Evidence for Strange-Quark Contributions to the Nucleon's Form Factors at Q2=0.108 (Ge V/c)2

F. E. Maas; K. Aulenbacher; S. Baunack; L. Capozza; J. Diefenbach; B. Gläser; T. Hammel; D. Von Harrach; Y. Imai; E. M. Kabuß; R. Kothe; J. H. Lee; A. Lorente; E. Schilling; D. Schwaab; M. Sikora; G. Stephan; G. Weber; C. Weinrich; I. Altarev; J. Arvieux; M. El-Yakoubi; R. Frascaria; R. Kunne; M. Morlet; S. Ong; J. Van De Wiele; S. Kowalski; B. Plaster; R. Suleiman; S. Taylor

doi:10.1103/PhysRevLett.94.152001

Evidence for Strange-Quark Contributions to the Nucleon's Form Factors at Q²=0.108 (Ge V/c)²

F. E. Maas, K. Aulenbacher, S. Baunack, L. Capozza, J. Diefenbach, B. Gläser, T. Hammel, D. Von Harrach, Y. Imai, E. M. Kabuß, R. Kothe, J. H. Lee, A. Lorente, E. Schilling, D. Schwaab, M. Sikora, G. Stephan, G. Weber, C. Weinrich, I. AltarevJ. Arvieux, M. El-Yakoubi, R. Frascaria, R. Kunne, M. Morlet, S. Ong, J. Van De Wiele, S. Kowalski, B. Plaster, R. Suleiman, S. Taylor

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Abstract

We report on a measurement of the parity violating asymmetry in the elastic scattering of polarized electrons off unpolarized protons with the A4 apparatus at MAMI in Mainz at a four momentum transfer value of Q² = 0.108 (GeV/c)² and at a forward electron scattering angle of 30° < θ_e < 40°. The measured asymmetry is A _LR(e→p) = [-1.36 ± 0.29(stat) ± 0.13(syst)] × 10^-6. The expectation from the standard model assuming no strangeness contribution to the vector current is A₀ = (-2.06 ± 0.14) × 10^-6. We have improved the statistical accuracy by a factor of 3 as compared to our previous measurements at a higher Q². We have extracted the strangeness contribution to the electromagnetic form factors from our data to be G_E ^s + 0.106G_M ^s = 0.071 ± 0.036 at Q² = 0.108 (GeV/c)². We again find the value for G_E ^s + 0.106G_M ^s to be positive, this time at an improved significance level of two σ.

Original language	English
Article number	152001
Pages (from-to)	1-4
Number of pages	4
Journal	Physical Review Letters
Volume	94
Issue number	15
DOIs	https://doi.org/10.1103/PhysRevLett.94.152001
State	Published - Apr 22 2005

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General Physics and Astronomy

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10.1103/PhysRevLett.94.152001

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Maas, F. E., Aulenbacher, K., Baunack, S., Capozza, L., Diefenbach, J., Gläser, B., Hammel, T., Von Harrach, D., Imai, Y., Kabuß, E. M., Kothe, R., Lee, J. H., Lorente, A., Schilling, E., Schwaab, D., Sikora, M., Stephan, G., Weber, G., Weinrich, C., ... Taylor, S. (2005). Evidence for Strange-Quark Contributions to the Nucleon's Form Factors at Q²=0.108 (Ge V/c)² Physical Review Letters, 94(15), 1-4. Article 152001. https://doi.org/10.1103/PhysRevLett.94.152001

@article{2e76d08481904d7d9cb939722fbb5864,

title = "Evidence for Strange-Quark Contributions to the Nucleon's Form Factors at Q2=0.108 (Ge V/c)2 ",

abstract = "We report on a measurement of the parity violating asymmetry in the elastic scattering of polarized electrons off unpolarized protons with the A4 apparatus at MAMI in Mainz at a four momentum transfer value of Q2 = 0.108 (GeV/c)2 and at a forward electron scattering angle of 30° < θe < 40°. The measured asymmetry is A LR(e→p) = [-1.36 ± 0.29(stat) ± 0.13(syst)] × 10-6. The expectation from the standard model assuming no strangeness contribution to the vector current is A0 = (-2.06 ± 0.14) × 10-6. We have improved the statistical accuracy by a factor of 3 as compared to our previous measurements at a higher Q2. We have extracted the strangeness contribution to the electromagnetic form factors from our data to be GE s + 0.106GM s = 0.071 ± 0.036 at Q2 = 0.108 (GeV/c)2. We again find the value for GE s + 0.106GM s to be positive, this time at an improved significance level of two σ.",

author = "Maas, {F. E.} and K. Aulenbacher and S. Baunack and L. Capozza and J. Diefenbach and B. Gl{\"a}ser and T. Hammel and {Von Harrach}, D. and Y. Imai and Kabu{\ss}, {E. M.} and R. Kothe and Lee, {J. H.} and A. Lorente and E. Schilling and D. Schwaab and M. Sikora and G. Stephan and G. Weber and C. Weinrich and I. Altarev and J. Arvieux and M. El-Yakoubi and R. Frascaria and R. Kunne and M. Morlet and S. Ong and {Van De Wiele}, J. and S. Kowalski and B. Plaster and R. Suleiman and S. Taylor",

year = "2005",

month = apr,

day = "22",

doi = "10.1103/PhysRevLett.94.152001",

language = "English",

volume = "94",

pages = "1--4",

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Maas, FE, Aulenbacher, K, Baunack, S, Capozza, L, Diefenbach, J, Gläser, B, Hammel, T, Von Harrach, D, Imai, Y, Kabuß, EM, Kothe, R, Lee, JH, Lorente, A, Schilling, E, Schwaab, D, Sikora, M, Stephan, G, Weber, G, Weinrich, C, Altarev, I, Arvieux, J, El-Yakoubi, M, Frascaria, R, Kunne, R, Morlet, M, Ong, S, Van De Wiele, J, Kowalski, S, Plaster, B, Suleiman, R & Taylor, S 2005, 'Evidence for Strange-Quark Contributions to the Nucleon's Form Factors at Q²=0.108 (Ge V/c)² ', Physical Review Letters, vol. 94, no. 15, 152001, pp. 1-4. https://doi.org/10.1103/PhysRevLett.94.152001

TY - JOUR

T1 - Evidence for Strange-Quark Contributions to the Nucleon's Form Factors at Q2=0.108 (Ge V/c)2

AU - Maas, F. E.

AU - Aulenbacher, K.

AU - Baunack, S.

AU - Capozza, L.

AU - Diefenbach, J.

AU - Gläser, B.

AU - Hammel, T.

AU - Von Harrach, D.

AU - Imai, Y.

AU - Kabuß, E. M.

AU - Kothe, R.

AU - Lee, J. H.

AU - Lorente, A.

AU - Schilling, E.

AU - Schwaab, D.

AU - Sikora, M.

AU - Stephan, G.

AU - Weber, G.

AU - Weinrich, C.

AU - Altarev, I.

AU - Arvieux, J.

AU - El-Yakoubi, M.

AU - Frascaria, R.

AU - Kunne, R.

AU - Morlet, M.

AU - Ong, S.

AU - Van De Wiele, J.

AU - Kowalski, S.

AU - Plaster, B.

AU - Suleiman, R.

AU - Taylor, S.

PY - 2005/4/22

Y1 - 2005/4/22

N2 - We report on a measurement of the parity violating asymmetry in the elastic scattering of polarized electrons off unpolarized protons with the A4 apparatus at MAMI in Mainz at a four momentum transfer value of Q2 = 0.108 (GeV/c)2 and at a forward electron scattering angle of 30° < θe < 40°. The measured asymmetry is A LR(e→p) = [-1.36 ± 0.29(stat) ± 0.13(syst)] × 10-6. The expectation from the standard model assuming no strangeness contribution to the vector current is A0 = (-2.06 ± 0.14) × 10-6. We have improved the statistical accuracy by a factor of 3 as compared to our previous measurements at a higher Q2. We have extracted the strangeness contribution to the electromagnetic form factors from our data to be GE s + 0.106GM s = 0.071 ± 0.036 at Q2 = 0.108 (GeV/c)2. We again find the value for GE s + 0.106GM s to be positive, this time at an improved significance level of two σ.

AB - We report on a measurement of the parity violating asymmetry in the elastic scattering of polarized electrons off unpolarized protons with the A4 apparatus at MAMI in Mainz at a four momentum transfer value of Q2 = 0.108 (GeV/c)2 and at a forward electron scattering angle of 30° < θe < 40°. The measured asymmetry is A LR(e→p) = [-1.36 ± 0.29(stat) ± 0.13(syst)] × 10-6. The expectation from the standard model assuming no strangeness contribution to the vector current is A0 = (-2.06 ± 0.14) × 10-6. We have improved the statistical accuracy by a factor of 3 as compared to our previous measurements at a higher Q2. We have extracted the strangeness contribution to the electromagnetic form factors from our data to be GE s + 0.106GM s = 0.071 ± 0.036 at Q2 = 0.108 (GeV/c)2. We again find the value for GE s + 0.106GM s to be positive, this time at an improved significance level of two σ.

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U2 - 10.1103/PhysRevLett.94.152001

DO - 10.1103/PhysRevLett.94.152001

M3 - Article

AN - SCOPUS:18144399689

SN - 0031-9007

VL - 94

SP - 1

EP - 4

JO - Physical Review Letters

JF - Physical Review Letters

IS - 15

M1 - 152001

ER -

Evidence for Strange-Quark Contributions to the Nucleon's Form Factors at Q²=0.108 (Ge V/c)²

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