Speaker
Description
In natural supersymmetric models defined by no worse than a part in
thirty electroweak fine-tuning, winos and binos are generically expected
to be much heavier than higgsinos. Moreover, the splitting between the
higgsinos is expected to be small, so that the visible decay products of
the heavier higgsinos are soft, rendering the higgsinos quasi-invisible
at the LHC. Within the natural SUSY framework, heavy electroweak gauginos
decay to $W$, $Z$ or $h$ bosons plus higgsinos in the ratio $\sim
2:1:1$, respectively. This is in sharp contrast to models with a
bino-like lightest superpartner and very heavy higgsinos, where the charged
(neutral) wino essentially always decays to a $W$ ($h$) boson and an
invisible bino. Wino pair production at the LHC, in natural SUSY, thus
leads to $VV$, $Vh$ and $hh+\not\!\!\!{E_T}$ final states ($V=W,Z$) where, for TeV
scale winos, the vector bosons and $h$ daughters are considerably
boosted. We identify eight different channels arising from the leptonic
and hadronic decays of the vector bosons and the decay $h\to b\bar{b}$,
each of which offers an avenue for wino discovery at the high luminosity
LHC (HL-LHC). By combining the signal in all eight channels we find,
assuming $\sqrt{s}=14$ TeV and an integrated luminosity of 3000
fb$^{-1}$, that the discovery reach for winos extends to $m(wino)\sim
1.1$~TeV, while the 95\% CL exclusion range extends to a wino mass of
almost 1.4~TeV. We also identify ``higgsino specific channels'' which
could serve to provide $3\sigma$ evidence that winos lighter than
1.2~TeV decay to light higgsinos rather than to a bino-like LSP, should
a wino signal appear at the HL-LHC.
