Related papers: Neutrino Cosmology after WMAP and LHC7
We consider a U(1)' gauge symmetry acting on three generations of right-handed neutrinos. The U(1)' symmetry is broken at the TeV scale and its remnant discrete symmetry makes one of the right-handed neutrinos stable. As a natural…
We consider right-handed neutrino pair production in generic $Z^\prime$ models. We propose a new, model-independent analysis using final states containing a pair of same-sign muons. A key aspect of this analysis is the reconstruction of the…
We show that in theories where neutrino masses arise from type I seesaw formula with three right handed neutrinos and where large atmospheric mixing angle owes its origin to an approximate leptonic $\mu-\tau$ interchange symmetry, the…
The existence of prolonged radiation domination prior to the Big Bang Nucleosynthesis (BBN), starting just after the inflationary epoch, is not yet established unanimously. If instead, the universe undergoes a non-standard cosmological…
We propose a simple testable model with mass generation mechanisms for dark matter and neutrino based on the gauged $U(1)_{B-L}$ symmetry and an exact $Z_2$ parity. The $U(1)_{B-L}$ symmetry is spontaneously broken at the TeV scale, by…
New models have recently been proposed in which a second Higgs doublet couples only to the lepton doublets and right-handed neutrinos, yielding Dirac neutrino masses. The vacuum value of this second "nu-Higgs" doublet is made very small by…
We consider non-universal 'minimal' Z' models, whose additional U(1) charge is a non-anomalous linear combination of the weak hypercharge Y, the baryon number B and the partial lepton numbers (L_e, L_mu, L_tau), with no exotic fermions…
We propose a model with the left-handed and right-handed continuous Abelian gauge symmetry; $U(1)_L\times U(1)_R$. Then three right-handed neutrinos are naturally required to achieve $U(1)_R$ anomaly cancellations, while several mirror…
We improve limits on $Z^\prime$ extensions of the Standard Model (SM) with light right-handed neutrinos. The presence of shared gauge interactions between the light right-handed neutrinos and other SM fermions allows for production of…
There are strong indications for neutrino masses and mixings in the data on solar neutrinos as well as in the observed deficit of muon neutrinos from the atmosphere. The COBE data and other analysis of the large scale structure in the…
Instead of anchoring the seesaw mechanism with the conventional heavy right-handed neutrino singlet, a small Majorana neutrino mass may be obtained just as well with the addition of a heavy triplet of leptons per family to the minimal…
We consider the phenomenology of the gauged abelian symmetry B + 3 (L_e - L_mu - L_tau). Right-handed neutrinos necessary to cancel triangle anomalies are used in a type-I seesaw scheme to create active neutrino masses. Breaking the B + 3…
After some general remarks about SU_L(4) electroweak unification, the model is extended to SU_L(4)xU_X(1) to accomodate fractionally charged quarks. The unification scale is expected to be in TeV region. A right-handed Majorana neutrino…
We study the structure of the neutrino mass matrix in the minimal gauged U(1)$_{L_\mu-L_\tau}$ model, where three right-handed neutrinos are added to the Standard Model in order to obtain non-zero masses for active neutrinos. Because of the…
We propose a new extension of the Standard Model by a $U(1)_{B-L}$ gauge symmetry in which the anomalies are canceled by two right-handed neutrinos plus four chiral fermions with fractional B-L charges. Two scalar fields that break the B-L…
Curiously in the minimal left right symmetric model, chiral symmetry that protects the electron's mass ($m_e$), due to parity (P), implies in the symmetry limit the vanishing of its neutrino mixing angles. We break the chiral symmetry…
The exchange symmetry between the muon neutrino and the tau neutrino for the neutrino mass matrix has been very useful in understanding the near maximal atmospheric neutrino mixing angle. However, this symmetry can not be imposed at the…
The presently observed cosmological baryon asymmetry has been finally determined at the time of the electroweak phase transition, when baryon and lepton number violating interactions fell out of thermal equilibrium. We discuss the…
We show that maximal atmospheric and large solar neutrino mixing can be implemented in SU(5) gauge theories, by making use of the $U(1)_F$ symmetry associated with a suitably defined family number $F$, together with a $\mathbbm{Z}_2$…
I suggest an effective model between the GUT and the electroweak scale. It only introduces the two symmetries of $U(1)_{B-L}$ and $U(1)_{D}$ besides the SM groups. The two symmetries are individually broken at the reheating temperature of…