Charged sleptons

This section contains limits on charged scalar leptons (${{\widetilde{\mathit \ell}}}$, with ${{\mathit \ell}}={{\mathit e}},{{\mathit \mu}},{{\mathit \tau}}$). Studies of width and decays of the ${{\mathit Z}}$ boson (use is made here of $\Delta \Gamma _{{\mathrm {inv}}}<2.0~$MeV, LEP 2000) conclusively rule out ${\mathit m}_{{{\widetilde{\mathit \ell}}_{{{R}}}}}<40~$GeV (41 GeV for ${{\widetilde{\mathit \ell}}_{{{L}}}}$) , independently of decay modes, for each individual slepton. The limits improve to 43$~$GeV ($43.5$ GeV for ${{\widetilde{\mathit \ell}}_{{{L}}}}$) assuming all 3 flavors to be degenerate. Limits on higher mass sleptons depend on model assumptions and on the mass splitting $\Delta \mathit m$= ${\mathit m}_{{{\widetilde{\mathit \ell}}}}–{\mathit m}_{{{\widetilde{\mathit \chi}}_{{{1}}}^{0}}}$. The mass and composition of ${{\widetilde{\mathit \chi}}_{{{1}}}^{0}}$ may affect the selectron production rate in ${{\mathit e}^{+}}{{\mathit e}^{-}}$ collisions through ${{\mathit t}}$-channel exchange diagrams. Production rates are also affected by the potentially large mixing angle of the lightest mass eigenstate ${{\widetilde{\mathit \ell}}_{{{1}}}}={{\widetilde{\mathit \ell}}_{{{R}}}}$ sin$\theta _{{{\mathit \ell}}}$ + ${{\widetilde{\mathit \ell}}_{{{L}}}}$ cos $\theta _{{{\mathit \ell}}}$. It is generally assumed that only ${{\widetilde{\mathit \tau}}}$ may have significant mixing. The coupling to the ${{\mathit Z}}$ vanishes for $\theta _{{{\mathit \ell}}}$=0.82. In the high-energy limit of ${{\mathit e}^{+}}{{\mathit e}^{-}}$ collisions the interference between ${{\mathit \gamma}}$ and ${{\mathit Z}}$ exchange leads to a minimal cross section for $\theta _{{{\mathit \ell}}}$=0.91, a value which is sometimes used in the following entries relative to data taken at LEP2. When limits on ${\mathit m}_{{{\widetilde{\mathit \ell}}_{{{R}}}}}$ are quoted, it is understood that limits on ${\mathit m}_{{{\widetilde{\mathit \ell}}_{{{L}}}}}$ are usually at least as strong.
Possibly open decays involving gauginos other than ${{\widetilde{\mathit \chi}}_{{{1}}}^{0}}$ will affect the detection efficiencies. Unless otherwise stated, the limits presented here result from the study of ${{\widetilde{\mathit \ell}}^{+}}{{\widetilde{\mathit \ell}}^{-}}$ production, with production rates and decay properties derived from the MSSM. Limits made obsolete by the recent analyses of ${{\mathit e}^{+}}{{\mathit e}^{-}}$ collisions at high energies can be found in previous Editions of this Review.
For decays with final state gravitinos (${{\widetilde{\mathit G}}}$), ${\mathit m}_{{{\widetilde{\mathit G}}}}$ is assumed to be negligible relative to all other masses.

R-parity conserving ${{\widetilde{\mathit \tau}}}$ (Stau) mass limit

INSPIRE   PDGID:
S046STA
Some earlier papers are now obsolete and have been omitted. They were last listed in our PDG 2014 edition: K. Olive, $\mathit et~al.$ (Particle Data Group), Chinese Physics C38 070001 (2014) (http://pdg.lbl.gov).

VALUE (GeV) CL% DOCUMENT ID TECN  COMMENT
$\bf{> 400}$ 95 1
TUMASYAN
2023AG
 CMS 2 hadronic ${{\mathit \tau}}$ + $\not E_T$, ${{\widetilde{\mathit \tau}}_{{{R,L}}}}$ $\rightarrow$ ${{\mathit \tau}}{{\widetilde{\mathit \chi}}_{{{1}}}^{0}}$, ${\mathit m}_{{{\widetilde{\mathit \chi}}_{{{1}}}^{0}}}$ = 1 GeV
$\text{none 115 - 340}$ 95 1
TUMASYAN
2023AG
 CMS 2 hadronic ${{\mathit \tau}}$ + $\not E_T$, ${{\widetilde{\mathit \tau}}_{{{L}}}}$ $\rightarrow$ ${{\mathit \tau}}{{\widetilde{\mathit \chi}}_{{{1}}}^{0}}$, ${\mathit m}_{{{\widetilde{\mathit \chi}}_{{{1}}}^{0}}}$ = 1 GeV
$\text{none 120 - 390}$ 95 2
AAD
2020H
 2 hadronic ${{\mathit \tau}}$ + $\not E_T$, ${{\widetilde{\mathit \tau}}_{{{R/L}}}}$ $\rightarrow$ ${{\mathit \tau}}{{\widetilde{\mathit \chi}}_{{{1}}}^{0}}$ , ${\mathit m}_{{{\widetilde{\mathit \chi}}_{{{1}}}^{0}}}$ = 0 GeV
$\text{none 90 - 150}$ 95 3
SIRUNYAN
2020P
 CMS 2 ${{\mathit \tau}}+\not E_T$, ${{\mathit \tau}_{{{h}}}}{{\mathit \tau}_{{{h}}}}$ and ${{\mathit \ell}}{{\mathit \tau}_{{{h}}}}$, ${\mathit m}_{{{\widetilde{\mathit \tau}}_{{{R}}}}}={\mathit m}_{{{\widetilde{\mathit \tau}}_{{{L}}}}}$, ${\mathit m}_{{{\widetilde{\mathit \chi}}_{{{1}}}^{0}}}$ = 1 GeV
$>85.2$ 4
ABBIENDI
2004
OPAL $\Delta \mathit m>$ 6 GeV, $\theta _{\tau }=\pi $/2, $\vert {{\mathit \mu}}\vert >$ 100~GeV, tan $\beta $=1.5
$>78.3$ 5
ACHARD
2004
L3 $\Delta \mathit m>$ 15 GeV, $\theta _{{{\mathit \tau}}}={{\mathit \pi}}$/2, $\vert {{\mathit \mu}}\vert >$200~GeV,tan $\beta {}\geq{}$2
$\bf{>81.9}$ 95 6
ABDALLAH
2003M
 DLPH $\Delta {{\mathit m}}>$15~GeV, all $\theta _{{{\mathit \tau}}}$
$>79$ 95 7
HEISTER
2002E
 ALEP $\Delta \mathit m>15$ GeV, $\theta _{{{\mathit \tau}}}=\pi $/2
$>76$ 95 7
HEISTER
2002E
 ALEP $\Delta \mathit m>15$ GeV, $\theta _{{{\mathit \tau}}}=0.91$
• • We do not use the following data for averages, fits, limits, etc. • •
$> 500$ 95 8
AABOUD
2018BT
 ATLS 2${{\mathit \ell}}+\not E_T$, ${\mathit m}_{{{\widetilde{\mathit \ell}}_{{{R}}}}}={\mathit m}_{{{\widetilde{\mathit \ell}}_{{{L}}}}}$, ${{\widetilde{\mathit \ell}}}={{\widetilde{\mathit e}}}$, ${{\widetilde{\mathit \mu}}}$, ${{\widetilde{\mathit \tau}}}$, ${\mathit m}_{{{\widetilde{\mathit \chi}}_{{{1}}}^{0}}}$ = 0 GeV
9
KHACHATRYAN
2017L
 CMS 2 ${{\mathit \tau}}+\not E_T$, ${{\widetilde{\mathit \tau}}_{{{L}}}}$ $\rightarrow$ ${{\mathit \tau}}{{\widetilde{\mathit \chi}}_{{{1}}}^{0}}$ , ${\mathit m}_{{{\widetilde{\mathit \chi}}_{{{1}}}^{0}}}$ = 0 GeV
$\text{none 109}$ 95 10
AAD
2016AA
 ATLS 2 hadronic ${{\mathit \tau}}$ + $\not E_T$, ${{\widetilde{\mathit \tau}}_{{{R/L}}}}$ $\rightarrow$ ${{\mathit \tau}}{{\widetilde{\mathit \chi}}_{{{1}}}^{0}}$ , ${\mathit m}_{{{\widetilde{\mathit \chi}}_{{{1}}}^{0}}}$ = 0 GeV
11
AAD
2012AF
 ATLS 2${{\mathit \tau}}$ + jets + $\not E_T$, GMSB
12
AAD
2012AG
 ATLS ${}\geq{}$ 1${{\mathit \tau}_{{{h}}}}$ + jets + $\not E_T$, GMSB
13
AAD
2012CM
 ATLS ${}\geq{}1{{\mathit \tau}}$ + jets + $\not E_T$, GMSB
$> 87.4$ 95 14
ABBIENDI
2006B
 OPAL ${{\widetilde{\mathit \tau}}_{{{R}}}}$ $\rightarrow$ ${{\mathit \tau}}{{\widetilde{\mathit G}}}$, all ${{\mathit \tau}}({{\widetilde{\mathit \tau}}_{{{R}}}}$)
$> 68$ 95 15
ABDALLAH
2004H
 DLPH AMSB, ${{\mathit \mu}}$ $>$ 0
$\text{none } {\mathit m}_{{{\mathit \tau}}}\text{-} \text{ 26.3}$ 95 6
ABDALLAH
2003M
 DLPH $\Delta {{\mathit m}}>{\mathit m}_{{{\mathit \tau}}}$, all $\theta _{{{\mathit \tau}}}$
1  TUMASYAN 2023AG searched in 138 ${\mathrm {fb}}{}^{-1}$ of ${{\mathit p}}{{\mathit p}}$ collisions at $\sqrt {s }$ = 13 TeV for or direct pair production of tau sleptons in events with two hadronically decaying tau leptons. No significant excess above the Standard Model expectations is observed. Limits are set on the mass of the tau slepton in models with ${{\widetilde{\mathit \tau}}}$ $\rightarrow$ ${{\mathit \tau}}{{\widetilde{\mathit \chi}}_{{{1}}}^{0}}$ for mass-degenerate, pure left-handed and pure right-handed tau sleptons, see their figures $4 - 7$. Limits are also set for the maximally mixed scenario with long-lived tau sleptons and ${{\widetilde{\mathit \tau}}}$ lifetimes of 0.01 mm to 2.5 mm, see their figure 8.
2  AAD 2020H presented ATLAS searches for direct production for ${{\widetilde{\mathit \tau}}}$ in final states with two hadronically decaying leptons and $\not E_T$. The analysis uses a dataset of ${{\mathit p}}{{\mathit p}}$ collisions at $\sqrt {s }$ = 13 TeV corresponding to an integrated luminosity of 139 ${\mathrm {fb}}{}^{-1}$. Exclusion limits at 95$\%$ C.L. are derived in scenarios of direct production of ${{\widetilde{\mathit \tau}}}$ pairs with each ${{\widetilde{\mathit \tau}}}$ decaying into a ${{\mathit \tau}}$ and the lightest neutralino ${{\widetilde{\mathit \chi}}_{{{1}}}^{0}}$ in simplified models where the ${{\widetilde{\mathit \tau}}_{{{R}}}}$ and ${{\widetilde{\mathit \tau}}_{{{L}}}}$ mass eigenstates are degenerate. Stau masses from 120GeV to 390GeV are excluded for a massless lightest neutralino, see their Fig. 7(a). If ${{\widetilde{\mathit \tau}}_{{{L}}}}$-only pair production is considered, the exclusion region extends between 155 GeV to 310 GeV, see their Fig. 7(b).
3  SIRUNYAN 2020P searched in 77.2 ${\mathrm {fb}}{}^{-1}$ of ${{\mathit p}}{{\mathit p}}$ collisions at $\sqrt {s }$ = 13 TeV for direct pair production of tau sleptons in events with a tau lepton pair and significant missing transverse momentum. Final states with two double hadronic decay of the tau leptons are considered, as well as where one of the tau leptons decays into an electron or a muon. No significant excess above the Standard Model expectations is observed. Limits are set on the stau mass in a simplified models where two tau sleptons are pair produced and decay to a tau lepton and the lightest neutralino, assuming either only left-handed stau production, see Figure 8, or assuming degenerate left- and right-handed stau production, see Figure 9.
4  ABBIENDI 2004 search for ${{\widetilde{\mathit \tau}}}{{\widetilde{\mathit \tau}}}$ production in acoplanar di-tau final states in the $183 - 208$~GeV data. See Fig.$~$15 for the dependence of the limits on ${\mathit m}_{{{\widetilde{\mathit \chi}}_{{{1}}}^{0}}}$ and for the limit at tan $\beta $=35. Under the assumption of 100\% branching ratio for ${{\widetilde{\mathit \tau}}_{{{R}}}}$ $\rightarrow$ ${{\mathit \tau}}$~${{\widetilde{\mathit \chi}}_{{{1}}}^{0}}$, the limit improves to 89.8~GeV for $\Delta \mathit m>$ 8$~$GeV. See Fig.~12 for the dependence of the limits on m$_{{{\widetilde{\mathit \chi}}_{{{1}}}^{0}}}$ at several values of the branching ratio and for their dependence on $\theta _{\tau }$. This limit supersedes ABBIENDI 2000G.
5  ACHARD 2004 search for ${{\widetilde{\mathit \tau}}}{{\widetilde{\mathit \tau}}}$ production in acoplanar di-tau final states in the $192 - 209$ GeV data. Limits on ${\mathit m}_{{{\widetilde{\mathit \tau}}_{{{R}}}}}$ are derived from a scan over the MSSM parameter space with universal GUT scale gaugino and scalar masses and ${\mathit m}_{{{\mathit 0}}}$, 1 ${}\leq{}$tan $\beta {}\leq{}$60 and $-2{}\leq{}\mu {}\leq{}$ 2 TeV. See Fig.~4 for the dependence of the limits on ${\mathit m}_{{{\widetilde{\mathit \chi}}_{{{1}}}^{0}}}$.
6  ABDALLAH 2003M looked for acoplanar ditaus $\text{+}\not E$ final states at $\sqrt {s }$ = $130 - 208$ GeV. A dedicated search was made for low mass ${{\widetilde{\mathit \tau}}}$s decoupling from the ${{\mathit Z}^{0}}$. The limit assumes B( ${{\widetilde{\mathit \tau}}}$ $\rightarrow$ ${{\mathit \tau}}{{\widetilde{\mathit \chi}}_{{{1}}}^{0}}$) = 100\%. See Fig.~20 for limits on the (${\mathit m}_{{{\widetilde{\mathit \tau}}}},{\mathit m}_{{{\widetilde{\mathit \chi}}_{{{1}}}^{0}}}$) plane and as function of the ${{\widetilde{\mathit \chi}}_{{{1}}}^{0}}$ mass and of the branching ratio. The limit in the low-mass region improves to 29.6 and 31.1 GeV for ${{\widetilde{\mathit \tau}}_{{{R}}}}$ and ${{\widetilde{\mathit \tau}}_{{{L}}}}$, respectively, at $\Delta \mathit m>$ ${\mathit m}_{{{\mathit \tau}}}$. The limit in the high-mass region improves to 84.7$~$GeV for ${{\widetilde{\mathit \tau}}_{{{R}}}}$ and $\Delta \mathit m>$ 15$~$GeV. These limits include and update the results of ABREU 2001.
7  HEISTER 2002E looked for acoplanar ditau + $\not E_T$ final states from ${{\mathit e}^{+}}{{\mathit e}^{-}}$ interactions between 183 and 209 GeV. The mass limit assumes B( ${{\widetilde{\mathit \tau}}}$ $\rightarrow$ ${{\mathit \tau}}{{\widetilde{\mathit \chi}}_{{{1}}}^{0}}$)=1. See their Fig.$~$4 for the dependence of the limit on $\Delta \mathit m$. These limits include and update the results of BARATE 2001.
8  AABOUD 2018BT searched in 36.1 ${\mathrm {fb}}{}^{-1}$ of ${{\mathit p}}{{\mathit p}}$ collisions at $\sqrt {s }$ = 13 TeV for direct electroweak production of charginos, chargino and next-to-lightest neutralinos and sleptons in events with two or three leptons (electrons or muons), with or without jets, and large missing transverse energy. No significant excess above the Standard Model expectations is observed. Limits are set on the slepton mass up to 500 GeV for massless ${{\widetilde{\mathit \chi}}_{{{1}}}^{0}}$, assuming degeneracy of ${{\widetilde{\mathit e}}}$, ${{\widetilde{\mathit \mu}}}$, and ${{\widetilde{\mathit \tau}}}$ and exploiting the 2${{\mathit \ell}}$ signature, see their Figure 8(b).
9  KHACHATRYAN 2017L searched in about 19 ${\mathrm {fb}}{}^{-1}$ of ${{\mathit p}}{{\mathit p}}$ collisions at $\sqrt {s }$ = 8 TeV for events with two ${{\mathit \tau}}$ (at least one decaying hadronically) and $\not E_T$. Results were interpreted to set constraints on the cross section for production of ${{\widetilde{\mathit \tau}}_{{{L}}}}$ pairs for ${\mathit m}_{{{\widetilde{\mathit \chi}}_{{{1}}}^{0}}}$=1 GeV. No mass constraints are set, see their Fig. 7.
10  AAD 2016AA summarized and extended ATLAS searches for electroweak supersymmetry in final states containing several charged leptons, $\not E_T$, with or without hadronic jets, in 20 ${\mathrm {fb}}{}^{-1}$ of ${{\mathit p}}{{\mathit p}}$ collisions at $\sqrt {s }$ = 8 TeV. The paper reports 95$\%$ C.L. exclusion limits on the cross-section for production of ${{\widetilde{\mathit \tau}}_{{{R}}}}$ and ${{\widetilde{\mathit \tau}}_{{{L}}}}$ pairs for various ${\mathit m}_{{{\widetilde{\mathit \chi}}_{{{1}}}^{0}}}$, using the 2 hadronic ${{\mathit \tau}}$ + $\not E_T$ analysis. The ${\mathit m}_{{{\widetilde{\mathit \tau}}_{{{R/L}}}}}$ = 109 GeV is excluded for ${\mathit m}_{{{\widetilde{\mathit \chi}}_{{{1}}}^{0}}}$ = 0 GeV, with the constraints being stronger for ${{\widetilde{\mathit \tau}}_{{{R}}}}$. See their Fig. 12.
11  AAD 2012AF searched in 2 fb${}^{-1}$ of ${{\mathit p}}{{\mathit p}}$ collisions at $\sqrt {s }$ = 7 TeV for events with two tau leptons, jets and large $\not E_T$ in a GMSB framework. No significant excess above the expected background was found and an upper limit on the visible cross section for new phenomena is set. A 95$\%$ C.L. lower limit of 32 TeV on the mGMSB breaking scale ${{\mathit \Lambda}}$ is set for ${{\mathit M}_{{{mess}}}}$ = 250 TeV, ${{\mathit N}_{{{S}}}}$ = 3, ${{\mathit \mu}}$ $>$ 0 and ${{\mathit C}_{{{grav}}}}$ = 1, independent of tan ${{\mathit \beta}}$.
12  AAD 2012AG searched in 2.05 fb${}^{-1}$ of ${{\mathit p}}{{\mathit p}}$ collisions at $\sqrt {s }$ = 7 TeV for events with at least one hadronically decaying tau lepton, jets, and large $\not E_T$ in a GMSB framework. No significant excess above the expected background was found and an upper limit on the visible cross section for new phenomena is set. A 95$\%$ C.L. lower limit of 30 TeV on the mGMSB breaking scale ${{\mathit \Lambda}}$ is set for ${{\mathit M}_{{{mess}}}}$ = 250 TeV, ${{\mathit N}_{{{S}}}}$ = 3, ${{\mathit \mu}}$ $>$ 0 and ${{\mathit C}_{{{grav}}}}$ = 1, independent of tan ${{\mathit \beta}}$. For large values of tan ${{\mathit \beta}}$, the limit on ${{\mathit \Lambda}}$ increases to 43 TeV.
13  AAD 2012CM searched in 4.7 fb${}^{-1}$ of ${{\mathit p}}{{\mathit p}}$ collisions at $\sqrt {s }$=7 TeV for events with at least one tau lepton, zero or one additional light lepton (${{\mathit e}}/{{\mathit \mu}}$) jets, and large $\not E_T$ in a GMSB framework. No significant excess above the expected background was found and an upper limit on the visible cross section for new phenomena is set. A 95\% C. L. lower limit of 54 TeV on the mGMSB breaking scale ${{\mathit \Lambda}}$ is set for ${{\mathit M}_{{{mess}}}}$ = 250 TeV, ${{\mathit N}_{{{S}}}}$ = 3, ${{\mathit \mu}}$ $>$ 0 and ${{\mathit C}_{{{grav}}}}$ = 1, for tan ${{\mathit \beta}}$ $>$ 20. Here the ${{\widetilde{\mathit \tau}}_{{{1}}}}$ is the NLSP.
14  ABBIENDI 2006B use 600 pb${}^{-1}$ of data from $\sqrt {s }$ = $189 - 209$ GeV. They look for events from pair-produced staus in a GMSB scenario with ${{\widetilde{\mathit \tau}}}$ NLSP including prompt ${{\widetilde{\mathit \tau}}}$ decays to ditaus + $\not E$ final states, large impact parameters, kinked tracks and heavy stable charged particles. Limits on the cross-section are computed as a function of m(${{\widetilde{\mathit \tau}}}$) and the lifetime, see their Fig. 7. The limit is compared to the $\sigma \cdot{}\mathit BR{}^{2}$ from a scan over the GMSB parameter space.
15  ABDALLAH 2004H use data from LEP~1 and $\sqrt {s }$ = $192 - 208$~GeV. They re-use results or re-analyze the data from ABDALLAH 2003M to put limits on the parameter space of anomaly-mediated supersymmetry breaking (AMSB), which is scanned in the region 1$<{{\mathit m}}_{3/2}<$50~TeV, 0$<{{\mathit m}_{{{0}}}}<$1000~GeV, 1.5$<$tan ${{\mathit \beta}}<$35, both signs of ${{\mathit \mu}}$. The constraints are obtained from the searches for mass degenerate chargino and neutralino, for SM-like and invisible Higgs, for leptonically decaying charginos and from the limit on non-SM ${{\mathit Z}}$ width of 3.2~MeV. The limit is for ${\mathit m}_{{{\mathit t}}}$ = 174.3~GeV (see Table 2 for other ${\mathit m}_{{{\mathit t}}}$ values). The limit improves to 75 GeV for ${{\mathit \mu}}$ $<$ 0.
References