Triplet scalars and dark matter at the LHC

We investigate the predictions of a simple extension of the standard model where the Higgs sector is composed of one $\mathrm{SU}(2{)}_L$ doublet and one real triplet. We discuss the general features of the model, including its vacuum structure, theoretical and phenomenological constraints, and expectations for Higgs collider studies. The model predicts the existence of a pair of light charged scalars and, for vanishing triplet vacuum expectation value, contains a cold dark matter candidate. When the latter possibility occurs, the charged scalars are long-lived, leading to a prediction of distinctive single charged track with missing transverse energy or double charged track events at the large hadron collider. The model predicts a significant excess of two-photon events compared to SM expectations due to the presence of a light charged scalar.

Figure 1

Predictions for $\delta$, as defined in Eq. (40), in the case of $x_0=0$ and $M_{H_1}=120\mathrm{GeV}$. Left panel shows the $\delta$ dependence on $M_{H^{+}}$. Different curves correspond to different values of $a_2$. Right panel shows the $\delta$ dependence on $a_2$, with different curves corresponding to different charged Higgs masses, $M_{H^{+}}$.

Figure 2

Values for $\delta$ in percent, as defined in Eq. (40), when $x_0=1\mathrm{GeV}$ and $M_{H_1}=120\mathrm{GeV}$.

Figure 3

Branching ratios for the singly charged Higgs as a function of $x_0$ for $M_{H_2}=150\mathrm{GeV}-\Delta M$ in Eq. (24) (left panel) and $M_{H_2}=300\mathrm{GeV}-\Delta M$ (right panel). Here, we have taken $M_{H_1}=120\mathrm{GeV}$.

Figure 4

Branching ratios for the singly charged Higgs as a function of $M_{H^{+}}$ when $x_0=1\mathrm{GeV}$ (left panel) and $x_0={10}^{-6}$ (right panel) using $M_{H_1}=120\mathrm{GeV}$.

Figure 5

Charged Higgs decay length as a function of $x_0$ for different values of $M_{H^{+}}$. The green line indicates the minimum needed for observation of a secondary vertex.

Figure 6

Branching ratios for $H_2$ as a function of its mass when $a_2=-1.0$ (left panel) and $a_2=0$ (right panel) using $M_{H_1}=120\mathrm{GeV}$.

Figure 7

Branching ratios for $H_2$ as a function of its mass when $a_2=+1.0$ using $M_{H_1}=120\mathrm{GeV}$.

Figure 8

Decay length of the heavy neutral Higgs versus $x_0$ for $a_2=-1$ (left panel) and $a_2=0$ (right panel).

Figure 9

Decay length of the heavy neutral Higgs versus $x_0$ when $a_2=1$.

Figure 10

Ratios between the various $H_2$ and $H^{+}$ decays when the scalars are heavy.

Figure 11

Left panel: LHC production rate of $H^{\pm }{H}_2$ and $H^{+}{H}^{-}$. Right panel: Tevatron production rate for the same channels.

Figure 12

LHC production rate of VBF $jj{H}^{\pm }{H}_2$ and VBF $jj{H}^{+}{H}^{-}$ of real triplet model.

Figure 13

LHC production of $j+H^{\pm }{H}_2$ and $j{H}^{\pm }{H}^{\mp }$.

Figure 14

LHC production of $\gamma H^{\pm }{H}_2$ and $\gamma H^{\pm }{H}^{\mp }$.

Figure 15

VBF production of triplet Higgs pairs at the LHC with VBF selection cuts. Solid lines are for basic cuts only and dashed lines are for VBF cuts.

Figure 16

$p_T(\gamma )$ distribution for $pp\to H^{\pm }{H}_2\to {\tau }^{\pm }\nu \gamma \gamma$ at the LHC.

Figure 17

$M_{\gamma \gamma }$ of $M_H=120\mathrm{GeV}$ distribution for CMS resolution.

Figure 18

Lepton transverse momentum, $p_T(\ell )$ from $\tau$ decay product of $H^{+}$.

Figure 19

$S/\sqrt{B}$ at $100{\mathrm{fb}}^{-1}$ for $\gamma \gamma$, $x_0={10}^{-3}\mathrm{GeV}$ and $x_0={10}^{-6}\mathrm{GeV}$, where black, red, and blue correspond to $a_2=-1$, 0, $+1$ respectively.

Figure 20

Rate for $H^{+}{H}_2\to \tau \nu b\overline{b}\to \ell b\overline{b}+{\mathrm{E̸}}_T$ at the Tevatron using the SM Higgs search event selection criteria.