Implications of partially degenerate neutrinos at a high scale in the light of KamLAND and WMAP

Electroweak radiative corrections can generate the neutrino (mass)$^2$ difference required for the large mixing angle solution (LMA) to the solar neutrino problem if two of the neutrinos are assumed degenerate at high energy. We test this possibility with the existing experimental knowledge of the low energy neutrino mass and mixing parameters. We derive restrictions on ranges of the high scale mixing matrix elements and obtain predictions for the low energy parameters required in order to get the LMA solution of the solar neutrino problem picked out by KamLAND. We find that in the case of standard model this is achieved only when the (degenerate) neutrino masses lie in the range (0.7-2) \eV which is at odds with the cosmological limit m_{\nu}<0.23 \eV (at $95$) established recently using WMAP results. Thus SM radiative corrections cannot easily generate the LMA solution in this scenario. However, the LMA solution is possible in case of the MSSM electroweak corrections with (almost) degenerate spectrum or with inverted mass hierarchy for limited ranges in the high scale parameters.Comment: 15 pages, LATEX includes five postscript figure

Effect of Hadron Dynamics on the Proton Lifetime

A detailed, quantitative re-examination of the effect of hadron dynamics on baryon decay, modeled in terms of Skyrme-field tunneling, indicates that any hadronic suppression should be quite mild. This appears to be another illustration of the `Cheshire-cat' phenomenon, that variation of the apportionment between description of the nucleon as a bag of quarks and description as a Skyrme field configuration has little influence on many nucleon properties. Perhaps the largest remaining uncertainty in evaluating the decay rate has to do with the overlap between a specified quark-antiquark configuration and a final meson state.Comment: minor corrections, 19 pages, 9 figure

Zee Model Confronts SNO Data

We reexamine the solution of the minimal Zee model by comparing with the data of the SNO experiment, and conclude that the model is strongly disfavored but not yet excluded by the observations. Two extensions of the Zee model are briefly discussed both of which introduce additional freedom and can accommodate the data.Comment: 16 pages LaTeX including 7 figure

Possible Gauge Theoretic Origin for Quark-Lepton Complementarity

Similarity between the weak interaction properties of quarks and leptons has led to suggestions that the origin of lepton mixing angles may be related to those of quarks. In this paper, we present a gauge model based on $SU(2)_L \times SU(2)_R\times SU(4)_c$ group that leads to a new form for the quark lepton complementarity which predicts the solar neutrino mixing angle in terms of the Cabibbo angle for the case of inverted mass hierarchy for neutrinos. We also indicate how these ideas can be implemented in an $E_6$ inspired trinification $SU(3)_C \times SU(3)_L \times SU(3)_R$ model, which is more closely allied to string theory by the AdS/CFT correspondence.Comment: 9 pages, latex, no figures; presentation improved; results unchanged; minor typos correcte

B --> Phi K_S and Supersymmetry

The rare decay B --> Phi K_S is a well-known probe of physics beyond the Standard Model because it arises only through loop effects yet has the same time-dependent CP asymmetry as B --> Psi K_S. Motivated by recent data suggesting new physics in B --> Phi K_S, we look to supersymmetry for possible explanations, including contributions mediated by gluino loops and by Higgs bosons. Chirality-preserving LL and RR gluino contributions are generically small, unless gluinos and squarks masses are close to the current lower bounds. Higgs contributions are also too small to explain a large asymmetry if we impose the current upper limit on B(B_s --> mu mu). On the other hand, chirality-flipping LR and RL gluino contributions can provide sizable effects and while remaining consistent with related results in B --> Psi K_S, Delta M_s, B --> X_s gamma and other processes. We discuss how the LR and RL insertions can be distinguished using other observables, and we provide a string-based model and other estimates to show that the needed sizes of mass insertions are reasonable.Comment: 33 pages, 32 figures, Updated version for PRD. Includes discussions of other recent works on this topic. Added discussions & plots for gluino mass dependence and effects of theoretical uncertaintie

Supersymmetry without R-parity : Constraints from Leptonic Phenomenology

R-parity conservation is an {\it ad hoc} assumption in the most popular version of the supersymmetric standard model. Most studies of models which do allow for R-parity violation have been restricted to various limiting scenarios. The single-VEV parametrization used in this paper provides a workable framework to analyze phenomenology of the most general theory of SUSY without R-parity. We perform a comprehensive study of leptonic phenomenology at tree-level. Experimental constraints on various processes are studied individually and then combined to yield regions of admissible parameter space. In particular, we show that large R-parity violating bilinear couplings are not ruled out, especially for large $\tan\beta$.Comment: 56 pages Revtex with figures incorporated; typos (including transcription typo in Table II) and minor corrections; proof-read version, to appear in Phys. Rev.

Neutrino masses in R-parity violating supersymmetric models

We study neutrino masses and mixing in R-parity violating supersymmetric models with generic soft supersymmetry breaking terms. Neutrinos acquire masses from various sources: Tree level neutrino--neutralino mixing and loop effects proportional to bilinear and/or trilinear R-parity violating parameters. Each of these contributions is controlled by different parameters and have different suppression or enhancement factors which we identified. Within an Abelian horizontal symmetry framework these factors are related and specific predictions can be made. We found that the main contributions to the neutrino masses are from the tree level and the bilinear loops and that the observed neutrino data can be accommodated once mild fine-tuning is allowed.Comment: 18 pages; minor typos corrected. To be published in Physical Review

Constraints On Radiative Neutrino Mass Models From Oscillation Data

The three neutrino Zee model and its extension including three active and one sterile species are studied in the light of new neutrino oscillation data. We obtain analytical relations for the mixing angle in solar oscillations in terms of neutrino mass squared differences. For the four neutrino case, we obtain the result $\mathsf{sin^2 2 \theta_\odot \approx 1 - [ (\Delta m^2_{Atm})^2/(4 \Delta m^2_{LSND} \Delta m^2_\odot) ]^2}$, which can accommodate both the large and small mixing scenarios. We show that within this framework, while both the SMA-MSW and the LMA-MSW solutions can easily be accommodated, it would be difficult to reconcile the LOW-QVO solutions. We also comment on the active-sterile admixture within phenomenologically viable textures.Comment: The paper has been substantially rewritten, especially in Section IV, though the basic results are unchanged. Some new references and an appendix have been adde

Photon polarization in radiative B decays

We study decay distributions in B -> K pi pi gamma, combining contributions from several overlapping resonances in a K pi pi mass range near 1400 MeV, (1^+) K_1(1400), (2^+) K^*_2(1430) and (1^-) K^*(1410). A method is proposed for using these distributions to determine a photon polarization parameter in the effective radiative weak Hamiltonian. This parameter is measured through an up-down asymmetry of the photon direction relative to the K pi pi decay plane. We calculate a dominant up-down asymmetry of 0.33 +- 0.05 from the K1(1400) resonance, which can be measured with about 10^8 B B-bar pairs, thus providing a new test for the Standard Model and a probe for some of its extensions.Comment: 22 pages, 3 figures, version to appear in Phys. Rev.

Suppressing the μ\mu and neutrino masses by a superconformal force

The idea of Nelson and Strassler to obtain a power law suppression of parameters by a superconformal force is applied to understand the smallness of the $\mu$ parameter and neutrino masses in R-parity violating supersymmetric standard models. We find that the low-energy sector should contain at least another pair of Higgs doublets, and that a suppression of \lsim O(10^{-13}) for the $\mu$ parameter and neutrino masses can be achieved generically. The superpotential of the low-energy sector happens to possess an anomaly-free discrete R-symmetry, either $R_3$ or $R_6$, which naturally suppresses certain lepton-flavor violating processes, the neutrinoless double beta decays and also the electron electric dipole moment. We expect that the escape energy of the superconformal sector is \lsim O(10) TeV so that this sector will be observable at LHC. Our models can accommodate to a large mixing among neutrinos and give the same upper bound of the lightest Higgs mass as the minimal supersymmetric standard model.Comment: 24 page