# Beam blowup due to synchro-beta resonance with/without beam-beam effects

## TL;DR

This paper investigates vertical emittance blowup in particle accelerators, attributing it to a synchro-beta resonance near the first synchrotron sideband, using simulations and a Vlasov model.

## Contribution

It introduces a Vlasov model explaining the beam blowup as a synchro-beta resonance, supported by simulation observations with and without beam-beam effects.

## Key findings

- Vertical emittance blowup observed in simulations.
- Blowup linked to synchro-beta resonance near the first sideband.
- Resonance occurs even without beam-beam effects.

## Abstract

A blowup of vertical emittance has been observed in particle tracking simulations with beam-beam and lattice misalignments. It was somewhat unexpected, since estimation without lattice errors did not predict such a blowup unless a residual vertical dispersion at the interaction point (IP) is larger than a certain amount. Later such a blowup has been seen in a tracking of lattices without beam-beam effect. A possible explanation of the blowup is given by a Vlasov model for an equilibrium of quadratic transverse moments in the synchrotron phase space. This model predicts such a blowup as a synchro-beta resonance mainly near the first synchrotron sideband of the main x-y coupling resonance line.