Exotic Higgs Decay via Charged Higgs

The most common search channel for heavy neutral Higgses in models with an extension of the Standard Model Higgs sector is $A/H^0\rightarrow \tau\tau$, which becomes ineffective when new decay modes of $A/H^0$ open. In this paper, we analyzed two such channels involving charged Higgses in the final states: $A/H^0 \rightarrow W^\pm H^\mp$ and $H^0 \rightarrow H^+H^-$. With the consequent decay of $H^\pm\rightarrow \tau\nu$, we found that the limits for $\sigma\times{BR}(gg \rightarrow A/H^0 \rightarrow W^\pm H^\mp)\times {BR}(H^\pm \rightarrow \tau \nu)$ vary from 30 to 10 fb for $m_{A/H^0}$ between 300 and 1000 GeV for 95% C.L. exclusion, and about 80 to 30 fb for 5$\sigma$ discovery. For $H^+H^-$ mode, 95% C.L. limits on $\sigma\times {BR}(gg\to H^0\to H^+ H^-)\times {BR}^2(H^\pm\to \tau\nu)$ vary from 9 to 4 fb for $m_{H^0}$ between 400 and 1000 GeV, while the 5$\sigma$ reach is about 20 to 10 fb. We further interpret the cross section limits in the Type II 2HDM parameter space. While $A\rightarrow W^\pm H^\mp$ offers great sensitivity in both $\sin(\beta-\alpha)$ versus $\tan\beta$ and $m_A$ versus $\tan\beta$ parameter space, $H^0\rightarrow H^+ H^-$ can cover most of the parameter space for $H^0$. Reach in $H^0\rightarrow W^\pm H^\mp$ is more limited, especially for $m_{H^0}>2 m_{H^\pm}$. It is, however, complementary to $H^0\rightarrow H^+ H^-$ when ${BR}(H^0\rightarrow H^+ H^-)$ is accidentally suppressed.Comment: 19 pages, 11 figures, version appear in JHE

Dark Matter in the Left Right Twin Higgs Model

In the left-right twin Higgs model, one of the neutral Higgses is a natural candidate for WIMP dark matter. We analyzed the dark matter relic density in this framework and identified regions of parameter space that provide the right amount of dark matter. We also studied the dark matter in the more general inert Higgs doublet model in which the mass splittings between the dark matter and other particles do not follow the relations in the left-right twin Higgs model.Comment: 18 page

Exotic Decays Of A Heavy Neutral Higgs Through HZ/AZ Channel

Models of electroweak symmetry breaking with extended Higgs sectors are theoretically well motivated. In this study, we focus on the Two Higgs Doublet Model with a low energy spectrum containing scalars $H$ and a pseudoscalar $A$. We study the decays $A\rightarrow HZ$ or $H\rightarrow AZ$, which could reach sizable branching fractions in certain parameter regions. With detailed collider analysis, we obtain model independent exclusion bounds as well as discovery reach at the 14 TeV LHC for the process: $gg\rightarrow A/H\rightarrow HZ/AZ$, looking at final states bbll, \tau\tau ll and ZZZ(4l2j) for l =e,\mu. We further interpret these bounds in the context of the Type II Two Higgs Doublet Model, considering three different classes of processes: $A\rightarrow h^0Z$, $A\rightarrow H^0Z$, and $H^0 \rightarrow AZ$, in which $h^0$ and $H^0$ are the light and heavy CP-even Higgses respectively. For 100 fb$^{-1}$ integrated luminosity at the 14 TeV LHC, we find that for parent particle mass around 300-400 GeV, $A\rightarrow h^0Z$ has the greatest reach when $H^0$ is interpreted as the 126 GeV Higgs: most regions in the tan\beta-sin(\beta-\alpha) parameter space can be covered by exclusion and discovery. For 126 GeV $h^0$, only relatively small tan\beta<10 (5) can be reached by exclusion (discovery). For $A\rightarrow H^0Z$, the reach is typically restricted to sin$(\beta-\alpha)\sim\pm 1$ with tan\beta <10 in bbll and \tau\tau ll channels. The ZZZ (4l2j) channel, on the other hand, covers a wide range of 0.3<|sin(\beta-\alpha)|<1 for tan\beta<4. $H^0\rightarrow AZ$ typically favors negative values of sin(\beta-\alpha), with exclusion/discovery reach possibly extending to all values of tan\beta. A study of exotic decays of extra Higgses would extend the reach at the LHC and provides nice complementarity to conventional Higgs search channels.Comment: 32 pages, 21 figure

Light Charged Higgs Bosons to AW/HW via Top Decay

While current ATLAS and CMS measurements exclude a light charged Higgs ($m_{H^\pm}<160$ GeV) for most of the parameter region in the context of the MSSM scenarios, these bounds are significantly weakened in the Type II 2HDM once the exotic decay channel into a lighter neutral Higgs, $H^\pm \to AW/HW$, is open. In this study, we examine the possibility of a light charged Higgs produced in top decay via single top or top pair production, with the subsequent decay $H^\pm \rightarrow AW/HW$, which can reach a sizable branching fraction at low $\tan\beta$ once it is kinematically permitted. With a detailed collider analysis, we obtain exclusion and discovery bounds for the 14 TeV LHC assuming the existence of a 70 GeV neutral scalar. Assuming ${\rm BR}(H^\pm \rightarrow AW/HW)=100\%$ and ${\rm BR}(A/H \rightarrow \tau\tau)=8.6\%$, the 95% exclusion limits on ${\rm BR}(t \rightarrow H^+ b)$ are about 0.2% and 0.03% for single top and top pair production respectively, with an integrated luminosity of 300 ${\rm fb}^{-1}$. The discovery reaches are about 3 times higher. In the context of the Type II 2HDM, discovery is possible at both large $\tan\beta > 17$ for 155 GeV $< m_{H^\pm} <$ 165 GeV, and small $\tan\beta < 6$ over the entire mass range. Exclusion is possible in the entire $\tan\beta$ versus $m_{H^\pm}$ plane except for charged Higgs masses close to the top threshold. The exotic decay channel $H^\pm \to AW/HW$ is therefore complementary to the conventional $H^\pm \rightarrow \tau\nu$ channel.Comment: 21 pages. arXiv admin note: text overlap with arXiv:1408.411

Probing Exotic Charged Higgs Decays in the Type-II 2HDM through Top Rich Signal at a Future 100 TeV pp Collider

The exotic decay modes of non-Standard Model Higgs bosons are efficient in probing the hierarchical Two Higgs Doublet Models (2HDM). In particular, the decay mode $H^\pm\to HW^\pm$ serves as a powerful channel in searching for charged Higgses. In this paper, we analyzed the reach for $H^\pm\to HW^\pm \to t\bar{t}W$ at a 100 TeV $pp$ collider, and showed that it extends the reach of the previously studied $\tau\tau W$ final states once above the top threshold. Top tagging technique is used, in combination with the boosted decision tree classifier. Almost the entire hierarchical Type-II 2HDM parameter space can be probed via the combination of all channels at low $\tan\beta$ region.Comment: 17 page