Prospects for sgoldstino search at the LHC

Abstract

In this paper we estimate the LHC sgoldstino discovery potential for the signatures with γγ and ZZ in a final state.It is well known, that exist models of supergravity breaking with relatively light sgoldstinos (scalar S and pseudoscalar P particles -superpartners of goldstino ψ). Such pattern emerges in a number of non-minimal supergravity models [1] and also in gauge mediation models if supersymmetry is broken via non-trivial superpotential (see, Ref.[2] and references therein). To the leading order in 1/F , where F is the parameter of supersymmetry breaking, and to zero order in MSSM gauge and Yukawa coupling constants, the interactions between the component fields of goldstino supermultiplet and MSSM fields have been derived in Ref. [3]. They correspond to the most attractive for collider studies processes where only one of these new particles appears in a final state. In this case light gravitino behaves exactly as goldstino. For sgoldstinos, as they are R-even, only sgoldstino couplings to goldstino and sgoldstino couplings to SM fields have been included as the most interesting phenomenologically.All relevant sgoldstino coupling constants presented in Ref.[3] are completely determined by the MSSM soft terms and the parameter of supersymmetry breaking F , but sgoldstino masses (m S , m P ) remain free. If sgoldstino masses are of the order of electroweak scale and √ F ∼ 1 TeV -sgoldstino may be detected in collisions of high energy particles at supercolliders [4,5].There are flavor-conserving and flavor-violating interactions of sgoldstino fields. As concerns flavor-conserving interactions, the strongest bounds arise from astrophysics and cosmology, that is √ F 10 6 GeV [6,7], or m 3/2 > 600 eV, for models with m S(P ) < 10 keV and MSSM soft flavor-conserving terms being of the order of electroweak scale. For the intermediate sgoldstino masses (up to a few MeV) constraints from the study of SN explosions and reactor experiments lead to √ F 300 TeV [7]. For heavier sgoldstinos, low energy processes (such as rare decays of mesons) provide limits at the level of √ F 500 GeV [7]. The collider experiments exhibit the same level of sensitivity to light sgoldstinos as rare meson decays. Indeed the studies [8,9,10,11] of the light sgoldstino (m S,P a f ew MeV) phenomenology based on the effective low-energy Lagrangian derived from N=1 linear supergravity yield the bounds: √ F 500 GeV (combined bound on Z → Sf f, Pf f [10]; combined bound on e + e − → γS, γP [9]) at M sof t ∼ 100 GeV, √ F 1 TeV [11] (combined bound on pp → gS, gP ) at gluino mass M 3 ≃ 500 GeV. Searches for heavier sgoldstinos at colliders, though exploiting another technique, results in similar bounds on the scale of supersymmetry breaking. Most powerful among the operating machines, LEP and Tevatron, give a constraint of the order of 1 TeV on supersymmetry breaking scale in models with light sgoldstinos. Indeed, the analysis carried out by DELPHI Collaboration [12] yields the limit 1

On the sgoldstino interpretation of the diphoton excess

“…The dominating production mechanism of sgoldstino at high energy pp collisions is gluon-gluon fusion [11,12] for typical hierarchy of soft supersymmetry breaking parameters: gluino is the heaviest gaugino while the soft trilinear couplings are of the same size as M i . The production cross section σ S is related to the decay of sgoldstino to gluons Γ(S → gg) = M 2 3 m 3 S 4πF 2 which is typically the main decay channel for √ F at TeV scale and m S < √ F which we will assume in what follows.…”

“…are closely related to each other (see, e.g. [12]). So, if the mixing is reasonably small and their masses are different one expects to observe γγ-peak at another invariant mass associated with the sgoldstino twin.…”

“…Interactions of the latter with the Standard Model particles are determined by soft supersymmetry breaking parameters and suppressed by the supersymmetry breaking scale √ F . Collider phenomenology of sgoldstinos with masses of order electroweak scale have been discussed for instance in [10,11,12,13,14,15,16,17,18]. In Refs.…”

LHC prospects in searches for neutral scalars in pp → γγ + jet

“…For the models with sgoldstino we present the estimates of the LHC sensitivity to the scale of supersymmetry breaking √ F for the same sets of MSSM soft parameters as ones considered in [7], see Table 5.…”

“…Both examples suggest that discovery potential of γγ + jet channel in searches for new physics is comparable to prospects of the inclusive channel. Note in passing that radion production and sgoldstino production in inclusive channel have been estimated for the first time [6,7] by making use of the rescaling procedure similar to the one we apply in this work.…”