Yayınlanmış 1 Ocak 2023 | Sürüm v1
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Measurements of the Electric and Magnetic Form Factors of the Neutron for Timelike Momentum Transfer

Oluşturanlar

  • 1. CERN

Açıklama

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 ${e}^{+}{e}^{-}\to \overline{n}n$ with data collected with the BESIII detector at the BEPCII accelerator, corresponding to an integrated luminosity of $354.6\text{}\text{}{\mathrm{pb}}^{-1}$ in total at twelve center-of-mass energies between $\sqrt{s}=2.0–2.95\text{}\text{}\mathrm{GeV}$. A relative uncertainty of 18% and 12% for the electric and magnetic form factors, respectively, is achieved at $\sqrt{s}=2.3935\text{}\text{}\mathrm{GeV}$. 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 ${R}_{\mathrm{em}}\equiv |{G}_{E}|/|{G}_{M}|$ 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.

Dosyalar

PhysRevLett.130.151905.pdf

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