The Born cross sections and effective form factors of the process <math><mrow><msup><mrow><mi>e</mi></mrow><mrow><mo>+</mo></mrow></msup><msup><mrow><mi>e</mi></mrow><mrow><mo>−</mo></mrow></msup><mo>→</mo><mi>Λ</mi><msup><mrow><mover><mrow><mi>Σ</mi></mrow><mrow><mo>¯</mo></mrow></mover></mrow><mrow><mn>0</mn></mrow></msup><mo>+</mo><mi>c</mi><mo>.</mo><mi>c</mi><mo>.</mo></mrow></math> are measured at 14 center-of-mass energy points from 2.3094 to 3.0800 GeV, based on data corresponding to an integrated luminosity of <math><mrow><mo>(</mo><mn>478.5</mn><mo>±</mo><mn>4.8</mn><mo>)</mo><mtext> </mtext><mtext> </mtext><msup><mrow><mi>pb</mi></mrow><mrow><mo>−</mo><mn>1</mn></mrow></msup></mrow></math> collected with the BESIII detector. A nonzero Born cross section is observed at the center-of-mass energy of 2.3094 GeV with a statistical significance of more than five standard deviations, and the cross sections at other energies are obtained with improved precision compared to earlier measurements from the BABAR Collaboration. The Born cross-section line shape is described better by a shape considering the strong-interaction effects than by a pQCD motivated functional form.

China

Russia

Sweden

Germany

Italy

JINR

Poland

Mongolia

United States

Türkiye

South Korea

United Kingdom

Measurement of the <math><mrow><msup><mrow><mi>e</mi></mrow><mrow><mo>+</mo></mrow></msup><msup><mrow><mi>e</mi></mrow><mrow><mo>−</mo></mrow></msup><mo>→</mo><mi>Λ</mi><msup><mrow><mover><mrow><mi>Σ</mi></mrow><mrow><mo>¯</mo></mrow></mover></mrow><mrow><mn>0</mn></mrow></msup><mo>+</mo><mi>c</mi><mo>.</mo><mi>c</mi><mo>.</mo></mrow></math> cross sections at <math><mrow><msqrt><mrow><mi>s</mi></mrow></msqrt></mrow></math> from 2.3094 to 3.0800 GeV