Browsing by Subject "Higgs"
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Item Open Access Evidence of Higgs Boson Production through Vector Boson Fusion(2015) Cerio, Benjamin CThe discovery of the Higgs boson in 2012 provided confirmation of the
proposed mechanism for preserving the electroweak $SU(2) \times U(1)$
gauge symmetry of the Standard Model of particle physics. It also
heralded in a new era of precision Higgs physics. This thesis presents a
measurement of the rate at which the Higgs boson is produced by vector
boson fusion in the $WW^{(\ast)}\rightarrow\,\ell\nu\ell\nu$ decay channel. With gauge boson couplings
in both the production and decay vertices, a VBF measurement in this
channel is a powerful probe of the $VVH$ vertex strength. Using
$4.5$~fb$^{-1}$ and $20.3$~fb$^{-1}$ of $pp$ collision data collected
at respective center-of-mass energies of 7 and $8 \tev$ in the ATLAS
detector, measurements of the statistical significance and the signal
strength are carried out in the Higgs mass range $100 \leq m_H \leq
200 \gev$. These measurements are enhanced with a boosted decision
tree that exploits the correlations between eight kinematic inputs in
order to separate signal and background processes. At the benchmark
Higgs mass of $125.36 \gev$, the significance of the data assuming the
background-only hypothesis to be true has been observed to be
$3.2\sigma$ ($2.7\sigma$ expected), constituting evidence of VBF Higgs boson
production. The measured signal strength (ratio of observed cross section times
branching ratio to that predicted by the SM) is
$1.27^{+0.53}_{-0.45}$. The inclusive cross section times
branching ratio is found to be $0.51^{+0.22}_{-0.17}$~pb at $\sqrts =
8 \tev$, consistent with the SM prediction of $0.34$~pb. No
significant deviations from the SM predictions for VBF Higgs boson
production are observed.
Item Open Access Search for a Fermiophobic Beyond the Standard Model Charged Higgs boson through W γ resonances for masses below 200 GeV(2023) Patel, Utsav MukeshA search for a beyond the Standard Model charged Higgs boson through a combined $W\gamma$ resonance is presented. The final state consists of an electron or a muon accompanied by at least one photon. The search is uses 140 fb$^{-1}$ of proton-proton collision data at a centre-of-mass energy of 13 TeV collected using the ATLAS detector within the Large Hadron Collider. A binned maximum likelihood fit is performed with signal samples in the mass range of 110 to 200 GeV. The invariant mass of the $W\gamma$ system is used as a discriminant in the statistical analysis methods. In this analysis, we place exclusion limits on producing a fermiophobic charged Higgs decaying to a $W\gamma$ pair through focuses on model-dependent and model-independent approaches. Exclusion limits are also presented for producing a fermiophobic charged Higgs through a di-Higgs Drell-Yan process with the requirement of at least one charged Higgs producing a $W\gamma$ pair of particles in the final state. As such, we extend the exclusion limits to cover the mass range of Beyond the Standard Model Higgs of 110-200 GeV.