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  • Open Daily: 10am - 10pm
    Alley-side Pickup: 10am - 7pm

    3038 Hennepin Ave Minneapolis, MN
    612-822-4611

Open Daily: 10am - 10pm | Alley-side Pickup: 10am - 7pm
3038 Hennepin Ave Minneapolis, MN
612-822-4611
Naturalness in the Standard Model and Beyond.

Naturalness in the Standard Model and Beyond.

Papaioannou, Anastasios Yiannaki

Paperback

Biology

Currently unavailable to order

ISBN10: 1243991410
ISBN13: 9781243991416
Publisher: Proquest Umi Dissertation Pub
Pages: 166
Weight: 0.68
Height: 0.35 Width: 7.44 Depth: 9.69
Language: English
After an introduction to the Standard Model of particle physics and the unresolved question of naturalness posed by its treatment of electroweak symmetry breaking, we consider several different theoretical approaches that attempt to answer this question. First, we present work in which we consider the possibility that the Higgs boson, the long-sought hypothetical particle intimately associated with electroweak symmetry breaking, has a much larger mass than is usually assumed. Absent direct experimental evidence for a light Higgs boson (m ∼ O (100 GeV)), and precision electroweak data consistent with a light Higgs notwithstanding, we propose a heavier (m ∼ O (500 GeV)), thus more natural, Higgs boson. This heavy Higgs can be made consistent with the precision electroweak data if we also extend the Standard Model via the inclusion of new fermionic states near the weak energy scale. These new states, in addition to bringing the heavy Higgs boson in line with the precision data, also serve as a candidate for the elusive dark matter that pervades the universe. From there we go on to consider the problem of naturalness from the perspective of supersymmetry, one of the most popular candidates for physics beyond the Standard Model. In particular, the theory of the Next-to-Minimal Supersymmetric Standard Model (NMSSM) has found favor in its ability to solve the problem of naturalness posed by the Standard Model, in its hints at unification of the strong, weak, and electromagnetic interactions at high energies, and in its ability to provide supersymmetric particles as dark matter candidates. The NMSSM, however, requires rather large superpartner masses in order to accommodate a Higgs boson heavier than current experimental bounds while still maintaining gauge unification at high energies. We explore the possibility of new supersymmetric states at intermediate energies between the weak scale and the unification scale, which preserve gauge unification and allow a heavier Higgs, with only moderately heavy superpartners. Finally, we explore the possibility that previous attempts to resolve the naturalness problem may be too limited in scope. Perhaps the anthropic principle can instead provide a new way to answer such questions. We consider the intriguing scenario in which our observed universe is but one region of a much larger multi-verse, and the constants of nature are not constant after all, but take on a range of values. The anthropic principle's unique answer to the problem of naturalness is that only those regions of the multiverse with unnatural or fine-tuned parameters can give rise to the physical processes and structures that are necessary for our very existence; those regions with more natural values are dead universes where life is impossible. In particular, we examine an implementation of a unified physical theory, the Minimal Supersymmetric Standard Model (MSSM), within this multi-verse framework, and its consequences for the naturalness of electroweak symmetry breaking.

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