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21 
Consequences of the dualized standard modelPfaudler, Jakov January 1998 (has links)
No description available.

22 
Multiple weak gauge boson production in high energy hadronic collisionsHussein, Mohammad Yousif January 1989 (has links)
The electroweak standard model, as wellknown, has been remarkably successful in describing a broad spectrum of high energy physics and has also given a satisfactory and consistent theoretical description of all the experimental data which has been obtained so far. The aim of the present work is to investigate some of the most important processes associated with the standard model which involve the charged intermediate bosons W(^±), the neutral intermediate boson Z, the pair production of weak gauge bosons and the Higgs boson. First of all we start with the study of the effect of the strong interaction on the direct production of weak gauge boson production at hadron colliders. We calculate the first order perturbative QCD corrections O(a(_s)) to the lowest order cross sections for photon and Z pair production at hadron colliders. The calculation contains divergences, represented in dimensional regularisation by poles of order O(1/ϵ) and O(1/ϵ(^2)), where ϵ = 4n(_2). The order O(1/ϵ(^2)) terms are eliminated when real and virtual corrections are combined, and the remaining 0(1/ϵ) corrections will be absorbed into the quark momentum distribution functions. We then study the production rate of weak gauge boson pairs for proton proton and protonantiproton colliders using single and double parton scattering mechanisms. We extrapolate to the next generation of hadron colliders with centreofmass energy E(_cm)= 10200 TeV. We find comparable values for the single and double scattering cross sections at very high energies. To expand our investigation, we study also the production rate of multiple gauge bosons at hadron supercolliders using the double parton scattering mechanism. These kinds of processes are important and represent a potential significant background for Higgs boson production. Finally, and for completeness, we study Higgs boson phenomenology, which now forms a substantial part of the physics program at the next generation of highenergy colliders. The calculation covers the production rate of single and double Higgs production at hadron colliders via gluongluon fusion, their branching ratios and decay widths.

23 
Fermi Liquid Study of Exotic Modes in Magnetically Ordered SystemsZhang, Yi January 2014 (has links)
Thesis advisor: Kevin S. Bedell / The Landau Fermi liquid theory is a very successful theory in condensed matter physics. It provides a phenomenological framework for describing thermodynamics, transport and collective modes of itinerant fermionic systems. In 1957, Silin described the spin waves in polarized Fermi liquids based on Landau Fermi liquid theory, which are related to series of components of the spherical harmonic expansion of the fermi surface. It has been proved by Pomeranchuck that for the Fermi surface to be stable, the Landau parameters should satisfy the relation: $F_l^{s,a}>(2l+1)$. Whenever the relation is violated, there will exist an instability of the Fermi surface known as a Pomeranchuck instability, such as the Stoner ferromagnetism when $F_0^a→ 1^+$, or phase separation when $F_0^s→ 1^+$. In 1959, Abrikosov and Dzyaloshinskii developed a ferromagnetic Fermi liquid theory(FFLT) of itinerant ferromagnetism based on Landau Fermi liquid theory, whose microscopic foundations were established later by Dzyaloshiskii and Kondratenko. Further studies had been made of this state using a generalized Pomeranchuck instability based on the FFLT of Blagoev, Engelbrecht and Bedell and Bedell and Blagoev. In this thesis, I study a magnetically ordered system with spin orbit magnetism, where the order parameter has a net spin current and no net magnetization in both two dimension and three dimension. Starting from a Fermi liquid theory, similar to that for a weak ferromagnet, I have shown that this excitation emerges from an exotic magnetic Fermi liquid state that is protected by a generalized Pomeranchuck condition. I derive the propagating mode using the Landau kinetic equation, and find that the dispersion of the mode has a $sqrt q$ behavior in leading order in 2D. I also find an instability toward superconductivity induced by this exotic mode, and a further analysis based on the forward scattering sum rule strongly suggests that this superconductivity has triplet pairing symmetry. I perform similar studies in the 3D case, with a slightly different magnetic system and find that the mode leads to a Lifshitzlike instability most likely toward an inhomogeneous magnetic state in one of the phases. I also study the collective modes in itinerant ferromagnetic system, which is related to the $F_0^a$ pomeranchuck instability. Using FFLT, I obtained the wellknown magnon (NambuGoldstone) mode and a gapped mode that was first found by Bedell and Blagoev. I have identified this mode as the Higgs boson (amplitude mode) of a ferromagnetic metal. This is identified as the Higgs since it can be shown that it corresponds to a fluctuation of the amplitude of the order parameter. I use this model to describe the itinerantelectron ferromagnetic material MnSi. By fitting the model with the existing experimental results, I calculate the dynamical structure function and see welldefined peaks contributed from the magnon and the Higgs. From my estimates of the relative intensity of the Higgs amplitude mode I expect that it can be seen in neutron scattering experiments on MnSi. / Thesis (PhD) — Boston College, 2014. / Submitted to: Boston College. Graduate School of Arts and Sciences. / Discipline: Physics.

24 
Search for the Higgs boson in the ZH > ℓ⁺ℓ⁻bb̄ channel at CDF Run IIEfron, Jonathan Zvi, January 2007 (has links)
Thesis (Ph. D.)Ohio State University, 2007. / Title from first page of PDF file. Includes bibliographical references (p. 126132).

25 
CMS Trigger strategies for the selection of MSSM Higgs bosons using electron taujet decay modesvan der Aa, Olivier 07 February 2005 (has links)
The thesis work concentrated on the developments of selection strategies for the observation of MSSM Higgs bosons in the context of the CMS experiment. The thesis shows, by an example with a MSSM (Minimal Supersymmetric Standard Model) Higgs decaying into two tau, how to define the trigger strategy. The method can be applied for any final state.

26 
Study of charged Higgs bosons in dilepton topantitop events with ATLAS at the Large Hadron ColliderMadsen, Alexander January 2011 (has links)
This thesis considers the search of charged Higgs bosons, which are predicted by several extensions of the Standard Model of particle physics. Light charged Higgs bosons (below the top quark mass) can appear in top quark decays and are assumed to decay exclusively to tauons. Two discriminating variables are presented that are sensitive to such a process taking place in topantitop events with two final state leptons. Distributions of these variables are computed for Monte Carlo simulations and for 35/pb of data from 7 TeV protonproton collisions recorded in 2010 by the ATLAS experiment at the LHC. Monte Carlo simulations are found to agree well with data, validating the use of these discriminating variables, but no conclusions about the existence of charged Higgs bosons can be made at this point.

27 
Search for the Higgs Boson Decaying to Two Tau Leptons in ProtonAntiproton Collisions at a Center of Mass Energy of 1.96 TeVElagin, Andrey 2011 December 1900 (has links)
A search for the Higgs boson decaying to tau tau using 7.8 fb^1 of pp collisions at 1.96 TeV collected with CDF II detector is presented. The search is sensitive to four production mechanisms of the Higgs boson: ggH, WH, ZH and VBF. Modes where one tau decay leptonically, and another decay, hadronically, are considered. Two novel techniques are developed and used in the search. A Probabilistic Particle Flow Algorithm is used for energy measurements of the hadronic tau candidates. The signal is discriminated from backgrounds by the Missing Mass Calculator, which allows for full invariant mass reconstruction of tau tau pair. The data are found to be consistent with the background only hypothesis. Therefore a 95% confidence level upper limit on the Standard Model Higgs boson cross section was set. At M_H=120 GeV/c^2 observed limit is 14.9 x sigma_SM x Br(H > tau tau).

28 
The Little Higgs mechanism and experimental constraints on the Littlest Higgs modelWeaver, Benjamin B. 25 November 2013 (has links)
We review the important features of Little Higgs models, illuminating the mechanisms that generate a naturally light Higgs field while avoiding excessive finetuning. The full spectrum of the Littlest Higgs model is analyzed in light of the recent discovery of the Higgs boson mass. We find viable regions in parameter space that are consistent with the standard model. / text

29 
Search for the Standard Model Higgs boson produced in association with tt and decaying into bb at 8 TeV with the ATLAS detector using the Matrix Element MethodNackenhorst, Olaf 08 June 2015 (has links)
No description available.

30 
Study of charged Higgs bosons using multijet final states with the ATLAS experiment at the LHCHallberg, Jesper January 2014 (has links)
The ATLAS experiment at the LHC is searching for evidence of charged Higgs bosons, without yet finding it. This report investigates the possibility of reconstructing charged Higgs bosons using multijet final states (pp > [b]tH+ > [b]bbbql\nu) with focus on fully hadronic H^+ > hW decays using a simulation of 500k events with m_{H+} = 250 GeV. After optimizing TMVA (Toolkit for Multivariate Analysis) input variables for BDT (Boosted Decision Trees), the mass of H+ was recreated with an efficiency of up to 26,7% (correct combinations).

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