Measured proton electromagnetic structure deviates from theoretical predictions.

Autor: Li R; Temple University, Philadelphia, PA, USA., Sparveris N; Temple University, Philadelphia, PA, USA. sparveri@temple.edu., Atac H; Temple University, Philadelphia, PA, USA., Jones MK; Thomas Jefferson National Accelerator Facility, Newport News, VA, USA., Paolone M; New Mexico State University, Las Cruces, NM, USA., Akbar Z; University of Virginia, Charlottesville, VA, USA., Gayoso CA; The College of William and Mary, Williamsburg, VA, USA., Berdnikov V; Catholic University of America, Washington, DC, USA., Biswas D; Hampton University, Hampton, VA, USA.; Virginia Polytechnic Institute & State University, Blacksburg, VA, USA., Boer M; Temple University, Philadelphia, PA, USA.; Virginia Polytechnic Institute & State University, Blacksburg, VA, USA., Camsonne A; Thomas Jefferson National Accelerator Facility, Newport News, VA, USA., Chen JP; Thomas Jefferson National Accelerator Facility, Newport News, VA, USA., Diefenthaler M; Thomas Jefferson National Accelerator Facility, Newport News, VA, USA., Duran B; Temple University, Philadelphia, PA, USA., Dutta D; Mississippi State University, Mississippi State, MS, USA., Gaskell D; Thomas Jefferson National Accelerator Facility, Newport News, VA, USA., Hansen O; Thomas Jefferson National Accelerator Facility, Newport News, VA, USA., Hauenstein F; Old Dominion University, Norfolk, VA, USA., Heinrich N; University of Regina, Regina, Saskatchewan, Canada., Henry W; Thomas Jefferson National Accelerator Facility, Newport News, VA, USA., Horn T; Catholic University of America, Washington, DC, USA., Huber GM; University of Regina, Regina, Saskatchewan, Canada., Jia S; Temple University, Philadelphia, PA, USA., Joosten S; Argonne National Laboratory, Lemont, IL, USA., Karki A; Mississippi State University, Mississippi State, MS, USA., Kay SJD; University of Regina, Regina, Saskatchewan, Canada., Kumar V; University of Regina, Regina, Saskatchewan, Canada., Li X; Duke University, Durham, NC, USA., Li WB; The College of William and Mary, Williamsburg, VA, USA., Liyanage AH; Hampton University, Hampton, VA, USA., Malace S; Thomas Jefferson National Accelerator Facility, Newport News, VA, USA., Markowitz P; Florida International University, University Park, FL, USA., McCaughan M; Thomas Jefferson National Accelerator Facility, Newport News, VA, USA., Meziani ZE; Argonne National Laboratory, Lemont, IL, USA., Mkrtchyan H; Artem Alikhanian National Laboratory, Yerevan, Armenia., Morean C; University of Tennessee, Knoxville, TN, USA., Muhoza M; Catholic University of America, Washington, DC, USA., Narayan A; Veer Kunwar Singh University, Arrah, India., Pasquini B; University of Pavia, Pavia, Italy.; Istituto Nazionale di Fisica Nucleare (INFN), Pavia, Italy., Rehfuss M; Temple University, Philadelphia, PA, USA., Sawatzky B; Thomas Jefferson National Accelerator Facility, Newport News, VA, USA., Smith GR; Thomas Jefferson National Accelerator Facility, Newport News, VA, USA., Smith A; Duke University, Durham, NC, USA., Trotta R; Catholic University of America, Washington, DC, USA., Yero C; Florida International University, University Park, FL, USA., Zheng X; University of Virginia, Charlottesville, VA, USA., Zhou J; Duke University, Durham, NC, USA.
Jazyk: angličtina
Zdroj: Nature [Nature] 2022 Nov; Vol. 611 (7935), pp. 265-270. Date of Electronic Publication: 2022 Oct 19.
DOI: 10.1038/s41586-022-05248-1
Abstrakt: The visible world is founded on the proton, the only composite building block of matter that is stable in nature. Consequently, understanding the formation of matter relies on explaining the dynamics and the properties of the proton's bound state. A fundamental property of the proton involves the response of the system to an external electromagnetic field. It is characterized by the electromagnetic polarizabilities 1 that describe how easily the charge and magnetization distributions inside the system are distorted by the electromagnetic field. Moreover, the generalized polarizabilities 2 map out the resulting deformation of the densities in a proton subject to an electromagnetic field. They disclose essential information about the underlying system dynamics and provide a key for decoding the proton structure in terms of the theory of the strong interaction that binds its elementary quark and gluon constituents. Of particular interest is a puzzle in the electric generalized polarizability of the proton that remains unresolved for two decades 2 . Here we report measurements of the proton's electromagnetic generalized polarizabilities at low four-momentum transfer squared. We show evidence of an anomaly to the behaviour of the proton's electric generalized polarizability that contradicts the predictions of nuclear theory and derive its signature in the spatial distribution of the induced polarization in the proton. The reported measurements suggest the presence of a new, not-yet-understood dynamical mechanism in the proton and present notable challenges to the nuclear theory.
(© 2022. The Author(s), under exclusive licence to Springer Nature Limited.)
Databáze: MEDLINE
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