Aspects of Neutrino Mass Matrices

After an Introduction briefly describing the rise and fall of the three-zero texture of the Zee model, we discuss still-allowed two-zero textures for the Majorana three-neutrino mass matrix. Finally, a model with two right-handed neutrinos and two Dirac texture zeros is described (FGY model) which can relate CP violation in leptogenesis to CP violation in long-baseline neutrino oscillations.Comment: 9 pages latex. Talk at Coral Gables 2003. Added reference

Structure of Equilenin at 100 K: an estrone-related steroid

The structure of the estrone-related steroid, Equilenin, C18H18O2 (systematic name 3-hy-droxy-13-methyl-11,12,13,14,15,16-hexa-hydro-cyclo-penta-[a]phen-anthren-17-one), has been determined at 100 K. The crystals are ortho-rhom-bic, P212121, and the absolute structure of the mol-ecule in the crystal has been determined by resonant scattering [Flack parameter = -0.05 (4)]. The C atoms of the A and B rings are almost coplanar, with an r.m.s. deviation from planarity of 0.0104 Å. The C ring has a sofa conformation, while the D ring has an envelope conformation with the methine C atom as the flap. The keto O atom and the methyl group are translated 0.78 and 0.79 Å, respectively, from the equivalent positions on 17β-estrone. In the crystal, mol-ecules are linked by O-H⋯O hydrogen bonds, forming chains parallel to the c-axis direction

Smart double panel with decentralised active dampers for control of sound transmission

This report presents the results of a theoretical study of active sound transmission control through a double panel. The double panel material and geometrical properties have been chosen so as to emulate section of an aircraft fuselage, or bodywork of a vehicle. It consists of two plates: an aluminium plate simply supported along all the edges and a honeycomb plate with all the edges free. The two plates, having the same length and width, are connected using elastic mounts, so that a double panel with a thin rectangular cavity between the plates is formed. Since the two plates are linked by the mounting system, and since the air is confined in the cavity between them, they form a structurally and acoustically coupled system. The sound transmission properties of the system are studied in such a way that the aluminium plate (“source panel”) is excited using a plane acoustic wave, while the honeycomb plate (“radiating panel”) radiates sound into free field.The aim of the active control is to reduce the sound transmitted in a broad frequency band, but with a particular focus on the reduction of the sound transmission at lower frequencies of the band. Decentralised velocity feedback control systems (applying active damping) are implemented, with purpose of reducing sound transmission at resonance frequencies. Control sensors and actuators are embedded into the double plate system as a regular array, so that a smart double panel is created. The theoretical study includes analysis of the passive sound transmission in terms of a parametric study, implementation of the active control using skyhook velocity sensors and skyhook force actuators, and the performance/stability analysis in case when reactive actuators and skyhook velocity sensors are used. In the latter case the actuating force is obtained using actuators located in the air cavity which can react off the two plate

Constraints on Deflation from the Equation of State of Dark Energy

In cyclic cosmology based on phantom dark energy the requirement that our universe satisfy a CBE-condition ({\it Comes Back Empty}) imposes a lower bound on the number $N_{\rm cp}$ of causal patches which separate just prior to turnaround. This bound depends on the dark energy equation of state $w = p/\rho = -1 - \phi$ with $\phi > 0$. More accurate measurement of $\phi$ will constrain $N_{\rm cp}$. The critical density $\rho_c$ in the model has a lower bound $\rho_c \ge (10^9 {\rm GeV})^4$ or $\rho_c \ge (10^{18} {\rm GeV})^4$ when the smallest bound state has size $10^{-15}$m, or $10^{-35}$m, respectively.Comment: 23 pages, 3 figures, typos fixe

3-3-1 exotic quark search at CERN LEPII-LHC

The 3-3-1 electroweak model is the simplest chiral extension of the standard model which predicts single and double charged bileptons and exotic quarks carrying -4/3 and 5/3 units of the positron charge. In this paper we study the possibilities of the production and decay of one of these exotic quarks at CERN LEPII-LHC collider. For typical vector bilepton, exotic quark masses and mixing angles we obtained between 20 and 750 events per year. Angular distributions are also presented.Comment: 5 pages, RevTex 3.1, 9 eps figures, to appear in Phys. Rev.

Primordial Black Holes, Hawking Radiation and the Early Universe

The 511 keV gamma emission from the galactic core may originate from a high concentration ($\sim 10^{22}$) of primordial black holes (PBHs) in the core each of whose Hawking radiation includes $\sim 10^{21}$ positrons per second. The PBHs we consider are taken as near the lightest with longevity greater than the age of the universe (mass $\sim 10^{12}$ kg; Schwarzschild radius $\sim 1$ fm). These PBHs contribute only a small fraction of cold dark matter, $\Omega_{PBH} \sim 10^{-8}$. This speculative hypothesis, if confirmed implies the simultaneous discovery of Hawking radiation and an early universe phase transition.Comment: 4 Page

Single Z' production at CLIC based on e^- gamma collisions

We analyze the potential of CLIC based on e- gamma collisions to search for new $Z'$ gauge boson. Single Z' production at e-gamma colliders in two SU(3)_C X SU(3)_L X U(1)_N models: the minimal model and the model with right-handed (RH) neutrinos is studied in detail. Results show that new Z' gauge bosons can be observed at the CLIC, and the cross sections in the model with RH neutrinos are bigger than those in the minimal one.Comment: 11 pages, 4 figures, To appear in JET

Search for Heavy Leptons at Hadron Colliders

Four models are considered which contain heavy leptons beyond the three families of the standard model. Two are fourth-generation extensions of the standard model in which the right-handed heavy leptons are either isosinglets or in an isodoublet; the other two are motivated by the aspon model of CP violation. In all these models, the heavy neutrino can either be heavier than, or comparable in mass to, the charged lepton leading to the possibility that the charged lepton is very long-lived. Production cross section and signatures for the heavy leptons are computed for the SSC and LHC.Comment: 17 pages(8 figures are not included),TRI-PP-92-9

The exact eigenstates of the neutrino mass matrix without CP-phase violation

In this paper we obtain the exact mass-eigenstates of the Majorana physical neutrinos. We start by taking into account a general $3\times3$ mass matrix without any CP-phase violation. It is then diagonalized by exactly solving an appropriate set of equations. The solution supplies straightforwardly the mass eigenvalues depending on the diagonal entries and mixing angles. Finally, the consequences of these analytical expressions are discussed assuming various phenomenological restrictions such as conserving the global lepton number $L=L_{e}-L_{\mu}-L_{\tau}$ and the $\mu-\tau$ interchange symmetry. The minimal absolute mass in the neutrino sector is also obtained since the two plausible scenarios invoked above are employed.Comment: 9 pages, no figure