Abstract
The spin polarizabilities of the nucleon are fundamental structure constants which describe the response of the nucleon spin to an incident polarized photon. The most model-independent way to measure the nucleon spin polarizabilities is the Compton scattering with polarization degrees of freedom. Three Compton scattering asymmetries on the proton were measured in the Δ(1232) region using a polarized incident photon beam and a polarized (or unpolarized) proton target at the Mainz Microtron (MAMI). These asymmetries are sensitive to values of the spin polarizabilities. Fits to asymmetry data were performed using a dispersion model calculation, and a separation of all four proton spin-polarizabilities in the multipole basis was achieved. The values of the proton spin polarizabilities are presented.
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References
B. R. Holstein, “Testing QCD at low energies”, Nucl. Phys. A 546, 213–232 (1992).
D. Babusci, G. Giordano, A. I. L’vov, G. Matone, and A. M. Nathan, “Low-energy Compton scattering of polarized photons on polarized nucleons”, Phys. Rev. C 58, 1013–1041 (1998).
J. Ahrens et al. (GDH and A2 Collab.), “First measurement of the Gerasimov–Drell–Hearn integral for 1H from 200 to 800 MeV”, Phys. Rev. Lett. 87, 022003 (2001).
H. Dutz et al. (GDH and A2 Collab.), “First measurement of the Gerasimov–Drell–Hearn integral for 1H from 0.7 to 1.8 GeV at ELSA”, Phys. Rev. Lett. 91, 192001 (2003).
M. Camen, K. Kossert, F. Wissmann, J. Ahrens, H.-J. Arends, R. Beck, G. Caselotti, P. Grabmayr, P. D. Harty, O. Jahn, P. Jennewein, R. Kondratiev, M. I. Levchuk, V. Lisin, A. I. L’vov, J. C. McGeorge, A. Natter, V. Olmos de Leon, M. Schumacher, B. Seitz, F. Smend, A. Thomas, W. Weihofen, and F. Zapadtka, “Backward spin polarizability of the proton”, Phys. Rev. C 65, 0302202 (2002).
K. B. Vijaya Kumar, J. A. McGovern, and M. C. Birse, “Spin polarisabilities of the nucleon at NLO in the chiral expansion”, Phys. Lett. B 479, 167–172 (2000).
G. C. Gellas, T. R. Hemmert, and U.-G. Meissner, “Complete one loop analysis of the nucleonś spin polarizabilities”, Phys. Rev. Lett. 85, 14–17 (2001).
S. Kondratyuk and O. Scholten, “Compton scattering on the nucleon at intermediate energies and polarizabilities in a microscopic model”, Phys. Rev. C 64, 024005 (2001).
A. M. Gasparyan, M. F. M. Lutz, and B. Pasquini, “Compton scattering from chiral dynamics with unitarity and causality”, Nucl. Phys. A 866, 79–92 (2011).
J. A. McGovern, D. R. Phillips, and H. W. Griesshammer, “Compton scattering from the proton in an effective field theory with explicit Delta degrees of freedom”, Eur. Phys. J. A 49, 12–31 (2013).
B. R. Holstein, D. Drechsel, P. Pasquini, and M. Vanderhaeghen, “Higher order polarizabilities of the proton”, Phys. Rev. C 61, 034316 (2000).
D. Drechsel, B. Pasquini, and M. Vanderhaeghen, “Dispersion relations in real and virtual Compton scattering”, Phys. Rep. 378, 99–205 (2003).
P. P. Martel et al. (A2 Collab. MAMI), “Measurements of double-polarized Compton scattering asymmetries and extraction of the proton spin polarizabilities”, Phys. Rev. Lett. 114, 112501 (2015).
C. Collicott, “Probing proton structure through single polarization observables of Compton scattering and photoproduction within the Δ(1232) region”, PhD. Thesis (Dalhousie University, 2015), p. 163.
A. Thomas, N. S. Borisov, H.-J. Arends, A. N. Fedorov, G. M. Gurevich, R. L. Kondratiev, M. Korolija, A. B. Lazarev, M. Martinez, W. Meyer, S. V. Mironov, A. B. Neganov, V. N. Pavlov, H. Ortega, G. Reicherz, and Yu. A. Usov, “The new frozen spin target at MAMI”, Phys. Part. Nucl. 44, 964–967 (2013).
G. Blanpied et al. (LEGS Collab.), “N → Δ transition and proton polarizabilities from measurements of p(γ, γ), p(γ, π0), and p(γ, π+)”, Phys. Rev. C 64, 025203 (2001).
V. Lensky and V. Pascalutsa, “Predictive powers of chiral perturbation theory in Compton scattering off protons”, Eur. Phys. J. C 65, 195–210 (2010).
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Gurevich, G.M., Lisin, V.P. & A2 collaboration. Measurement of the proton spin polarizabilities at MAMI. Phys. Part. Nuclei 48, 111–116 (2017). https://doi.org/10.1134/S1063779617010105
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DOI: https://doi.org/10.1134/S1063779617010105