Essays about: "scalar"

Showing result 1 - 5 of 147 essays containing the word scalar.

  1. 1. Gravitational Collapse of a Massless Scalar Field in a Theory of Minimally Modified Gravity

    University essay from KTH/Fysik

    Author : Atabak Fathe Jalali; [2024]
    Keywords : Theoretical physics; astrophysics; modified gravity; minimally modified gravity; gravitational collapse; VCDM; scalar collapse; apparent horizon; numerical relativity; Teoretisk fysik; astrofysik; modifierad gravitation; minimalt modifierad gravitation; gravitationskollaps; VCDM; skalär kollaps; uppenbar horisont; numerisk relativitet;

    Abstract : This thesis explores the spherically symmetric gravitational collapse of a massless scalar field in a minimally modified gravity theory denoted VCDM (V replaces $\Lambda$ in the $\Lambda$CDM abbreviation), a class of theories propagating the same degrees of freedom as general relativity at the expense of broken 4D diffeomorphism invariance. Numerical evolution of the equations of motion reveals that for small initial scalar profile amplitudes, no black hole forms from the collapse. READ MORE

  3. 2. Exploring electroweak symmetry breaking in the scale-invariant Two-Higgs-Doublet Model

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

    Author : Erik Rustas; [2023]
    Keywords : Two-Higgs-Doublet Models; 2HDM; Scale-invariance; Baryogenesis; BSM; Baryon Asymmetry; Coleman-Weinberg Potential; Theoretical Particle Physics; Physics and Astronomy;

    Abstract : This thesis investigates the properties of a general scale-invariant Two-Higgs-Doublet Model and its phenomenological consequences with focus on the scalar sector. The concept suggests that introducing more CP-violation, both spontaneous and explicit, may make it possible to meet the Sakharov conditions and account for the Universe's baryon asymmetry. READ MORE

  4. 3. Cosmological Horizons and the Unruh Effect

    University essay from Uppsala universitet/Teoretisk fysik

    Author : Niklas Engelhardt Önne; [2023]
    Keywords : Unruh effect; quantum scalar fields; Bogoliubov transformations; accelerated observers; Minkowski spacetime; cosmological horizons; Rindler observers; special relativity; QFT; Unruh-effekten; skalära kvantfält; Bogoliubov-transformationer; accelererande referenssystem; Minkowski rumtid; kosmologiska horisonter; Rindlerobservatörer; speciell relativitetsteori; QFT;

    Abstract : The black hole information paradox, which states that the evaporation of black holes due to Hawking radiation results in a violation of the conservation of quantum information, is arguably one of the most fundamental problems in all of modern physics. Through the equivalence principle, the essence of the problem can be understood and studied in the context of much simpler flat spacetime (described by the theory of special relativity); in this context the Hawking radiation takes the form of the so-called Unruh effect, a thermal effect in the vacuum of a Minkowski quantum field theory that can be measured by accelerated observers. READ MORE

  5. 4. The Higgs Width in Higgs production in association with a W+ boson

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

    Author : Wijeratne Mohandiramge Umashi Navisha Fernando; [2023]
    Keywords : Higgs boson; Higgs width; off-shell; on-shell; narrow-width approximation; MadGraph5_MC@NLO; W boson; supersymmetry; dark matter; Physics and Astronomy;

    Abstract : The width of the Higgs boson is a quantity that cannot be measured directly from the on-shell Higgs peak; it would have to be measured indirectly. In 2013, Caola and Melnikov developed a method to determine the Higgs width by using off-shell and on-shell cross-sections and applying the narrow-width approximation. READ MORE

  6. 5. Investigating the response of terrestrial evapotranspiration to droughts in Africa : A combined remote sensing and modeling approach

    University essay from Luleå tekniska universitet/Rymdteknik

    Author : Yang Foo; [2023]
    Keywords : earth observation; terrestrial evapotranspiration; drought; vegetation-climate interactions;

    Abstract : Climate change is posing a significant threat to terrestrial ecosystems worldwide, in part due to the more frequent occurrence of extreme climatic events such as droughts. While the importance of drought impacts on vegetation has been widely recognized, the time-dependent characteristics of drought-induced response remain insufficiently understood. READ MORE