327 research outputs found

    Testing neutrino instability with active galactic nuclei

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    Active galactic nuclei and gamma ray bursts at cosmological distances are sources of high-energy electron and muon neutrinos and provide a unique test bench for neutrino instability. The typical lifetime-to-mass ratio one can reach there is τ/m∼500Mpc/cEν∼500\tau/m\sim 500 Mpc/cE_{\nu}\sim 500 s/eV. We study the rapid decay channel νi→νj+ϕ\nu_i\to\nu_j+\phi, where ϕ\phi is a massless or very light scalar (possibly a Goldstone boson), and point out that one can test the coupling strength of gijνiνjg_{ij}\nu_i\nu_j down to g_{ij}\lsim 10^{-8} eV/m by measuring the relative fluxes of νe\nu_{e}, νμ\nu_{\mu} and ντ\nu_{\tau}. This is orders of magnitude more stringent bound than what one can obtain in other phenomena, e.g. in neutrinoless double beta decay with scalar emission.Comment: 3 page

    Sterile neutrino signals from supernovae

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    We investigate the effects of a mixing of active and sterile neutrinos on the ratios of supernova electron neutrino flux (FeF_e) and antineutrino flux (FeˉF_{\bar e}) to the total flux of the other neutrino and antineutrino flavours (FaF_a). We assume that the heaviest (in the normal hierarchy) Standard Model neutrino ν3\nu_3 mixes with a sterile neutrino resulting in a pair of mass eigenstates with a small mass gap. Using the density matrix formalism we solve numerically the the evolution of neutrino states in the envelope of a supernova and determine the flux ratios Fe/FaF_e/F_a and Feˉ/FaF_{\bar{e}}/F_a as a function of the active-sterile mixing angle and for the experimentally allowed range of the standard active-active mixing angle θ13\theta_{13}.Comment: 5 pages, 3 figures. This is the corrected version to be published in Physical Review

    Planets orbiting Quark Nova compact remnants

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    We explore planet formation in the Quark Nova scenario. If a millisecond pulsar explodes as a Quark Nova, a protoplanetary disk can be formed out of the metal rich fall-back material. The propeller mechanism transfers angular momentum from the born quark star to the disk that will go through viscous evolution with later plausible grain condensation and planet formation. As a result, earth-size planets on circular orbits may form within short radii from the central quark star. The planets in the PSR1257+12 system can be explained by our model if the Quark Nova compact remnant is born with a period of ∼0.5\sim 0.5 ms following the explosion. We suggest that a good portion of the Quark Nova remnants may harbour planetary systems

    Inhomogeneous Structures in Holographic Superfluids: II. Vortices

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    We study vortex solutions in a holographic model of Herzog, Hartnoll, and Horowitz, with a vanishing external magnetic field on the boundary, as is appropriate for vortices in a superfluid. We study relevant length scales related to the vortices and how the charge density inside the core of the vortex behaves as a function of temperature or chemical potential. We extract the critical superfluid velocity from the vortex solutions, study how it behaves as a function of the temperature, and compare it to earlier studies and to the Landau criterion. We also comment on the possibility of a Berezinskii-Kosterlitz-Thouless vortex confinement-deconfinement transition.Comment: 32 pages, 10 figures, typos corrected, references adde

    Effects of periodic matter in kaon regeneration

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    We study the effects of periodic matter in kaon regeneration, motivated by the possibility of parametric resonance in neutrino oscillations. The large imaginary parts of the forward kaon-nucleon scattering amplitudes and the decay width difference ΔΓ\Delta\Gamma prevent a sizable enhancement of the KL→KSK_L\to K_S transition probability. However, some interesting effects can be produced using regenerators made of alternating layers of two different materials. Despite the fact that the regenerator has a fixed length one can obtain different values for the probability distribution of the KLK_L decay into a final state. Using a two-arm regenerator set up it is possible to measure the imaginary parts of the K0(Kˉ0)K^0(\bar{K}^0)-nucleon scattering amplitudes in the correlated decays of the ϕ\phi-resonance. Combining the data of the single-arm regenerator experiments with direct and reverse orders of the matter layers in the regenerator one can independently measure the CP violating parameter δ\delta

    Physical Browsing - a novel HCI paradigm for people on the move

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    International audienceRFID tag readers have recently appeared into mobile phones and other types of tags and readers are also coming-most notably visual tags which can be read by a software in a camera phone. This will open up new possibilities for using RFID and visual tags broadly in consumer and industrial applications. In this paper we outline a concept called Physical Browsing, present some implementations of it and discuss the implications this concept could bring to car and transportation applications

    Landau-Zener problem in a three-level neutrino system with non-linear time dependence

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    We consider the level-crossing problem in a three-level system with non-linearly time-varying Hamiltonian (time-dependence t−3t^{-3}). We study the validity of the so-called independent crossing approximation in the Landau-Zener model by making comparison with results obtained numerically in density matrix approach. We also demonstrate the failure of the so-called "nearest zero" approximation of the Landau-Zener level-crossing probability integral.Comment: 11 pages, 3 figures. To be published in Physical Review

    Inhomogeneous Structures in Holographic Superfluids I : Dark Solitons

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    25 pages, 17 figure files, LaTeXWe begin an investigation of inhomogeneous structures in holographic superfluids. As a first example, we study domain wall like defects in the 3+1 dimensional Einstein-Maxwell-Higgs theory, which was developed as a dual model for a holographic superconductor. In [1], we reported on such "dark solitons" in holographic superfluids. In this work, we present an extensive numerical study of their properties, working in the probe limit. We construct dark solitons for two possible condensing operators, and find that both of them share common features with their standard superfluid counterparts. However, both are characterized by two distinct coherence length scales (one for order parameter, one for charge condensate). We study the relative charge depletion factor and find that solitons in the two different condensates have very distinct depletion characteristics. We also study quasiparticle excitations above the holographic superfluid, and find that the scale of the excitations is comparable to the soliton coherence length scales.Peer reviewe

    Thermalization and entanglement following a non-relativistic holographic quench

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    We develop a holographic model for thermalization following a quench near a quantum critical point with non-trivial dynamical critical exponent. The anti-de Sitter Vaidya null collapse geometry is generalized to asymptotically Lifshitz spacetime. Non-local observables such as two-point functions and entanglement entropy in this background then provide information about the length and time scales relevant to thermalization. The propagation of thermalization exhibits similar "horizon" behavior as has been seen previously in the conformal case and we give a heuristic argument for why it also appears here. Finally, analytic upper bounds are obtained for the thermalization rates of the non-local observables.Comment: 33 pages, 11 figures. v2: minor typos corrected, references added, a new section added in the appendix, published versio
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