2,911 research outputs found
ZZ' Mixing in Presence of Standard Weak Loop Corrections
We derive a method for a common treatment of Z' exchange, QED corrections,
and weak loops. It is based on the form factor approach to the description of
weak loop corrections to partial Z widths and cross sections. Problems
connected with ZZ' mixing are discussed with special care. Our theoretical
results are applied to the package ZFITTER. We demonstrate two different ways
to the data analysis - one based on an extension of the standard model cross
sections, the other on model-independent formulae together with the Z width
calculations in presence of a Z'. With the resulting package ZEFIT+ZFITTER,
LEP1 data from fermion pair production, including Bhabha scattering, can be
analysed on, but also off the Z peak. Further, the code may be used at very
high energies, e.g. in the region of a possible future linear e+e- collider.Comment: Latex, 24 pages, a typo in eqs. 23,24 correcte
Photon collimator system for the ILC Positron Source
High energy e+e- linear colliders are the next large scale project in
particle physics. They need intense sources to achieve the required luminosity.
In particular, the positron source must provide about 10E+14 positrons per
second. The positron source for the International Linear Collider (ILC) is
based on a helical undulator passed by the electron beam to create an intense
circularly polarized photon beam. With these photons a longitudinally polarized
positron beam is generated; the degree of polarization can be enhanced by
collimating the photon beam. However, the high photon beam intensity causes
huge thermal load in the collimator material. In this paper the thermal load in
the photon collimator is discussed and a flexible design solution is presented.Comment: 22 pages, 19 figures, 8 tables, cross-reference to table 4 fixe
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