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Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 15 of 15 for “"Four-fermion"”.
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Four-Fermion production at LEP using the OPAL detector
… energies between 183 and 209 GeV. <br>Four-fermion final states stemming from decays of the Z$gamma^*$ into <br>$ <br>m q ar{q}l^+l^-$, where l stands for electrons or muons, has been investigated. Cross-sections have been calculated for all centre-of-mass energies and compared to those …
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Chiral symmetry restoration in the three-dimensional four-fermion model at non-zero temperature and density
The phase structure of the three-dimensional four-fermion model with a Z2 chiral symmetry at non-zero temperature Tor non-zero chemical potential μ is investigated. The main purpose of the study is to serve as an orientation for the more complex problem of the chiral phase transition in Quantum …
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Strongly coupled fermions on the lattice
… states by coupling them to additional composite fermions. These composite fermions would arise as bound states via an auxiliary Yukawa interaction. Hence in the continuum limit mirror modes will be forced to decouple from the spectrum without breaking chiral symmetry. This proposal led to many …
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W-pair production near threshold in unstable particle effective theory
… this thesis we present a dedicated study of the four-fermion production process e- e+ ---> mu- nubar_mu u dbar X near the W-pair production threshold, in view of its importance for a precise determination of the W-boson mass at the ILC. The calculation is performed in the framework of …
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Phase transitions in lattice gauge theories
… and density is then summarized. The use of a four-fermion coupling as an improved extrapolation parameter over the bare quark mass in Monte Carlo simulations is discussed. A mean field analysis of finite density QCD is then presented, including the effects of additional chiral invariant …
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Spontaneous CP symmetry breaking in top-condensation models
… are dynamically generated. We started with a new four-fermion interaction such that it can be rewritten using two auxiliary fields. These fields become dynamical and play a similar role as the Higgs field in the SM but being now composite. We considered the one and the three quark-generation cases.
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Untersuchung von ZZ Endzustaenden mit dem OPAL-Detektor
… section. Using <br>a more general analysis, four fermion events have been selected without <br>making any special requirements concerning the invariant masses of <br>the fermion pairs. Comparisions with Standard Model predictions have been <br>performed. The ZZ production cross section is …
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Search For Contact Interactions Using The Dimuon Mass Spectrum In P-P Collisions At Sqrt(s) = 8 Tev At Cms
… the manifestation of compositeness can be a four-fermion contact interaction. The experimental signal for contact interactions is a non-resonant enhancement of the number of events in the high-mass region of the dimuon mass spectrum. This dissertation describes a detailed search strategy for …
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Search For Contact Interactions In The Dielectron Channel In P-P Collisions At Sqrt(s) = 8 Tev At Cms
… <p>The existence of preons will be manifest as a four fermion contact</p> <p>interaction in the annihilation of a quark and anti-quark, in a p-p collision, producing positron-electron pairs. At high mass,</p> <p>such pairs are also produced from off-shell Z and gamma bosons. This thesis provides a …
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Looking Beyond the Standard Model from the Lattice
… show evidence for a possible light Goldstino-the fermionic analogue of a massless goldstone boson. In chapter 4, we study the phase structure of the gauged NJL model on the lattice to verify continuum calculations that predict a possible second order phase transition corresponding to a line of new …
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Ground state and thermal dynamics of strong interaction
… terms of quarks which interact by a local chiral four-fermion NJL-interaction at a scale of order 1 GeV. To address the non-perturbative dynamics, we derive renormalization group flow equations in next to leading order in the derivative expansion that go beyond the leading renormalizable couplings …
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Efficient Monte Carlo Sampling of Lattice Field Theories
… due to the exceptional configurations in fermionic Lattice Field Theories and probability distributions of the two-point functions in bosonic Lattice Field Theories are investigated. In the context of four-fermion interactions, a family of discrete Hubbard-Stratonovich sampling schemes are …
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Search for contact interactions in the dimuon channel in p-p collisions at sqrt(s) = 7 tev at cms
… new physics </p> <p>interaction in the form of a four-fermion contact interaction </p> <p>arises between them. Experimentally the signal is manifest as </p> <p>a deviation from the SM prediction in the high-mass tail for </p> <p>the invariant mass distribution of the opposite-sign dimuon pairs. …
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Bhabha scattering in e⁺e⁻ collisions at TRISTAN
… cross section is also compared with various four-fermion contact interaction models, and confidence level lower limits on the composite scale, A, are determined. In addition, the limits on VV model are converted to SM-break-down scales, which indicate the validity of the SM down to the …
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Effective Field Theories for Physics Beyond the Standard Model
… diboson and electroweak sectors, combining these four data sectors in a global fit for the first time. We will assess the interplay between these sectors, shedding light on the interplay between the Higgs and top sectors in particular. By comparing with previous fits, we will highlight the …