Abstract
We consider a rather minimal extension of the Standard Model involving just one extra particle, namely a single $SU(2)_L$ singlet scalar $S^{++}$ and its antiparticle $S^{--}$. We propose a model independent effective operator, which yields an effective coupling of $S^{\pm \pm}$ to pairs of same sign weak gauge bosons, $W^{\pm} W^{\pm}$. We also allow tree-level couplings of $S^{\pm \pm}$ to pairs of same sign right-handed charged leptons $l^{\pm}_Rl'^{\pm}_R$ of the same or different flavour. We calculate explicitly the resulting two-loop diagrams in the effective theory responsible for neutrino mass and mixing. We propose sets of benchmark points for various $S^{\pm \pm}$ masses and couplings which can yield successful neutrino masses and mixing, consistent with limits on charged lepton flavour violation (LFV) and neutrinoless double beta decay. We discuss the prospects for $S^{\pm \pm}$ discovery at the LHC, for these benchmark points, including single and pair production and decay into same sign leptons plus jets and missing energy. The model represents a minimal example of the complementarity between neutrino physics (including LFV) and the LHC, involving just one new particle, the $S^{\pm \pm}$.
Highlights
Loop neutrino mass models are often characterised by additional Higgs doublets and singlets
In appendix B we present a new correlation for elements of the light neutrino mass matrix, which arises for a certain category of benchmark points and which is, in principle, testable
We have considered the implications of a rather minimal extension of the Standard Model involving just one extra particle, namely a single SU(2)L singlet scalar S++ and its antiparticle S−−
Summary
We aim to construct the vertex SW W in terms of an effective field theory involving only SM-fields as well as the SU(2) singlet scalar S,. We will always assume that this scale Λ represents a physical cutoff, which in particular means that any particles in the full theory beyond the scalar S are assumed to be heavier than Λ Note, that this might not necessarily be the case if the UV-. Where (G+, G−, GZ) are the longitudinal components of the massive vectors (W +, W −, Z0) and the VEV is given by v = 246 GeV, it is easy to see that the only relevant component of eq (2.4) is given by Inserting this into eq (2.3) and realising that only the third term H0H0(DμH+)(DμH+) plays a role, one can derive three relevant vertices: Lrelevant = LSGG + LSGW + LSW W ,. E.g. for LHC-related studies, effectively the whole relevant part of the Lagrangian will in practice be LSGG from eq (2.8)
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.