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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 20 of 49 for “"unitarity"”.
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The Cosmological Implications of Unitarity
The unitarity of time evolution is a vitally important constituent of our descriptions of fundamental interactions via quantum field theory. The implications of unitarity for scattering amplitudes are well understood, for example through the optical theorem and cutting rules. In contrast, the …
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Quenching normal Bose gases to Unitarity
… regime, and reveal the three-body contact at unitarity.
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Causality and unitarity in the early universe
… conditions. The remaining chapters focus on unitarity. Chapter 6 introduces an open effective theory of inflation in the decoupling limit, constructed using non-linearly realized symmetries. It explores two-point functions, and bispectra in Minkowski and de Sitter spacetimes, and the matching …
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Symmetries, unitarity and positivity of cosmological effective field theories
… modify EFT power counting rules and perturbative unitarity methods when Lorentz boosts are spontaneously broken. This allows us to determine the region of parameter space for which cosmological EFTs are weaklycoupled on sub-horizon scales. Finally we provide a new way to derive positivity bounds …
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The study of a multiperipheral model with continued cross channel unitarity.
Massachusetts Institute of Technology. Dept. of Physics. Thesis. 1973. Ph.D.
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The cosmological bootstrap and the analytic wavefunction
… by directly imposing physical principles such as unitarity, locality, symmetry, and analyticity on cosmological correlators. In this thesis we explore the consequences of two such principles: unitarity and analyticity. We show that unitarity implies a set of consistency relations among …
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Hadronic productions of a Higgs boson in association with two jets at next-to-leading order
… amplitudes and we give a detailed review of unitarity based and on-shell methods. Using these unitarity methods we derive the cut-constructible pieces of the general φ-MHV amplitudes in which the positions of the two negative gluons are arbitrary. We then generate the cut-constructible pieces …
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Unitary representations of rational Cherednik algebras and Hecke algebras
… that the KZ functor defined in [16] preserves unitarity in type A. Finally, we formulate a few conjectures concerning the classification of unitary representations for other types and the preservation of unitarity by the KZ functor and the restriction functors defined in [2].
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The Phase of the Cosmological Wavefunction
The principles of symmetry, unitarity, and locality form a vital foundation for our descriptions of fundamental physics. Their implications for particle physics are well established, through, for instance, the spin–statistics theorem, the optical theorem, and the CPT theorem. In contrast, their …
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B [right arrow] ([rho]/[omega]) [gamma] at BaBar
… extracted and the length of the far side of the unitarity triangle is determined.
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From Static Potentials to High-Energy Scattering
… on saturation effects manifesting S-matrix unitarity at ultra-high energies. The model combines perturbative gluon exchange with the non-perturbative stochastic vacuum model which describes color confinement via flux-tube formation of color fields. We compute the chromo-field distributions …
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Determination of the Neutral B Meson and Neutral B(s) Meson Mixing Matrix Elements in 2+1 Lattice QCD
… for xi that can be used directly as input for Unitarity constraints.
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Study of pion production from the two-nucleon system within a relativistic unitary model
… model, consistent with two- and three-body unitarity, for the NN and πNN coupled systems. The model is based on effective hadronic interactions. After describing the theoretical input, we compare the predicted NN phase parameters with the phase shift analysis. Our predictions for the NN → …
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Measurement of the lifetimes of B meson mass eigenstates
… is extremely useful for over-constraining the Unitarity Triangle and thereby inferring if CP violation in the quark sector is entirely explained within the Standard Model. From ... of data collected by CDF up to February 13, 2004, we obtain a wealth of results, most importantly: ... Several of …
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An analysis of pion photoproduction
… amplitudes in such a way as to satisfy unitarity and utilize the resonance structure contained in the pion nucleon elastic amplitudes. Starting from the energy-dependent solution, energy-independent partial-wave solutions are obtained at a set of energies from threshold to 1.8 GeV. The …
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A continuum path integral approach to the simulation of a unitary gas
… delta function potential that has been tuned to unitarity i.e.the scattering length $a_{s}=-\infty$. A path integral Monte Carlo simulation of such a system is performed using an exact novel zero-range, delta function pair propagator which has been tuned to the unitary limit so that essentially …
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Effective field theory of the electroweak sector
… of loop corrections. Furthermore, the issue of unitarity violation is shown to be irrelevant in an effective field theory. There are nine dimension-six operators which generate corrections to precision electroweak quantities through gauge boson propagators. I start with an analysis involving …
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Chaos and Thermalization in Quantum Many-Body Systems and Gravity
… and to do so in a way that is consistent with unitarity. This technique allows us to calculate correlation measures such as entanglement entropy or logarithmic negativity, as well as measures of information recovery from subsystems, in chaotic systems ranging from spin chains and quantum field …
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