TY - JOUR

T1 - Measurements of the Electric and Magnetic Form Factors of the Neutron for Timelike Momentum Transfer

AU - BESIII Collaboration

AU - Achasov, M N

AU - Boyko, I

AU - Chen, C

AU - Chen, G

AU - Chen, M L

AU - Nikolaev, I B

AU - Мучной, Николай Юрьевич

N1 - Measurements of the Electric and Magnetic Form Factors of the Neutron for Timelike Momentum Transfer / BESIII Collaboration // Physical Review Letters. – 2023. – Vol. 130, No. 15. – P. 151905. – DOI 10.1103/physrevlett.130.151905.

PY - 2023/4/14

Y1 - 2023/4/14

N2 - We present the first measurements of the electric and magnetic form factors of the neutron in the timelike (positive q^{2}) region as function of four-momentum transfer. We explored the differential cross sections of the reaction e^{+}e^{-}→n[over ¯]n with data collected with the BESIII detector at the BEPCII accelerator, corresponding to an integrated luminosity of 354.6  pb^{-1} in total at twelve center-of-mass energies between sqrt[s]=2.0-2.95  GeV. A relative uncertainty of 18% and 12% for the electric and magnetic form factors, respectively, is achieved at sqrt[s]=2.3935  GeV. Our results are comparable in accuracy to those from electron scattering in the comparable spacelike region of four-momentum transfer. The electromagnetic form factor ratio R_{em}≡|G_{E}|/|G_{M}| is within the uncertainties close to unity. We compare our result on |G_{E}| and |G_{M}| to recent model predictions, and the measurements in the spacelike region to test the analyticity of electromagnetic form factors.

AB - We present the first measurements of the electric and magnetic form factors of the neutron in the timelike (positive q^{2}) region as function of four-momentum transfer. We explored the differential cross sections of the reaction e^{+}e^{-}→n[over ¯]n with data collected with the BESIII detector at the BEPCII accelerator, corresponding to an integrated luminosity of 354.6  pb^{-1} in total at twelve center-of-mass energies between sqrt[s]=2.0-2.95  GeV. A relative uncertainty of 18% and 12% for the electric and magnetic form factors, respectively, is achieved at sqrt[s]=2.3935  GeV. Our results are comparable in accuracy to those from electron scattering in the comparable spacelike region of four-momentum transfer. The electromagnetic form factor ratio R_{em}≡|G_{E}|/|G_{M}| is within the uncertainties close to unity. We compare our result on |G_{E}| and |G_{M}| to recent model predictions, and the measurements in the spacelike region to test the analyticity of electromagnetic form factors.

UR - https://pubmed.ncbi.nlm.nih.gov/37115883/

UR - https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=85153779550&origin=inward

UR - https://elibrary.ru/item.asp?id=61724886

U2 - 10.1103/PhysRevLett.130.151905

DO - 10.1103/PhysRevLett.130.151905

M3 - Article

C2 - 37115883

VL - 130

SP - 151905

JO - Physical Review Letters

JF - Physical Review Letters

SN - 0031-9007

IS - 15

ER -