Inverting a Supernova: Neutrino Mixing, Temperatures and Binding Energy

We show that the temperatures of the emergent non-electron neutrinos and the binding energy released by a galactic Type II supernova are determinable, assuming the Large Mixing Angle (LMA) solution is correct, from observations at the Sudbury Neutrino Observatory (SNO) and at Super-Kamiokande (SK). If the neutrino mass hierarchy is inverted, either a lower or upper bound can be placed on the neutrino mixing angle $\theta_{13}$, and the hierarchy can be deduced for adiabatic transitions. For the normal hierarchy, neither can $\theta_{13}$ be constrained nor can the hierarchy be determined. Our conclusions are qualitatively unchanged for the proposed Hyper-Kamiokande detector.Comment: Following astro-ph/0208035, we adopt electron and non-electron neutrino spectra with very small differences. Conclusions change

Trilepton Signal of Grand Unified Models at the Tevatron

At the Tevatron, the most promising channel to detect supersymmetry is three leptons plus missing energy, where the leptons are $e$'s and/or $\mu$'s. This final state appears from the production of chargino and second lighetst neutralino. However in grand unified models with universal scalar masses at the grand unified scale, this final state mostly consists of $\tau$'s which are hard to detect. We show that for some regions of non universality in the scalar masses at the GUT scale based on unifying groups like SU(5) or SO(10), the final state mostly consists of 3$l$+${\rlap/E}_T$ and $\tau ll$+${\rlap/E}_T$. The first mode has very high detection efficiency and the second one is expected to have high detection efficency as well. We also show that these models can have enough events in these modes to be detected in RUN II.Comment: 7 pages, latex, 6 figure

Heavy Majorana neutrinos in e^-e^- collisions

We discuss the process $e^-e^- \to W^- W^-$ mediated by heavy Majorana neutrino exchange in the t- and u channel. In our model the cross section for this reaction is a function of the masses (m_N) of the heavy Majorana neutrinos and mixing parameters (U_{eN}) originating from mixing between the ordinary left-handed standard model neutrinos and additional singlet right-handed neutrino fields. Taking into account the standard model background and contraints from low energy measurements, we present discovery limits in the (m_N,U_{eN}^2) plane. We also discuss how to measure in principle the CP violating phases, i.e., the relative phases between the mixing parameters.Comment: 18 pages with 7 postscript figures included, uses epsfig.st

Higgs-Pair Production and Measurement of the Triscalar Coupling at LHC(8,14)

We simulate the measurement of the triscalar Higgs coupling at LHC(8,14) via pair production of h(125 GeV). We find that the most promising hh final state is bb gamma gamma. We account for deviations of the triscalar coupling from its SM value and study the effects of this coupling on the hh cross-section and distributions with cut-based and multivariate methods. Our fit to the hh production matrix element at LHC(14) with 3 ab^-1 yields a 40% uncertainty on this coupling in the SM and a range of 25-80% uncertainties for non-SM values.Comment: 4 pages, 7 page

Up-Down Unification, Neutrino Masses and Rare Lepton Decays

In a recent paper, we showed that tree level up-down unification of fermion Yukawa couplings is a natural consequence of a large class of supersymmetric models. They can lead to viable quark masses and mixings for moderately large values of $\tan\beta$ with interesting and testable predictions for CP violation in the hadronic sector. In this letter, we extend our discussion to the leptonic sector focusing on one particular class of these models, the supersymmetric left-right model with the seesaw mechanism for neutrino masses. We show that fitting the solar and the atmospheric neutrino data considerably restricts the Majorana-Yukawa couplings of the leptons in this model and leads to predictions for the decay $\tau\to \mu +\gamma$, which is found to be accessible to the next generation of rare decay searches. We also show that the resulting parameter space of the model is consistent with the requirements of generating adequate baryon asymmetry through lepton-number violating decays of the right-handed neutrino.Comment: 16 pages, latex, 6 figures, typos correcte

Upper Bounds on Lepton-number Violating Processes

We consider four lepton-number violating (\lv) processes: (a) neutrinoless double-beta decay (0\nu\beta\beta), (b) Delta L = 2 tau decays, (c) Delta L = 2 rare meson decays and (d) nuclear muon-positron conversion. In the absence of exotic \lv interactions, the rates for these processes are determined by effective neutrino masses _{\ell_1\ell_2}, which can be related to the sum of light neutrino masses, the neutrino mass-squared differences, the neutrino mixing angles, a Dirac phase and two Majorana phases. We sample the experimentally allowed ranges of _{\ell_1\ell_2} based on neutrino oscillation experiments as well as cosmological observations, and obtain a stringent upper bound _{\ell_1\ell_2} \lsim 0.14 eV. We then calculate the allowed ranges for _{\ell_1\ell_2} from the experimental rates of direct searches for the above Delta L = 2 processes. Comparing our calculated rates with the currently or soon available data, we find that only the $0\nu\beta\beta$ experiment may be able to probe _{ee} with a sensitivity comparable to the current bound. Muon-positron conversion is next in sensitivity, while the limits of direct searches for the other Delta L = 2 processes are several orders of magnitude weaker than the current bounds on _{\ell_1\ell_2}. Any positive signal in those direct searches would indicate new contributions to the \lv interactions beyond those from three light Majorana neutrinos.Comment: 20 pages, revtex4, 2 figures (5 files), Version published in Physical Review

Electric dipole moments and b-τ\tau unification in the presence of an intermediate scale in SUSY grand unification

We show that an intermediate gauge symmetry breaking scale can be a significant source of electric dipole moments for the electron and neutron in supersymmetric grand unified theories. New phases, similar to that of the CKM matrix, appear which do not arise from the supersymmetry (SUSY) breaking operators. To illustrate, we choose some grand unified SUSY models having an intermediate gauge symmetry breaking scale with some attractive features. We also show how well the $b-\tau$ unification hypothesis works in this class of models.Comment: 14 pages(Latex), 2 PS Figures (uuencoded, epsf.tex

Infra-red stable fixed points of R-parity violating Yukawa couplings in supersymmetric models

We investigate the infra-red stable fixed points of the Yukawa couplings in the minimal version of the supersymmetric standard model with R-parity violation. Retaining only the R-parity violating couplings of higher generations, we analytically study the solutions of the renormalization group equations of these couplings together with the top- and b-quark Yukawa couplings. We show that only the B-violating coupling $\lambda^{''}_{233}$ approaches a non-trivial infra-red stable fixed point, whereas all other non-trivial fixed point solutions are either unphysical or unstable in the infra-red region. However, this fixed point solution predicts a top-quark Yukawa coupling which is incompatible with the top quark mass for any value of $\tan\beta$.Comment: Plain latex to be run twice, 12 pages. Replaced with version to appear in Physics Letters