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Naturalness and light higgsinos: a powerful reason to build ILC

J. List, H. Baer, M. Berggren, S.L. Lehtinen, K. Fujii, J. Yan, T. Tanabe

in 38th International Conference on High Energy Physics

Contribution: pdf


A core prediction of natural Supersymmetry is the
existence of four light higgsinos not too far above the
mass of the $Z$ boson. The small mass splittings amongst
the higgsinos -- typically 5-20\,GeV --
imply very little visible energy release from decays of heavier
In particular, if other SUSY particles are quite heavy,
as can be the case in SUSY with radiatively-driven naturalness,
the higgsinos are extremely hard to detect at hadron
colliders. The clean environment of electron-positron
colliders with $\sqrt{s} > 2m_{\mathrm{higgsino}}$, however, would allow for a decisive
search for the required light higgsinos.
Thus, $e^+e^-$ colliders should either discover or exclude natural SUSY.
We present a detailed study of higgsino pair production at
the proposed International Linear $e^+e^-$ Collider which is under
consideration for construction in Japan.
A variety of precision measurements should allow for
extraction of underlying parameters and provide a window onto
physics at the grand unified scale.