Portal interactions within leptogenesis and precision observables -- and -- Quantum theory of orbitally-degenerate impurities in superconductors

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dc.contributor.authorLe Dall, Matthias
dc.contributor.supervisorRitz, Adam
dc.contributor.supervisorDe Sousa, Rogério Costa Reis
dc.date.accessioned2017-09-08T19:44:56Z
dc.date.available2017-09-08T19:44:56Z
dc.date.copyright2017en_US
dc.date.issued2017-09-08
dc.degree.departmentDepartment of Physics and Astronomyen_US
dc.degree.levelDoctor of Philosophy Ph.D.en_US
dc.description.abstractIn the first part of the thesis, the need for physics beyond the Standard Model, as attested to by the evidence of dark matter, motivates us to study the effects of introducing into the standard theory of Leptogenesis a hidden sector scalar coupled to the Standard Model through the Higgs portal. We find that the new interactions are not constrained by the Davidson-Ibarra bound, thus allowing us to lower the mass scale of Leptogenesis into the TeV range, accessible to experiments. We then consider a broader class of new physics models below the electroweak scale, and classify precision observables according to whether or not deviations from the Standard Model at current levels of sensitivity can be explained purely in terms of new light degrees of freedom. We find that hadronic precision observables, e.g. those that test fundamental symmetries such as electric dipole moments, are unambiguous pointers to new UV physics. In the second part of the thesis, motivated by recent measurements of the spatial structure of impurities embedded in superconductors (SC), we study the effect of superconductivity on impurity states by generalizing the Anderson model of a quantum s-wave impurity to include orbital degeneracy. We find that the proximity effect induces an electron-electron attractive potential on the impurity site that mirrors the BCS pairing mechanism, resulting in the appearance of atomic Cooper pairs within the superconducting energy gap, called Yu-Shiba-Rusinov (YSR) states. We find that electron orbital degeneracy allows YSR states to have non-trivial orbital quantum numbers thus opening the possibility for optical transitions among YSR states. We enumerate the one-photon selection rules that apply to YSR states, unveiling transitions to the vacuum state that are forbidden in the normal state.en_US
dc.description.scholarlevelGraduateen_US
dc.identifier.bibliographicCitationLeptogenesis and the Higgs Portal, Matthias Le Dall, Adam Ritz, Phys.Rev. D90 (2014) no.9, arXiv:1408.2498 [hep-ph]en_US
dc.identifier.bibliographicCitationSensitivity to light weakly-coupled new physics at the precision frontier, Matthias Le Dall, Maxim Pospelov, Adam Ritz, Phys.Rev. D92 (2015) no.1, arXiv:1505.01865 [hep-ph]en_US
dc.identifier.urihttp://hdl.handle.net/1828/8551
dc.languageEnglisheng
dc.language.isoenen_US
dc.rightsAvailable to the World Wide Weben_US
dc.subjectParticle Physics Phenomenologyen_US
dc.subjectPrecision Observablesen_US
dc.subjectLeptogenesisen_US
dc.subjectBeyond the Standard Modelen_US
dc.subjectSuperconductivityen_US
dc.subjectQuantum impuritiesen_US
dc.subjectYSR statesen_US
dc.subjectCondensed matteren_US
dc.subjectNoiseen_US
dc.titlePortal interactions within leptogenesis and precision observables -- and -- Quantum theory of orbitally-degenerate impurities in superconductorsen_US
dc.typeThesisen_US

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