arXiv subjects

Gerard Jungman

Publications and source records attributed to Gerard Jungman.

26 records · Page 2Linked to original sources

arXiv1995

Weighing the Universe with the Cosmic Microwave Background

Variations in $Ω$, the total density of the Universe, leave a clear and distinctive imprint on the power spectrum of temperature fluctuations in the cosmic microwave background (CMB). This signature is virtually independent of other cosmological parameters or details of particular cosmological models. We evaluate the precision with which $Ω$ can be determined by a CMB map as a function of sky coverage, pixel noise, and beam size. For example, assuming only that the primordial density perturbations were adiabatic and with no prior information on the values of any other cosmological parameters, a full-sky CMB map at $0.5^\circ$ angular resolution and a noise level of $15\,μ{\rm K}$ per pixel can determine $Ω$ with a variance of 5\%. If all other cosmological parameters are fixed, $Ω$ can be measured to better than 1\%.

astro-ph↗

arXiv1995

Gamma Rays from Neutralino Annihilation

We calculate the flux of cosmic gamma rays expected {}from the annihilation of neutralinos in the Galactic halo. Our calculation of the annihilation cross section to two photons improves the existing calculations by inclusion of exact one-loop diagrams for the amplitudes involving Higgs boson and chargino states as well as those involving fermion and sfermion states. A survey of supersymmetric parameter space shows that numerous models would be observable at the $3σ$ level with an air Cerenkov telescope with an exposure of $10^4 \meter^2 \yr$.

hep-ph↗

arXiv1994

Model-Independent Comparison of Direct vs. Indirect Detection of Supersymmetric Dark Matter

We compare the rate for elastic scattering of neutralinos from various nuclei with the flux of upward muons induced by energetic neutrinos from neutralino annihilation in the Sun and Earth. We consider both scalar and axial-vector interactions of neutralinos with nuclei. We find that the event rate in a kg of germanium is roughly equivalent to that in a $10^5$- to $10^7$-m$^2$ muon detector for a neutralino with primarily scalar coupling to nuclei. For an axially coupled neutralino, the event rate in a 50-gram hydrogen detector is roughly the same as that in a 10- to 500-m$^2$ muon detector. Expected experimental backgrounds favor forthcoming elastic-scattering detectors for scalar couplings while the neutrino detectors have the advantage for axial-vector couplings.

hep-ph↗

arXiv1994

Neutrinos From Particle Decay in the Sun and Earth

Weakly interacting massive particles (WIMPs) may be indirectly detected by observation of upward muons induced by energetic neutrinos from annihilation of WIMPs that have accumulated in the Sun and/or Earth. Energetic muon neutrinos come from the decays of $τ$ leptons, $c$, $b$, and $t$ quarks, gauge bosons, and Higgs bosons produced by WIMP annihilation. We provide analytic expressions, suitable for computing the flux of upward muons, for the neutrino energy spectra from decays of all these particles in the center of the Sun and Earth. These analytic expressions should obviate the need for Monte Carlo calculations of the upward-muon flux. We investigate the effects of polarization of the gauge bosons on the neutrino spectra and find that they are small. We also present simple expressions for the second moments of the neutrino distributions which can be used to estimate the rates for observation of neutrino-induced muons from WIMP annihilation.

hep-ph↗

arXiv1993

Cosmic-Ray Antiprotons from Neutralino Annihilation into Gluons

We estimate the flux of cosmic-ray antiprotons expected from the annihilation of neutralinos in the galactic halo. The antiproton signal may offer an important alternative detection scheme in the case that neutralino annihilation proceeds mainly to the two-gluon final state.

astro-ph↗

arXiv1993

Cosmological Consequences of Spontaneous Lepton Number Violation in $SO(10)$ Grand Unification, EFI-93-07

Cosmological constraints on grand unified theories with spontaneous lepton number violation are analysed. We concentrate on $SO(10)$, the simplest of the models possessing this property. It has been noted previously that the consistency of these models with the observed baryon asymmetry generically implies strict upper bounds on the light neutrino masses. In this paper, we analyze the situation in detail. We find that minimal models of fermion masses face difficulties, but that it is possible for these models to generate an adequate baryon asymmetry via non-equilibrium lepton number violating processes when the right-handed neutrino masses are near their maximum possible values. This condition uniquely picks out the minimal gauge symmetry breaking scheme. A non-minimal model is also analyzed, with somewhat different conclusions due to the nature of the imposed symmetries.

hep-ph↗

arXiv1993

Fermion Masses in SO(10)

Yukawa coupling constant unification together with the known fermion masses is used to constrain SO(10) models. We consider the case of one (heavy) generation, with the tree-level relation $m_b=m_τ$, calculating the limits on the intermediate symmetry breaking scales. This analysis extends previous analyses which addressed only the simplest symmetry breaking schemes. In the case where the low energy model is the standard model with one Higgs doublet, there are very strong constraints due to the known limits on the top mass and the tau neutrino mass. The two Higgs doublet case is less constrained. Finally we address the role of a speculative constraint on the tau neutrino mass, arising from the cosmological implications of anomalous $B+L$ violation in the early universe.

hep-ph↗

arXiv1992

P and T Violation From Certain Dimension Eight Weinberg Operators

Dimension eight operators of the Weinberg type have been shown to give important contributions to CP violating phenomena, such as the electric dipole moment of the neutron. In this note we show how operators related to these (and expected to occur on equal footing) can give rise to time-reversal violating phenomena such as atomic electric dipole moments. We also estimate the induced parity violating phenomena such as small ``wrong'' parity admixtures in atomic states and find that they are negligible. Uses harvmac.tex and epsf.tex; one figure submitted as a uuencoded, compressed EPS file.

hep-ph↗