Essays about: "Quantum Fields Theory"

Showing result 11 - 15 of 23 essays containing the words Quantum Fields Theory.

  1. 11. Discussions on Dai-Freed Anomalies

    University essay from Uppsala universitet/Teoretisk fysik

    Author : Huaiyu Li; [2019]
    Keywords : Anomaly; Quantum Fields Theory; Dai-Freed Theorem; Topology;

    Abstract : In both field theories of high energy physics and field theories of condensed matter theories anomalies have been imposing constraints and bringing up new theories. While the perturbational and local anomalies from triangle diagrams are well-developed, we follow and review two works leading to non-perturbational global anomalies both related with Atiyah-Patogi-Sieger (APS) index theorem. READ MORE

  3. 12. Nonequilibrium gauge field in Two Particle Irreducible real time formalism

    University essay from Lunds universitet/Institutionen för astronomi och teoretisk fysik - Genomgår omorganisation; Lunds universitet/Teoretisk partikelfysik - Geonomgår omorganisation

    Author : Rasmus Hansen; [2019]
    Keywords : Gauge field; non-equilibrium; quantum field theory; Physics and Astronomy;

    Abstract : The purpose of this thesis is to study what effect a photon field has on the equations of motion and the decay of a charged scalar field in thermal equilibrium at finite temperature and outside of thermal equilibrium. To do this we calculate the two-particle irreducible effective action for the mean fields and propagators and derive their equations of motion. READ MORE

  4. 13. Asymptotic Symmetries and Faddeev-Kulish states in QED and Gravity

    University essay from Stockholms universitet/Fysikum

    Author : David Gaharia; [2019]
    Keywords : Faddeev-Kulish; BMS; Bondi-Metzner-Sachs; Asymptotic Symmetries; Asymptotic States; Wilson Lines; Infrared Divergence; Bloch-Nordsieck; Large Gauge Transformations; Fock; QED; Quantum Electrodynamics; Perturbative Quantum Gravity; PQG; U 1 ; Transformations; Mandelstam Quantization;

    Abstract : When calculating scattering amplitudes in gauge and gravitational theories one encounters infrared (IR) divergences associated with massless fields. These are known to be artifacts of constructing a quantum field theory starting with free fields, and the assumption that in the asymptotic limit (i.e. READ MORE

  5. 14. Geometric Phases in Classical and Quantum Systems

    University essay from Uppsala universitet/Teoretisk fysik

    Author : Simon Godskesen; [2019]
    Keywords : Berry s phase; geometric phase;

    Abstract : We are accustomed to think the phase of single particle states does not matter. After all, the phase cancels out when calculating physical observables. However, the geometric phase can cause interference even in single particle states and can be measured. READ MORE

  6. 15. Near-local density approximation approach to one-dimensional lattice systems

    University essay from Lunds universitet/Matematisk fysik; Lunds universitet/Fysiska institutionen

    Author : Basheer Joudeh; [2018]
    Keywords : DFT; Hartree; Hartree-Fock; LDA; BALDA; Mean-field; Hubbard; SOFT; Physics and Astronomy;

    Abstract : Describing many-body quantum systems has been an analytically and computationally challenging task since the advent of quantum mechanics. However, in the past 50 years as a result of our technological advancement and the emergence of methods such as density-functional theory (DFT), we have taken crucial steps forward regarding our ability to study and understand large quantum systems. READ MORE