Speaker
Description
Electromagnetic interaction of colliding beams leads to perturbations in their motion as a whole (coherent effect resulting in orbit shift) as well as to the motion of individual particles (incoherent effect resulting in particles re-distribution. In colliders the effect influences its luminosity in two ways. First, the number of collisions is changed in comparison to expected values; second, the calibration of luminosity performed with van-der-Meer scan is biased. For example, in LHC this bias is at the level more than 1%.
Currently the estimation of the effect is based on Gaussian model for particles densities in colliding beams. However, for more precise calculations (for example, it is desired the luminosity precision will be known at the level below 1% in HL-LHC) one can find models of beam-beam force taking into account deviations of beam shape from Gaussianity.
In this report we present the model for incoherent interaction of Q-Gaussian colliding beams. It is believed this represents adequate description for non-Gaussian tails. The comparison with regular Gaussian model is performed for LHC conditions. Also, the evolution of the effect during van-der-Meer scan is demonstrated.
