Beam-size effect and particle losses at B-factories KEKB and PEP-II

In the colliders, the macroscopically large impact parameters give a substantial contribution to the standard cross section of the e+e−→e+e−γ process. These impact parameters may be much larger than the transverse sizes of the colliding bunches. It means that the standard cross section of this process has to be substantially modified. In the present paper such a beam-size effect is calculated for bremsstrahlung at B-factories KEKB and PEP-II. We find out that this effect reduces beam losses due to bremsstrahlung by about 20%.