppm
A(Gs0) 6.37 ppm GsE 0.004 ? 0.014(stat) ?
0.013(syst)
HAPPEX-H
Q2 0.1089 0.0011 (GeV/c)2 APV -1.60 ? 0.12
(stat) ? 0.05 (syst) ppm
A(Gs0) -1.640 ppm ? 0.041 ppm GsE 0.088
GsM 0.004 ? 0.011(stat) ? 0.005(syst) ?
0.004(FF)
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HAPPEX-II 2005 Preliminary Results

• Three bands
• Inner Project to axis for 1-D error bar
• Middle 68 probability contour
• Outer 95 probability contour

Preliminary HAPPEX 2005 data
Caution the combined fit is approximate.
Correlated errors and assumptions not taken into
account
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World data confronts theoretical predictions
16. Skyrme Model - N.W. Park and H. Weigel, Nucl.
Phys. A 451, 453 (1992). 17. Dispersion Relation
- H.W. Hammer, U.G. Meissner, D. Drechsel, Phys.
Lett. B 367, 323 (1996). 18. Dispersion Relation
- H.-W. Hammer and Ramsey-Musolf, Phys. Rev. C
60, 045204 (1999). 19. Chiral Quark Soliton
Model - A. Sliva et al., Phys. Rev. D 65, 014015
(2001). 20. Perturbative Chiral Quark Model - V.
Lyubovitskij et al., Phys. Rev. C 66, 055204
(2002). 21. Lattice - R. Lewis et al., Phys.
Rev. D 67, 013003 (2003). 22. Lattice charge
symmetry -Leinweber et al, Phys. Rev. Lett. 94,
212001 (2005) hep-lat/0601025
Preliminary results from 2005 data
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Summary
Preliminary
Preliminary

• Suggested large values at Q20.1 GeV2
• Ruled out

• Large possible cancellation at Q20.2 GeV2
• Very unlikely given constraint at 0.1 GeV2
• G0 back angle at low Q2 (error bar1.5 of mp)
  maintains sensitivity to discover GMS

• Possible large values at Q2gt0.4 GeV2
• G0 backangle, finished Spring 2007
• HAPPEX-III - 2008

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Strange form factors of the proton
A recent fit to the worlds data for
Q2lt0.3GeV2 R. D. Young et al., nucl-ex/0604010
GEs rsQ2. rs -0.06 0.41
GeV2 GMs ms. ms 0.12 0.55
0.07
Includes data from SAMPLE, PVA4, G0, HAPPEX (2004)
Lattice QCD calculation of GMs
D. B. Leinweber et al., PRL 94(2055)212001
GMs (-0.046 0.019)mn
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References
mrst2004
Ann. Rev. Nucl. Part. Sci. 2001. 51189-217, D.
Beck, R. McKeown
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PV Electron Scattering to Measure Weak NC
Amplitudes
Interference with EM amplitude makes NC amplitude
accessible
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Weak coupling constants for the lightest quarks