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Evidence of Higgs Boson Production through Vector Boson Fusion

dc.contributor.advisor Kotwal, Ashutosh V Cerio, Benjamin C. 2015-05-12T20:44:08Z 2015-09-26T04:30:04Z 2015
dc.description.abstract <p>The discovery of the Higgs boson in 2012 provided confirmation of the</p><p>proposed mechanism for preserving the electroweak $SU(2) \times U(1)$</p><p>gauge symmetry of the Standard Model of particle physics. It also</p><p>heralded in a new era of precision Higgs physics. This thesis presents a</p><p>measurement of the rate at which the Higgs boson is produced by vector</p><p>boson fusion in the $WW^{(\ast)}\rightarrow\,\ell\nu\ell\nu$ decay channel. With gauge boson couplings</p><p>in both the production and decay vertices, a VBF measurement in this</p><p>channel is a powerful probe of the $VVH$ vertex strength. Using</p><p>$4.5$~fb$^{-1}$ and $20.3$~fb$^{-1}$ of $pp$ collision data collected</p><p>at respective center-of-mass energies of 7 and $8 \tev$ in the ATLAS</p><p>detector, measurements of the statistical significance and the signal</p><p>strength are carried out in the Higgs mass range $100 \leq m_H \leq</p><p>200 \gev$. These measurements are enhanced with a boosted decision</p><p>tree that exploits the correlations between eight kinematic inputs in</p><p>order to separate signal and background processes. At the benchmark</p><p>Higgs mass of $125.36 \gev$, the significance of the data assuming the</p><p>background-only hypothesis to be true has been observed to be</p><p>$3.2\sigma$ ($2.7\sigma$ expected), constituting evidence of VBF Higgs boson</p><p>production. The measured signal strength (ratio of observed cross section times</p><p>branching ratio to that predicted by the SM) is</p><p>$1.27^{+0.53}_{-0.45}$. The inclusive cross section times</p><p>branching ratio is found to be $0.51^{+0.22}_{-0.17}$~pb at $\sqrts =</p><p>8 \tev$, consistent with the SM prediction of $0.34$~pb. No</p><p>significant deviations from the SM predictions for VBF Higgs boson</p><p>production are observed.</p>
dc.subject Physics
dc.subject Particle physics
dc.subject BDT
dc.subject boson
dc.subject fusion
dc.subject Higgs
dc.title Evidence of Higgs Boson Production through Vector Boson Fusion
dc.type Dissertation
dc.department Physics
duke.embargo.months 4

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