Charged Higgs Signal Research Articles

Confronting dark fermion with a doubly charged Higgs in the left–right symmetric model

We consider a fermionic dark matter (DM) in the left–right symmetric framework by introducing a pair of vector-like (VL) doublets in the particle spectrum. The stability of the DM is ensured through an unbroken mathcal {Z}_2 symmetry. We explore the parameter space of the model compatible with the observed relic density and direct and indirect detection cross sections. The presence of charged dark fermions opens up an interesting possibility for the doubly charged Higgs signal at LHC and ILC. The signal for the doubly charged scalar decaying into the dark sector is analyzed in multilepton final states for a few representative parameter choices consistent with DM observations.

Possibility of Observing Charged Higgs in the Single Top Production Channel at LHC

Single top quark production through weak interactions is an important source of charged Higgs in the Minimal Super Symmetric Standard Model. In the s-channel single top production ,charged Higgs having largest cross-section may appear as a propagator in the form of heavy resonance state decaying to a pair of top and bottom quark. In this paper the channel under consideration is $pp \rightarrow H^{\pm}\rightarrow tb \rightarrow b\bar{b}W^{\pm} \rightarrow b\bar{b}\tau^{\pm} \nu_{\tau}$, where top quark exclusively decays into a pair of b quark and W boson while W boson subsequently decays to $\tau$ jet and neutrino. So the final state is characterized by the presence of two b jets, hadronic $\tau$ decay and missing transverse energy.It has been demonstrated that the charged Higgs signal observability is possible within the available MSSM parameter space (tan$\beta$, $m_{H^{\pm}})$ respecting all experimental and theoretical constraints due to presence of QCD multijet and electroweak background events at LHC. In order to show the observability potential of charged Higgs, the charged Higgs signal are well observed or excluded in a wide range of phase space particular ($\beta > 35$ at 500 $fb^{-1}$ , $\beta > 25$ at 1000 $fb^{-1}$ , $\beta > 15$ at 3000 $fb^{-1}$ ) at $\sqrt{s}=$14 TeV.

Search for more sensitive observables to charged scalar in $B \rightarrow D^{(*)}\tau\nu_{\tau}$ decays.

It has been known that $B \rightarrow D^{(*)} \tau \nu_{\tau}$ are good observables in the search for the charged Higgs. The recent obervation of deviation from standard-model by almost 4$\sigma$ by Babar, Belle and LHCb in $R(D^{(*)})$ revived the interest in possible signal of presence of charged Higgs in these modes. But such a large deviation in the rates, where standard-model has tree level contribution, coming from a charged Higgs alone is highly unlikely. However these decay modes are good probes to search for small charged Higgs signal if we can construct sensitive observables in these modes. In this work we would like to propose four new observables which shows much more sensitivity to the presence of charged Higgs than the usual observables such as $A_{\lambda}^{D^{(*)}}$ and $A_{\theta}^{D^{(*)}}$. These four observable are (1) $\frac{1}{A_{\lambda}^{D}}$, (2) $Y_{1}(q^{2}) = \frac{A^{D}_{\theta}}{A^{D}_{\lambda}}$, (3) $Y_{2}(q^{2}) = \frac{d\Gamma(B \rightarrow D^{*}\tau\nu_{\tau})}{d\Gamma_{D}(\lambda_{\tau}=+1/2) - d\Gamma_{D}(\lambda_{\tau}=-1/2)}$ and (4) $Y_{3}(q^{2}) = (\frac{q^{2}}{m^{2}_{\tau}})(A^{D}_{\lambda} + 1)\frac{1}{A^{D}_{\lambda}}$.

Probing heavy charged Higgs boson at the LHC

Signature of heavier charged Higgs boson, much above the top quark mass, is investigated at the LHC Run 2 experiments, following its decay mode via top and bottom quark focusing on both hadronic and leptonic signal final states. The generic two Higgs doublet model framework is considered with a special emphasis on supersymmetry motivated Type II model. The signal is found to heavily affected by the huge irreducible backgrounds due to the top pair production and QCD events. The jet substructure technique is used to tag moderately boosted top jets in order to reconstruct charged Higgs mass. The simple cut based analysis is performed optimizing various kinematic selections, and the signal sensitivity is found to be reasonable for only lower range of charged Higgs masses for very high luminosity 3000 fb$^{-1}$ option. However, employing the multi-variate analysis(MVA) technique, a remarkable improvement in signal sensitivity is achieved. We find, the charged Higgs signal for the mass range about $300-600$ is observable with 1000 fb$^{-1}$ luminosity option. However, for more high luminosity option 3000 fb$^{-1}$, the discovery potential can be extended to $700-800$ GeV.

The s-channel charged Higgs in the fully hadronic final state at LHC

With the current measurements performed by CMS and ATLAS experiments, the light charged Higgs scenario ($m_{H^{\pm}}$ $<$ 160 GeV), is excluded for most of the parameter space in the context of MSSM. However, there is still possibility to look for heavy charged Higgs boson particularly in the $s$-channel single top production process where the charged Higgs may appear as a heavy resonance state and decay to $t\bar{b}$. The production process under consideration in this paper is $pp \ra H^{\pm} \ra t\bar{b}~+~h.c.$, where the top quark decays to $W^{+}b$ and $W^{+}$ boson subsequently decays to two light jets. It is shown that despite the presence of large QCD and electroweak background events, the charged Higgs signal can be extracted and observed at a large area of MSSM parameter space ($m_{H^{\pm}}$,tan$\beta$) at LHC. The observability of charged Higgs is potentially demonstrated with 5$\sigma$ contours and $95\%$ confidence level exclusion curves at different integrated LHC luminosities assuming a nominal center of mass energy of $\sqrt{s}$ = 14 TeV.

Observability of triple or double charged Higgs production in two Higgs doublet model type II at an e+e- linear collider

In this paper the charged Higgs signal through triple or double Higgs production in a two Higgs doublet model (2HDM) type II is studied. The main production process is e+e- →H+H-H0 followed by the charged Higgs decay to a pair of τν and the neutral Higgs decay to [Formula: see text]. The alternative process H+W-H0 is also included as a source of charged Higgs signal in the analysis. The focus is on a future e+e- linear collider operating at [Formula: see text]. The final state under consideration [Formula: see text] is suitable for electroweak background rejection using the b-tagging tools. It is shown that although the signal cross-section is small, with a reasonable background suppression, high signal significance values are achievable at an integrated luminosity 500 fb-1 depending on the charged Higgs mass, tan β and the CP-odd neutral Higgs mass. Finally results are quoted in terms of the signal significance for charged Higgs in the mass range 160 &lt; mH± &lt; 400 GeV .

Single top events as a source of light charged Higgs in the fully hadronic final state at LHC

The single top production proceeds through different channels at LHC. The t-channel production which has a cross section at the level of one third of the ttbar, can be regarded as a source of light charged Higgs boson through top quark decay to charged Higgs. Due to the low jet multiplicity and characteristic kinematic features of this process, a signal selection can be designed to extract charged Higgs signal from the background processes. In this paper, taking MSSM as the theoretical framework, The light charged Higgs signal from single top events is analyzed. The charged Higgs is assumed to decay to tau nu and the hadronic decay of tau leptons is analyzed. Different charged Higgs mass hypotheses are analyzed and a scan over the parameter space (mH+,tanbeta) is performed. It is shown that this process has the potential to exclude large areas of parameter space, while with enough data, a 5 sigma discovery would also be possible. Finally 95% C.L. exclusion and 5 sigma contours are provided for different integrated luminosities of LHC.

Observability of light charged Higgs decay to muon in top quark pair events at LHC

In this paper the charged Higgs signal through the decay to a pair of muon and neutrino (H -> mu nu) is analyzed. The analysis attempts to estimate the amount of muonic signal of the charged Higgs at LHC at a center of mass energy of 14 TeV. The signal process is the top quark pair production with one of the top quarks decaying to a charged Higgs (non SM anomalous top quark decay) and the other decaying to a W boson which is assumed to decay hadronically to two light jets. Due to the small branching ratio of charged Higgs decay to muon, results are quoted for data corresponding to an integrated luminosity of 300 fb^-1 which is expected to be collected at the LHC high luminosity regime. It is shown that a signal significance close to 5 down to below 1 is achievable for a charged Higgs mass in the range 80 GeV < m(H \pm) < 150 GeV taking the top quark pair production with both top quarks decaying to W bosons as the main irreducible background.

Interplay between the charged Higgs and squark-gluino events at the LHC

In some extensions of the standard model with extended Higgs sectors, events from new particle production may pass the selection criteria for Higgs search in different channels at the LHC---14 TeV and mimic Higgs signals. This intriguing possibility is illustrated by PYTHIA based simulations using several representative points in the parameter space of the minimal supersymmetric standard model (MSSM) including a point in the minimal supergravity model consistent with the dark matter (DM) relic density data. Our simulations explore the interplay between the charged Higgs signal and typical squark-gluino events. We argue that the standard selections like the one based on the polarization properties of the $\ensuremath{\tau}$'s from charged Higgs decay, though adequate for handling the SM backgrounds, may not be very efficient in the presence of SUSY backgrounds. We then propose an alternative search strategy based on pure kinematics which sufficiently controls both the SM and the MSSM backgrounds. For charged Higgs masses (${H}^{\ifmmode\pm\else\textpm\fi{}}$) in the deep decoupling regime ($600\text{ }\text{ }\mathrm{GeV}\ensuremath{\lesssim}{m}_{{H}^{\ifmmode\pm\else\textpm\fi{}}}\ensuremath{\lesssim}800\text{ }\text{ }\mathrm{GeV}$) this method works well and extends the LHC reach close to 800 GeV for an integrated luminosity of $30\text{ }\text{ }{\mathrm{fb}}^{\ensuremath{-}1}$ with or without the SUSY background. For a lighter charged Higgs a judicious combination of the old selections and some of the cuts proposed by us may disentangle the Higgs signal from the squark-gluino backgrounds quite effectively.

Prospects for supersymmetric charged Higgs boson discovery at the Fermilab Tevatron and the CERN Large Hadron Collider

We investigate the prospects for heavy charged Higgs boson production through the mechanisms $p\overline{p}(\mathrm{pp})\ensuremath{\rightarrow}{H}^{\ifmmode\pm\else\textpm\fi{}}tb+X$ at the upgraded Fermilab Tevatron and at the upcoming LHC at CERN, respectively. We focus on the minimal supersymmetric standard model case and include the leading quantum corrections at high $\mathrm{tan}\ensuremath{\beta}.$ A detailed study is performed for all important production modes and basic background processes for the $t\overline{t}b\overline{b}$ signature. At the upgraded Tevatron a charged Higgs signal is potentially viable in the $220--250 \mathrm{GeV}$ range or excluded at 95% C.L. up to $300 \mathrm{GeV}.$ At the LHC, a ${H}^{\ifmmode\pm\else\textpm\fi{}}$ of mass up to $800 \mathrm{GeV}$ can be discovered at $5\ensuremath{\sigma}$ or else be excluded up to a mass of $\ensuremath{\sim}1.5 \mathrm{TeV}.$ The presence of SUSY quantum effects may highly influence the discovery potential in both machines and can typically shift these limits by $200 \mathrm{GeV}$ at the LHC.

Distinguishing a charged Higgs signal from a heavy WR signal

It is shown that non-Standard Model bosons should obey an observable asymmetry in their decays to taus. This assymetry enables a distinction to be made between charged Higgs boson signals and heavy right-handed W boson signals, by reconstructing the orientation of the τ with respect to the beam axis.

Discovery limit of the charged Higgs boson via top quark decay at future hadron colliders

We study the kinematic cuts which can be used to enhance the charged Higgs signal over the W boson background, for m H± > m w , in the decay of a heavy top quark at LHC energy. With suitable cuts it is possible to ensure a sizeable signal and a signal-to-background ratio ≳ 1 up to m H±⋍m t−20 GeV , which hold throughout the allowed coupling parameter (tan β) space in the minimal SUSY model. Thus one should be able to search for the charged Higgs boson to within 20 GeV of the parent top quark mass at the LHC/SSC colliders, i.e., up to 130 GeV for m t⋍150 GeV , going up to 180 GeV for m t⋍200 GeV .

SEARCH FOR CHARGED HIGGS BOSONS AT SSC

We examine the possibility of finding charged Higgs bosons (H±) at the SSC. The charged Higgs boson is produced with a top quark via a gluon+bottom quark interaction (g+b→H+t). For the two Higgs doublet models, H± decays predominantly into t+b. Since the background from QCD processes will be very severe for this decay mode, we studied the H±→τ+ν decay mode. Even for this mode, background from the processes pp→W+t+spectators→ℓ+νℓ+t+spectators will be very high. In the two Higgs doublet models, it is very difficult to extract the charged Higgs signal for reasonable values of the ratio of the two vacuum expectation values ( tan β=v1/v2).