Exclusive production of double light neutral mesons at the e+e− colliders

In this work we investigate the exclusive production of a pair of light neutral mesons in <a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"><a:msup><a:mi>e</a:mi><a:mo>+</a:mo></a:msup><a:msup><a:mi>e</a:mi><a:mo>−</a:mo></a:msup></a:math> annihilation, where the final state bears an even <c:math xmlns:c="http://www.w3.org/1998/Math/MathML" display="inline"><c:mi>C</c:mi></c:math>-parity. The production processes can be initiated via the photon fragmentation or the nonfragmentation mechanism. While the fragmentation contribution can be rigorously accounted, the nonfragmentation contributions are calculated within the framework of collinear factorization, where only the leading-twist light-cone distribution amplitudes (LCDAs) of mesons are considered. Mediately solely by the nonfragmentation mechanism, the production rates of double light neutral pseudoscalar mesons are too small to be observed at the commissioning <e:math xmlns:e="http://www.w3.org/1998/Math/MathML" display="inline"><e:msup><e:mi>e</e:mi><e:mo>+</e:mo></e:msup><e:msup><e:mi>e</e:mi><e:mo>−</e:mo></e:msup></e:math> facilities. In contrast, the production rates of a pair of light neutral vector mesons are greatly amplified owing to the significant kinematic enhancement brought by the fragmentation mechanism. It is found that, at <g:math xmlns:g="http://www.w3.org/1998/Math/MathML" display="inline"><g:msqrt><g:mi>s</g:mi></g:msqrt><g:mo>=</g:mo><g:mn>3.77</g:mn><g:mtext> </g:mtext><g:mtext> </g:mtext><g:mi>GeV</g:mi></g:math>, after including the destructive interference between the nonfragmentation and fragmentation contributions, the production rates for <i:math xmlns:i="http://www.w3.org/1998/Math/MathML" display="inline"><i:msup><i:mi>e</i:mi><i:mo>+</i:mo></i:msup><i:msup><i:mi>e</i:mi><i:mo>−</i:mo></i:msup><i:mo stretchy="false">→</i:mo><i:msup><i:mi>ρ</i:mi><i:mn>0</i:mn></i:msup><i:msup><i:mi>ρ</i:mi><i:mn>0</i:mn></i:msup></i:math> and <l:math xmlns:l="http://www.w3.org/1998/Math/MathML" display="inline"><l:msup><l:mi>ρ</l:mi><l:mn>0</l:mn></l:msup><l:mi>ω</l:mi></l:math> can be lowered by about 10% and 30% relative to the fragmentation predictions. Future precise measurement of these exclusive double neutral vector meson production channels at BESIII experiment may provide useful constraints on the LCDAs of light vector mesons.