arXiv subjects

Felix Kling

Publications and source records attributed to Felix Kling.

96 records · Page 6Linked to original sources

arXiv2016

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 $\tanβ$ 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 ${\rm BR}(A/H \rightarrow ττ)=8.6\%$, 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 $\tanβ> 17$ for 155 GeV $< m_{H^\pm} <$ 165 GeV, and small $\tanβ< 6$ over the entire mass range. Exclusion is possible in the entire $\tanβ$ 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 $H^\pm \rightarrow τν$ channel.

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arXiv2016

Charged Higgs Search via $AW^\pm/HW^\pm$ Channel

Models of electroweak symmetry breaking with extended Higgs sectors are theoretically well motivated. In this study, we focus on models with a low energy spectrum containing a pair of charged scalars $H^\pm$, as well as a light scalar H and/or a pseudoscalar A. We study the $H^\pm tb$ associated production with $H^\pm \to AW/HW$, which could reach sizable branching fractions in certain parameter regions. With detailed collider analysis, we obtain the exclusion bounds as well as discovery reach at the 14 TeV LHC for the process $pp \to H^\pm tb \to AW^\pm tb/HW^\pm tb \to ττbbWW, bbbbWW$. We find that for a daughter particle mass of 70 GeV, the 95% C.L. exclusion reach in $σ$xBR varies from about 60 fb to 25 fb, for $m_{H^\pm}$ ranging from 150 GeV to 500 GeV with 300 fb$^{-1}$ integrated luminosity in the $ττ$ mode. We further interpret these bounds in the context of Type II Two Higgs Doublet Model. The exclusion region in the $m_{H^\pm}-\tanβ$ plane can be extended to $m_{H^\pm}=$ 600 GeV, while discovery is possible for $m_{H^\pm}\lesssim$ 400 GeV with 300 fb$^{-1}$ integrated luminosity. The exotic decay mode $H^\pm \to AW^\pm/HW^\pm$ offers a complementary channel to the conventional mode $H^\pm \to τν$ for charged Higgs searches.

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arXiv2014

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, ττll and ZZZ(4l2j) for l =e,μ. 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 tanβ-sin(β-α) parameter space can be covered by exclusion and discovery. For 126 GeV $h^0$, only relatively small tanβ<10 (5) can be reached by exclusion (discovery). For $A\rightarrow H^0Z$, the reach is typically restricted to sin$(β-α)\sim\pm 1$ with tanβ<10 in bbll and ττll channels. The ZZZ (4l2j) channel, on the other hand, covers a wide range of 0.3<|sin(β-α)|<1 for tanβ<4. $H^0\rightarrow AZ$ typically favors negative values of sin(β-α), with exclusion/discovery reach possibly extending to all values of tanβ. A study of exotic decays of extra Higgses would extend the reach at the LHC and provides nice complementarity to conventional Higgs search channels.

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arXiv2014

Constraining Type II 2HDM in Light of LHC Higgs Searches

We study the implication of the LHC Higgs search results on the Type II Two Higgs-Doublet Model. In particular, we explore the scenarios in which the observed 126 GeV Higgs signal is interpreted as either the light CP-even Higgs $h^0$ or the heavy CP-even Higgs $H^0$. Imposing both theoretical and experimental constraints, we analyze the surviving parameter regions in $m_H$ ($m_h$), $m_A$, $m_{H^\pm}$, $\tanβ$ and $\sin(β- α)$. We further identify the regions that could accommodate a 126 GeV Higgs with cross sections consistent with the observed Higgs signal. We find that in the $h^0$-126 case, we are restricted to narrow regions of $\sin(β-α) \approx \pm 1$ with $\tanβ$ up to 4, or an extended region with $0.55 < \sin(β-α) < 0.9$ and $1.5 < \tanβ< 4$. The values of $m_H$, $m_A$ and $m_{H^\pm}$, however, are relatively unconstrained. In the $H^0$-126 case, we are restricted to a narrow region of $\sin(β-α) \sim 0$ with $\tanβ$ up to about 8, or an extended region of $\sin(β-α) $ between $-0.8$ to $-0.05$, with $\tanβ$ extended to 30 or higher. $m_A$ and $m_{H^\pm}$ are nearly degenerate due to $Δρ$ constraints. Imposing flavor constraints shrinks the surviving parameter space significantly for the $H^0$-126 case, limiting $\tanβ\lesssim 10$, but has little effect in the $h^0$-126 case. We also investigate the correlation between $γγ$, $VV$ and $bb/ττ$ channels. $γγ$ and $VV$ channels are most likely to be highly correlated with $γγ:VV \sim 1$ for the normalized cross sections.

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arXiv2013

Exotic Higgs Decay via AZ/HZ Channel: a Snowmass Whitepaper

While the conventional searches for the Higgs boson focus on its decays to Standard Model (SM) particles: gamma gamma, ZZ, WW, bb and tau tau, in this study, we explore the decays A --> HZ or H --> AZ. Such decays could appear in the exotic decay of the observed SM-like Higgs h --> AZ with a light A, or for extra Higgses in beyond the SM new physics scenarios with an extended Higgs sector. We study the exclusion bounds as well as discovery reach at the LHC for various combinations of (m_A, m_H) for the process: gg --> A/H --> HZ/AZ --> bbll for l =e, mu. We find that for 14 TeV LHC with 300 fb^{-1} integrated luminosity, the 95% C.L. limits on the cross-section for gg --> A/H --> HZ/AZ --> bbll vary between about 30 fb to a few fb for the parent heavy Higgs mass in the range 200 GeV to 600 GeV, while the limits for 5 sigma discovery are about 2-3 times larger. Comparing with the specific case of Next to Minimal Supersymmetric Standard Model, we find that this channel could be useful for heavy Higgs searches, especially for Higgs masses below 350 GeV.

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arXiv2012

Tagging single Tops

Top taggers which identify and reconstruct boosted top quarks have been established as novel tools for a multitude of LHC analyses. We show how single top production in association with a light-flavor or bottom jet can be observed in the boosted phase space regime. The full top reconstruction as part of the tagging algorithm allows us to define a distinctive kinematic angle which clearly separates different single top production processes.

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