Measurement of the generalized spin polarizabilities of the neutron in the low-$Q^2$ region

Vincent Sulkosky , Chao Peng , Jian-Ping Chen , Alexandre Deur , Sergey Abrahamyan , Konrad A. Aniol , David S. Armstrong , Todd Averett , Stephen J. Bailey , Arie Beck , Pierre Bertin (1) , Florentin Butaru , Werner Boeglin , Alexandre Camsonne (1) , Gordon D. Cates , Chia-Cheh Chang , Seonho Choi , Eugene Chudakov , Luminita Coman , Juan C. Cornejo , Brandon Craver , Francesco Cusanno , Raffaele de Leo , Cornelis W. de Jager , Joseph D. Denton , Seema Dhamija , Robert Feuerbach , John M. Finn , Salvatore Frullani , Kirsten Fuoti , Haiyan Gao , Franco Garibaldi , Olivier Gayou , Ronald Gilman , Alexander Glamazdin , Charles Glashausser , Javier Gomez , Jens-Ole Hansen , David Hayes , F. William Hersman , Douglas W. Higinbotham , Timothy Holmstrom , Thomas B. Humensky , Charles E. Hyde , Hassan Ibrahim , Mauro Iodice , Xiandong Jiang , Lisa J. Kaufman , Aidan Kelleher , Kathryn E. Keister , Wooyoung Kim , Ameya Kolarkar , Norm Kolb , Wolfgang Korsch , Kevin Kramer , Gerfried Kumbartzki , Luigi Lagamba , Vivien Lainé (1) , Geraud Laveissiere (1) , John J. Lerose , David Lhuillier (2) , Richard Lindgren , Nilanga Liyanage , Hai-Jiang Lu , Bin Ma , Demetrius J. Margaziotis , Peter Markowitz , Kathleen R. Mccormick , Mehdi Meziane , Zein-Eddine Meziani , Robert Michaels , Bryan Moffit , Peter Monaghan , Sirish Nanda , Jennifer Niedziela , Mikhail Niskin , Ronald Pandolfi , Kent D. Paschke , Milan Potokar , Andrew Puckett , Vina A. Punjabi , Yi Qiang , Ronald D. Ransome , Bodo Reitz , Rikki Roché , Arun Saha , Alexander Shabetai , Simon Širca , Jaideep T. Singh , Karl Slifer , Ryan Snyder , Patricia Solvignon , Robert Stringer , Ramesh Subedi , William A. Tobias , Ngyen Ton , Paul E. Ulmer , Guido Maria Urciuoli , Eric Voutier (3) , Kebin Wang , Lu Wan , Bogdan Wojtsekhowski , Seungtae Woo , Huan Yao , Jing Yuan , Xiaohui Zhan , Xiaochao Zheng , Lingyan Zhu

1 LPC - Laboratoire de Physique de Clermont
2 DPHN - Département de Physique Nucléaire (ex SPhN)
3 LPSC - Laboratoire de Physique Subatomique et de Cosmologie

Understanding the nucleon spin structure in the regime where the strong interaction becomes truly strong poses a challenge to both experiment and theory. At energy scales below the nucleon mass of about 1 GeV, the intense interaction among the quarks and gluons inside the nucleon makes them highly correlated. Their coherent behaviour causes the emergence of effective degrees of freedom, requiring the application of non-perturbative techniques such as chiral effective field theory1. Here we present measurements of the neutron’s generalized spin polarizabilities that quantify the neutron’s spin precession under electromagnetic fields at very low energy-momentum transfer squared down to 0.035 GeV2. In this regime, chiral effective field theory calculations2,3,4 are expected to be applicable. Our data, however, show a strong discrepancy with these predictions, presenting a challenge to the current description of the neutron’s spin properties.

Mots clés: experimental results; nucleon: structure; spin: precession; n: spin; spin: polarizability; momentum transfer: low; Jefferson Lab; effective field theory: chiral; electromagnetic field; strong interaction; nonperturbative

Domaines: Physique Générale [physics.gen-ph]

Vincent Sulkosky, Chao Peng, Jian-Ping Chen, Alexandre Deur, Sergey Abrahamyan, et al.. Measurement of the generalized spin polarizabilities of the neutron in the low-$Q^2$ region. Nature Physics, 2021, 17 (6), pp.687-692. ⟨10.1038/s41567-021-01245-9⟩. ⟨hal-03263588⟩