Scalar Dark Matter in a scale-invariant real-Singlet extension of the Standard Model
(2025) FYSK04 20251Department of Physics
Particle and nuclear physics
- Abstract
- This thesis explores a classically conformal extension of the Standard Model featuring a real scalar singlet field as a Dark Matter candidate. In this framework, electroweak symmetry breaking arises radiatively via the Coleman-Weinberg mechanism, foregoing explicit mass scales and preserving classical scale invariance at tree level. The singlet scalar, stabilized by an imposed Z2 symmetry, is investigated as a possible thermal relic candidate whose viability and cosmological abundance are tied to its portal coupling with the Higgs field. The one-loop effective potential is constructed and renormalized using the Gildener-Weinberg prescription. A detailed phenomenological analysis is carried out using a toolchain comprising ScannerS, SARAH,... (More)
- This thesis explores a classically conformal extension of the Standard Model featuring a real scalar singlet field as a Dark Matter candidate. In this framework, electroweak symmetry breaking arises radiatively via the Coleman-Weinberg mechanism, foregoing explicit mass scales and preserving classical scale invariance at tree level. The singlet scalar, stabilized by an imposed Z2 symmetry, is investigated as a possible thermal relic candidate whose viability and cosmological abundance are tied to its portal coupling with the Higgs field. The one-loop effective potential is constructed and renormalized using the Gildener-Weinberg prescription. A detailed phenomenological analysis is carried out using a toolchain comprising ScannerS, SARAH, SPheno, and MicrOMEGAs. The model is tested against theoretical constraints including perturbativity, vacuum stability, and electroweak precision bounds, as well as experimental data from Planck, XENON1T, and LZ. (Less)
- Popular Abstract
- The question of how fast the Earth spins around its star might pop up in one's mind at some point in one's life. The answer is known and equal to 107.000km/h. How fast does the Earth spin around the center of its Galaxy? The answer is also known; it is too fast. And, to this, many questions arise. Our current theory explaining our excessive speed is Dark Matter. Dark Matter refers to a different type of matter than the one we are surrounded by throughout our lives, one that does not interact with light, making it invisible or "dark" to us.
Let us imagine our entire galaxy as a merry-go-round (lekplatssnurror på svenska). If we were standing closer to the center, we would spin slower, and as we neared the edge, spin faster. Our galaxy... (More) - The question of how fast the Earth spins around its star might pop up in one's mind at some point in one's life. The answer is known and equal to 107.000km/h. How fast does the Earth spin around the center of its Galaxy? The answer is also known; it is too fast. And, to this, many questions arise. Our current theory explaining our excessive speed is Dark Matter. Dark Matter refers to a different type of matter than the one we are surrounded by throughout our lives, one that does not interact with light, making it invisible or "dark" to us.
Let us imagine our entire galaxy as a merry-go-round (lekplatssnurror på svenska). If we were standing closer to the center, we would spin slower, and as we neared the edge, spin faster. Our galaxy works exactly the same. The problem now is that the edge of our merry-go-round does not spin as fast as the Earth, even if we assume we are the ones standing at the absolute edge. This cannot be explained since Earth is indeed not on the edge of the Milky Way. One might be tempted to simply assume that our Solar System is spinning a bit faster around the galactic center, which may account for this anomaly. However, that's not the case. Observations show that our entire Solar System is moving at speeds comparable to those of nearby stars within our galaxy. Moreover, these speeds are also consistent with the speeds of solar systems in distant galaxies located at similar distances from their respective merry-go-round centers. So how does Dark Matter help? It is rather simple. Once the mass of Dark Matter is added to our galaxy, it increases the size of our merry-go-round. This enables the distance from the center to the edges to be longer, allowing them to spin faster. We have thus evaded the cost of a necessary speeding ticket at the cost of another question. What is Dark Matter?
This question is the focus of this thesis. We will investigate if adding the simplest possible particle to the Standard Model (which is the model of all the particles we know of, such as electrons), can explain all the Dark Matter we think exists within our Galaxy. Since we cannot see it directly, we will try to indirectly narrow down its characteristics via processes that it partakes in and that we can observe. We will check its contributions to well-established experimental and theoretical mechanisms and verify that its proposed existence does not nullify what we know. We now turn to attempt to answer this arising fundamental question: Could a simple extension to the Standard Model account for the vast, invisible mass shaping our Galaxy's motion? (Less)
Please use this url to cite or link to this publication:
http://lup.lub.lu.se/student-papers/record/9204428
- author
- Pim, Eleftheria Anna Iris LU
- supervisor
- organization
- course
- FYSK04 20251
- year
- 2025
- type
- M2 - Bachelor Degree
- subject
- keywords
- scalar dark matter scale-invariant conformal real singlet real-singlet extension Standard Model Coleman Weinberg Gildener loop-corrected loop corrections
- language
- English
- id
- 9204428
- date added to LUP
- 2025-06-25 14:49:39
- date last changed
- 2025-06-25 14:49:39
@misc{9204428,
abstract = {{This thesis explores a classically conformal extension of the Standard Model featuring a real scalar singlet field as a Dark Matter candidate. In this framework, electroweak symmetry breaking arises radiatively via the Coleman-Weinberg mechanism, foregoing explicit mass scales and preserving classical scale invariance at tree level. The singlet scalar, stabilized by an imposed Z2 symmetry, is investigated as a possible thermal relic candidate whose viability and cosmological abundance are tied to its portal coupling with the Higgs field. The one-loop effective potential is constructed and renormalized using the Gildener-Weinberg prescription. A detailed phenomenological analysis is carried out using a toolchain comprising ScannerS, SARAH, SPheno, and MicrOMEGAs. The model is tested against theoretical constraints including perturbativity, vacuum stability, and electroweak precision bounds, as well as experimental data from Planck, XENON1T, and LZ.}},
author = {{Pim, Eleftheria Anna Iris}},
language = {{eng}},
note = {{Student Paper}},
title = {{Scalar Dark Matter in a scale-invariant real-Singlet extension of the Standard Model}},
year = {{2025}},
}