TeV-scale particles and LHC events with dijet pairs

TL;DR

This paper proposes a theoretical model involving ultraheavy scalar diquarks and vectorlike quarks to explain certain high-energy jet events observed at the LHC, predicting specific multi-jet signatures for future experimental tests.

Contribution

It introduces a renormalizable theory with new particles that can account for observed LHC jet events and suggests specific experimental signatures for validation.

Findings

Two CMS events with four high pT jets may be explained by an 8.5 TeV diquark.

A CMS excess in dijet pairs is consistent with a 0.95 TeV vectorlike quark.

Predicted signals include dijet resonance pairs around 1 and 2 TeV with multi-jet invariant masses in the 5-8 TeV range.

Abstract

Scalar particles that couple to two up quarks may be produced at the LHC even if they are ultraheavy, in the $8-10$ TeV mass range. A renormalizable theory that includes a diquark particle of this type ($S_{uu}$), two vectorlike quarks ($\chi_1, \chi_2$), and a gauge-singlet pseudoscalar, predicts LHC signals involving four or more jets of very high $p_T$. Two remarkable events observed by the CMS experiment, each involving four high $p_T$-jets, may be due to an $S_{uu}$ of mass near 8.5 TeV, and a $\chi_2$ mass of 2.1 TeV. A separate excess reported by CMS in the nonresonant dijet pair search is consistent with a $\chi_1$ mass of $0.95$ TeV. This hypothesis may be tested through CMS and ATLAS searches for signals with a pair of dijet resonances of masses clustered around 1 TeV, and separately around 2 TeV, which have $4j$ invariant masses in the $5-8$ TeV range. These additional signals would arise from cascade decays of $S_{uu} \to \chi_2 \chi_2 $, which lead to $5j$ and $6j$ events with invariant masses around 8 TeV. Depending on the couplings of the heavy colored particles, additional signals are possible, involving for example highly-boosted top quarks.