These limits are from ${{\mathit e}^{+}}$ ${{\mathit e}^{-}}$ $\rightarrow$ ${{\mathit \mu}^{*}}{{\mathit \mu}}$ and depend on transition magnetic coupling between ${{\mathit \mu}}$ and ${{\mathit \mu}^{*}}$. All limits assume ${{\mathit \mu}^{*}}$ $\rightarrow$ ${{\mathit \mu}}{{\mathit \gamma}}$ decay. Limits from LEP are for chiral coupling, whereas all other limits are for nonchiral coupling, ${{\mathit \eta}_{{L}}}$ = ${{\mathit \eta}_{{R}}}$ = 1. In most papers, the limit is expressed in the form of an excluded region in the $\lambda −{\mathit m}_{{{\mathit \mu}^{*}}}$ plane. See the original papers.

For limits prior to 1987, see our 1992 edition (Physical Review D45 S1 (1992)).

VALUE (GeV) CL% DOCUMENT ID TECN  COMMENT $\bf{> 5700}$ 95 1 SIRUNYAN 2020 AJ CMS ${{\mathit p}}$ ${{\mathit p}}$ $\rightarrow$ ${{\mathit \mu}}{{\mathit \mu}^{*}}{{\mathit X}}$ • • We do not use the following data for averages, fits, limits, etc. • • $> 3800$ 95 2 SIRUNYAN 2019 Z CMS ${{\mathit p}}$ ${{\mathit p}}$ $\rightarrow$ ${{\mathit \mu}}{{\mathit \mu}^{*}}{{\mathit X}}$ $> 2800$ 95 3 AAD 2016 BM ATLS ${{\mathit p}}$ ${{\mathit p}}$ $\rightarrow$ ${{\mathit \mu}}{{\mathit \mu}^{*}}{{\mathit X}}$ $> 2470$ 95 4 KHACHATRYAN 2016 AQ CMS ${{\mathit p}}$ ${{\mathit p}}$ $\rightarrow$ ${{\mathit \mu}}{{\mathit \mu}^{*}}{{\mathit X}}$ $> 3000$ 95 5 AAD 2015 AP ATLS ${{\mathit p}}$ ${{\mathit p}}$ $\rightarrow$ ${{\mathit \mu}^{(*)}}{{\mathit \mu}^{*}}{{\mathit X}}$ $> 2200$ 95 6 AAD 2013 BB ATLS ${{\mathit p}}$ ${{\mathit p}}$ $\rightarrow$ ${{\mathit \mu}}{{\mathit \mu}^{*}}{{\mathit X}}$ $> 1900$ 95 7 CHATRCHYAN 2013 AE CMS ${{\mathit p}}$ ${{\mathit p}}$ $\rightarrow$ ${{\mathit \mu}}{{\mathit \mu}^{*}}{{\mathit X}}$ $> 1750$ 95 8 AAD 2012 AZ ATLS ${{\mathit p}}$ ${{\mathit p}}$ $\rightarrow$ ${{\mathit \mu}^{(*)}}{{\mathit \mu}^{*}}{{\mathit X}}$ 1  SIRUNYAN 2020AJ search for ${{\mathit \mu}^{*}}$ production in 2 ${{\mathit \mu}}$2 ${{\mathit j}}$ final states in ${{\mathit p}}{{\mathit p}}$ collisions at $\sqrt {s }$ = 13 TeV. The quoted limit assumes ${{\mathit \Lambda}}$ = ${\mathit m}_{{{\mathit \mu}^{*}}}$, ${{\mathit f}}$ = ${{\mathit f}^{\,'}}$ = 1. The contact interaction is included. See their Fig.11 for exclusion limits in ${\mathit m}_{{{\mathit \mu}^{*}}}-{{\mathit \Lambda}}$ plane. 2  SIRUNYAN 2019Z search for ${{\mathit \mu}^{*}}$ production in ${{\mathit \ell}}{{\mathit \ell}}{{\mathit \gamma}}$ final states in ${{\mathit p}}{{\mathit p}}$ collisions at $\sqrt {s }$ = 13 TeV. The quoted limit assumes $\Lambda $ = ${\mathit m}_{{{\mathit \mu}^{*}}}$, ${{\mathit f}}$ = ${{\mathit f}^{\,'}}$ = 1. The contact interaction is included in the ${{\mathit \mu}^{*}}$ production and decay amplitudes. 3  AAD 2016BM search for ${{\mathit \mu}^{*}}$ production in ${{\mathit \mu}}{{\mathit \mu}}{{\mathit j}}{{\mathit j}}$ events in ${{\mathit p}}{{\mathit p}}$ collisions at $\sqrt {s }$ = 8 TeV. Both the production and decay are assumed to occur via a contact interaction with $\Lambda $ = ${\mathit m}_{{{\mathit \mu}^{*}}}$. 4  KHACHATRYAN 2016AQ search for single ${{\mathit \mu}^{*}}$ production in ${{\mathit p}}{{\mathit p}}$ collisions at $\sqrt {s }$ = 8 TeV. The limit above is from the ${{\mathit \mu}^{*}}$ $\rightarrow$ ${{\mathit \mu}}{{\mathit \gamma}}$ search channel assuming ${{\mathit f}}$ = ${{\mathit f}^{\,'}}$ = 1, ${\mathit m}_{{{\mathit \mu}^{*}}}$ = $\Lambda $. See their Table 7 for limits in other search channels or with different assumptions. 5  AAD 2015AP search for ${{\mathit \mu}^{*}}$ production in evens with three or more charged leptons in ${{\mathit p}}{{\mathit p}}$ collisions at $\sqrt {s }$ = 8 TeV. The quoted limit assumes ${{\mathit \Lambda}}$ = ${\mathit m}_{{{\mathit \mu}^{*}}}$, ${{\mathit f}}$ = ${{\mathit f}^{\,'}}$ = 1. The contact interaction is included in the ${{\mathit \mu}^{*}}$ production and decay amplitudes. 6  AAD 2013BB search for single ${{\mathit \mu}^{*}}$ production in ${{\mathit p}}{{\mathit p}}$ collisions with ${{\mathit \mu}^{*}}$ $\rightarrow$ ${{\mathit \mu}}{{\mathit \gamma}}$ decay. ${{\mathit f}}$ = ${{\mathit f}^{\,'}}$ = 1, and ${{\mathit \mu}^{*}}$ production via contact interaction with ${{\mathit \Lambda}}$ = ${\mathit m}_{{{\mathit \mu}^{*}}}$ are assumed. 7  CHATRCHYAN 2013AE search for single ${{\mathit \mu}^{*}}$ production in ${{\mathit p}}{{\mathit p}}$ collisions with ${{\mathit \mu}^{*}}$ $\rightarrow$ ${{\mathit \mu}}{{\mathit \gamma}}$ decay. ${{\mathit f}}$ = ${{\mathit f}^{\,'}}$ = 1, and ${{\mathit \mu}^{*}}$ production via contact interaction with ${{\mathit \Lambda}}$ = ${\mathit m}_{{{\mathit \mu}^{*}}}$ are assumed. 8  AAD 2012AZ search for ${{\mathit \mu}^{*}}$ production via four-fermion contact interaction in ${{\mathit p}}{{\mathit p}}$ collisions with ${{\mathit \mu}^{*}}$ $\rightarrow$ ${{\mathit \mu}}{{\mathit \gamma}}$ decay. The quoted limit assumes ${{\mathit \Lambda}}$ = ${\mathit m}_{{{\mathit \mu}^{*}}}$. See their Fig. 8 for the exclusion plot in the mass-coupling plane.

References:

SIRUNYAN 2020AJ JHEP 2005 052 Search for an excited lepton that decays via a contact interaction to a lepton and two jets in proton-proton collisions at $\sqrt{s} =$ 13 TeV SIRUNYAN 2019Z JHEP 1904 015 Search for excited leptons in $\ell\ell\gamma$ final states in proton-proton collisions at $\sqrt{s}=$ 13 TeV AAD 2016BM NJP 18 073021 A Search for an Excited Muon Decaying to a Muon and Two Jets in ${{\mathit p}}{{\mathit p}}$ Collisions at $\sqrt {s }$ = 8 TeV with the ATLAS Detector KHACHATRYAN 2016AQ JHEP 1603 125 Search for Excited Leptons in Proton-Proton Collisions at $\sqrt {s }$ = 8 TeV AAD 2015AP JHEP 1508 138 Search for New Phenomena in Events with Three or More Charged Leptons in ${{\mathit p}}{{\mathit p}}$ Collisions at $\sqrt {s }$ = 8 TeV with the ATLAS Detector AAD 2013BB NJP 15 093011 Search for Excited Electrons and Muons in $\sqrt {s }$ = 8 TeV Proton$−$Proton Collisions with the ATLAS Detector CHATRCHYAN 2013AE PL B720 309 Search for Excited Leptons in ${{\mathit p}}{{\mathit p}}$ Collisions at $\sqrt {s }$ = 7 TeV AAD 2012AZ PR D85 072003 Search for Excited Leptons in Proton$−$Proton Collisions at $\sqrt {s }$ = 7 TeV with the ATLAS Detector