Sökning: "Unitarity"

Visar resultat 1 - 5 av 9 avhandlingar innehållade ordet Unitarity.

1. 1. 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

3. 2. Strings, Branes and Non-trivial Space-times

   Författare :Jonas Björnsson; Stephen Hwang; Ioannis Bakas; Karlstads universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; String theory; Membranes; BRST; p -branes; p -branes; Non-compact backgrounds; WZNW-model; No-ghost theorem; Unitarity; Hermitian symmetric spaces; CFT; Physics; Fysik; Physics; Fysik;

   Sammanfattning : This thesis deals with different aspects of string and /p/-brane theories. One of the motivations for string theory is to unify the forces in nature and produce a quantum theory of gravity. /p/-branes and related objects arise in string theory and are related to a non-perturbative definition of the theory. 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. B-physics potential of the ATLAS experiment and performance of the ATLAS Transition Radiation Tracker

   Författare :Chafik Driouichi; Teoretisk partikelfysik - Geonomgår omorganisation; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; ATLAS; B-physics; LHC; Bc meson; Elementary particle physics; Transition Radiation Tracker; quantum field theory; Elementarpartikelfysik; kvantfältteori; Fysicumarkivet A:2004:Driouichi;

   Sammanfattning : The ATLAS experiment is one of the four experiments at the Large Hadron Collider (LHC), which is supposed to be operational in early 2007. Proton-proton collisions at an unprecedented center-of-mass energy of 14 TeV will probe new frontiers of the universe, hopefully providing a better understanding of the laws governing our universe. LÄS MER

7. 5. Dualities, Symmetries and Unbroken Phases in String Theory : Probing the Composite Nature of the String

   Författare :Johan Engquist; Joseph Minahan; Charlotte Kristjansen; Uppsala universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Physics; Theoretical Physics; String Theory; M-Theory; Higher Spin Gauge Theory; Super Yang-Mills Theory; Anti-de Sitter Spacetime; Singletons; Massless Higher Spin Gauge Fields; AdS CFT Correspondence; Spin Chains; Semiclassical Strings; Tensionless Limits; Conformal Symmetry; Supersymmetry; Higher Spin Gauge Symmetry; Integrability; Fysik; Physics; Fysik;

   Sammanfattning : The thesis treats aspects of string/M-theory in anti-de Sitter spacetimes and their supersymmetric completions. By applying the AdS/CFT correspondence, as well as models of spin chains and singletons, we try to attain a better understanding of the underlying symmetries and the unbroken phases of string/M-theory. LÄS MER