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Difference between two species of emu hides a test for lepton flavour violation
High Energy Physics - Phenomenology · Submitted 8 Dec 2016
abstract compiled · 2026-09-23 · no language-model review
The authors' main claim We argue that an LHC measurement of some simple quantities related to the ratio of rates of e+mu- to e-mu+ events is surprisingly sensitive to as-yet unexcluded R-parity violating supersymmetric models with non-zero lambda-prime 231 couplings.
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The abstract, sentence by sentence
We argue that an LHC measurement of some simple quantities related to the ratio of rates of e+mu- to e-mu+ events is surprisingly sensitive to as-yet unexcluded R-parity violating supersymmetric models with non-zero lambda-prime 231 couplings. The search relies upon the approximate lepton universality in the Standard Model, the sign of the charge of the proton, and a collection of favourable detector biases. The proposed search is unusual because: it does not require any of the displaced vertices, hadronic neutralino decay products, or squark/gluino production relied upon by existing LHC RPV searches; it could work in cases in which the only light sparticles were smuons and neutralinos; and it could make a discovery (though not necessarily with optimal significance) without requiring the computation of a leading-order Monte Carlo estimate of any background rate. The LHC has shown no strong hints of post-Higgs physics and so precision Standard Model measurements are becoming ever more important. We argue that in this environment growing profits are to be made from searches that place detector biases and symmetries of the Standard Model at their core - searches based around `controls' rather than around signals.
background contribution method result interpretation main claim
| # | sentence | role | the authors' own work | states the main conclusion | strength |
|---|---|---|---|---|---|
| s0 | We argue that an LHC measurement of some simple quantities related to the ratio of rates of e+mu- to e-mu+ events is surprisingly sensitive to as-yet unexcluded R-parity violating supersymmetric models with non-zero lambda-prime 231 couplings. | contribution 0.95 | 0.36 | 0.84 | hedged possibility 0.48 |
| s1 | The search relies upon the approximate lepton universality in the Standard Model, the sign of the charge of the proton, and a collection of favourable detector biases. | method 0.94 | 0.24 | 0.05 | asserted 0.99 |
| s2 | The proposed search is unusual because: it does not require any of the displaced vertices, hadronic neutralino decay products, or squark/gluino production relied upon by existing LHC RPV searches; it could work in cases in which the only light sparticles were smuons and neutralinos; and it could make a discovery (though not necessarily with optimal significance) without requiring the computation of a leading-order Monte Carlo estimate of any background rate. | contribution 0.90 | 0.42 | 0.14 | hedged possibility 0.73 |
| s3 | The LHC has shown no strong hints of post-Higgs physics and so precision Standard Model measurements are becoming ever more important. | background 0.99 | 0.04 | 0.03 | asserted 0.98 |
| s4 | We argue that in this environment growing profits are to be made from searches that place detector biases and symmetries of the Standard Model at their core - searches based around `controls' rather than around signals. | interpretation 0.68 | 0.17 | 0.24 | asserted 0.83 |
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The paper
Original abstract
We argue that an LHC measurement of some simple quantities related to the ratio of rates of e+mu- to e-mu+ events is surprisingly sensitive to as-yet unexcluded R-parity violating supersymmetric models with non-zero lambda-prime 231 couplings. The search relies upon the approximate lepton universality in the Standard Model, the sign of the charge of the proton, and a collection of favourable detector biases. The proposed search is unusual because: it does not require any of the displaced vertices, hadronic neutralino decay products, or squark/gluino production relied upon by existing LHC RPV searches; it could work in cases in which the only light sparticles were smuons and neutralinos; and it could make a discovery (though not necessarily with optimal significance) without requiring the computation of a leading-order Monte Carlo estimate of any background rate. The LHC has shown no strong hints of post-Higgs physics and so precision Standard Model measurements are becoming ever more important. We argue that in this environment growing profits are to be made from searches that place detector biases and symmetries of the Standard Model at their core - searches based around `controls' rather than around signals.
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How the literature uses it
1 arXiv paper cite this in 3 sentences
What it cites · 23 sentences without a confident label
Uses the method or tool of 4 papers
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The generated samples were hadronised using [ref] through the Pythia-PGS interface, with detector simulation provided by [ref] .
PYTHIA 6.4 Physics and Manual · Monte Carlo simulations · 1.00
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Models of RPV SUSY are simulated using with additional model “RPV MSSM” [ref] .
Beyond the Minimal Supersymmetric Standard Model: from theory to phenomenology · Signal simulation · 0.98
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The MadEvent matrix element was matched to the parton shower using the shower-$k_T$ scheme [ref] with $p_T$-ordered showers.
QCD radiation in the production of heavy colored particles at the LHC · Background simulation · 1.00
Uses data or values from 2 papers
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We work, however, with a simplified model in which the only light sparticles are the left smuon and the neutralino, and so we neglect those other vertices.] The best current limits [ref] on $λ'_231$ come from neutrino muon deep inelastic scattering data and demand [equation] if the bottom squark is not decoupled.
Bounds on R-parity Violating Couplings at the Weak Scale and at the GUT Scale · Beyond the Standard Model · 0.84
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The reconstruction efficiency as reported by ATLAS [ref] is consistent to within 2% over most of the $η-ϕ$ plane, with the exception of the region $|η|<0.1$, where cabling and services enter the inner parts of the detector.
Muon reconstruction performance of the ATLAS detector in proton--proton collision data at $\sqrt{s}$=13 TeV · Effects of detector geometry · 0.92
Cites as background 6 papers
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There is even an OSDF search from ATLAS [ref] which targets LFV production caused by the simultaneous presence of two lambda prime couplings.
Search for lepton flavour violation in the emu continuum with the ATLAS detector in sqrt(s) = 7 TeV pp collisions at the LHC · Generic different flavour constraints: $μ^±e^∓$ · 0.93
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OSDF examples include: the ATLAS RPV LFV $λ'_312$ search for a sneutrino resonance decaying to an OSDF $μ^±e^∓$ [ref] ; a later version of the same search that considers also $λ'_321$ [ref] ; ATLAS searches for chargino and neutralino production [ref] ; a CMS dilepton invariant mass scan [ref] .
Search for direct production of charginos, neutralinos and sleptons in final states with two leptons and missing transverse momentum in pp collisions at sqrt(s) = 8 TeV with the ATLAS detector · Generic different flavour constraints: $μ^±e^∓$ · 0.97
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OSDF examples include: the ATLAS RPV LFV $λ'_312$ search for a sneutrino resonance decaying to an OSDF $μ^±e^∓$ [ref] ; a later version of the same search that considers also $λ'_321$ [ref] ; ATLAS searches for chargino and neutralino production [ref] ; a CMS dilepton invariant mass scan [ref] .
Search for physics beyond the standard model in dilepton mass spectra in proton-proton collisions at sqrt(s) = 8 TeV · Generic different flavour constraints: $μ^±e^∓$ · 0.97
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