# Accelerator limits for stable ${{\widetilde{\boldsymbol \chi}}_{{1}}^{0}}$ INSPIRE search

Unless otherwise stated, results in this section assume spectra, production rates, decay modes, and branching ratios as evaluated in the MSSM, with gaugino and sfermion mass unification at the GUT scale. These papers generally study production of ${{\widetilde{\mathit \chi}}_{{i}}^{0}}{{\widetilde{\mathit \chi}}_{{j}}^{0}}$ ($\mathit i{}\geq{}$1, $\mathit j{}\geq{}$2), ${{\widetilde{\mathit \chi}}_{{1}}^{+}}{{\widetilde{\mathit \chi}}_{{1}}^{-}}$ , and (in the case of hadronic collisions) ${{\widetilde{\mathit \chi}}_{{1}}^{+}}{{\widetilde{\mathit \chi}}_{{2}}^{0}}$ pairs. The mass limits on ${{\widetilde{\mathit \chi}}_{{1}}^{0}}$ are either direct, or follow indirectly from the constraints set by the non-observation of ${{\widetilde{\mathit \chi}}_{{1}}^{\pm}}$ and ${{\widetilde{\mathit \chi}}_{{2}}^{0}}$ states on the gaugino and higgsino MSSM parameters $\mathit M_{2}$ and $\mu$. In some cases, information is used from the nonobservation of slepton decays.

Obsolete limits obtained from ${{\mathit e}^{+}}{{\mathit e}^{-}}$ collisions up to $\sqrt {\mathit s }$=184 GeV have been removed from this compilation and can be found in the 2000 Edition (The European Physical Journal C15 1 (2000)) of this Review. $\Delta \mathit m={\mathit m}_{{{\widetilde{\mathit \chi}}_{{2}}^{0}}}–{\mathit m}_{{{\widetilde{\mathit \chi}}_{{1}}^{0}}}$.

VALUE (GeV) CL% DOCUMENT ID TECN  COMMENT
1
 2009
THEO
$>40$ 95 2
 2004 H
OPAL all tan $\beta$, $\Delta \mathit m>$5~GeV, $>$500~GeV, ${{\mathit A}_{{0}}}$ = 0
$>42.4$ 95 3
 2004
ALEP all tan $\beta$, all $\Delta \mathit m$, all
$>39.2$ 95 4
 2003 M
DLPH all tan $\beta$, ${\mathit m}_{{{\widetilde{\mathit \nu}}}}>$500~GeV
$\bf{>46}$ 95 5
 2003 M
DLPH all tan $\beta$, all $\Delta \mathit m$, all
$>32.5$ 95 6
 2000 D
L3 tan $\beta >0.7$, $\Delta \mathit m>3$ GeV, all $\mathit m_{0}$
• • • We do not use the following data for averages, fits, limits, etc. • • •
7
 2014 K
ATLS
1  DREINER 2009 show that in the general MSSM with non-universal gaugino masses there exists no model-independent laboratory bound on the mass of the lightest neutralino. An essentially massless ${{\mathit \chi}_{{1}}^{0}}$ is allowed by the experimental and observational data, imposing some constraints on other MSSM parameters, including ${{\mathit M}_{{2}}}$, ${{\mathit \mu}}$ and the slepton and squark masses.
2  ABBIENDI 2004H search for charginos and neutralinos in events with acoplanar leptons+jets and multi-jet final states in the $192 - 209$~GeV data, combined with the results on leptonic final states from ABBIENDI 2004 . The results hold for a scan over the parameter space covering the region 0 $<{{\mathit M}_{{2}}}<$5000~GeV, $-1000<{{\mathit \mu}}$ $<$1000~GeV and tan ${{\mathit \beta}}$ from 1 to 40. This limit supersedes ABBIENDI 2000H.
3  HEISTER 2004 data collected up to 209 GeV. Updates earlier analysis of selectrons from HEISTER 2002E, includes a new analysis of charginos and neutralinos decaying into stau and uses results on charginos with initial state radiation from HEISTER 2002J. The limit is based on the direct search for charginos and neutralinos, the constraints from the slepton search and the Higgs mass limits from HEISTER 02 using a top mass of 175$~$GeV, interpreted in a framework with universal gaugino and sfermion masses. Assuming the mixing in the stau sector to be negligible, the limit improves to 43.1$~$GeV. Under the assumption of MSUGRA with unification of the Higgs and sfermion masses, the limit improves to 50$~$GeV, and reaches 53$~$GeV for ${{\mathit A}_{{0}}}$ = 0. These limits include and update the results of BARATE 2001 .
4  ABDALLAH 2003M uses data from $\sqrt {s }$ = $192 - 208$ GeV. A limit on the mass of ${{\widetilde{\mathit \chi}}_{{1}}^{0}}$ is derived from direct searches for neutralinos combined with the chargino search. Neutralinos are searched in the production of ${{\widetilde{\mathit \chi}}_{{1}}^{0}}{{\widetilde{\mathit \chi}}_{{2}}^{0}}$, ${{\widetilde{\mathit \chi}}_{{1}}^{0}}{{\widetilde{\mathit \chi}}_{{3}}^{0}}$, as well as ${{\widetilde{\mathit \chi}}_{{2}}^{0}}{{\widetilde{\mathit \chi}}_{{3}}^{0}}$ and ${{\widetilde{\mathit \chi}}_{{2}}^{0}}{{\widetilde{\mathit \chi}}_{{4}}^{0}}$ giving rise to cascade decays, and ${{\widetilde{\mathit \chi}}_{{1}}^{0}}{{\widetilde{\mathit \chi}}_{{2}}^{0}}$ and ${{\widetilde{\mathit \chi}}_{{1}}^{0}}{{\widetilde{\mathit \chi}}_{{2}}^{0}}$, followed by the decay ${{\widetilde{\mathit \chi}}_{{2}}^{0}}$ $\rightarrow$ ${{\widetilde{\mathit \tau}}}{{\mathit \tau}}$ . The results hold for the parameter space defined by values of $\mathit M_{2}<$ 1 TeV, $\vert {{\mathit \mu}}\vert {}\leq{}$2~TeV with the ${{\widetilde{\mathit \chi}}_{{1}}^{0}}$ as LSP. The limit is obtained for tan $\beta$ = 1 and large , where ${{\widetilde{\mathit \chi}}_{{2}}^{0}}{{\widetilde{\mathit \chi}}_{{4}}^{0}}$ and chargino pair production are important. If the constraint from Higgs searches is also imposed, the limit improves to 49.0 GeV in the $\mathit m{}^{{\mathrm {max}}}_{h}$ scenario with ${\mathit m}_{{{\mathit t}}}$=174.3 GeV. These limits update the results of ABREU 2000J.
5  ABDALLAH 2003M uses data from $\sqrt {s }$ = $192 - 208$ GeV. An indirect limit on the mass of ${{\widetilde{\mathit \chi}}_{{1}}^{0}}$ is derived by constraining the MSSM parameter space by the results from direct searches for neutralinos (including cascade decays and ${{\widetilde{\mathit \tau}}}{{\mathit \tau}}$ final states), for charginos (for all $\Delta \mathit m_{+}$) and for sleptons, stop and sbottom. The results hold for the full parameter space defined by values of $\mathit M_{2}<$ 1 TeV, $\vert {{\mathit \mu}}\vert {}\leq{}2~$TeV with the ${{\widetilde{\mathit \chi}}_{{1}}^{0}}$ as LSP. Constraints from the Higgs search in the $\mathit m{}^{{\mathrm {max}}}_{h}$ scenario assuming ${\mathit m}_{{{\mathit t}}}$=174.3 GeV are included. The limit is obtained for tan $\beta {}\geq{}$ 5 when stau mixing leads to mass degeneracy between ${{\widetilde{\mathit \tau}}_{{1}}}$ and ${{\widetilde{\mathit \chi}}_{{1}}^{0}}$ and the limit is based on ${{\widetilde{\mathit \chi}}_{{2}}^{0}}$ production followed by its decay to ${{\widetilde{\mathit \tau}}_{{1}}}{{\mathit \tau}}$. In the pathological scenario where and $\vert {{\mathit \mu}}\vert$ are large, so that the ${{\widetilde{\mathit \chi}}_{{2}}^{0}}$ production cross section is negligible, and where there is mixing in the stau sector but not in stop nor sbottom, the limit is based on charginos with soft decay products and an ISR photon. The limit then degrades to 39 GeV. See Figs. $40 - 42$ for the dependence of the limit on tan $\beta$ and ${\mathit m}_{{{\widetilde{\mathit \nu}}}}$. These limits update the results of ABREU 2000W.
6  ACCIARRI 2000D data collected at $\sqrt {\mathit s }$=189 GeV. The results hold over the full parameter space defined by $0.7{}\leq{}$tan $\beta {}\leq{}60$, 0${}\leq{}\mathit M_{2}{}\leq{}2$ TeV, $\mathit m_{0}{}\leq{}500$ GeV, $\vert \mu \vert {}\leq{}2$ TeV The minimum mass limit is reached for tan $\beta$=1 and large $\mathit m_{0}$. The results of slepton searches from ACCIARRI 1999W are used to help set constraints in the region of small $\mathit m_{0}$. The limit improves to 48 GeV for $\mathit m_{0}{ {}\gtrsim{} }200$ GeV and tan $\beta { {}\gtrsim{} }10$. See their Figs.$~6 - 8$ for the tan $\beta$ and $\mathit m_{0}$ dependence of the limits. Updates ACCIARRI 1998F.
7  AAD 2014K sets limits on the ${{\mathit \chi}}$-nucleon spin-dependent and spin-independent cross sections out to ${\mathit m}_{{{\mathit \chi}}}$ = 10 TeV.
References:
PR D90 012004 Search for Dark Matter in Events with a ${{\mathit Z}}$ Boson and Missing Transverse Momentum in ${{\mathit p}}{{\mathit p}}$ Collisions at $\sqrt {s }$ = 8 TeV with the ATLAS Detector
EPJ C35 1 Search for Chargino and Neutralino Production at $\sqrt {s }$ = 192 to 209 GeV at LEP
PL B583 247 Absolute Mass Lower Limit for the Lightest Neutralino of the MSSM from ${{\mathit e}^{+}}{{\mathit e}^{-}}$ Data at $\sqrt {s }$ up to 209 GeV
EPJ C31 421 Searches for Supersymmetric Particles in ${{\mathit e}^{+}}{{\mathit e}^{-}}$ Collisions up to 208 GeV and Interpretation of the Results within the MSSM
PL B472 420 Search for Charginos and Neutralinos in ${{\mathit e}^{+}}{{\mathit e}^{-}}$ Collisions at $\sqrt {s }$ = 189 GeV