Color octet scalars and high $p_T$ four-jet events at the LHC

We study the effect of color octet scalars on the high transverse momenta four-jet cross section at the LHC. We consider both weak singlet and doublet scalars, concentrating on the case of small couplings to quarks. We find that a relatively early discovery at the LHC is possible for a range of scalar masses.

Figure 1

Feynman diagrams contributing to the $pp\to SS$ scattering.

Figure 2

Diagrams representing color octet scalar decay $S\to gg$.

Figure 3

Diagram for a weak doublet color octet scalar decay to gluons through a quark loop.

Figure 4

Tree-level diagram contributing to the weak doublet color octet scalar decays $S_I^0\to Zgg$ and $S^{\pm }\to W^{\pm }gg$.

Figure 5

The four-jet cross section per bin of the invariant mass of the highest and lowest $p_T$ jets for the invariant mass cut (9) and different $p_T$ cuts: (a) 200 GeV, (b) 300 GeV, and (c) 400 GeV. The black curve is the standard model background. The colored curves: red, orange, and green, correspond to the signal of an SU(2) singlet color octet scalar of mass 300 GeV, 500 GeV, and 750 GeV, respectively. The bin size is 20 GeV.

Figure 6

The significance of the SU(2) singlet color octet scalar four-jet signal within the invariant mass window $0.9M_s\le m_{14}\le 1.1M_s$ as a function of the scalar mass for $E_{\mathrm{c}.\mathrm{m}.}=14\mathrm{TeV}$, $p_T>200\mathrm{GeV}$, and an integrated luminosity of $1{\mathrm{fb}}^{-1}$ (blue), $5{\mathrm{fb}}^{-1}$ (green), and $10{\mathrm{fb}}^{-1}$ (orange).

Figure 7

Same as Fig. 6, but for $E_{\mathrm{c}.\mathrm{m}.}=7\mathrm{TeV}$.

Figure 8

The logarithmic plot of the SU(2) doublet color octet scalar $2Z+4\mathrm{\text{jets}}$ signal significance as a function of the scalar mass parameter $m_S$ for ${\lambda }_i=1/2$, $E_{\mathrm{c}.\mathrm{m}.}=7\mathrm{TeV}$, $p_T>100\mathrm{GeV}$, and an integrated luminosity of $1{\mathrm{fb}}^{-1}$ (blue), $5{\mathrm{fb}}^{-1}$ (green), and $10{\mathrm{fb}}^{-1}$ (orange).

Figure 9

Same as Fig. 8, but for $E_{\mathrm{c}.\mathrm{m}.}=14\mathrm{TeV}$.