Abstract
New physics close to the electroweak scale is well motivated by a number of theoretical arguments. However, colliders, most notably the Large Hadron Collider (LHC), have failed to deliver evidence for physics beyond the Standard Model. One possibility for how new electroweak-scale particles could have evaded detection so far is if they carry only electroweak charge, i.e. are color neutral. Future $e^+e^-$ colliders are prime tools to study such new physics. Here, we investigate the sensitivity of $e^+e^-$ colliders to scalar partners of the charged leptons, known as sleptons in supersymmetric extensions of the Standard Model. In order to allow such scalar lepton partners to decay, we consider models with an additional neutral fermion, which in supersymmetric models corresponds to a neutralino. We demonstrate that future $e^+e^-$ colliders would be able to probe most of the kinematically accessible parameter space, i.e. where the mass of the scalar lepton partner is less than half of the collider's center-of-mass energy, with only a few days of data. Besides constraining more general models, this would allow to probe some well motivated dark matter scenarios in the Minimal Supersymmetric Standard Model, in particular the incredible bulk and stau co-annihilation scenarios.
Highlights
The hierarchy problem and the weakly interacting massive particle paradigm both point to new physics close to the electroweak scale
While it is possible that the scale of new physics is beyond the reach of the Large Hadron Collider (LHC), it is possible that new electroweak-scale particles are lurking in a blind spot of the LHC
We examine the prospects of future lepton colliders to probe scenarios where the SM is extended by scalar partners of the charged leptons
Summary
The hierarchy problem and the weakly interacting massive particle paradigm both point to new physics close to the electroweak scale. We consider a spectrum where only one smuon or stau is close to the mass of the neutral fermion χ and assume the slepton decays exclusively to χ and the SM lepton of the same flavor as the slepton Such an approach allows us to explore the sensitivity of future eþe− colliders to general. As we will demonstrate, achieving significant polarization fractions would make it considerably easier to probe sleptons at a fcuetnutreer-olefp-mtoansscoelnliedregri.esWphiffislffie≤w5e00prGeseeVnt, results only for we can readily extrapolate from our results that an eþe− collider with larger center-of-mass energy could probe sleptonps ffiaffi lmost all the way to the pair production threshold ml ≲ s=2 for any mass gap ml − mχ with a few fb−1 of data This analysis is directly applicable to a number of dark matter scenarios—simplified, stand-alone, or within the MSSM—that can be constrained by the mass of the lightest slepton.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
