The surprising influence of late charged current weak interactions on Big Bang Nucleosynthesis

The weak interaction charged current processes ($\nu_e+n\leftrightarrow p+e^-$, $\bar\nu_e +p\leftrightarrow n+e^+$, $n\leftrightarrow p+e^-+\bar\nu_e$) interconvert neutrons and protons in the early universe and have significant influence on Big Bang Nucleosynthesis (BBN) light-element abundance yields, particulary that for $^{4}{\rm He}$. We demonstrate that the influence of these processes is still significant even when they operate well below temperatures $T\sim0.7\,{\rm MeV}$ usually invoked for "weak freeze-out," and in fact down nearly into the alpha-particle formation epoch ($T \approx 0.1\,{\rm MeV}$). This physics is correctly captured in commonly used BBN codes, though this late-time, low-temperature persistent effect of the isospin-changing weak processes, and the sensitivity of the associated rates to lepton energy distribution functions and blocking factors are not widely appreciated. We quantify this late-time influence by analyzing weak interaction rate dependence on the neutron lifetime, lepton energy distribution functions, entropy, the proton-neutron mass difference, and Hubble expansion rate. The effects we point out here render BBN a keen probe of any beyond-standard-model physics that alters lepton number/energy distributions, even subtly, in epochs of the early universe all the way down to near $T=100\,{\rm keV}$.Comment: 27 pages, 8 figure

Majorana Neutrino Magnetic Moment and Neutrino Decoupling in Big Bang Nucleosynthesis

We examine the physics of the early universe when Majorana neutrinos (electron neutrino, muon neutrino, tau neutrino) possess transition magnetic moments. These extra couplings beyond the usual weak interaction couplings alter the way neutrinos decouple from the plasma of electrons/positrons and photons. We calculate how transition magnetic moment couplings modify neutrino decoupling temperatures, and then use a full weak, strong, and electromagnetic reaction network to compute corresponding changes in Big Bang Nucleosynthesis abundance yields. We find that light element abundances and other cosmological parameters are sensitive to magnetic couplings on the order of 10^{-10} Bohr magnetons. Given the recent analysis of sub-MeV Borexino data which constrains Majorana moments to the order of 10^{-11} Bohr magnetons or less, we find that changes in cosmological parameters from magnetic contributions to neutrino decoupling temperatures are below the level of upcoming precision observations.Comment: 19 pages, 9 figure

Probing neutrino physics with a self-consistent treatment of the weak decoupling, nucleosynthesis, and photon decoupling epochs

We show that a self-consistent and coupled treatment of the weak decoupling, big bang nucleosynthesis, and photon decoupling epochs can be used to provide new insights and constraints on neutrino sector physics from high-precision measurements of light element abundances and cosmic microwave background observables. Implications of beyond-standard-model physics in cosmology, especially within the neutrino sector, are assessed by comparing predictions against five observables: the baryon energy density, helium abundance, deuterium abundance, effective number of neutrinos, and sum of the light neutrino mass eigenstates. We give examples for constraints on dark radiation, neutrino rest mass, lepton numbers, and scenarios for light and heavy sterile neutrinos.Comment: 29 pages, 10 figure

Neutrino energy transport in weak decoupling and big bang nucleosynthesis

We calculate the evolution of the early universe through the epochs of weak decoupling, weak freeze-out and big bang nucleosynthesis (BBN) by simultaneously coupling a full strong, electromagnetic, and weak nuclear reaction network with a multi-energy group Boltzmann neutrino energy transport scheme. The modular structure of our code provides the ability to dissect the relative contributions of each process responsible for evolving the dynamics of the early universe in the absence of neutrino flavor oscillations. Such an approach allows a detailed accounting of the evolution of the $\nu_e$, $\bar\nu_e$, $\nu_\mu$, $\bar\nu_\mu$, $\nu_\tau$, $\bar\nu_\tau$ energy distribution functions alongside and self-consistently with the nuclear reactions and entropy/heat generation and flow between the neutrino and photon/electron/positron/baryon plasma components. This calculation reveals nonlinear feedback in the time evolution of neutrino distribution functions and plasma thermodynamic conditions (e.g., electron-positron pair densities), with implications for: the phasing between scale factor and plasma temperature; the neutron-to-proton ratio; light-element abundance histories; and the cosmological parameter \neff. We find that our approach of following the time development of neutrino spectral distortions and concomitant entropy production and extraction from the plasma results in changes in the computed value of the BBN deuterium yield. For example, for particular implementations of quantum corrections in plasma thermodynamics, our calculations show a $0.4\%$ increase in deuterium. These changes are potentially significant in the context of anticipated improvements in observational and nuclear physics uncertainties.Comment: 37 pages, 12 Figures, 6 Table

Variáveis agronômicas e variabilidade viral entre videiras sintomáticas e assintomáticas para viroses.

Os objetivos deste trabalho foram avaliar variáveis agronômicas em videiras com e sem sintomas de virose e caracterizar isolados virais destas plantas

Social Entrepreneurship im deutschen Wohlfahrtsstaat: hybride Organisationen zwischen Markt, Staat und Gemeinschaft

Die Verfasser fragen nach der Bedeutung gesellschaftlichen Unternehmertums im etablierten deutschen System der Wohlfahrtsproduktion. Die Frage, ob gesellschaftliches Unternehmertum als Lückenbüßer oder Innovationsinkubatoren im sozialen Dienstleistungssektor fungieren, erfordert neben der Theoriebildung sowohl begriffliche Differenzierungen als auch empirische Überprüfungen. So müssen die organisationssoziologisch gesehen hybriden Sozialunternehmen von sozialen Unternehmen unterschieden werden. Am Beispiel der Bereiche Altenpflege und Kinder-/Jugendhilfe kann gezeigt werden, in wie fern der Sektor soziale Dienstleistungen zwar vom Typus der hybriden Sozialunternehmen geprägt ist, die empirischen Daten jedoch auch deutlich die Stabilität und Pfadabhängigkeit des bisherigen Wohlfahrtsmusters belegen. Mit ihrer Analyse der spezifischen Produktionsbedingungen des sozialen Dienstleistungssektors in Deutschland zeigen die Verfasser, dass eine Übertragung des angelsächsisch geprägten "social entrepreneurship"-Ansatzes auf die Realität des deutschen Wohlfahrtsstaates nur bedingt möglich ist, da Begrifflichkeiten und Konzepte an das jeweilige wohlfahrtsstaatliche Regime angepasst werden müssen und die jeweiligen institutionellen Konzepte zu berücksichtigen sind. (ICE2

Hochschulräte als neues Steuerungsinstrument? Eine empirische Analyse der Mitglieder und Aufgabenbereiche

Die vorliegende Studie liefert erstmalig einen repräsentativen Überblick über die Struktur, die Zusammensetzung und erste Erfahrungen mit den Arbeitsweisen von Hochschulräten in Deutschland, Österreich und der Schweiz. Hochschulräte werden als neue Steuerungsinstrumente im "Mehrebenensystem" von Hochschulen gesehen, die auf den von Sozialwissenschaftlern konstatierten Trend zu einer "Zerfaserung" von Staatlichkeit hinweisen und zu einer Verschiebung von Organisationsverantwortung beitragen können. (Textauszug

Scattered manifold-valued data approximation

ISSN:0029-599XISSN:0945-324