A Gravity Dual and LHC Study of Single-Sector Supersymmetry Breaking

TL;DR

The work constructs a string-inspired 5D gravity dual with a deformed AdS$_5$ slice to realize single-sector SUSY breaking without messenger fields, naturally generating a split superpartner spectrum via bulk localization and IR dynamics. Through AdS/CFT, it maps to a 4D holographic description where the first two SM generations are composite and SUSY breaking communicates primarily through gauge mediation, with a messenger scale around $M\simeq 110$ TeV and $F/M\approx 90$ TeV. The model predicts heavy first/second-generation scalars ($\mathcal{O}(5-10)\,\text{TeV}$), lighter gauginos and third-generation states, a gravitino LSP and a neutralino NLSP with a characteristic $2\gamma+\not\!E_T$ collider signature, and shows discovery prospects at the LHC with $1-10\ \mathrm{fb}^{-1}$. It also analyzes FCNC and tachyonic-stop constraints, obtaining a viable spectrum and outlining cosmological and model-building implications for future work and UV completion.

Abstract

We propose a gravitational dual of ``single-sector'' models of supersymmetry breaking which contain no messenger sector and naturally explain the scale of supersymmetry breaking and the fermion mass hierarchy. In five dimensions these models can be given a simple interpretation. Inspired by flux-background solutions of type IIB supergravity, a metric background that deviates from AdS_5 in the IR breaks supersymmetry, while the fermion mass hierarchy results from the wavefunction overlap of bulk fermions with a UV-confined Higgs field. The first and second generation squarks and sleptons, which are localized near the IR brane, directly feel the supersymmetry breaking and obtain masses of order 10 TeV. These are interpreted as composite states of the dual 4D theory. The gauginos and third generation squarks and sleptons are elementary states that obtain soft masses of order 1 TeV at the loop level via direct gauge mediation. This particle spectrum leads to distinctive signatures at the LHC, similar to the usual gauge mediation with a neutralino NLSP that decays promptly to a gravitino LSP, but with lower event rates. Nevertheless we show that with 1-10 fb^{-1} of LHC data "single-sector" models can easily be detected above background and distinguished from conventional gravity and gauge mediation.

Figures (6)

• Figure 1: The generic mass spectrum of the 5D gravity model showing the heavy first and second generation scalars and lighter third generation scalars, gluinos, neutralinos and charginos. The LSP is the gravitino (not shown).
• Figure 2: The scalar mass-squared (\ref{['musf']}) as a function of $b$ for three values of $z_1^{-1} =$ 1, 10 and 100 TeV, with ${\epsilon}=0.05$. Not shown are the exponentially small values at $b \mathrel{\hbox{$<$} {\hbox{$\sim$}}} 1/2$. The values $b < 1$ correspond to a UV-localized mode, whereas $b > 1$ is IR-localized.
• Figure 3: The photon differential $p_T$ distribution in our example model, compared to a comparable GMSB model, with only nominal cuts (cf. Sec. \ref{['nrc']}). High $p_T$ bins are especially useful as discriminators, and would be statistically significant with 10 fb$^{-1}$ of data.
• Figure 4: Comparison of the single-sector diphoton signal (solid) to background (dashed) of Eq. (\ref{['bg1']}). Here both the photon $p_T$ and event $\hbox{$\not \space E_T$}$ distributions are shown. Only nominal cuts (cf. Sec. \ref{['nrc']}) are made.
• Figure 5: Comparison of the single-sector diphoton signal (solid) to background (dashed) Eq. (\ref{['bg1']}). Here both photon $p_T$ and event $\hbox{$\not \space E_T$}$ distributions are shown. Cuts to remove background, Eq. (\ref{['brc']}), have been made, removing virtually all the background. It can be seen that the signal will be spectacularly visible.