The fundamental limitation of the luminosity in electron-positron colliders is well known to be the beam - beam limit since late 1960's. Extensive theoretical and experimental studies on existing machines have shown that the limit could be described in terms of a constant maximum value parameter called "x parameter". According to this phenomenological rule it was also believed that at least a factor 2 could be gained by going to a round colliding beam scheme but not really proven experimentally.
The work performed under the present INTAS contract has confirmed such expectation through new theoretical approaches and advanced simulations. In order to validate such results a new design of the M-ring in Novosibirsk has been extensively studied and corresponding magnetic components have been built (as for instance super-conducting solenoid to produce non coupled round beams at the collision point), but not yet installed on the ring. Though great effort has been made, the initial aim of the project to compare experimentally the flat and round beam schemes and to improve the luminosity of VEPP2-M, has not been achieved during the time duration of the present contract. However the whole work is rather positive and effort of transforming VEPP2-M for validating the round beam concept should continue prior to the construction of a dedicated round beam e+e- factory.