Effective theory for neutral resonances and a statistical dissection of the ATLAS diboson excess

Abstract

We classify the complete set of dimension-5 operators relevant for the resonant production of a singlet of spin 0 or 2 linearly coupled to the Standard Model (SM). We compute the decay width of such states as a function of the effective couplings, and provide the matching to various well-motivated New Physics scenarios. We then investigate the possibility that one of these neutral resonances be at the origin of the excess in diboson production recently reported by the ATLAS collaboration. We perform a shape analysis of the excess under full consideration of the systematic uncertainties to extract the width ${\Gamma }_{\mathrm{tot}}$ of the hypothetical resonance, finding it to be in the range 26 GeV $<{\Gamma }_{\mathrm{tot}}<$ 144 GeV at 95\% C.L. We then point out that the three overlapping selections $WW$, $WZ$, $ZZ$ reported by ATLAS follow a joint trivariate Poisson distribution, which opens the possibility of a thorough likelihood analysis of the event rates. The background systematic uncertainties are also included in our analysis. We show that the data do not require $WZ$ production and could thus in principle be explained by neutral resonances. We then use both the information on the width and the cross section, which prove to be highly complementary, to test the effective Lagrangians of singlet resonances. Regarding specific models, we find that neither scalars coupled via the Higgs-portal nor the Randall-Sundrum (RS) radion can explain the ATLAS anomaly. The RS graviton with all matter on the infrared (IR) brane can in principle fit the observed excess, while the RS model with matter propagating in the bulk requires the presence of IR brane kinetic terms for the gauge fields.

31 pages

References in corpus (18)

• The automated computation of tree-level and next-to-leading order differential cross sections, and their matching to parton shower simulations
• MadAnalysis 5, a user-friendly framework for collider phenomenology
• Light scalar at LHC: the Higgs or the dilaton?
• Searching for the Kaluza-Klein Graviton in Bulk RS Models
• Unified explanation of the $eejj$, diboson and dijet resonances at the LHC
• Electroweak Breaking on a Soft Wall
• Minimal Left-Right Symmetric Dark Matter
• A W' boson near 2 TeV: predictions for Run 2 of the LHC
• Warped Electroweak Breaking Without Custodial Symmetry
• Suppressing Electroweak Precision Observables in 5D Warped Models
• Heavy Higgs bosons and the 2 TeV $W^{\prime }$ boson
• Interpretations of the ATLAS Diboson Anomaly
• 2 TeV Walking Technirho at LHC?
• A composite Heavy Vector Triplet in the ATLAS di-boson excess
• A scalar hint from the diboson excess?
• Stringy origin of diboson and dijet excesses at the LHC
• 2 TeV Higgs boson and diboson excess at the LHC
• Extra $Z^{\prime }$s and $W^{\prime }$s in Heterotic--String Derived Models

Cited by in corpus (14)

• Scattering Light by Light at 750 GeV at the LHC
• Measuring the diphoton coupling of a 750 GeV resonance
• Resonances at the LHC beyond the Higgs: The Scalar/Tensor Case
• Multiboson production in W' decays
• The ATLAS Di-boson Excess Could Be an R-parity Violating Di-smuon Excess
• The Global Higgs as a Signal for Compositeness at the LHC
• A 2 TeV $W_R$, Supersymmetry, and the Higgs Mass
• ATLAS diboson excess from low scale supersymmetry breaking
• Understanding diboson anomalies
• Sharpening the shape analysis for higher-dimensional operator searches
• Alternative search strategies for a BSM resonance fitting ATLAS diboson excess
• The Diboson Excesses in Leptophobic $U(1{)}_{\mathrm{LP}}$ Models from String Theories
• Angular observables for spin discrimination in boosted diboson final states
• Heavy Higgs Coupled to Vector-like Quarks: Strong CP Problem and Search Prospects at the 14 TeV LHC