Supersymmetry with a sister Higgs boson

We consider a simple addition to the minimal supersymmetric Standard Model (MSSM) of a “sister Higgs” (${\mathrm{\Sigma }}_d$), a Higgs field that participates in electroweak symmetry breaking but does not give any direct masses to Standard Model matter fields. If this new field carries charge under a new gauge group, $G_s$, the Higgs mass is naturally much larger than in the MSSM due to a next-to-minimal supersymmetric Standard Model–type interaction, but with ${\mathrm{\Sigma }}_d$ playing the role of $H_d$. The addition of the sister Higgs allows new $R$-parity violating operators ${\mathrm{\Sigma }}_d{H}_{d}E$, which are less constrained than a conventional leptonic $R$-parity violation. Unification motivates the presence of colored $G_s$-charged fields, whose production can lead to new $b$-rich final states and modifications to decays of gluinos, as well as new opportunities for $R$-parity violation. The presence of additional sister charges allows the possibilities that a lightest sister-charged particle (LSiP) could be stable, although we find the possibility of a LSiP dark matter candidate is generally very constrained.

Figure 1

IR values of $\tan \beta$ and ${\lambda }_u$ when scanning over the range [0,4] for the UV inputs $g_S$, ${\lambda }_u$, and $y_t$. Different ranges for $g_S(1\mathrm{TeV})$ are denoted by different symbols, circle: $g_S<0.5$, square: $0.5\le g_S<1$, cross: $1\le g_S<1.5$, and diamond: $g_S\ge 1.5$. The lines show the parameters for which a Higgs of 125 GeV is achieved at tree level (solid line), with stops of 250 GeV (dashed line), 500 GeV (dotted line) and 1 TeV (dot-dashed line).

Figure 2

Example spectrum of fermions, in our simplified limit. States in red are charged under the global $U(1{)}_s$. No special ordering of mass scales is implied.

Figure 3

Example spectrum of scalars and vector bosons, in our simplified limit. States in red are charged under the global $U(1{)}_s$.

Figure 4

Bounds on $Z_s-Z$ mixing expressed in terms of $m_{Z_s}$, $\tan \beta$, and $g_s$, from precision electroweak constraints of the $\rho$-parameter (red lines) and direct collider searches for dilepton resonances [31] (blue lines). The latter are derived assuming that $Z_s$ has the same branching ratios to leptons as the SM $Z^0$. The region below each line is excluded.

Figure 5

Saturating the bounds for the $\rho$-parameter, there can be a sizable contribution to $Z^0{h}^0$ production at the Tevatron through resonant $Z_s$ production. At the LHC, it is a small correction to the SM process.

Figure 6

Squark and stop decay modes in the leptonic sister RPV scenario.

Figure 7

Distribution of $m_T^{{\tau }_1}+m_T^{{\tau }_2}$ for the event selection of the ATLAS search in [44]. The SM background, as estimated in [44], is displayed in gray, and the measured data is shown as black dots. Two benchmark signals with masses at the boundary of the this analysis’ reach are displayed as well: (left panel) degenerate first and second generation squark LSPs decaying as $\tilde{q}\to q^{\prime }{\tau }^{\pm }$, and (right panel) stop LSP decaying as $\tilde{t}\to b{\tau }^{+}$.

Figure 8

Neutralino LSP decay modes induced by leptonic sister RPV.

Figure 9

Chargino LSP decay modes induced by leptonic sister RPV.

Figure 10

Slepton and Sneutrino LSP decays induced by leptonic sister RPV.

Figure 11

(Left panel) Direct detection bounds on $g_s$ vs $m_{Z_s}$ fixing $\tan \beta =4$ and ${\lambda }_u=0.6$, assuming that dark matter is dominantly the gaugino LSiP, ${\tilde{W}}_s$. The gray region is excluded due to large $Z-Z_s$ mixing, and the colored regions are allowed when the mixing of ${\tilde{W}}_s$ with ${\tilde{\mathrm{\Sigma }}}_s$ is sufficiently suppressed, which can be achieved with ${\mu }_{\varphi },{\mu }_{\mathrm{\Sigma }}\sim \mathcal{O}(1)\mathrm{TeV}$. (Right panel) ${\tilde{W}}_s$ relic abundance, assuming $m_{Z_s}=600\mathrm{GeV}$.

Figure 12

Relative ${\tilde{W}}_s{\tilde{W}}_s$ annihilation cross section to $Z^0{h}^0$ vs light SM fermions as a function of $m_{Z_s}$. The LSiP mass is set to $m_{{\tilde{W}}_s}=m_{Z_s}/2$.

Figure 13

Topology of a 3-body squark decay to two invisible sister particles.

Figure 14

Contrast between the ${\cancel{E}}_T$ and $H_T$ distributions of 2- and 3-body squark decays. We assume $m_{\tilde{q}}=400\mathrm{GeV}$; for the 2-body decay, the mass of the invisible particle is 200 GeV, and for the 3-body decay the two invisible particles have mass of 100 GeV.

Figure 15

(a) Gluino decay topology to ${\tilde{d}}_g{D}_g$, resulting in final states with $2j+4b+{\tilde{\chi }}^0$. (b) Benchmark spectrum with small splitting between $m_{{\tilde{d}}_g}$ and $m_{D_g}+m_{{\tilde{\chi }}^0}$.