Search for mono-Higgs signals at the LHC in the $B-L$ supersymmetric standard model

We study mono-Higgs signatures emerging in the $B-L$ supersymmetric standard model induced by new channels not present in the minimal supersymmetric standard model, i.e., via topologies in which the mediator is either a heavy $Z^{\prime }$, with mass of $\mathcal{O}(2\mathrm{TeV})$, or an intermediate $h^{\prime }$ (the lightest $CP$-even Higgs state of $B-L$ origin), with a mass of $\mathcal{O}(0.2\mathrm{TeV})$. The mono-Higgs probe considered is the standard model-like Higgs state recently discovered at the Large Hadron Collider, so as to enforce its mass reconstruction for background reduction purposes. With this in mind, its two cleanest signatures are selected: $\gamma \gamma$ and $Z{Z}^{*}\to 4l$ ($l=e$, $\mu$). We show how both of these can be accessed with foreseen energy and luminosity options using a dedicated kinematic analysis performed in the presence of partonic, showering, hadronization and detector effects.

Figure 1

Mono-Higgs as a final state: $q\overline{q}\to {\tilde{\chi }}_1^0{\tilde{\chi }}_i^0\to {\tilde{\chi }}_1^0{\tilde{\chi }}_1^{0}h$ with $\tilde{q}$ exchange (left diagram), $gg\to A^{(\prime )}/h^{(\prime )}/H^{(\prime )}\to {\tilde{\chi }}_1^0{\tilde{\chi }}_i^0\to {\tilde{\chi }}_1^0{\tilde{\chi }}_1^{0}h$ (top-right diagram) and $q\overline{q}\to Z^{(\prime )}\to {\tilde{\chi }}_1^0{\tilde{\chi }}_i^0\to {\tilde{\chi }}_1^0{\tilde{\chi }}_1^{0}h$ (bottom-right diagram).

Figure 2

Mono-Higgs as an intermediate state: $qq\to {\tilde{\chi }}_1^0{\tilde{\chi }}_1^{0}h$ with $\tilde{q}\tilde{q}$ exchange (left diagram), $gg\to A^{(\prime )}\to Z^{(\prime )}h\to {\tilde{\chi }}_1^0{\tilde{\chi }}_1^{0}h/\nu \overline{\nu }h$ plus $q\overline{q}\to Z^{(\prime )}\to Z^{(\prime )}h\to {\tilde{\chi }}_1^0{\tilde{\chi }}_1^{0}h/\nu \overline{\nu }h$ (center diagrams) and $gg\to A^{(\prime )}/h^{(\prime )}/H^{(\prime )}\to A^{(\prime )}/h^{(\prime )}/H^{(\prime )}h\to {\tilde{\chi }}_1^0{\tilde{\chi }}_1^{0}h$ and $q\overline{q}\to Z^{(\prime )}\to A^{(\prime )}h\to {\tilde{\chi }}_1^0{\tilde{\chi }}_1^{0}h$ (right diagrams).

Figure 3

Mono-Higgs as an initial state: $q\overline{q}\to {\tilde{\chi }}_1^0{\tilde{\chi }}_1^{0}h$ with $q\tilde{q}$ exchange (left diagram), $q\overline{q}\to Z^{(\prime )}h\to {\tilde{\chi }}_1^0{\tilde{\chi }}_1^{0}h/\nu \overline{\nu }h$ with $q$ exchange (center diagram) and $q\overline{q}\to A^{(\prime )}/h^{(\prime )}/H^{(\prime )}h\to {\tilde{\chi }}_1^0{\tilde{\chi }}_1^{0}h$ with $q$ exchange, respectively.

Figure 4

(Left panel) Number of events of both the signal ($pp\to Z^{\prime }\to Zh\to \gamma \gamma +{\cancel{E}}_T$) and its relevant backgrounds generated at 14 TeV and normalized per bin width after $300{\mathrm{fb}}^{-1}$ of integrated luminosity vs ${\cancel{E}}_T$ after considering all cuts applied by ATLAS [52]. (Right panel) The gray and green points are the signal benchmarks excluded by LEP constraints [$M_{Z^{\prime }}/g_{B-L}<6\mathrm{TeV}$ and ${\theta }^{\prime }>\mathcal{O}({10}^{-3})$, respectively], and the red points are the allowed ones, all mapped vs the $Z^{\prime }$ mass. The red circled point is the last benchmark point in Table 2. The blue and red dashed lines are the one and two sigma exclusion limits, respectively, by ATLAS [52].

Figure 5

Number of events of both the signal ($pp\to h^{\prime }\to hh\to \gamma \gamma +{\cancel{E}}_T$) and its relevant backgrounds generated at 14 TeV and normalized per bin width after $300{\mathrm{fb}}^{-1}$ of integrated luminosity vs ${\cancel{E}}_T$ (top panel) and $M_T(\gamma \gamma )$ (bottom panel) after considering all cuts applied by ATLAS [52].

Figure 6

The red points are the allowed signal benchmarks mapped vs the LSP mass. The red circled points are the first three benchmark points in Table 2. The blue and red dashed lines are one and two sigma exclusion limits, respectively, by ATLAS [52].

Figure 7

Number of events of both signals ($pp\to Z^{\prime }\to Zh\to 4l+{\cancel{E}}_T$ on the top plus $pp\to h^{\prime }\to hh\to 4l+{\cancel{E}}_T$ on the bottom) and their relevant backgrounds generated at 14 TeV and normalized per bin width after $300{\mathrm{fb}}^{-1}$ of integrated luminosity vs ${\cancel{E}}_T$. The cuts described in the text have been applied here.