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Short description.

The search is for pair-produced WIMPS, where the presence of the interaction is detected by the observation of an ISR photon and nothing else. At ILC (but not LHC) this kind of interaction can be described in a almost model-independent  way with EFT. Apart from the obvious ee→nunu + ISR ireducible background, also ee→ ee (down the beam-pipe)  + ISR are the backgrounds. No dedicated signal simulation is needed; one can simply reweight  the ee→nunu + ISR gamma-spectrum (as a function of theta and E_gamma)  to be that of any signal

This benchmark in particular can probe two features:

  • Photon detection and measurement.
  • Hermeticity, in particular the performance of the very forward calorimeters.

Main observables.

The main (and only) direct observables for the signal is the momentum of the ISR photon, The physics observable is the exclusion/discovery WIMPs in the mediator-mass/coupling plane for different lorentz-structures of the interaction.

Optimisation deliverables.

  • Gamma detection efficiency at all angles, in all relevant calorimeters.
  • Rejection power of the very forward calorimeters against other activity than the ISR.

IDR plots & note.

Supporting note (overleaf) :

pdf :

Photon reconstruction : The number of reconstructed photons per generated photon as a function of the signal photon energy.


BCal vetoing  : Comparison between IDR-L and IDR-S models on the number of BCal clusters. The histograms are stacked. (500~fb$^{-1}$, no beam polarization).


Sensitivity : 95\% confidence level exclusion limits for different effective operators with a realistic sharing of the polarization at 4ab$^{-1}$ of H20 scenario; $(--,-+,+-,++)=(10\%,40\%,40\%,10\%)$.$\sqrt{s}=500$~GeV.



Analyzer(s):Ahmed Mustahid Ryo Yonamine
Filip Zarnecki, Moritz Habermehl


Previous analyses by Christoph Bartels & al. :'Characterising WIMPs at a future e+e Linear Collider', arxiv:1206.6639.  Finishing study by Moriz Habermehl & al. : 'WIMP searches at the International Linear Collider' PoS ICHEP2016 (2016) 155, arxiv:1702.05377

Moritz Habermehl : "Dark Matter at the International Linear Collider",


The GitHub repository is ILDbench_WIMP in the ILDAnaSoft project.

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