Search results for "seesaw mechanism"
showing 10 items of 56 documents
Gravity triggered neutrino condensates
2010
In this work we use the Schwinger-Dyson equations to study the possibility that an enhanced gravitational attraction triggers the formation of a right-handed neutrino condensate, inducing dynamical symmetry breaking and generating a Majorana mass for the right-handed neutrino at a scale appropriate for the seesaw mechanism. The composite field formed by the condensate phase could drive an early epoch of inflation. We find that to the lowest order, the theory does not allow dynamical symmetry breaking. Nevertheless, thanks to the large number of matter fields in the model, the suppression by additional powers in G of higher order terms can be compensated, boosting them up to their lowest ord…
Right Handed Sneutrino Dark Matter in Inverse and Linear seesaw scenarios
2012
We consider supersymmetric models in which the right-handed sneutrino is a viable WIMP dark matter candidate. These are either simple extensions of the Minimal Supersymmetric Standard Model or models with the addition of an extra U(1) group. All of them can explain small neutrino masses, through either the Inverse or the Linear Seesaw mechanism. We investigate the properties of the dark matter candidate naturally arising in these scenarios. We check for phenomenological bounds, such as correct relic abundance, consistency with direct detection cross section limits and laboratory constraints. Especially, we comment on limitations of the model space due to lepton flavour violating charged lep…
Links between CP violation in leptogenesis and low energy supersymmetry
2008
The seesaw mechanism makes leptogenesis a very attractive solution to the baryon asymmetry problem. If the baryon asymmetry of the Universe (BAU) was made via leptogenesis, any observation of CP violation in the lepton sector, for instance CP violation in neutrino oscillations, would support leptogenesis by demonstrating that CP is not a symmetry of leptons. The question is whether a stronger link exists between CP violation at low energies and leptogenesis. In our work we address this question, in the framework of a supersymmetric scenario where new constraints given by the low energy footprints of the high energy theory can be imposed, namely the current experimental bounds on lepton flav…
Unifying left–right symmetry and 331 electroweak theories
2017
We propose a realistic theory based on the $\mathrm{SU(3)_c \otimes SU(3)_L \otimes SU(3)_R \otimes U(1)_{X}}$ gauge group which requires the number of families to match the number of colors. In the simplest realization neutrino masses arise from the canonical seesaw mechanism and their smallness correlates with the observed V-A nature of the weak force. Depending on the symmetry breaking path to the Standard Model one recovers either a left-right symmetric theory or one based on the $\mathrm{SU(3)_c \otimes SU(3)_L \otimes U(1)}$ symmetry as the "next" step towards new physics.
Constrained SUSY seesaws with a 125 GeV Higgs
2012
Motivated by the ATLAS and CMS discovery of a Higgs-like boson with a mass around 125 GeV, and by the need of explaining neutrino masses, we analyse the three canonical SUSY versions of the seesaw mechanism (type I, II and III) with CMSSM boundary conditions. In type II and III cases, SUSY particles are lighter than in the CMSSM (or the constrained type I seesaw), for the same set of input parameters at the universality scale. Thus, to explain $m_{h^0} \simeq 125 GeV$ at low energies, one is forced into regions of parameter space with very large values of $m_0$, $M_{1/2}$ or $A_0$. We compare the squark and gluino masses allowed by the ATLAS and CMS ranges for $m_{h^0}$ (extracted from the …
Sensitivity to the Higgs sector of supersymmetric-seesaw models in the lepton flavor violatingτ→μf0(980)decay
2009
In this work we study the lepton flavor violating (LFV) semileptonic $\ensuremath{\tau}\ensuremath{\rightarrow}\ensuremath{\mu}{f}_{0}(980)$ decay within the context of SUSY-Seesaw Models, where the MSSM spectrum is extended by three right-handed neutrinos and their SUSY partners, and where the seesaw mechanism is used to generate the neutrino masses. We estimate its decay rate when it proceeds via the Higgs-mediated channel $\ensuremath{\tau}\ensuremath{\rightarrow}\ensuremath{\mu}{H}^{*}\ensuremath{\rightarrow}\ensuremath{\mu}{f}_{0}(980)$, where $H$ refers to the $CP$-even MSSM Higgs bosons ${h}^{0}$ and ${H}^{0}$, and the lepton flavor violating $\ensuremath{\tau}\ensuremath{\mu}H$ vert…
Soft leptogenesis in the inverse seesaw model
2006
We consider leptogenesis induced by soft supersymmetry breaking terms ("soft leptogenesis"), in the context of the inverse seesaw mechanism. In this model there are lepton number (L) conserving and L-violating soft supersymmetry-breaking B-terms involving the singlet sneutrinos which, together with the -- generically small-- L-violating parameter responsible of the neutrino mass, give a small mass splitting between the four singlet sneutrino states of a single generation. In combination with the trilinear soft supersymmetry breaking terms they also provide new CP violating phases needed to generate a lepton asymmetry in the singlet sneutrino decays. We obtain that in this scenario the lepto…
Bounds on the triplet fermions in type-III seesaw and implications for collider searches
2021
Type-III seesaw is a simple extension of the Standard Model~(SM) with the SU$(2)_\text{L}$ triplet fermion with zero hypercharge. It can explain the origin of the tiny neutrino mass and flavor mixing. After the electroweak symmetry breaking the light neutrino mass is generated by the seesaw mechanism which further ensures the mixings between the light neutrino and heavy neutral lepton mass eigenstates. If the triplet fermions are around the electroweak scale having sizable mixings with the SM sector allowed by the correct gauge symmetry, they can be produced at the high energy colliders leaving a variety of characteristic signatures. Based on a simple and concrete realizations of the model …
Hefty MSSM-like light Higgs in extended gauge models
2011
It is well known that in the MSSM the lightest neutral Higgs h^0 must be, at the tree level, lighter than the Z boson and that the loop corrections shift this stringent upper bound up to about 130 GeV. Extending the MSSM gauge group in a suitable way, the new Higgs sector dynamics can push the tree-level mass of h^0 well above the tree-level MSSM limit if it couples to the new gauge sector. This effect is further pronounced at the loop level and h^0 masses in the 140 GeV ballpark can be reached easily. We exemplify this for a sample setting with a low-scale U(1)_R x U(1)_B-L gauge symmetry in which neutrino masses can be implemented via the inverse seesaw mechanism.
Supersymmetric mass spectra and the seesaw type-I scale
2012
We calculate supersymmetric mass spectra with cMSSM boundary conditions and a type-I seesaw mechanism added to explain current neutrino data. Using published, estimated errors on SUSY mass observables for a combined LHC+ILC analysis, we perform a theoretical $\chi^2$ analysis to identify parameter regions where pure cMSSM and cMSSM plus seesaw type-I might be distinguishable with LHC+ILC data. The most important observables are determined to be the (left) smuon and selectron masses and the splitting between them, respectively. Splitting in the (left) smuon and selectrons is tiny in most of cMSSM parameter space, but can be quite sizeable for large values of the seesaw scale, $m_{SS}$. Thus,…