Strahinja Lukić, Ivan Smiljanić
Three methods for handling beam-beam effects in luminosity measurement at ILC are tested and evaluated in this work. The first method represents an optimization of the LEP-type asymmetric selection cuts that reduce the counting biases. The second method uses the experimentally resonstructed shape of the $\sqrt{s'}$ spectrum to determine the Beamstrahlung component of the bias. The last, recently proposed method, relies on the reconstruction of the collision-frame velocity to define the selection function in the collision frame both in experiment and in theory. Thus the luminosity expression is insensitive to the difference between the CM frame of the collision and the lab frame. Both the second and the third method are accurate to better than one permille of the total luminosity, but the collision-frame method has the distinct advantage of being independent of the knowledge of the beam parameters. The compatibility of diverse selection cuts for background reduction with the collision-frame method is addressed.
View original:
http://arxiv.org/abs/1211.6869
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