Diphoton resonances in the renormalizable coloron model

The renormalizable coloron model, which has previously been shown in the literature to be consistent with a wide array of theoretical and precision electroweak constraints, includes a pair of spinless bosons (one scalar, one pseudoscalar). We show that either of them, or both together if they are degenerate, could be responsible for the diphoton resonance signal for which both CMS and ATLAS have seen evidence. Because either of these bosons would be produced and decay through loops of spectator fermions, the absence of signals in dijet, $t\overline{t}$, and electroweak boson pair channels is not a surprise.

Figure 1

The heavy black rim (left panel) encloses the region of the $N_Q$ vs $n_q$ plane for which the renormalizable coloron model’s scalar boson $s$ is consistent with the 750 GeV diphoton signal and other constraints. The region shown in green (diagonally hatched) matches the $1\text{−}\sigma$ resonance diphoton cross section of Eq. (1). Also shown are the regions excluded by $s\to WW$ searches depicted with crosshatching [12], by $s\to ZZ$ searches depicted in blue (dark gray) [13] and by dijet searches depicted in red (lighter gray) [14]. The regions with translucent gray overlays correspond to values of $(N_Q,n_q)$ that are not theoretically preferred (see text for details). Left: Plot in the $(N_Q,n_q)$ plane for the values $\sin \chi =0$, $m_{\mathcal{A}}=m_{G_H}=1\mathrm{TeV}$, and $v_s=2\mathrm{TeV}$. Depending on the spectator fermions included, this region is sensitive to the RGE constraints discussed in Appendix pp3. Right: Plot in the $(\sin \chi ,v_s)$ plane for parameter values $m_{\mathcal{A}}=m_{G_H}=1\mathrm{TeV}$, and $(N_Q,n_q)=(6,5)$.

Figure 2

Scalar boson ($s$) decay width and branching ratios as a function of $\sin \chi$, for the parameter values $m_{\mathcal{A}}=m_{G_H}=1\mathrm{TeV}$ and $(N_Q,n_q)=(6,5)$.

Figure 3

The heavy black rim encloses the region of the $N_Q$ vs $n_q$ plane for which the renormalizable coloron model’s pseudoscalar boson $\mathcal{A}$ alone (left panel) or a degenerate $s$, $\mathcal{A}$ pair (right panel) is consistent with the 750 GeV diphoton signal and other constraints. Details are as in the caption for the left-hand panel of Fig. 1 (except that $\sin \chi$ is irrelevant for the $\mathcal{A}$ boson). The allowed region in each panel is unaffected by the RGE constraints in Appendix pp3.

Figure 4

Ratio of the scalar to the pseudoscalar component of the diphoton signal as a function of $N_Q$, for quasidegenerate $m_{\mathcal{A}}=m_s=750\mathrm{GeV}$. All three possible physical cases are shown $n_q=N_Q$ (blue circles), $n_q=N_Q-1$ (red squares), and $n_q=N_Q-3$ (black triangles).