ATLAS diboson excess from low scale supersymmetry breaking

Christoffer Petersson,Riccardo Torre

doi:10.1007/jhep01(2016)099

Abstract

We provide an interpretation of the recent ATLAS diboson excess in terms of a class of supersymmetric models in which the scale of supersymmetry (SUSY) breaking is in the few TeV range. The particle responsible for the excess is the scalar superpartner of the Goldstone fermion associated with SUSY breaking, the sgoldstino. This scalar couples strongly to the Standard Model vector bosons and weakly to the fermions, with all coupling strengths determined by ratios of soft SUSY breaking parameters over the SUSY breaking scale. Explaining the ATLAS excess selects particular relations and ranges for the gaugino masses, while imposing no constraints on the other superpartner masses. Moreover, this signal hypothesis predicts a rate in the $Z\gamma$ final state that is expected to be observable at the LHC Run II already with a few fb$^{-1}$ of integrated luminosity.

Highlights

We provide an interpretation of the recent ATLAS diboson excess in terms of a class of supersymmetric models in which the scale of supersymmetry (SUSY) breaking is in the few TeV range
We study the compatibility of this signal hypothesis with the excess, identify the relevant region of the parameter space and discuss the relations to other searches in correlated channels, such as γγ and Zγ
To assess the compatibility of a sgoldstino signal with the ATLAS diboson excess, we compare the number of signal events the sgoldstino gives rise to with the number of excess events reported by ATLAS

Summary

The sgoldstino model

If SUSY is realized in Nature, since the SM particles are not mass-degenerate with their superpartners, it must be in a broken phase at low energies. One way to take into account the interactions of the goldstino and sgoldstino is to promote all the usual MSSM soft terms to SUSY operators involving the goldstino superfield in eq (2.1). Note that by taking the auxiliary component of X and inserting its vev, FX = f , one recovers the usual gaugino mass terms. The goldstino or sgoldstino interactions are obtained by taking the fermion or scalar component of X. The interactions in eq (2.4f) arise from the operator m2φ/(4f 2)(X†X) in the Kahler potential, from which the soft mass mφ = ma for the CP-even and CP-odd sgoldstino scalars φ and a arises. The interactions between the sgoldstino and the SM fermions arise from superpotential operators such as (Au/f )XQHuU c, which, upon taking the auxiliary component of X and inserting its vev, give ris√e to the usual A-terms. Since Γφ/mφ is below 10% for the sgoldstino in the relevant region of the parameter space, eq (2.6), which assumes the narrow width approximation, is always reliable

Explaining the diboson excess

Other analyses

Findings

Conclusions