Dirac neutrinos and dark matter stability from lepton quarticity

Abstract

A mis padres por ayudarme y apoyarme siempre. A Olaia porque contigo todo es más fácil. A mis hermanos aunque crean que estoy tronao.A mi abuelita porque dirá que si lo explico yo se entiende todo y a mi abuelito que le hubiera encantado leerla. A Ravioli por ayudarme a escribir la tesis y a Daphne por intentar sabotearla.I also acknowledge the funding from the Spanish FPI fellowship BES-2016-076643.Out of the physics realm I have to foremost thank my extended family and specially my parents. Their constant support, love and guidance have made me who I am, and their advice proved to be good even when I ignored it. I also have to thank my childhood friends for being how they are, because when we all took diverging paths, friendship continued and we still find time to converge.My final thank you goes to Olaia, because enduring me for all these years is a PhD in itself. This thesis is also yours. So long and thanks for all the fish. ContentsAcknowledgements iii 1 List of scientific publications

Bound-state dark matter and Dirac neutrino masses

“…The four CP-even mass eigenstates are denoted as S [7] of the "incomplete" tree-level seesaw mechanism, involving the exchange of a single heavy messenger, called (3,1) in Ref. [11].…”

“…We propose a simple implementation of the bound-state dark matter scenario in which DM constituents induce calculable neutrino mass at the radiative level. Dark matter is a QCD bound state QQ stabilized by the same conserved B − L symmetry associated to the Dirac nature of neutrinos [7].…”

Seesaw Dirac neutrino mass through dimension-six operators

“…Apart from the standard model gauge symmetry SUð3Þ C ⊗ SUð2Þ L ⊗ Uð1Þ Y , another symmetry must be imposed to protect the Diracness of neutrino fields. We will choose this symmetry to be the Z 4 quarticity symmetry described in [11][12][13]42]. The SUð3Þ C ⊗ SUð2Þ L ⊗ Uð1Þ Y ⊗ Z 4 symmetry is broken by the vacuum expectation values (vev) of the scalars.…”

“…Such scenarios can arise in context of many symmetries ranging from Uð1Þ X symmetries [16,20] to Abelian discrete Z n symmetries [11,[22][23][24]41] up to various types of more complex flavor symmetries containing non-Abelian groups [12,13,33]. Keeping this in mind, Table I is divided into two columns.…”

“…Dirac neutrinos also emerge in conventional four dimentional gauge theories with an adequate extra symmetry. One appealing possibility is the quarticity symmetry, which was originally suggested in [11][12][13]. This mechanism uses a version of Uð1Þ L lepton number symmetry broken into its subgroup Z 4 .…”