Mirror Leptons Research Articles

Matter-parity constraints on particle spectrum in three-generation Calabi-Yau manifolds.

An analysis of the particle spectrum after intermediate scale breaking in the three-generation Calabi-Yau manifold CP/sup 3//times/CP/sup 2//Z/sub 3/ is given. The spectrum is investigated within the framework of intermediate scale breaking which preserves matter parity and breaks the rank-six gauge group SU(3)/sub /ital C///times/SU(3)/sub /ital L///times/SU(3)/sub /ital R// to the standard-model gauge group SU(3)/sub /ital C///times/SU(2)/sub /ital L///times/U(1)/sub /ital Y//. It is shown that a large number of particles and mirror particles associated with the extra families and mirror families on CP/sup 3//times/CP/sup 3//Z/sub 3/ can all be made superheavy through mass generation induced by nonrenormalizable interactions that are present in the superpotential below the compactification scale. The final spectrum of the compactified superstring below the intermediate-mass scale breaking is shown to be the spectrum of the standard /ital N/=1 supersymmetry theory and a few additional exotic leptons. Some of these exotic leptons are hybrid structures containing equal mixture of leptons and mirror leptons.

Yukawa couplings and phenomenology of a three-generation superstring model.

Armed with the explicitly calculated Yukawa couplings and knowledge of discrete symmetries we discuss the phenomenology of the three-generation superstring model suggested by Yau. We consider the possibility of CP violation induced through the complex moduli of the Calabi-Yau space (i.e., through the complex parameters in the equations that define the manifold). On analyzing the dimension-four terms in the superpotential in search of F-flat directions, we find that F-flat directions generally lead to extra massless quarks and mirror quarks as well as extra massless leptons and mirror leptons in the low-energy spectrum. We then consider a non-F-flat scenario that has only three quark and lepton generations at low energies. We also analyze other aspects of the model such as constraints of sin/sup 2/theta/sub w/ on the intermediate scale and the neutrino masses and we argue that neutron-antineutron oscillation may be observable in this class of models.

Production of mirror fermions near the Z 0 peak

Several attractive theories predict the existence of mirror fermions. There is a good theoretical reason to expect that the lightest mirror fermions might have relatively long lifetimes. We explore the experimental consequences of such a possibility, focusing on mirror lepton production at the SLC near the Z 0 resonance. We find that by going slightly off resonance or by polarizing the electron beam one can clearly distinguish the mirror leptons from ordinary leptons.

Leptonic CP-violation and mirror leptons

We study leptonic CP-violation within a single fermion generation in an extended electro-weak model where new right-handed leptons, so-called mirror leptons, exist and mix with standard left-handed leptons. Essential differences are pointed out between the mixing of a left-handed neutrino with a mirror neutrino in such a model and the ordinary mixing of two left-handed neutrinos in the standard model. E.g. in the mirror case CP-violation may occur even if neutrinos are Dirac particles. The number of physical CP-violation phases is determined for different mixing schemes and parameterizations of the leptonic weak currents in terms of these phases are presented.

Mirror-lepton phenomenology in a left-right model with ultralight Dirac neutrinos.

A study of the production and decay of heavy mirror leptons is presented in the framework of a left-right model that yields ultralight Dirac neutrinos. Qualitative limits on the masses of the light neutrinos are also presented in terms of bounds on the heavy-mirror-lepton masses.

P [formula omitted] Events with missing energy: Evidence for a fourth neutrino?

It is proposed that recently observed events at UA1 may be explained through the existence of a new heavy neutrino, belonging to a possible new sequential or mirror lepton family.

Muon Decay and the Majorana Neutrino

Recently, the Berkeley group reported the precise and excellent experimental result on the e+ spectrum end point in /1+ decay.') In order to get the lower limit for the possible heavier (righthanded) gauge boson mass M( Wz»380 GeV, they have used the following assumptions made by Beg, Budny, Mohapatra and Sirlin;Z) (i) the manifest left-right symmetry in the charged current sector, (ii) no mirror leptons, (iii) the CP invariance, (iv) the smallness of all neutrino masses (Ll j =(mjlmp)4{.l), m" being the f.I. mass. In this note, we shall reinterpret this Berkeley result from the viewpoint of the massive Majorana neutrino, and show the information which we can draw from this result for the case where the right-handed Majorana neutrino (Nn+k) has a quite large mass mn+kl m,,~ 1. Namely, the fourth assumption (Ll j 4{.l) is reexamined by taking into account the effect due to the neutrino mixing. In order to be self-contained, we shall start from the effective lepton-hadron weak interaction Hamiltonian to treat the 7[+ decay;

Mirror leptons

We study the effects of the mixing of leptons and mirror leptons in charged current and neutral current processes at low energy. Expressions are derived for all relevant measurable quantities, taking into account various radiative constraints. We discuss the effects of the new phenomenon of neutrino-mirror-neutrino oscillations which may occur with light mirror neutrinos. Using a recent data set we determine the allowed ranges of the mixing angles and of sin 2θ w in several mixing models, distinguished by different assumptions on the mirror neutrino masses. We conclude that sizeable mixing is possible and that some mixing angles have a strong negative correlation with sin 2θ w.

Unification constraints on mirror fermion mass scale

The mass scale M F of conjugated, on mirror, fermions with V + A weak charged interactions is investigated in connection with grand unified models. Using extended SO(10) as an example, it has been demonstrated that this mass scale is below 1–10 TeV. Assuming that the mirror quarks are heavy (= M F ) but the mirror leptons light ( M L ≈80GeV/c 2 ), radiatively corrected values of sin 2 θ W ( M L ) are evaluated. The effect of heavy fermions on the Weinberg angle was found to be typically of order δ(sin 2 θ W ( M L )/sin 2 θ W ( M L ≲−0.6% per family. Corrections to the unification mass appear to be more significant: δ M X / M X ≲−7% per family (in the minimal Higgs model). It has been shown that expanding the Higgs sector will considerably increase the value of sin 2 θ W ( M L ) and decrease the value of M X .