Measurement of the proton spin structure at long distances
Abstract
Measuring the spin structure of protons and neutrons tests our understanding of how they arise from quarks and gluons, the fundamental building blocks of nuclear matter. At long distances the coupling constant of the strong interaction becomes large, requiring non-perturbative methods to calculate quantum chromodynamics processes, such as lattice gauge theory or effective field theories. Here we report proton spin structure measurements from scattering a polarized electron beam off polarized protons. The spin-dependent cross-sections were measured at large distances, corresponding to the region of low momentum transfer squared between 0.012 and 1.0 GeV. This kinematic range provides unique tests of chiral effective field theory predictions. Our results show that a complete description of the nucleon spin remains elusive, and call for further theoretical works, e.g. in lattice quantum chromodynamics. Finally, our data extrapolated to the photon point agree with the Gerasimov-Drell-Hearn sum rule, a fundamental prediction of quantum field theory that relates the anomalous magnetic moment of the proton to its integrated spin-dependent cross-sections.
Keywords
Cite
@article{arxiv.2102.02658,
title = {Measurement of the proton spin structure at long distances},
author = {X. Zheng and A. Deur and H. Kang and S. E. Kuhn and M. Ripani and J. Zhang and K. P. Adhikari and S. Adhikari and M. J. Amaryan and H. Atac and H. Avakian and L. Barion and M. Battaglieri and I. Bedlinskiy and F. Benmokhtar and A. Bianconi and A. S. Biselli and S. Boiarinov and M. Bondi and F. Bossu and P. Bosted and W. J. Briscoe and J. Brock and W. K. Brooks and D. Bulumulla and V. D. Burkert and C. Carlin and D. S. Carman and J. C. Carvajal and A. Celentano and P. Chatagnon and T. Chetry and J. -P. Chen and S. Choi and G. Ciullo and L. Clark and P. L. Cole and M. Contalbrigo and V. Crede and A. D'Angelo and N. Dashyan and R. De Vita and M. Defurne and S. Diehl and C. Djalali and V. A. Drozdov and R. Dupre and M. Ehrhart and A. El Alaoui and L. Elouadrhiri and P. Eugenio and G. Fedotov and S. Fegan and R. Fersch and A. Filippi and T. A. Forest and Y. Ghandilyan and G. P. Gilfoyle and K. L. Giovanetti and F. -X. Girod and D. I. Glazier and R. W. Gothe and K. A. Griffioen and M. Guidal and N. Guler and L. Guo and K. Hafidi and H. Hakobyan and M. Hattawy and T. B. Hayward and D. Heddle and K. Hicks and A. Hobart and T. Holmstrom and M. Holtrop and Y. Ilieva and D. G. Ireland and E. L. Isupov and H. S. Jo and K. Joo and S. Joosten and C. D. Keith and D. Keller and A. Khanal and M. Khandaker and C. W. Kim and W. Kim and F. J. Klein and A. Kripko and V. Kubarovsky and L. Lanza and M. Leali and P. Lenisa and K. livingston and E. Long and I. J. D. MacGregor and N. Markov and L. Marsicano and V. Mascagna and B. McKinnon and D. G. Meekins and T. Mineeva and M. Mirazita and V. Mokeev and C. Mullen and P. Nadel-Turonski and K. Neupane and S. Niccolai and M. Osipenko and A. I. Ostrovidov and M. Paolone and L. Pappalardo and K. Park and E. Pasyuk and W. Phelps and S. K. Phillips and O. Pogorelko and J. Poudel and Y. Prok and B. A. Raue and J. Ritman and A. Rizzo and G. Rosner and P. Rossi and J. Rowley and F. Sabatie and C. Salgado and A. Schmidt and R. A. Schumacher and M. L. Seely and Y. G. Sharabian and U. Shrestha and S. Sirca and K. Slifer and N. Sparveris and S. Stepanyan and I. I. Strakovsky and S. Strauch and V. Sulkosky and N. Tyler and M. Ungaro and L. Venturelli and H. Voskanyan and E. Voutier and D. P. Watts and X. Wei and L. B. Weinstein and M. H. Wood and B. Yale and N. Zachariou and Z. W. Zhao},
journal= {arXiv preprint arXiv:2102.02658},
year = {2022}
}
Comments
Published version. 10 pages, 5 figures. 20 pages of supplementary material (data tables and a figure)