Conventional searches for the charged Higgs boson using its production in association with Standard Model (SM) quarks is notoriously weak in the mid-tanB range. Hoping to find an alternate channel to fill this gap, the production of the charged Higgs boson in association with supersymmetric squarks is studied. Using Monte Carlo generators the production at the LHC is simulated within the non universal Higgs mass model (NUHM). If the six parameters of the model (m0, m1/2, A0, tanB, u, mA) induce small masses of the stop, sbottom and charged Higgs, the production cross section can be of the order pb. Through scans of the input parameter the cross section is maximized, with the requirement that the stop decays directly to a neutralino - simplifying detection, in the point (m0, m1/2, A0, tanB, u, mA) = (190, 187, -1147, 179, 745, 13.2) where the cross section is 559 fb. The production is compared to the irreducible backgrounds stop, stop, t, tbar and t, tbar + 2 jets. The former poses no severe constraints and can be easily removed using appropriate cuts. The latter, SM background, has a cross section almost 1000 times larger and strong cuts must be imposed to suppress it. Neglecting hadronization and systematic effects, we show that a 5 sigma discovery is possible at 133 fb-1. In this range, mH+ = 194 GeV and tanB = 13.2, other channels have little or no prospects of detecting the charged Higgs and the studied process shows good prospects for complementing charged Higgs searches at the LHC in the mid-tanB range.

Thèse doctorat : Physique Théorique : Strasbourg 1 : 2006. / Titre provenant de l'écran-titre. Bibliogr. 5 p.

Reproduction de : Thèse de doctorat : Physique nucléaire : Lyon 1 : 2002. / Titre provenant de l'écran titre. 85 réf. bibliogr.

<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> / Dissertation

The rate of decay of the process W -> Wγ is well-defined by the Standard Model, so measured deviation is a strong but indirect indicator of non-Standard Model physics. Deviations of this coupling strength can be parameterized, in a model independent, general sense, into two parameters, Δk and λ.

Zugl.: Karlsruhe, Univ., Diss., 2008

Thesis (Ph.D.) - University of Glasgow, 2007. / Ph.D. thesis submitted to the Department of Physics and Astronomy, Faculty of Physical Sciences, University of Glasgow, 2007. Includes bibliographical references. Print version also available.

Thesis (M.Sc.). / Written for the Dept. of Physics. Title from title page of PDF (viewed 2009/06/25). Includes bibliographical references.

University, Diss., 2006--Karlsruhe.

Techn. Hochsch., Diss., 2004--Aachen.