White dwarf axions, PAMELA data, and flipped-SU(5)

Recently, there are two hints arising from physics beyond the standard model. One is a possible energy loss mechanism due to emission of very weakly interacting light particles from white dwarf stars, with a coupling strength ~ 0.7x10^{-13}, and another is the high energy positrons observed by the PAMELA satellite experiment. We construct a supersymmetric flipped-SU(5) model, SU(5)xU(1)_X with appropriate additional symmetries, [U(1)_H]_{gauge}x[U(1)_RxU(1)_\Gamma]_{global}xZ_2, such that these are explained by a very light electrophilic axion of mass 0.5 meV from the spontaneously broken U(1)_\Gamma and two component cold dark matters from Z_2 parity. We show that in the flipped-SU(5) there exists a basic mechanism for allowing excess positrons through the charged SU(2) singlet leptons, but not allowing anti-proton excess due to the absence of the SU(2) singlet quarks. We show the discovery potential of the charged SU(2) singlet E at the LHC experiments by observing the electron and positron spectrum. With these symmetries, we also comment on the mass hierarchy between the top and bottom quarks.Comment: 13 pages and 2 figure

Gamma-ray and synchrotron emission from neutralino annihilation in the Large Magellanic Cloud

We calculate the expected flux of gamma-ray and radio emission from the LMC due to neutralino annihilation. Using rotation curve data to probe the density profile and assuming a minimum disk, we describe the dark matter halo of the LMC using models predicted by N-body simulations. We consider a range of density profiles including the NFW profile, a modified NFW profile proposed by Hayashi et al.(2003) to account for the effects of tidal stripping, and an isothermal sphere with a core. We find that the gamma-ray flux expected from these models may be detectable by GLAST for a significant part of the neutralino parameter space. The prospects for existing and upcoming Atmospheric Cherenkov Telescopes are less optimistic, as unrealistically long exposures are required for detection. However, the effects of adiabatic compression due to the baryonic component may improve the chances for detection by ACTs. The maximum flux we predict is well below EGRET's measurements and thus EGRET does not constrain the parameter space. The expected synchrotron emission generally lies below the observed radio emission from the LMC in the frequency range of 19.7 to 8550 MHz. As long as <2x 10^-26 cm^3 s^-1 for a neutralino mass of 50 GeV, the observed radio emission is not primarily due to neutralinos and is consistent with the assumption that the main source is cosmic rays. We find that the predicted fluxes, obtained by integrating over the entire LMC, are not very strongly dependent on the inner slope of the halo profile, varying by less than an order of magnitude for the range of profiles we considered.Comment: 24 pages, 5 figures; detailed discussion of how the neutralino induced signals compare with the cosmic-ray induced ones was added. Main conclusions unchanged. Matches accepted version, to appear in Astroparticle Physic

Technetium-99m-labeled nanofibrillar cellulose hydrogel for in vivo drug release

Peer reviewe

Assessment of labelled products with different radioanalytical methods: study on 18F-fluorination reaction of 4-[18F]fluoro-N-[2-[1-(2-methoxyphenyl)-1-piperazinyl]ethyl-N-2-pyridinyl-benzamide (p-[18F]MPPF)

Peer reviewe

Dark Matter Evidence, Particle Physics Candidates and Detection Methods

The problem of the dark matter in the universe is reviewed. A short history of the subject is given, and several of the most obvious particle candidates for dark matter are identified. Particular focus is given to weakly interacting, massive particles (WIMPs) of which the lightest supersymmetric particle is an interesting special case and a usful template. The three detection methods: in particle accelerators, by direct detection of scattering in terrestrial detectors, and indirect detection of products from dark matter particle annihilation in the galactic halo, are discussed and their complementarity is explained. Direct detection experiments have revealed some possible indications of a dark matter signal, but the situation is quite confusing at the moment. Very recently, also indirect detection has entered a sensitivity region where some particle candidates could be detectable. Indeed, also here there are some (presently non-conclusive) indications of possible dark matter signals, like an interesting structure at 130 GeV gamma-ray energy found in publicly available data from the Fermi-LAT space detector. The future of the field will depend on whether WIMPs are indeed the dark matter, something that may realistically be probed in the next few years. If this exciting scenario turns out to be true, we can expect a host of other, complementary experiments in the coming decade. If it is not true, the time scale and methods for detection will be much more uncertain.Comment: To be published in Annalen der Physik special issue DARK MATTER edited by M. Bartelmann and V. Springel; Ann.Phys. (Berlin) 524, (2012

SNOC: a Monte-Carlo simulation package for high-z supernova observations

We present a Monte-Carlo package for simulation of high-redshift supernova data, SNOC. Optical and near-infrared photons from supernovae are ray-traced over cosmological distances from the simulated host galaxy to the observer at Earth. The distances to the sources are calculated from user provided cosmological parameters in a Friedmann-Lemaitre universe, allowing for arbitrary forms of ``dark energy''. The code takes into account gravitational interactions (lensing) and extinction by dust, both in the host galaxy and in the line-of-sight. The user can also choose to include exotic effects like a hypothetical attenuation due to photon-axion oscillations. SNOC is primarily useful for estimations of cosmological parameter uncertainties from studies of apparent brightness of Type Ia supernovae vs redshift, with special emphasis on potential systematic effects. It can also be used to compute standard cosmological quantities like luminosity distance, lookback time and age of the universe in any Friedmann-Lemaitre model with or without quintessence.Comment: 16 pages, 3 figure

Particle Dark Matter Physics: An Update

This write--up gives a rather elementary introduction into particle physics aspects of the cosmological Dark Matter puzzle. A fairly comprehensive list of possible candidates is given; in each case the production mechanism and possible ways to detect them (if any) are described. I then describe detection of the in my view most promising candidates, weakly interacting massive particles or WIMPs, in slightly more detail. The main emphasis will be on recent developments.Comment: Invited talk at the 5th Workshop on Particle Physics Phenomenology, Pune, India, January 1998; 21 pages, LaTeX with equation.st