arXiv subjects
Publications and source records attributed to Andreas Ringwald.
We study the gravitational clustering of big bang relic neutrinos onto existing cold dark matter and baryonic structures within the flat $Λ$CDM model. We then discuss the implications of clustering for scattering-based relic neutrino detection methods, ranging from flux detection via Cavendish-type torsion balances, to target detection using accelerator beams and cosmic rays.
We study the gravitational clustering of big bang relic neutrinos onto existing cold dark matter (CDM) and baryonic structures within the flat $Λ$CDM model, using both numerical simulations and a semi-analytical linear technique, with the aim of understanding the neutrinos' clustering properties for direct detection purposes. In a comparative analysis, we find that the linear technique systematically underestimates the amount of clustering for a wide range of CDM halo and neutrino masses. This invalidates earlier claims of the technique's applicability. We then compute the exact phase space distribution of relic neutrinos in our neighbourhood at Earth, and estimate the large scale neutrino density contrasts within the local Greisen--Zatsepin--Kuzmin zone. With these findings, we discuss the implications of gravitational neutrino clustering for scattering-based detection methods, ranging from flux detection via Cavendish-type torsion balances, to target detection using accelerator beams and cosmic rays. For emission spectroscopy via resonant annihilation of extremely energetic cosmic neutrinos on the relic neutrino background, we give new estimates for the expected enhancement in the event rates in the direction of the Virgo cluster.
This rapporteur review covers selected results presented in the Parallel Session HEA2 (High Energy Astrophysics 2) of the 10th Marcel Grossmann Meeting on General Relativity, held in Rio de Janeiro, Brazil, July 2003. The subtopics are: ultra high energy cosmic ray anisotropies, the possible connection of these energetic particles with powerful gamma ray bursts, and new exciting scenarios with a strong neutrino-nucleon interaction in the atmosphere.
Resonant annihilation of extremely high-energy cosmic neutrinos on big-bang relic anti-neutrinos (and vice versa) into Z-bosons leads to sizable absorption dips in the neutrino flux to be observed at Earth. The high-energy edges of these dips are fixed, via the resonance energies, by the neutrino masses alone. Their depths are determined by the cosmic neutrino background density, by the cosmological parameters determining the expansion rate of the universe, and by the large redshift history of the cosmic neutrino sources. We investigate the possibility of determining the existence of the cosmic neutrino background within the next decade from a measurement of these absorption dips in the neutrino flux. As a by-product, we study the prospects to infer the absolute neutrino mass scale. We find that, with the presently planned neutrino detectors (ANITA, Auger, EUSO, OWL, RICE, and SalSA) operating in the relevant energy regime above 10^{21} eV, relic neutrino absorption spectroscopy becomes a realistic possibility. It requires, however, the existence of extremely powerful neutrino sources, which should be opaque to nucleons and high-energy photons to evade present constraints. Furthermore, the neutrino mass spectrum must be quasi-degenerate to optimize the dip, which implies m_{nu} >~ 0.1 eV for the lightest neutrino. With a second generation of neutrino detectors, these demanding requirements can be relaxed considerably.
We review recent theoretical results from our systematic study of QCD-instanton contributions to eP processes, involving a hard momentum scale Q. The main issues are: the absence of IR divergencies due to a dynamical suppression of instantons with large size rho > 1/Q, the reliable calculability of instanton-induced amplitudes and our inclusive framework to systematically calculate properties of the instanton-induced multi-parton final state.
This talk describes the physics input of QCDINS, a Monte Carlo event generator for QCD-instanton induced scattering processes in deep-inelastic scattering.
There exists the possibility that the cross-section for the nonperturbative production of many, ${\cal O}(α_W^{-1} \simeq 30 )$, weak gauge bosons may be as large as ${\cal O}(100\ {\rm pb}\ -\ 10\ μ$b$)$ above a parton-parton center-of-mass threshold in the range $2.4\ -\ 30$ TeV. We review the theoretical considerations which lead to this suggestion and outline its phenomenological implications, both for present cosmic ray as well as for future collider experiments. (Lecture presented at the 4th Hellenic School on Elementary Particle Physics, September 2-20, 1992, Corfu, Greece) (Figures not included, available by ordinary mail)