Sökning: "Amplitudes"

Visar resultat 1 - 5 av 278 avhandlingar innehållade ordet Amplitudes.

  1. 1. Automorphic string amplitudes

    Författare :Henrik Gustafsson; Chalmers tekniska högskola; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; Eisenstein series; string theory; automorphic forms; U-duality; non-perturbative effects; Whittaker vectors; instantons;

    Sammanfattning : This thesis explores the non-perturbative properties of higher derivative interactions appearing in the low-energy expansion of four-graviton scattering amplitudes in toroidal compactifications of type IIB string theory. We summarise the arguments for finding such higher derivative corrections in terms of automorphic forms using U-duality, supersymmetry and string perturbation theory. LÄS MER

  3. 2. Maximal Unitarity at Two Loops : A New Method for Computing Two-Loop Scattering Amplitudes

    Författare :Kasper J. Larsen; Lisa Freyhult; David Kosower; Joseph Minahan; Paul Heslop; Uppsala universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Amplitudes; NNLO calculations; Quantum Chromodynamics; Unitarity; Fysik med inriktning mot elementarpartikelfysik; Physics with specialization in Elementary Particle Physics;

    Sammanfattning : The study of scattering amplitudes beyond one loop is necessary for precision phenomenology for the Large Hadron Collider and may also provide deeper insights into the theoretical foundations of quantum field theory. In this thesis we develop a new method for computing two-loop amplitudes, based on unitarity rather than Feynman diagrams. LÄS MER

  4. 3. A Kerr-full Study of Higher-Spin Amplitudes : An on-shell construction of higher-spin amplitudes for black holes and strings

    Författare :Paolo Pichini; Henrik Johansson; Donal O'Connell; Uppsala universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; scattering amplitudes; higher-spin theory; black holes; string theory; gravitational waves; Theoretical Physics; Teoretisk fysik;

    Sammanfattning : Recently, it was shown that Kerr black holes can be described via the classical infinite-spin limit of a special class of scattering amplitudes in a massive higher-spin quantum field theory. Although this approach has successfully obtained state-of-the-art results for spinning black-hole binaries, only the three-point amplitude that describes Kerr is known in full generality and a full understanding of the underlying Lagrangian is still missing. LÄS MER

  5. 4. Scattering Amplitudes in Supersymmetric Quantum Chromodynamics and Gravity

    Författare :Gregor Kälin; Henrik Johansson; Lance J. Dixon; Uppsala universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Scattering Amplitudes; Supersymmetric Gauge Theory; Supergravity; Quantum Chromodynamics; Physics and Astronomy specializing in Theoretical Physics; Fysik och astronomi med inriktning mot teoretisk fysik;

    Sammanfattning : Quantum field theory is a theoretical framework for the description of nature in terms of fundamental particles, fields and their interactions. In the quantum regime, elementary scattering processes are observables in many experiments and studied in theoretical physics. LÄS MER

  7. 5. The Chirality-Flow Formalism and Optimising Scattering Amplitudes

    Författare :Andrew Lifson; Partikel- och kärnfysik; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Spinor-helicity formalism; Chirality-flow formalism; Helicity amplitudes; Standard Model; QED; QCD; Optimisations; Colour expansion; Phenomenology; Fysicumarkivet A:2023:Lifson;

    Sammanfattning : This thesis is composed of five papers, which all attempt to optimise calculations of scattering amplitudes in high-energy-physics collisions. These scattering amplitudes are a key part of theoretical predictions for particle-physics experiments like the Large Hadron Collider at CERN. LÄS MER