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Updates and Plans for Beam-Beam and MDI

Spencer Gessner, SLAC

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SLAC-LBNL Meeting

December 15, 2025

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Update #1

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https://arxiv.org/abs/2511.20912

New manuscript on Beamstrahlung at 10 TeV Colliders submitted to PRAB.

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Main result: It is possible to write down a set of equations that describe the beamstrahlung lumi spectrum and depend only on the Upsilon parameter and bunch length (or equivalently nγ). The lumi spectrum has a “universal shape” that doesn’t depend on collision energy for fixed Upsilon.

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Update #2

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Peter and Jinseo have been working with Arianna to get radiative and non-radiative Bhabha scattering into WarpX.

  • Pull requests have been created but some further integration work may be necessary.

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Michael Peskin has indicated interest in working on the “Beam Size Effect” which is a feature of GUINEA-PIG.

  • The Beam Size Effect relates to interesting theoretical questions about the transition between incoherent and collective effects.
  • What is the best theoretical framework to address the beam size effect and what is the best framework for implementation in WarpX?
    • Explore limits and stitch together with quantum synchrotron.

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Peter will work on adding crab waist to WarpX.

  • Already implemented.
  • Need unit test.
  • Validation.

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Anna Kinderman (rotation student, UCSC)

  • GUINEA-PIG to OpenPMD wrapper

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Update #3

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I spoke to Manuela Boscolo and Fabrizio Palla about contributions that our group could make to the MDI work.

  • We identified luminosity monitoring as a topic of interest.
  • Combines beam-beam modeling, Bhabha scattering, beam physics and detector studies.
  • Current lead is Mogens Dam who acknowledged limited progress in this area.

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Manuela and Fabrizio are very enthusiastic about us taking this on!

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Update #4

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Paper on WarpX beam-beam. . .

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  • Algorithms
  • Test cases
  • Speed comparison

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