Vigdor L. Teplitz

Cosmological implications of massive, unstable neutrinos

We consider the cosmological consequences of the existence of massive, neutral, weakly interacting leptons (v/sub H/). Bounds are calculated on the v/sub H/ mass, lifetime, and allowed interaction strength by assuming minimal modification of the standard big-bang model. Our chief conclusions are :(1) The v/sub H/ may be stable if its mass is greater than a few GeV. (2) For intermediate masses, for which the v/sub H/ must be unstable, if its principal decay mode creates photons, masses less than 10/sup -/2 MeV are ruled out and its lifetime must be less than 1 year. (3) If the v/sub H/ decays exclusively into neutrinos, it may have a considerably longer lifetime and give rise to a present-day enerfy density sufficiently high to make the universe radiation-dominated and closed.

MIRROR MATTER MACHOS

Abstract We propose that the massive compact halo objects (MACHOs) observed in the recent microlensing experiments with an apparent best fit mass of about 0.5 M ⊙ are objects made out of “mirror” baryonic matter rather than familiar baryons. Such a possibility arises naturally within the framework of mirror matter models proposed recently to accommodate the sterile neutrinos that seem necessary to solve all the neutrino puzzles simultaneously. We show that, for mirror matter parameters that fit the neutrino observations, the maximum mass of mirror stars is of order 0.5 M ⊙ and their main sequence lifetimes are much less than the age of the universe. They are likely to be black holes. Mirror matter machos have the advantage that they do not suffer from the problems encountered in the conventional red, brown or white dwarf interpretation. The calculations also apply to the question of how the world of familiar matter would be different if all fundamental mass parameters were.

Structures in the mirror universe

The idea of the universe having a mirror sector in which all particles and forces are identical to those in the familiar sector has been proposed recently in the context of neutrino physics as well as superstring theories some time ago. Assuming that all the quark and charged lepton masses in the mirror universe are scaled by a common factor, ζ, as is required in one interpretation of the neutrino data, we investigate domains of the parameter ζ where physical conditions are favorable for the formation of compact structures given the initial condition ΩB Ω ( denoting the mirror baryon). We consider both isocurvature and curvature perturbations; we address primordial mirror molecule formation, mirror Compton cooling, mirror Silk and collisionless damping, and various mirror cooling mechanisms that can lead to compact mirror structures for various regions of ζ space, so that the mirror model can be confronted with astrophysical observations. For isocurvature perturbations, we find a variety of possible structural final states. For curvature (or adiabatic) perturbations, we find a likelihood that part of ζ space would result in detectable effects that are not observed, while a part would not.

Supernova Bounds on the Dark Photon Using Its Electromagnetic Decay

Abstract The hypothetical massive dark photon ( γ ′ ) which has kinetic mixing with the SM photon can decay electromagnetically to e + e − pairs if its mass m exceeds 2 m e , and otherwise into three SM photons. These decays yield cosmological and supernovae associated signatures. We briefly discuss these signatures, particularly in connection with the supernova SN1987A, and delineate the extra constraints that arise on the mass and mixing parameter of the dark photon. In particular, we find that for dark photon mass m γ ′ in the 5–20 MeV range arguments based on supernova 1987A observations lead to a bound on ϵ which is about 300 times stronger than the presently existing bounds based on energy loss arguments.

Infrared Kuiper belt constraints

We compute the temperature and IR signal of particles of radius a and albedo α at heliocentric distance R, taking into account the emissivity effect, and give an interpolating formula for the result. We compare with analyses of COBE DIRBE data by others (including recent detection of the cosmic IR background) for various values of heliocentric distance R, particle radius a, and particle albedo α. We then apply these results to a recently developed picture of the Kuiper belt as a two-sector disk with a nearby, low-density sector (40<R<50-90 AU) and a more distant sector with a higher density. We consider the case in which passage through a molecular cloud essentially cleans the solar system of dust. We apply a simple model of dust production by comet collisions and removal by the Poynting-Robertson effect to find limits on total and dust masses in the near and far sectors as a function of time since such a passage. Finally, we compare Kuiper belt IR spectra for various parameter values. Results of this work include: (1) numerical limits on Kuiper belt dust as a function of (R, a, α) on the basis of four alternative sets of constraints, including those following from recent discovery of the cosmic IR background by Hauser et al.; (2) application to the two-sector Kuiper belt model, finding mass limits and spectrum shape for different values of relevant parameters including dependence on time elapsed since last passage through a molecular cloud cleared the outer solar system of dust; and (3) potential use of spectral information to determine time since last passage of the Sun through a giant molecular cloud.

Mirror dark matter and galaxy core densities

We present a particle physics realization of a recent suggestion by Spergel and Steinhardt that collisional but dissipationless dark matter may resolve the core density problem in dark matter-dominated galaxies such as the dwarf galaxies. The realization is the asymmetric mirror universe model introduced to explain the neutrino puzzles and the microlensing anomaly. The mirror baryons are the dark matter particles with the desired properties. The time scales are right for resolution of the core density problem and formation of mirror stars (MACHOs observed in microlensing experiments). The mass of the region homogenized by Silk damping is between a dwarf and a large galaxy.

Unexplained Sets of Seismographic Station Reports and A Set Consistent with a Quark Nugget Passage

In 1984 Edward Witten proposed that an extremely dense form of matter composed of up, down, and strange quarks may be stable at zero pressure (Witten, 1984). Massive nuggets of such dense matter, if they exist, may pass through the Earth and be detectable by the seismic signals they generate (de Rujula and Glashow, 1984). With this motivation we investigated over 1 million seismic data reports to the U.S. Geological Survey for the years 1990-1993 not associated with epicentral sources. We report two results: (1) with an average of about 0.16 unassociated reports per minute after data cuts, we found a significant excess over statistical expectation for sets with 10 or more reports in 10 min; and (2) in spite of a very small a priori probability from random reports, we found one set of reports with arrival times and other features appropriate to signals from an epilinear source. This event has the properties predicted for the passage of a nugget of strange quark matter through the Earth, although there is no direct confirmation from other phenomenologies. Manuscript received 20 June 2002.

Effects of proton decay on the cosmological future

We calculate, for an open universe, the densities of radiation and matter at large times if the proton has a lifetime tau/sub p/ of about 10/sup 30/ years; we consider the contributions to these densities from the decay of matter in both clumps and interstellar gas. For times t>tau/sub p/, the energy density of the universe, for k<0 (where k is the geometric constant in the Robertson--Walker metric), is eventually dominated by the contribution of a very tenuous e/sup +/e/sup -/ plasma, much too thin for direct e/sup +/e/sup -/ annihilation and perhaps too thin for gravitational collapse. For a closed (cyclical) universe, current ideas in particle physics imply that the baryon to photon ratio will be identical for each cycle; thus the effect of entropy production will be to enlarge the cosmic scale, from cycle to cycle, by a cycle expansion factor ..cap alpha... We compute ..cap alpha.., taking into account entropy production both by stellar nucleosynthesis and by proton decay.

Mirror dark matter and galaxy core densities of galaxies

We present a particle physics realization of a recent suggestion by Spergel and Steinhardt that collisional but dissipationless dark matter may resolve the core density problem in dark matter-dominated galaxies such as the dwarf galaxies. The realization is the asymmetric mirror universe model introduced to explain the neutrino puzzles and the microlensing anomaly. The mirror baryons are the dark matter particles with the desired properties. The time scales are right for resolution of the core density problem and formation of mirror stars (MACHOs observed in microlensing experiments). The mass of the region homogenized by Silk damping is between a dwarf and a large galaxy.

Limits on Pauli principle violation by nucleons

We consider nuclei produced in core collapse supernovas and subjected to a high neutron flux. We show that an accelerator mass spectrometry experiment that searches for traces of anomalous iron isotopes could set limits of the order of 10{sup {minus}20}{endash}10{sup {minus}25} on (or perhaps discover) Pauli principle violation by neutrons. A similar search for anomalous Co isotopes could set limits in the range 10{sup {minus}13}{endash}10{sup {minus}18} on Pauli principle violation by protons. We show that existing data on oxygen can be used to set a limit of about 10{sup {minus}17} in one proposed model of such violation. {copyright} {ital 1999} {ital The American Physical Society}