1,948 research outputs found

    Neutrino Mass and New Physics

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    We review the present state of and future outlook for our understanding of neutrino masses and mixings. We discuss what we think are the most important perspectives on the plausible and natural scenarios for neutrinos and what may have the most promise to throw light on the flavor problem of quarks and leptons. We focus on the seesaw mechanism which fits into the big picture of particle physics such as supersymmetry and grand unification providing a unified approach to flavor problem of quarks and leptons. We argue that in combination with family symmetries, this may be at the heart of a unified understanding of flavor puzzle. We also discuss other new physics ideas such as neutrinos in models with extra dimensions and possible theoretical implications of sterile neutrinos. We outline some tests for the various schemes.Comment: 90 pages and 9 figures; With permission from the Annual Review of Nuclear and Particle Science. Final version of this material is scheduled to appear in the Annual Review of Nuclear and Particle Science Vol. 56, to be published in November 2006 by Annual Reviews (http://www.annualreviews.org); some references and parts of text update

    Light MSSM Higgs boson mass to three-loop accuracy

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    The light CP even Higgs boson mass, Mh, is calculated to three-loop accuracy within the Minimal Supersymmetric Standard Model (MSSM). The result is expressed in terms of DRbar parameters and implemented in the computer program H3m. The calculation is based on the proper approximations and their combination in various regions of the parameter space. The three-loop effects to Mh are typically of the order of a few hundred MeV and opposite in sign to the two-loop corrections. The remaining theory uncertainty due to higher order perturbative corrections is estimated to be less than 1 GeV.Comment: 39 pages, 13 figures. v2: minor changes, typos fixe

    Flavor conversion of cosmic neutrinos from hidden jets

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    High energy cosmic neutrino fluxes can be produced inside relativistic jets under the envelopes of collapsing stars. In the energy range E ~ (0.3 - 1e5) GeV, flavor conversion of these neutrinos is modified by various matter effects inside the star and the Earth. We present a comprehensive (both analytic and numerical) description of the flavor conversion of these neutrinos which includes: (i) oscillations inside jets, (ii) flavor-to-mass state transitions in an envelope, (iii) loss of coherence on the way to observer, and (iv) oscillations of the mass states inside the Earth. We show that conversion has several new features which are not realized in other objects, in particular interference effects ("L- and H- wiggles") induced by the adiabaticity violation. The neutrino-neutrino scattering inside jet and inelastic neutrino interactions in the envelope may produce some additional features at E > 1e4 GeV. We study dependence of the probabilities and flavor ratios in the matter-affected region on angles theta13 and theta23, on the CP-phase delta, as well as on the initial flavor content and density profile of the star. We show that measurements of the energy dependence of the flavor ratios will, in principle, allow to determine independently the neutrino and astrophysical parameters.Comment: 56 pages, 19 figures. Minor changes. Accepted by JHEP

    Gravitino Dark Matter in Tree Level Gauge Mediation with and without R-parity

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    We investigate the cosmological aspects of Tree Level Gauge Mediation, a recently proposed mechanism in which the breaking of supersymmetry is communicated to the soft scalar masses by extra gauge interactions at the tree level. Embedding the mechanism in a Grand Unified Theory and requiring the observability of sfermion masses at the Large Hadron Collider, it follows that the Lightest Supersymmetric Particle is a gravitino with a mass of the order of 10 GeV. The analysis in the presence of R-parity shows that a typical Tree Level Gauge Mediation spectrum leads to an overabundance of the Dark Matter relic density and a tension with the constraints from Big Bang Nucleosynthesis. This suggests to relax the exact conservation of the R-parity. The underlying SO(10) Grand Unified Theory together with the bounds from proton decay provide a rationale for considering only bilinear R-parity violating operators. We finally analyze the cosmological implications of this setup by identifying the phenomenologically viable regions of the parameter space.Comment: 28 pages, 5 figures. References added. To appear in JHE

    Mass hierarchy, 2-3 mixing and CP-phase with Huge Atmospheric Neutrino Detectors

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    We explore the physics potential of multi-megaton scale ice or water Cherenkov detectors with low (1\sim 1 GeV) threshold. Using some proposed characteristics of the PINGU detector setup we compute the distributions of events versus neutrino energy EνE_\nu and zenith angle θz\theta_z, and study their dependence on yet unknown neutrino parameters. The (Eνθz)(E_\nu - \theta_z) regions are identified where the distributions have the highest sensitivity to the neutrino mass hierarchy, to the deviation of the 2-3 mixing from the maximal one and to the CP-phase. We evaluate significance of the measurements of the neutrino parameters and explore dependence of this significance on the accuracy of reconstruction of the neutrino energy and direction. The effect of degeneracy of the parameters on the sensitivities is also discussed. We estimate the characteristics of future detectors (energy and angle resolution, volume, etc.) required for establishing the neutrino mass hierarchy with high confidence level. We find that the hierarchy can be identified at 3σ3\sigma -- 10σ10\sigma level (depending on the reconstruction accuracies) after 5 years of PINGU operation.Comment: 39 pages, 21 figures. Description of Fig.3 correcte

    R-parity violation in SU(5)

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    We show that judiciously chosen R-parity violating terms in the minimal renormalizable supersymmetric SU(5) are able to correct all the phenomenologically wrong mass relations between down quarks and charged leptons. The model can accommodate neutrino masses as well. One of the most striking consequences is a large mixing between the electron and the Higgsino. We show that this can still be in accord with data in some regions of the parameter space and possibly falsified in future experiments.Comment: 30 pages, 1 figure. Revised version. To appear in JHE

    Numerical instability of the Akhmediev breather and a finite-gap model of it

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    In this paper we study the numerical instabilities of the NLS Akhmediev breather, the simplest space periodic, one-mode perturbation of the unstable background, limiting our considerations to the simplest case of one unstable mode. In agreement with recent theoretical findings of the authors, in the situation in which the round-off errors are negligible with respect to the perturbations due to the discrete scheme used in the numerical experiments, the split-step Fourier method (SSFM), the numerical output is well-described by a suitable genus 2 finite-gap solution of NLS. This solution can be written in terms of different elementary functions in different time regions and, ultimately, it shows an exact recurrence of rogue waves described, at each appearance, by the Akhmediev breather. We discover a remarkable empirical formula connecting the recurrence time with the number of time steps used in the SSFM and, via our recent theoretical findings, we establish that the SSFM opens up a vertical unstable gap whose length can be computed with high accuracy, and is proportional to the inverse of the square of the number of time steps used in the SSFM. This neat picture essentially changes when the round-off error is sufficiently large. Indeed experiments in standard double precision show serious instabilities in both the periods and phases of the recurrence. In contrast with it, as predicted by the theory, replacing the exact Akhmediev Cauchy datum by its first harmonic approximation, we only slightly modify the numerical output. Let us also remark, that the first rogue wave appearance is completely stable in all experiments and is in perfect agreement with the Akhmediev formula and with the theoretical prediction in terms of the Cauchy data.Comment: 27 pages, 8 figures, Formula (30) at page 11 was corrected, arXiv admin note: text overlap with arXiv:1707.0565

    Degenerate and Other Neutrino Mass Scenarios and Dark Matter

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    I discuss in this talk mainly three topics related with dark matter motivated neutrino mass spectrum and a generic issue of mass pattern, the normal versus the inverted mass hierarchies. In the first part, by describing failure of a nontrivial potential counter example, I argue that the standard 3 ν\nu mixing scheme with the solar and the atmospheric Δm2\Delta m^2's is robust. In the second part, I discuss the almost degenerate neutrino (ADN) scenario as the unique possibility of accommodating dark matter mass neutrinos into the 3 ν\nu scheme. I review a cosmological bound and then reanalyze the constraints imposed on the ADN scenario with the new data of double beta decay experiment. In the last part, I discuss the 3 ν\nu flavor transformation in supernova (SN) and point out the possibility that neutrinos from SN may distinguish the normal versus inverted hierarchies of neutrino masses. By analyzing the neutrino data from SN1987A, I argue that the inverted mass hierarchy is disfavored by the data

    Supersymmetric next-to-next-to-leading order corrections to Higgs boson production in gluon fusion

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    We compute the total cross section for the production of a light CP even Higgs boson within the framework of supersymmetric QCD up to next-to-next-to-leading order. Technical subtleties in connection to the evaluation of three-loop Feynman integrals with many mass scales are discussed in detail and explicit results for the counterterms of the evanescent couplings are provided. The new results are applied to several phenomenological scenarios which are in accordance with the recent discovery at the LHC. In a large part of the still allowed parameter space the KK factor of the supersymmetric theory is close to the one of the Standard Model. However, for the case where one of the top squarks is light, a deviation of more than 5% in the next-to-next-to-leading order prediction of the cross section can be observed where at the same time the predicted Higgs boson mass has a value of about 125 GeV.Comment: 37 page

    Rapidity and Centrality Dependence of Proton and Anti-proton Production from Au+Au Collisions at sqrt(sNN) = 130GeV

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    We report on the rapidity and centrality dependence of proton and anti-proton transverse mass distributions from Au+Au collisions at sqrt(sNN) = 130GeV as measured by the STAR experiment at RHIC. Our results are from the rapidity and transverse momentum range of |y|<0.5 and 0.35 <p_t<1.00GeV/c. For both protons and anti-protons, transverse mass distributions become more convex from peripheral to central collisions demonstrating characteristics of collective expansion. The measured rapidity distributions and the mean transverse momenta versus rapidity are flat within |y|<0.5. Comparisons of our data with results from model calculations indicate that in order to obtain a consistent picture of the proton(anti-proton) yields and transverse mass distributions the possibility of pre-hadronic collective expansion may have to be taken into account.Comment: 4 pages, 3 figures, 1 table, submitted to PR
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