364 research outputs found

    Atmospheric and Solar Neutrino Oscillations in \nuMSSM and Beyond

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    We show how a unified description of the various two-flavor neutrino oscillation solutions, allowed by the atmospheric and solar neutrino experiments, are naturally realized within the framework of ν\nuMSSM (MSSM augmented with the seesaw mechanism) and beyond, especially grand unified theories. A general mechanism for achieving maximal mixing to resolve the atmospheric anomaly is discussed, and applied to the flipped SU(5) model. Except in the case of MSSM and SU(5), a light sterile neutrino is an inevitable consequence of our considerations. The bi-maximal neutrino mixing scenario is one of the options considered. Neutrino hot dark matter can arise in models with maximal νμνs\nu_{\mu}-\nu_s oscillations. A U(1){\cal U}(1) flavor symmetry, motivated by the charged fermion mass hierarchies and the magnitudes of the CKM matrix elements, plays a central role.Comment: 14 pp, LATEX. Typos are corrected, possibilities of the neutrino HDM in various scenarios are emphasize

    Gravity Waves and Gravitino Dark Matter in μ\mu-Hybrid Inflation

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    We propose a novel reformulation of supersymmetric (more precisely μ\mu-) hybrid inflation based on a local U(1) or any suitable extension of the minimal supersymmetric standard model (MSSM) which also resolves the μ\mu problem. We employ a suitable Kahler potential which effectively yields quartic inflation with non-minimal coupling to gravity. Imposing the gravitino Big Bang Nucleosynthesis (BBN) constraint on the reheat temperature (Tr106T_r \lesssim 10^6 GeV) and requiring a neutralino LSP, the tensor to scalar ratio (rr) has a lower bound r0.004r \gtrsim 0.004. The U(1) symmetry breaking scale lies between 10810^8 and 101210^{12} GeV. We also discuss a scenario with gravitino dark matter whose mass is a few GeV.Comment: 5 pages, 4 figures, revised version to appear in Physics Letters

    Higgs Inflation, Seesaw Physics and Fermion Dark Matter

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    We present an inflationary model in which the Standard Model Higgs doublet field with non-minimal coupling to gravity drives inflation, and the effective Higgs potential is stabilized by new physics which includes a dark matter particle and right-handed neutrinos for the seesaw mechanism. All of the new particles are fermions, so that the Higgs doublet is the unique inflaton candidate. With central values for the masses of the top quark and the Higgs boson, the renormalization group improved Higgs potential is employed to yield the scalar spectral index ns0.968n_s \simeq 0.968, the tensor-to-scalar ratio r0.003r \simeq 0.003, and the running of the spectral index α=dns/dlnk5.2×104\alpha=dn_s/d \ln k \simeq -5.2 \times 10^{-4} for the number of e-folds N0=60N_0=60 (ns0.962n_s \simeq 0.962, r0.004r \simeq 0.004, and α7.5×104\alpha \simeq -7.5 \times 10^{-4} for N0=50N_0=50). The fairly low value of r0.003r \simeq 0.003 predicted in this class of models means that the ongoing space and land based experiments are not expected to observe gravity waves generated during inflation. [Dedicated to the memory of Dr. Paul Weber (1947 - 2015). Paul was an exceptional human being and a very special friend who will be sorely missed.]Comment: 15 pages, 3 figure

    Bi-maximal Neutrino Mixings And Proton Decay In SO(10) With Anomalous Flavor U(1){\cal U}(1)

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    By supplementing supersymmetric SO(10) with an anomalous U(1){\cal U}(1) flavor symmetry and additional `matter' superfields carrying suitable U(1){\cal U}(1) charges, we explain the charged fermion mass hierarchies, the magnitudes of the CKM matrix elements, as well as the solar and atmospheric neutrino data. We stress bi-maximal vacuum neutrino mixings, and indicate how the small or large mixing angle MSW solution can be incorporated. The U(1){\cal U}(1) symmetry also implies that τpKν[SO(10)](10100)τpKν[minimal SU(5)]\tau_{p\to K\nu}[SO(10)]\sim (10-100)\cdot \tau_{p\to K\nu}[{\rm minimal}~SU(5)].Comment: 4 pages, revte

    \theta_13, Rare Processes and Proton Decay in Flipped SU(5)

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    We consider an extended flipped SU(5) model, supplemented by a flavor U(1){\cal U}(1) symmetry, which yields bi-large neutrino mixings, charged fermion mass hierarchies and CKM mixings. The third leptonic mixing angle \te_{13} turns out to lie close to 0.07, and neutrino CP violation can be estimated from the observed baryon asymmetry. For lepton flavor violating processes we find the branching ratios, {\rm BR}(\mu \to e\ga)\sim {\rm BR}(\tau \to e \ga) \sim 10^{-4}\cdot {\rm BR}(\tau \to \mu \ga) \stackrel{<}{_\sim}5\cdot 10^{-14}. The proton lifetime τpπ0e+10341036\tau_{p\to \pi^0 e^{+}}\simeq 10^{34}-10^{36} yrs.Comment: Discussion on leptogenesis and CP violation, and references adde

    Anomalous U(1): Solving Various Puzzles Of MSSM And SU(5) GUT

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    We discuss how an anomalous U(1) symmetry when appended to MSSM and SUSY GUTs [e.g. SU(5)] can help overcome a variety of puzzles related to charged fermion masses and mixings, flavor changing processes, proton decay and neutrino oscillations. Proton lifetime for SU(5) GUT, in particular, is predicted in a range accessible to the ongoing or planned searches.Comment: Presented at NOON2001 Workshop, Kashiwa, Japan, 5-8 Dec. 200

    From Hybrid to Quadratic Inflation With High-Scale Supersymmetry Breaking

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    Motivated by the reported discovery of inflationary gravity waves by the BICEP2 experiment, we propose an inflationary scenario in supergravity, based on the standard superpotential used in hybrid inflation. The new model yields a tensor-to-scalar ratio r ~ 0.14 and scalar spectral index ns ~ 0.964, corresponding to quadratic (chaotic) inflation. The important new ingredients are the high-scale, (1.6-10) x 10^13 GeV, soft supersymmetry breaking mass for the gauge singlet inflaton field and a shift symmetry imposed on the K\"ahler potential. The end of inflation is accompanied, as in the earlier hybrid inflation models, by the breaking of a gauge symmetry at (1.2-7.1) x 10^16 GeV, comparable to the grand-unification scale.Comment: Version with minor corrections to appear in PL

    An Improved Supersymmetric SU(5)

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    By supplementing minimal supersymmetric SU(5) (MSSU(5)) with a flavor U(1){\cal U}(1) symmetry and two pairs of 15ˉ+15\bar{15}+15 `matter' supermultiplets, we present an improved model which explains the charged fermion mass hierarchies and the magnitudes of the CKM matrix elements, while avoiding the undesirable asymptotic mass relations ms=mμ,md/ms=me/mμm_s=m_{\mu}, m_d/m_s = m_e/m_{\mu}. The strong coupling αs(MZ)\alpha_s (M_Z) is predicted to be approximately 0.115, and the proton lifetime is estimated to be about five times larger than the MSSU(5) value. The atmospheric and solar neutrino puzzles are respectively resolved via maximal νμντ\nu_{\mu}-\nu_{\tau} and small mixing angle νeνs\nu_e-\nu_s MSW oscillations, where νs\nu_s denotes a sterile neutrino. The U(1){\cal U}(1) symmetry ensures not only a light νs\nu_s but also automatic `matter' parity.Comment: 11 pp. LATEX. Version with minor addition accepted for publication in Physics Letters
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