Revision 2

Accepted · core change · record

Changes against revision 1:

Title · changed: Revision 1: What sets the beam-beam tune-shift limit in electron-positron colliders; Revision 2: What sets the beam-beam tune-shift limit in electron-positron colliders?
Plain: Colliding beams focus each other; above a certain strength they blow up, and that ceiling is known from experience rather than derived.
Precise: In $e+e-$ ring colliders the vertical beam-beam parameter $\xi_y$ has saturated in operation at approximately 0.03-0.09 (highest values at LEP and KEKB), with simulations suggesting higher limits at stronger damping; with crab-waist collisions and beamstrahlung, coherent X-Z instabilities intervene. Derive the maximal $\xi_y$ as a function of radiation damping time per turn, synchrotron tune, Piwinski angle and beamstrahlung parameters, and compare with SuperKEKB, DAFNE and LEP data.
Settled by · changed · core: Revision 1: A theory or strong-strong simulation predicting xi_y,max for the three colliders within 20 percent with one set of assumptions.; Revision 2: A theory or strong-strong simulation predicting $\xi_y,\mathrm{max}$ for the three colliders within 20 percent with one set of assumptions.
Kind: well-posed
Answer type: value
References: (empty)
Literature status: open
Status note: (empty)
Posed since: (empty)

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