arXiv subjects

Taimoor Khurshid

Publications and source records attributed to Taimoor Khurshid.

6 recordsLinked to original sources

arXiv2024

Analysis of trilinear Higgs self coupling in Two Higgs Doublet model at lepton collider

In this study, computational analysis of neutral Higgs bosons $h$, $H$ and $A$ is carried out within the parameter space of Two Higgs Doublet Model (2HDM) type-I in exact alignment limit of $\sin{(β- α)} = 1$ at compact linear collider. Assuming Compact Linear Collider (CLIC) scenario where the electron-positron beams will be collided at $\sqrt{s}$ = 1.5 TeV. Two different values of predicted integrated luminosities are used in our calculations, 1000 $fb^{-1}$ and 2500 $fb^{-1}$. Three signal processes $e^+ e^- \rightarrow Zhh \rightarrow jjb\bar{b}b\bar{b}$, $e^+ e^- \rightarrow ZHH \rightarrow jjb\bar{b}b\bar{b}$ and $e^+ e^- \rightarrow Zhh \rightarrow jjb\bar{b}b\bar{b}$ are selected for analysis. The polarized colliding beams are used to enhance the signal production cross-section. Low $\tanβ$ and equal Higgs masses regime is chosen in favor of Hadronic decay of $Z$ boson and $H \rightarrow b\bar{b}$. Different signal scenarios are selected and event generation is performed for each process separately. The $W$ and $Z$ boson, as well as top quark backgrounds are analyzed. Signal significance is computed at each Higgs mass hypothesis for three signal processes. After a comprehensive study, we did not find sizeable amount of signal events on top of the background but still, signal significance is found to be larger than 1, without taking into account the detector effects and systematics. The maximum calculated value of signal significance is observed to lie in the range of 150 $\leq$ $m_H$ $\leq$ 250 GeV for $Zhh$ while for $ZHH$ the range is 175 $\leq$ $m_H$ $\leq$ 200 GeV at 1000 $fb^{-1}$ and 175 $\leq$ $m_H$ $\leq$ 225 GeV region at 2500 $fb^{-1}$. Similarly, for $ZAA$ process, the significance is highest at $m_A$ = 175 GeV for both 1000 and 2500 $fb^{-1}$.

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arXiv2023

Effect of Polarized Colliding Beam on Higgs Boson production at the Lepton Collider

Different production processes involving the Higgs boson, such as annihilation and W/Z boson fusion, will be observed in the International Linear Collider (ILC). The ILC operates at a center-of-mass (CM) energy of $\sqrt{s}$ = 200-1000 GeV. The study reveals that the production cross-section can either be enhanced or reduced depending on the CM energy and the specific combination used, which has implications for selecting appropriate production processes. Additionally, this investigation highlights that by polarizing beams, the number of measurable observables increases. These observables, such as left$~$right asymmetry, detailed effective polarization, and adequate effective luminosity, are crucial to ascertain contemporary physical parameters in physics models absurdly the Standard Model (SM).

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arXiv2023

Pair production of heavy charged gauge bosons in $pp$ collisions at LHC

Two opposite charged new heavy gauge boson pair production at the Large Hadron Collider (LHC) is presented in this paper. These bosons are known as $W^{'}$ boson due to the reason that it is the heavy version of Standard Model's weak force carrier, the $W$ boson. The production cross section and decay width in proton-proton ($pp$) collision at \sqrts~= 8 TeV are calculated for different masses and coupling strengths of $W^{'}$. Efficiencies for different signal regions and branching ratios for different decay channels are computed. In this study, the pair production ($W^{'^{+}}W^{'^{-}}$) is considered in emerging new physics as a result of $pp$ collision at \sqrts~= 8 TeV at the LHC with final state containing two tau ($τ$) leptons and two neutrinos (each $W^{'}$ decay to $τ$ and its neutrino). The event selection efficiency similar to the CMS experiment is used for the mass of $W^{'}$ to set lower limits for different coupling strengths of $W^{'}$ and results are presented in this work. For heavy gauge bosons, when coupling strength is similar to that of Standard Model's $W$ boson, the mass of $W^{'}$ below 305 GeV are excluded at confidence level of $95\%$.

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arXiv2021

Probing triple higgs self coupling and effect of beam polarization in lepton colliders

One of the main objectives of almost all future (lepton) colliders is to measure the self-coupling of triple Higgs in the Standard Model. By elongating the Standard Model's scalar sector, using incipient Higgs doublet along with a quadratic (Higgs) potential should reveal many incipient features of the model and the possibility of the emergence of additional Higgs self-couplings. The self-coupling of the Higgs boson helps in reconstructing the scalar potential. The main objective of this paper is to extract Higgs self-coupling by numerically analyzing several scattering processes governed by two Higgs doublet models (2HDM). These scattering processes include various possible combinations of final states in the triple Higgs sector. The determination of production cross-section of scattering processes is carried out using two different scenarios, with and without polarization of incoming beam and is extended to a center of mass energy up to $\sqrt{s}$ = 3 $TeV$. The computation is carried out in Type-1 2HDM. Here we consider the case of exact alignment limit ($s_{βα}$ = 1) and masses of extra Higgs state are equal that is $m_H = m_{H^0} = m_{A^0} = m_{H^\pm}$. This choice is made to minimize the oblique parameters. The decays of the final state of each process are investigated to estimate the number of events at integrated luminosity of $1ab^{-1}$ and $3ab^{-1}$.

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arXiv2021

Double and Triple Higgs Boson Production at Future Linear Colliders

In this paper such processes which act as a source of double Higgs production (2H) as well as triple Higgs production (3H) at future linear colliders are analyzed with in 2HDM and its special type-II, MSSM at various center of mass energies. The main aim of this study is to compute and also compare the cross-sections in double and triple Higgs production processes at the future linear colliders. The production of double charged Higgs boson ($H^{+}H^{-}$) as well as triple Higgs boson ($H^{+}H^{-}H^{0}$),($H^{+}H^{-}h^{0}$) are considered for study at two center of mass energies (1.5 TeV and 3 TeV) within two models 2HDM and MSSM at future linear colliders. It is observed that for double charged Higgs production process (H${}^{+}$H${}^{-}$) the resulting cross-section values are almost same in both the models (in 2HDM and MSSM). On the other hand in the case of Triple Higgs production process ($H^{+}H^{-}H^{0}$), ($H^{+}H^{-}h{0}$) several orders of enhancement in cross-sections is observed in 2HDM as compared to MSSM. Similarly two types of processes, neutral Higgs pair production ($A^{0} H^{0}$) as well as ($A^{0} h^{0}$) and triple neutral Higgs production ($h^{0}h^{0}A^{0}$) is analyzed in 2HDM type-I at the future linear $μ^{+}$$μ^{-\ }$ collider for various values of center of mass energies from 500 GeV to 3000 GeV (0.5 TeV to 3 TeV). It is observed that the cross-section for neutral Higgs pair production ($A^{0} h^{0}$) process is comparatively greater than that of neutral Higgs pair production ($A^{0} H^{0}$) process. Similarly for neutral Higgs Triple production ($h^{0}h^{0}A^{0}$) an enhancement is seen in cross-sections with increase of tanß.

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arXiv2021

Correlation between the scaling factor of the yukawa coupling and cross section for the $e^+ e^- \rightarrow hhf\overline{f}$ ($f\neq t$) in type-I 2HD

The objective of this study is to correlate the scaling factor of the Standard Model (SM) like Higgs boson and the cross section ratio of the process $e^+ e^- \rightarrow hhf\overline{f}$ where $f\neq t$, normalized to SM predictions in the type I of the Two Higgs Doublet Model. All calculations have been performed at $\sqrt{s}=500$ GeV and $1 \leq \tanβ \leq 30$ for masses $m_H = m_A = m_{H^\pm} = 300GeV$ and $m_H=300$ GeV, $m_A=m_{H^\pm}=500$ GeV. The working scenario is by taking without alignment limit, that is $s_{β-α}= 0.98$ and $s_{β-α}= 0.99,$ $0.995$, which gives the enhancement in the cross section, particularly a few times greater than the predictions of the SM due to resonant-impacts of the additional heavy neutral Higgs bosons. This shows that enhancement in cross section occurs on leaving the alignment i.e., $s_{β-α}=1$, at which all the higgs that couple to vector bosons and fermions have the same values as in SM at tree level. A large value of enhancement factor is obtained at $s_{β-α}= 0.98$ compared to $s_{β-α}= 0.99,$ $0 .995$. Furthermore, the decrease in the enhancement factor is observed for the case when $m_H=300$ GeV, $m_A=m_{H^\pm}=500$ GeV. The behavior of the scaling factor with $\tanβ$ is also studied, which shows that for large values of $\tanβ$, the scaling factor becomes equal to $s_{β-α}$. Finally a convincing correlation is achieved by taking into account, the experimental and theoretical constraints e.g, perturbative unitarity, vacuum stability and electroweak oblique parameters.

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