Essays about: "qed"

Showing result 1 - 5 of 20 essays containing the word qed.

1. 1. Implementing the chirality-flow formalism for tree-level massless QCD in MadGraph

   University essay from Lunds universitet/Fysiska institutionen; Lunds universitet/Teoretisk partikelfysik - Geonomgår omorganisation

   Author : Adam Warnerbring; [2023]
   Keywords : Theoretical physics; The chirality-flow formalism; Physics and Astronomy;

   Abstract : The chirality-flow formalism provides a simple but efficient way to rewrite and evaluate Feynman diagrams and has recently been shown to also optimize automated numerical scattering matrix element evaluations in massless tree-level QED. In this thesis we extend the numerical QED model to massless tree-level QCD in the MadGraph5_aMC@NLO framework. READ MORE

3. 2. Asymptotic Symmetries and Dressed States in QED and QCD

   University essay from Stockholms universitet/Fysikum

   Author : Saimeng Zhou; [2023]
   Keywords : Dressed states; Large gauge transformation; Faddeev-Kulish formalism; Generalized coherent state operator; Wilson line; Infrared divergence; Asymptotic Hamiltonian; QED; QCD;

   Abstract : Infrared divergences arising in theories with massless gauge bosons have been shown to cancel in scattering amplitudes when using dressed states constructed from the Faddeev- Kulish approach to the asymptotic states. It has been established that these states are closely related to asymptotic symmetries of the theory, that is, non-vanishing gauge trans- formations at the asymptotic boundary. READ MORE

4. 3. MadGraph Implementations of the Chirality-Flow Formalism for QED

   University essay from Lunds universitet/Fysiska institutionen; Lunds universitet/Teoretisk partikelfysik - Geonomgår omorganisation

   Author : Emil Boman; [2023]
   Keywords : Physics and Astronomy;

   Abstract : The chirality-flow formalism has been proven to simplify the calculation of helicity amplitudes, both analytically and in a first numerical implementation developed as an extension of MadGraph5_aMC@NLO. Expanding on this work, two new implementations have been developed. READ MORE

5. 4. Scattering of Charge Carriers in 2+1-Dimensional Quantum Field Theory

   University essay from Karlstads universitet/Institutionen för ingenjörsvetenskap och fysik (from 2013)

   Author : David Savinainen; [2023]
   Keywords : Quantum field theory; Scattering; S-matrix; Hannesdottir; Schwartz;

   Abstract : The aim of this thesis is to examine the hard $S$-matrix for QED and QCD, due to Hannesdottir and Schwartz [1], both recreating known results, and finding new results in lower dimensions. Electrons by themselves are not gauge invariant, and in the massless limit do not give finite $S$-matrix elements for individual processes; one needs to add together seemingly arbitrary combinations of diagrams in order to be able to calculate the scattering cross-section. READ MORE

6. 5. Computational modelling of photosynthetic excitons coupled to a microcavity

   University essay from Lunds universitet/Fysiska institutionen; Lunds universitet/Beräkningsbiologi och biologisk fysik - Genomgår omorganisation; Lunds universitet/Institutionen för astronomi och teoretisk fysik - Genomgår omorganisation

   Author : Ilmari Turunen; [2022]
   Keywords : Cavity QED; LH2; Chlorophyll; Exciton; Polariton; Transition dipole moment; Absorbance; Physics and Astronomy; Chemistry; Biology and Life Sciences;

   Abstract : Cavity quantum electrodynamics (QED) is a theory that is used for describing the interaction between matter and cavity modes. Not until relatively recently, cavity QED has been extended to the study of photosynthetic light-harvesting complexes (LHCs). READ MORE