Search

In this work we present octonionic duality for membranes. We start with a discussion on the relation of the Yang-Mills theories and the the supermembrane Hamiltonian in the light-cone gauge. We further derive the self-duality equations for the membranes and discuss the integrability of the system in 7 and 3 dimensions. Finally, we present classical Euclidean time solutions of these equations and examine the supersymmetries left intact by the self-duality equations. [ABSTRACT FROM AUTHOR]

The predictions of the MSSM are discussed in the light of recent LEP and SLD precision data. The full supersymmetric one-loop corrections to the effective weak mixing angle are considered. Potentially dangerous, large logarithmic sparticle corrections are cancelled. The relative difference factor Δk between the mixing angle defined as a ratio of couplings and the experimentally obtained angle is discussed and it is found that Δk is dominated by the oblique corrections, while the non-oblique overall supersymmetric EW and SQCD corrections are negligible. We also reconsider the next to minimal supersymmetric standard model (NMSSM) as a natural solution to the μ problem and show that both the stability and the cosmological domain wall problems are eliminated if we impose a discrete Z2 R-symmetry on the non-renormalizable operators of the theory. [ABSTRACT FROM AUTHOR]

The non-supersymmetric as well as the supersymmetric hybrid inflationary model is reviewed. The scenario of baryogenesis via a primordial leptogenesis is discussed and the rôle of the non-perturbative electroweak sphaleron effects is analyzed in detail. A supersymmetric model based on a left-right symmetric gauge group, which ‘naturally' leads to hybrid inflation, is presented. The μ problem is solved, in this model, and the baryon asymmetry of the universe is produced through leptogenesis. For masses of νμ, ντ from the small angle MSW resolution of the solar-neutrino problem and super-Kamiokande, maximal νμ−ντ mixing can be achieved. The required values of the relevant parameters are, however, quite small. [ABSTRACT FROM AUTHOR]

The recent developments on neutrino-nucleus interactions at low and intermediate energies are reviewed and discussed in conjunction with the recent data of atmospheric-, solar- and accelerator-neutrino experiments. The theoretical nuclear physics approaches used to interpret and predict phenomena for which neutrinos play a crucial rôle are also investigated. We emphasize the implications of neutrino reactions and properties in astrophysical phenomena and atmospheric-neutrino problems. [ABSTRACT FROM AUTHOR]

The nuclear structure physics of double beta decay transitions is reviewed, starting from the consideration of fundamental symmetries of the nuclear many-body problem. The problems found in the use of the quasiparticle random phase approximation (QRPA) and related approximations, in dealing with the calculation of nuclear double beta decay observables, are understood in terms of the mixing between isospin collective and intrinsic variables. [ABSTRACT FROM AUTHOR]

The theoretical concepts of a chirally symmetric meson field theory are reviewed and an overview of the most relevant applications in nuclear physics is given. This includes a unified description of the vacuum properties of hadrons, finite nuclei and hot, dense and strange nuclear matter in an extended chiral SU(3)L × SU(3)R σ − ω model. [ABSTRACT FROM AUTHOR]

I review the motivation for and status of searches for violation of muon- and electron-number conservation, concentrating on muon-initiated processes. I then discuss the progress expected in the next few years, concentrating on a new experiment, E940 at BNL (the MECO experiment). It will improve the experimental sensitivity for the process μ−N → e−N to below 10−16, roughly 4 orders of magnitude better than the current limit. [ABSTRACT FROM AUTHOR]

Nuclear double-beta decay provides an extraordinarily broad potential to search for beyond-standard-model physics, which is already probing the TeV scale, on which new physics should manifest itself. The following possibilities are reviewed here. First, the results of present-generation experiments are presented. The most sensitive one of them — the Heidelberg-Moscow experiment in the Gran Sasso - probes the electron mass in the sub-eV region and has recently reached a limit of ∼0.1 eV. This limit has striking influence on presently discussed neutrinomass scenarios. Based to a large extent on the theoretical work of the Heidelberg Double Beta Group in the last two years, results are obtained also for SUSY models (R-parity breaking, sneutrino mass), leptoquarks (leptoquark-Higgs coupling), compositeness, right-handed W boson mass, test of special relativity and the equivalence principle in the neutrino sector and others. These results are comfortably competitive to corresponding results from high-energy accelerators like TEVATRON, HERA, etc. One of the enriched 76Ge detectors also yields the most-stringent limits for cold dark matter (WIMPs) to date by using raw data. Second, future perspectives of ββ research are discussed. A new Heidelberg experimental proposal (GENIUS) will allow us to increase the sensitivity for Majorana neutrino masses from the present level of at best 0.1 eV down to 0.01 or even 0.001 eV. Its physical potential would be a breakthrough into the multi-TeV range for many beyond-standard models. Its sensitivity for neutrino-oscillation parameters would be larger than all present terrestrial neutrino-oscillation experiments and those planned for the future. It could probe directly the large-angle, and for almost-degenerate neutrino-mass scenarios even the small-angle solution of the solar-neutrino problem. It would further, already in a first step using only 100 kg of natural Ge detectors, cover almost the full MSSM parameter space for prediction of neutralinos as cold dark matter, making the experiment competitive to LHC in the search for supersymmetry. Finally GENIUS could be used as the first real-time detector of solar pp neutrinos. [ABSTRACT FROM AUTHOR]

Theory suggests the existence of neutrino masses, but little more. Facts are coming close to revealing our fantasy: solar- and atmospheric-neutrino data strongly indicate the need for neutrino conversions, while LSND provides an intriguing hint. The simplest ways to reconcile these data in terms of neutrino oscillations invoke a light sterile neutrino in addition to the three active ones. Out of the four neutrinos, two are maximally mixed and lie at the LSND scale, while the others are at the solar-mass scale. These schemes can be distinguished at neutral-current-sensitive solar- and atmospheric-neutrino experiments. I discuss the simplest theoretical scenarios, where the lightness of the sterile neutrino, the nearly maximal atmospheric-neutrino mixing and the generation of Δm⊙2 and Δmatm2 all follow naturally from the assumed lepton-number symmetry and its breaking. Although the most likely interpretation of the present data is in terms of neutrino-mass-induced oscillations, one still has room for alternative explanations, such as flavor-changing neutrino interactions, with no need for neutrino mass or mixing. Such flavor-violating transitions arise in theories with strictly massless neutrinos and may lead to other sizeable flavor non-conservation effects, such as μ → e + γ, μ − e conversion in nuclei, unaccompanied by neutrinoless double-beta decay. [ABSTRACT FROM AUTHOR]

A review of the problems of neutrino mass, mixing and oscillations is given. Possible phenomenological schemes of neutrino mixing are discussed. The most important consequences of neutrino mixing-neutrino oscillations are considered in some detail. The data of atmospheric, solar and LSND experiments are discussed. The results of phenomenological analysis of the data under the assumption of the mixing of three and four massive neutrinos are briefly presented. [ABSTRACT FROM AUTHOR]

The standard model predicts a ratio of 2 for the number of atmospheric muon to electron neutrinos, while super-Kamiokande and others measure a much smaller value (1.30±0.02 for super-Kamiokande). Super-Kamiokande is also able to measure roughly the direction and the energy of the neutrinos. The zenith-angle dependence for the muon neutrinos suggests that suggests that the muon neutrinos oscillate into a third neutrino species, either into the τ neutrino or a sterile neutrino. This finding is investigated within the supersymmetric model. The neutrinos mix with the neutralinos, this meaning the wino, the bino and the two higgsinos. The 7×7 mass matrix is calculated on the tree level. One finds that the mass matrix has three linearly dependent rows, which means that two masses are zero. They are identified with the two lightest neutrino masses. The fit of the super-Kamiokande data to oscillations between three neutrinos yields, together with the result of supersymmetry, that the third neutrino mass lies between 2 × 10−2 and 10−1 eV. The two lightest neutrino masses are in supersymmetry on the tree level zero. The averaged electron neutrino mass which is the essential parameter in the neutrinoless double-beta decay is given by 〈mνe〉 ⋍ mν3P3e≤0.8×10−2 eV (95% confidence limit). It is derived from the super-Kamiokande data in this supersymmetric model to be two orders smaller than the best value (1 eV) from the neutrinoless double-beta decay. [ABSTRACT FROM AUTHOR]