Using NSPT for the Removal of Hypercubic Lattice Artifacts

The treatment of hypercubic lattice artifacts is essential for the calculation of non-perturbative renormalization constants of RI-MOM schemes. It has been shown that for the RI'-MOM scheme a large part of these artifacts can be calculated and subtracted with the help of diagrammatic Lattice Perturbation Theory (LPT). Such calculations are typically restricted to 1-loop order, but one may overcome this limitation and calculate hypercubic corrections for any operator and action beyond the 1-loop order using Numerical Stochastic Perturbation Theory (NSPT). In this study, we explore the practicability of such an approach and consider, as a first test, the case of Wilson fermion bilinear operators in a quenched theory. Our results allow us to compare boosted and unboosted perturbative corrections up to the 3-loop order.Comment: 7 pages, 6 figures, talk presented at the 32nd International Symposium on Lattice Field Theory (Lattice 2014), 23-28 June 2014, New York, USA; PoS(LATTICE2014)29

Discretization Errors for the Gluon and Ghost Propagators in Landau Gauge using NSPT

The subtraction of hypercubic lattice corrections, calculated at 1-loop order in lattice perturbation theory (LPT), is common practice, e.g., for determinations of renormalization constants in lattice hadron physics. Providing such corrections beyond 1-loop order is however very demanding in LPT, and numerical stochastic perturbation theory (NSPT) might be the better candidate for this. Here we report on a first feasibility check of this method and provide (in a parametrization valid for arbitrary lattice couplings) the lattice corrections up to 3-loop order for the SU(3) gluon and ghost propagators in Landau gauge. These propagators are ideal candidates for such a check, as they are available from lattice simulations to high precision and can be combined to a renormalization group invariant product (Minimal MOM coupling) for which a 1-loop LPT correction was found to be insufficient to remove the bulk of the hypercubic lattice artifacts from the data. As a bonus, we also compare our results with the ever popular H(4) method.Comment: 7 pages, 5 figures, presented at the 31st International Symposium on Lattice Field Theory (Lattice 2013), 29 July - 3 August 2013, Mainz, German

Life-Cycle Portfolio Choice with Stock Market Loss Framing: Explaining the Empirical Evidence

We develop a life-cycle model with optimal consumption, portfolio choice, and flexible work hours for households with loss-framing preferences giving them disutility if they experience losses from stock investments. Structural estimation using U.S. data shows that the model tracks the empirical age-pattern of stock market participants’ financial wealth, stock shares, and work hours remarkably well. Including stock market participation costs in the model allows us to also predict low stock market participations rates observed in the overall population. Allowing for heterogeneous agents further improves explanatory power and accounts for the observed discrepancy in wealth accumulation between stockholders and non-stockholders

SU(3) Landau gauge gluon and ghost propagators using the logarithmic lattice gluon field definition

We study the Landau gauge gluon and ghost propagators of SU(3) gauge theory, employing the logarithmic definition for the lattice gluon fields and implementing the corresponding form of the Faddeev-Popov matrix. This is necessary in order to consistently compare lattice data for the bare propagators with that of higher-loop numerical stochastic perturbation theory (NSPT). In this paper we provide such a comparison, and introduce what is needed for an efficient lattice study. When comparing our data for the logarithmic definition to that of the standard lattice Landau gauge we clearly see the propagators to be multiplicatively related. The data of the associated ghost-gluon coupling matches up almost completely. For the explored lattice spacings and sizes discretization artifacts, finite-size and Gribov-copy effects are small. At weak coupling and large momentum, the bare propagators and the ghost-gluon coupling are seen to be approached by those of higher-order NSPT.Comment: 18 pages, 19 figures, 5 table

Investigation of Learners' Experience with Nature : aSouth African and German Perspective

The research project compares two different gegraphical and cultural areas (Bremen/ Durban) regarding their experience of nature with the help of a standardized questionnaire (n=1682). Additionally, semi-structured interviews were conducted whereof four contrasting examples were analysed. Main results are: learners from Bremen and Durban engage in encounters with nature on a regular basis together with their families and friends. Rarely, they enage in such activities with their school. Besides this, a significant difference regarding connectedness with nature (Bremen M=3.14, SD=.64; Durban M=3.59, SD=.54), environmental identity (M=3.15, SD=.71; M=3.69, SD=.65) as well as intention to act nature-orientated (M=3.04, SD=.47; M=3.23, SD=.43) and sustainable (M=2.87, SD=.90; M=3.67, SD=.97) could be measured. In both groups an alienated and idealized perception of nature could be revealed

Flottenbetrieb von elektrischen und autonomen Serviceagenten im städtischen Personennahverkehr

Es wird ein autonomes Personenbeförderungssystem mit ausschließlich durch erneuerbare Energie angetriebenen Fahrzeugen konzipiert und im Gesamtsystem simuliert. Die Ergebnisse zeigen technische, ökonomische und ökologische Potentiale für Städte auf, welche durch die systematische Einsatzplanung eines an der individuellen Mobilitätsnachfrage orientierten elektrischen Massenverkehrsmittels entstehen können. Damit wird eine Methode zum Erreichen der Ziele der Energiewende im Verkehr vorgestellt

Protonation and ring closure of stereoisomeric alpha-substituted cinnamic acids in superacidic media studied by 13C NMR spectroscopy and computations

Five alpha-substituted cinnamic acids [(E)- and (Z)-2,3-diphenyl-, (E)- and (Z)-3-(2-methoxyphenyl)-2-phenyl- and (E)-2-(2-methoxyphenyl)-3-phenyl-propenoic acids] have been protonated in fluorosulfonic acid at -78 degrees C, Protonation of the carboxylic group and a second protonation on the methoxy group at -78 degrees C or the ring bearing the methoxy group at 0 degrees C have been observed by C-13 NMR spectroscopy Upon protonation (Z)-alpha-phenylcinnamic acid is transformed to a protonated indenol derivative, Dehydrative ring closure begins at -78 degrees C and goes to completion at 0 degrees C, Similar transformations of the other studied Z-acid are suppressed by the deactivating effect of the protonated methoxy group. Only protonation has been observed for the E-acids at -78 degrees C as well as 0 degrees C, Calculations at the HF/3-21G level provide the equilibrium structures of the corresponding cations, Results of IGLO/C-13 NMR shift calculations are in good agreement with the experimental findings

An experimental analysis of equal punishment games

In equal punishment games first the proposer suggests how to split the pie, i.e. a positive monetary reward. Unlike in the ultimatum game, the responder can decide among many (for proposer and responder) equal penalty payments. To exclude negative payoffs, punishment was bounded from above depending on the proposal and the (for proposer and responder) same show up-fee, our only treatment variable. Although inequality aversion (Bolton and Oekenfels, 1999, and Fehr and Schmidt, 1999) predicts zero-punishments, we observe positive punishments which, however, became smaller in the repetition. Initial fairness is often substituted in the repetition by extreme greed. Whereas greed is sticky, fairness is more characteristic for initial inclinations and not a stable behavioral pattern