Consistency and interpretation of the LHC dijet excesses

Abstract

ATLAS observed a limit for the cross section of dijet resonances, which is weaker than expected for a mass slightly below $\ensuremath{\approx}1\text{ }\text{ }\mathrm{TeV}$. In addition, CMS reported hints for the (nonresonant) pair production of dijet resonances $X$ via a particle $Y$ at a very similar mass range with a local (global) significance of $3.6\ensuremath{\sigma}$ ($2.5\ensuremath{\sigma}$) at ${m}_{X}\ensuremath{\approx}950\text{ }\text{ }\mathrm{GeV}$. In this article, we show that, using the preferred range for ${m}_{X}$ from the ATLAS analysis, one can reinterpret the CMS analysis of didijets in terms of a resonant search with $Y\ensuremath{\rightarrow}XX$, with a significantly reduced look-elsewhere effect, finding an excess for ${m}_{Y}\ensuremath{\approx}3.6\text{ }\text{ }\mathrm{TeV}$ with a significance of $4.0\ensuremath{\sigma}$ ($3.2\ensuremath{\sigma}$) locally (globally). We present two possible UV completions capable of explaining the (di)dijet excesses, one containing two scalar diquarks, the other one involving heavy gluons based on an $SU(3{)}_{1}\ifmmode\times\else\texttimes\fi{}SU(3{)}_{2}\ifmmode\times\else\texttimes\fi{}SU(3{)}_{3}$ gauge symmetry, spontaneously broken to $SU(3)$ color. In the latter case, nonperturbative couplings are required, pointing toward a composite or extradimensional framework. In fact, using 5D anti--de Sitter space-time, one obtains the correct mass ratio for ${m}_{X}/{m}_{Y}$, assuming the $X$ is the lowest-lying resonance, and predicts a third (di)dijet resonance with a mass around $\ensuremath{\approx}2.2\text{ }\text{ }\mathrm{TeV}$.