arXiv subjects

Nadia Kausar

Publications and source records attributed to Nadia Kausar.

5 recordsLinked to original sources

arXiv2022

Possibility of observing charged Higgs in the single top production via its $τ$ lepton decay at LHC

Single top quark production through weak interactions is considered to be an important source of charged Higgs in the Minimal Super Symmetric Standard Model. In the s-channel single top production 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. The process under investigation is $pp \rightarrow H^{\pm}\rightarrow tb \rightarrow b\bar{b}W^{\pm} \rightarrow b\bar{b}τ^{\pm} ν_τ$, where top quark exclusively decays into a pair of bottom quark and W boson while W boson subsequently decays to $τ$ jet and neutrino. So the final state is characterized by the presence of two b jets, hadronic $τ$ decay and missing transverse energy. Within the presence of QCD multijet and electroweak background events at LHC, it has been demonstrated that the charged Higgs signal observability is possible within the available MSSM parameter space (tan$β$, $m_{H^{\pm}})$ respecting all experimental and theoretical constraints. In order to show the observability potential of charged Higgs, the exclusion curves at 95$\%$ confidence level and 5$σ$ contours are plotted at different integrated luminosities with $\sqrt{s}=$14 TeV.

hep-ph↗

arXiv2021

Charged Higgs Observability via Charged Higgs Pair Production at Future Lepton Collider

The observability of charged Higgs $ H^{\pm} $ has been investigated at future lepton collider by assuming type-I 2HDM, at a centre of mass energy $ \sqrt{s}=1.5$ TeV. The signal process chain is $ e^{+}e^{-} \rightarrow Z^{*}/ γ^{*}\rightarrow H^{+} H^{-}\rightarrow H W^{+} H W^{-}\rightarrow b \overline{b} jjb \overline{b} jj$. The process proceed through virtual gamma and Z-boson exchange in S-channel. Several benchmark points are selected and events are analyzed to reconstruct the mass of charged Higgs bosons $ H^{\pm} $. The value of $\tanβ$ is kept relatively high to enhance the branching ratio of $ H\rightarrow b\overline{b} $ to benefit the signal processes. The main SM background processes produced is $ t\overline{t} $. Signal selection and significance efficiencies are calculated at integrated luminosities of $100 fb^{-1} $ and $ 500 fb^{-1} $. The reconstructed and corrected mass of charged Higgs bosons $ H^{\pm} $ is determined. Through analyzing the results, it is demonstrated that charged Higgs bosons can be discovered through pair production process via its bosonic decays. This study is supposed to provide the experimentalists a good way to examine the Higgs bosons beyond SM, as well as to check the validity of 2HDM models in considered parameter space.

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arXiv2021

Observability of 2HDM Neutral Higgs Bosons in fully hadronic decay at future linear collider

The study aims to investigate the observability of pseudoscalar Higgs boson $A$ and neutral heavy CP even Higgs boson $H$, at different benchmark points, in the framework of type-I 2HDM. The study is done for $e^{-}e^{+}$ collisions at $\sqrt{s}$ = 1000 GeV centre of mass energy (c.o.m.) a possible scenario in future lepton collider. The associated production of $A$ and $H$ in $e+ e-$ collisions are investigated in fully hadronic final state in two different channels. The first one is $AH \to ZHH \to j\bar{j} b \bar{b}b\bar{b}$ while the other one is $AH \to b \bar{b}b\bar{b}$. The observability of neutral heavy Higgs and pseudoscalar Higgs signal is possible within the parameter space $ (\tan β, m_{A}) $ which satisfies all experimental and theoretical constraints. The CP odd and CP even Higgs bosons in all scenarios are observable when signal exceeds $ 5σ$, which is the final extracted value of signal significance. The signal significance is calculated at different integrated luminosities. It is concluded from current analysis that fully hadronic channel is promising for search and measurement of the neutral Higgs Bosons in 2HDM.

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arXiv2020

Charged Higgs observability 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 $pp \rightarrow H^{\pm}\rightarrow tb \rightarrow b\bar{b}W^{\pm} \rightarrow b\bar{b}τ^{\pm} ν_τ$, where top quark exclusively decays into a pair of b quark and W boson while W boson subsequently decays to $τ$ jet and neutrino. So the final state is characterized by the presence of two b jets, hadronic $τ$ decay and missing transverse energy.It has been demonstrated that the charged Higgs signal observability is possible within the available MSSM parameter space (tan$β$, $m_{H^{\pm}})$ 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 ($β> 35$ at 500 $fb^{-1}$ , $β> 25$ at 1000 $fb^{-1}$ , $β> 15$ at 3000 $fb^{-1}$ ) at $\sqrt{s}=$14 TeV.

hep-ph↗

arXiv2020

Constraints on $H^\pm$ parameter space in 2HDM at $\sqrt{s}=$ 8 TeV and $\sqrt{s}=$ 13 TeV

This paper reflects the heavy Higgs scenario where the mass of charged Higgs is equal to or greater than 200 GeV. The CMS observed and expected values of upper limits on the product $σ_H^\pm BR(H^\pm \rightarrow tb^\mp)$, assuming $H^\pm \rightarrow tb^\mp=1$, both at 8 TeV (at integrated luminosity of 19.7 $fb^{-1}$ ) and 13 TeV (at integrated luminosity of 35.9 $fb^{-1}$ ) c.m energies are used. By comparing these expected and observed upper limits with computational values , we find out the expected and observed exclusion regions of charged Higgs parameter space ($ m_H^\pm - tanβ$ space ) in 2HDM both at $\sqrt{s}=$8 and $\sqrt{s}=$ 13 TeV. We compare the expected and observed exclusion regions and observe that exclusion regions made by observed upper limits are always greater than the exclusion made by expected upper limits both at 8 and 13 TeV c.m energies. Only in the mass range from 200 GeV to 220 GeV the expected exclusion region is greater than the observed one only at $\sqrt{s}=$13 TeV. We also equate the exclusion regions at these two different center of mass energies and find that the expected exclusion region and observed exclusion region at $\sqrt{s}=$13 TeV are always greater than the expected exclusion region and observed exclusion region at $\sqrt{S}=$8 TeV respectively.

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