Radiative muon (pion) pair production in high-energy electron positron annihilation: The Case of small invariant pair mass

The process of muon (pion) pair production with small invariant mass in electronApositron high- energy annihilation, accompanied by emission of a hard photon at large angles, is considered. Wend that the DrellAYan picture for the differential cross section is valid in the charge-even experimental set-up. Radiative corrections both for the electron block and for thenal state block are taken into account. � ¸c³µE·¥´ ¶·µI¥¸¸ µi· §µ¢ ´¨O ³Oµ´´µ° (¶¨µ´´µ °) ¶ ·O ¢ ¶·µI¥¸¸¥ O²¥±E·µ´-¶µ§¨E·µ´´µ° ´´¨£¨²OI¨¨ ¸ µi· §µ¢ ´¨¥³ ·¥ ²O´µ£µ |¥¸E±µ£µ ´¥±µ²²¨´¥ ·´µ£µ EµEµ´ . �µ± § ´µ, IEµ ¤¨EE¥- ·¥´I¨ ²O´µ¥ ¸¥I¥´¨¥ µ¶¨¸O¢ ¥E¸O ¢ · ³± I ¶·µI¥¸¸ "·¥²² AŸ´ ¢ § ·O¤µ¢µ-I¥E´µ° ¶µ¸E ´µ¢±¥ O±¸¶¥·¨³¥´E . � ¤¨ I¨µ´´O¥ ¶µ¶· ¢±¨ ± O²¥±E ·µ´´µ³E i²µ±E ¨ ±µ´¥I´µ³E ¸µ¸EµO´¨O ¶·¨¢¥¤¥´O ¢ ´ ²¨E¨I¥¸±µ³ ¢¨¤¥.