arXiv subjects
Publications and source records attributed to V. Pleitez.
Assuming the existence of right-handed neutrinos, we consider an electroweak model based on the gauge symmetry $SU(4)_L\otimes U(1)_N$. We study the neutral currents coupled to all neutral vector bosons present in the theory. There are no flavor changing neutral currents at tree level, coupled with the lightest neutral vector boson.
We consider flavor changing neutral current effects coming from the $Z'$ exchange in 3-3-1 models. We show that the mass of this extra neutral vector boson may be less than 2 TeV and discuss the problem of quark family discrimination.
We investigate the sensitivity of some weak processes to a Cabibbo--Kobayashi--Maskawa mixing in the leptonic sector. Values for mixing angles and masses compatible with several experimental accelerator data were found. We discuss in this context neutrino oscillations, cosmological and astrophysical consequences as well.
We consider generalizations of the standard model (SM) which are based on the gauge symmetry $SU(n)_c\otimes SU(m)_L\otimes U(1)_N$. Although the most interesting possibilities occur when $n=3$, we will consider also the cases $n=4,5$ both with $m=3,4$. Models with left-right symmetry, horizontal symmetries and the possible embedding in a larger group (grand unification scenarios) are briefly discussed.
We consider effective interactions among excited spin-1/2 and spin-3/2 leptons with the usual ones. Assuming that these new leptons are lighter than the Z0 we will study the constraints on their masses and compositeness scale coming from the leptonic Z0 partial width.
The ratio $Δm_K/m_K$ within the standard model with 3 generations is calculated as a function of the CP nonconserving phase $δ_{13}$ and the quark masses $m_c,m_t$ assuming the current values of the Cabibbo-Kobayashi-Maskawa mixing angles. We have found that varying $δ_{13}$ and $m_c$ within the allowed range, not all the values for the top quark mass fit the experimental value for that ratio.
We consider an $SU(3)_L\otimes U(1)_N$ model for the electroweak interactions which includes extra charged leptons which do not mix with the known leptons. These new leptons couple to $Z^0$ only through vector currents. We consider constraints on the mass of one of these leptons coming from the $Z^0$-width and from the muon $(g-2)$ factor. The last one is less restrictive than the former.
We consider a model for the electroweak interactions with $SU(3)_L\otimes U(1)_N$ gauge symmetry. We show that, it is the conservation of $F=L+B$ which forbids massive neutrinos and the neutrinoless double beta decay, $(ββ)_{0ν}$. Explicit and spontaneous breaking of $F$ imply that the neutrinos have an arbitrary mass and $(ββ)_{0ν}$ proceeds also with some contributions that do not depend explicitly on the neutrino mass.
We comment a model based on the $SU(3)_c \otimes SU(3)_L \otimes U(1)_X$ gauge symmetry recently proposed by Frampton. We stressed that the analysis of flavor changing neutral currents impose strong constraints on th emasses of the new gauge bosons of the model.
We study the constraints on masses and mixing angles imposed by the measured $Z^0$ invisible width, in a model in which a singlet right-handed neutrino mixes with all the Standard Model neutrinos.
We study the Glashow-Iliopoulos-Maiani mechanism for flavor-changing-neutral-currents suppression in both, the gauge and Higgs sectors, for models with $SU(3)_L\otimes U(1)_N$ gauge symmetry. The models differ one from the other only with respect to the representation content. The main features of these models are that in order to cancel the triangle anomalies the number of families must be divisible by three (the number of colors) and that the lepton number is violated by some lepton-gauge bosons and lepton-scalar interactions.
The $SU(3)_c\otimes SU(3)_L\otimes U(1)_N$ model of Pisano and Pleitez extends the Standard Model in a particularly nice way, so that for example the anomalies cancel only when the number of generations is divisible by three. The original version of the model has some problems accounting for the lepton masses. We resolve this problem by modifying the details of the symmetry breaking sector in the model.
We consider the possibility that the $τ$ decay puzzle, if it is confirmed in future experiments, is a consequence of the Kobayashi-Maskawa mixing in the leptonic sector
We analize the current data on $τ$-lepton decays and show that they are consistent with the Standard Model
We consider a gauge model based on $SU(3)\otimes U(1)$ symmetry in which the lepton number is violated explicitly by charged scalar and gauge bosons, including a vector field with double electric charge. Although there exist in the literature several models based on a $SU(3)\otimes U(1)$ gauge symmetry, our model has a different representation content and a quite different new physics at an, in principle, arbitrary mass scale. This is possibly the simplest way to enlarge the gauge group $SU_L(2)\otimes U_Y(1)$ in order to have doubly charged gauge bosons, without losing the natural features of the standard electroweak model. The price we must pay is the introduction of exotic quarks, with electric charge $5/3$ and $-4/3$. A previous version of the model was considered several months ago concerning the possibility that in this kind of models neutrinoless double beta decay proceeds even for massless neutrinos and with scalar exchange instead of vector exchange. Our work is in press in Physical Review D.