2,307 research outputs found

    MiniBooNE and a (CP)^2 = -1 sterile neutrino

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    It has been taken as granted that the observation of two independent mass-squared differences necessarily fixes the number of underlying mass eigenstates as three, and that the addition of a sterile neutrino provides an additional mass-squared difference. The purpose of this Letter is to argue that if one considers a sterile neutrino component that belongs to the (CP)^2 = - 1 sector, then both of the stated claims are false. We also outline how the results reported here, when combined with the forthcoming MiniBooNE data and other experiments, can help settle the issue of the CP properties of the sterile neutrino; if such a component does indeed exist.Comment: Mod. Phys. Lett. A (in press, 8 pages

    Front Form Spinors in Weinberg-Soper Formalism and Melosh Transformations for any Spin

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    Using the Weinberg-Soper formalism we construct the front form (j,0)⊕(0,j)(j,0)\oplus(0,j) spinors. Explicit expressions for the generalised Melosh transformations up to spin two are obtained. The formalism, without explicitly invoking any wave equations, reproduces spin one half front-form results of Melosh, Lepage and Brodsky, and Dziembowski.Comment: 16 Pages, RevTex. We continue to receive reprint requests for this paper. So we now archive it her

    Tunnelling Characteristics of Stone-Wales Defects in Monolayers of Sn and Group-V Elements

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    Topological defects in ultrathin layers are often formed during synthesis and processing, thereby, strongly influencing their electronic properties . In this paper, we investigate the role of Stone-Wales (SW) defects in modifying the electronic properties of the monolayers of Sn and group-V elements. The calculated results find the electronic properties of stanene (monolayer of Sn atoms) to be strongly dependent on the concentration of SW-defects e.g., defective stanene has nearly zero band gap (~ 0.03 eV) for the defect concentration of 2.2 x 10^13 cm^-2 which opens up to 0.2 eV for the defect concentration of 3.7 x 10^13 cm^-2. In contrast, SW-defects appear to induce conduction states in the semiconducting monolayers of group-V elements. These conduction states act as channels for electron tunnelling, and the calculated tunnelling characteristics show the highest differential conductance for the negative bias with the asymmetric current-voltage characteristics. On the other hand, the highest differential conductance was found for the positive bias in stanene. Simulated STM topographical images of stanene and group-V monolayers show distinctly different features in terms of their cross-sectional views and distance-height profiles which can serve as fingerprints to identify the topological defects in the monolayers of group-IV and group-V elements in experiments.Comment: 18 pages, 5 figures, 1 tabl

    Editorial: The cognitariat

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    Today's world of disorganized capitalism or post-Fordism relies on a cognitariat of highly-educated, occupationally-insecure workers who are both voluble and newsworthy..

    Comparative experimental and Density Functional Theory (DFT) study of the physical properties of MgB2 and AlB2

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    In present study, we report an inter-comparison of various physical and electronic properties of MgB2 and AlB2. Interestingly, the sign of S(T) is +ve for MgB2 the same is -ve for AlB2. This is consistent our band structure plots. We fitted the experimental specific heat of MgB2 to Debye Einstein model and estimated the value of Debye temperature (theta) and Sommerfeld constant (gamma) for electronic specific heat. Further, from gamma the electronic density of states (DOS) at Fermi level N(EF) is calculated. From the ratio of experimental N (EF) and the one being calculated from DFT, we obtained value of Lembda to be 1.84, thus placing MgB2 in the strong coupling BCS category. The electronic specific heat of MgB2 is also fitted below Tc using pi-model and found that it is a two gap superconductor. The calculated values of two gaps are in good agreement with earlier reports. Our results clearly demonstrate that the superconductivity of MgB2 is due to very large phonon contribution from its stretched lattice. The same two effects are obviously missing in AlB2 and hence it is not superconducting. DFT calculations demonstrated that for MgB2 the majority of states come from Sigma and Pi 2p states of boron on the other hand Sigma band at Fermi level for AlB2 is absent. This leads to a weak electron phonon coupling and also to hole deficiency as Pi bands are known to be of electron type and hence obviously the AlB2 is not superconducting. The DFT calculations are consistent with the measured physical properties of the studied borides, i.e., MgB2 and AlB2Comment: 16 pages Text + Figs: comments/suggestions welcome ([email protected])/www.freewebs.com/vpsawana

    Neutrino oscillations with disentanglement of a neutrino from its partners

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    We bring attention to the fact that in order to understand existing data on neutrino oscillations, and to design future experiments, it is imperative to appreciate the role of quantum entanglement. Once this is accounted for, the resulting energy-momentum conserving phenomenology requires a single new parameter related to disentanglement of a neutrino from its partners. This parameter may not be CP symmetric. We illustrate the new ideas, with potentially measurable effects, in the context of a novel experiment recently proposed by Gavrin, Gorbachev, Veretenkin, and Cleveland. The strongest impact of our ideas is on the resolution of various anomalies in neutrino oscillations and on neutrino propagation in astrophysical environments.Comment: 6 page

    Dark matter: A spin one half fermion field with mass dimension one?

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    We report an unexpected theoretical discovery of a spin one half matter field with mass dimension one. It is based on a complete set of eigenspinors of the charge conjugation operator. Due to its unusual properties with respect to charge conjugation and parity it belongs to a non standard Wigner class. Consequently, the theory exhibits non-locality with (CPT)^2 = - I. Its dominant interaction with known forms of matter is via Higgs, and with gravity. This aspect leads us to contemplate it as a first-principle candidate for dark matter.Comment: 5 pages, RevTex, v2: slightly extended discussion, new refs. and note adde
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