Charm and Beauty Production at HERA-B

The HERA-B experiment at DESY has acquired a data set of approximately 300,000 decays J/psi -> l+l- during its 2002/2003 data-taking period. These data are used to analyze the production of heavy quarks in proton-nucleus interactions at a center-of-mass energy of 41.6 GeV. In this article, preliminary results of two measurements are discussed, a measurement of nuclear effects in the production of J/psi mesons and a measurement of the b-bbar production cross section.Comment: 4 pages, 3 figures, to appear in Proc. XIII International Workshop on Deep Inelastic Scattering (DIS2005), April 27 - May 1, 2005, Madison, Wisconsi

Field Theory of Disordered Elastic Interfaces at 3-Loop Order: Critical Exponents and Scaling Functions

For disordered elastic manifolds in the ground state (equilibrium) we obtain the critical exponents for the roughness and the correction-to-scaling up to 3-loop order, i.e. third order in $\epsilon=4-d$, where $d$ is the internal dimension $d$. We also give the full 2-point function up to order $\epsilon^{2}$, i.e. at 2-loop order.Comment: v1: 74 pages, 88 figures; v2: paper split into to parts; v3: typos corrected and hyper-ref enable

Incommensurate nematic fluctuations in the two-dimensional Hubbard model

We analyze effective d-wave interactions in the two-dimensional extended Hubbard model at weak coupling and small to moderate doping. The interactions are computed from a renormalization group flow. Attractive d-wave interactions are generated via antiferromagnetic spin fluctuations in the pairing and charge channels. Above Van Hove filling, the d-wave charge interaction is maximal at incommensurate diagonal wave vectors, corresponding to nematic fluctuations with a diagonal modulation. Below Van Hove filling a modulation along the crystal axes can be favored. The nematic fluctuations are enhanced by the nearest-neighbor interaction in the extended Hubbard model, but they always remain smaller than the dominant antiferromagnetic, pairing, or charge density wave fluctuations.Comment: 8 pages, 4 figures; figures improve

Field Theory of Disordered Elastic Interfaces at 3-Loop Order: The β\beta-Function

We calculate the effective action for disordered elastic manifolds in the ground state (equilibrium) up to 3-loop order. This yields the renormalization-group $\beta$-function to third order in $\epsilon=4-d$, in an expansion in the dimension $d$ around the upper critical dimension $d=4$. The calculations are performed using exact RG, and several other techniques, which allow us to resolve consistently the problems associated with the cusp of the renormalized disorder.Comment: This is the first part of arXiv:1707.09802v1. The remaining part is in arXiv:1707.09802v2. 47 pages, 67 figures. v2: typos corrected and hyper-ref enable

Influence parameters of impact grinding mills

Significant parameters for impact grinding mills were investigated. Final particle size was used to evaluate grinding results. Adjustment of the parameters toward increased charge load results in improved efficiency; however, it was not possible to define a single, unified set to optimum grinding conditions

The low-metallicity QSO HE 2158-0107: A massive galaxy growing by the accretion of nearly pristine gas from its environment?

[abridged] The metallicities of AGN are usually well above solar in their NLR, often reaching up to several times solar in their broad-line regions. Low-metallicity AGN are rare objects which have so far always been associated with low-mass galaxies hosting low-mass BHs (M_BH<10^6Msun). In this paper we present IFS data of the low-redshift QSO HE 2158-0107 for which we find strong evidence for sub-solar NLR metallicities associated with a massive BH (M_BH~3x10^8Msun). The QSO is surrounded by a large extended emission-line region reaching out to 30kpc from the QSO in a tail-like geometry. We present optical and near-IR images and investigate the properties of the host galaxy. The SED of the host is rather blue, indicative of a significant young age stellar population formed within the last 1Gyr. A 3sigma upper limit of L_bulge<4.5x10^10Lsun for the H band luminosity and a corresponding stellar mass upper limit of M_bulge<3.4x10^10Msun show that the host is offset from the local BH-bulge relations. This is independently supported by the kinematics of the gas. Although the stellar mass of the host galaxy is lower than expected, it cannot explain the exceptionally low metallicity of the gas. We suggest that the extended emission-line region and the galaxy growth are caused by the infall of nearly pristine gas from the environment of the QSO host. Minor mergers of dwarf galaxies or the theoretically predicted smooth accretion of cold gas are both potential drivers behind that process. Since the metallicity of the gas in the NLR is much lower than expected, we suspect that the external gas has already reached the galaxy centre and may even contribute to the current feeding of the BH. HE 2158-0107 appears to represent a particular phase of substantial BH and galaxy growth that can be observationally linked with the accretion of external material from its environment.Comment: 14 pages, 12 figures, accepted for publication in A&

The properties of the extended warm ionised gas around low-redshift QSOs and the lack of extended high-velocity outflows

(Abridged) We present a detailed analysis of a large sample of 31 low-redshift, mostly radio-quiet type 1 QSOs observed with integral field spectroscopy to study their extended emission-line regions (EELRs). We focus on the ionisation state of the gas, size and luminosity of extended narrow line regions (ENLRs), which corresponds to those parts of the EELR dominated by ionisation from the QSO, as well as the kinematics of the ionised gas. We detect EELRs around 19 of our 31 QSOs (61%) after deblending the unresolved QSO emission and the extended host galaxy light in the integral field data. We identify 13 EELRs to be entirely ionised by the QSO radiation, 3 EELRs are composed of HII regions and 3 EELRs display signatures of both ionisation mechanisms at different locations. The typical size of the ENLR is 10kpc at a median nuclear [OIII] luminosity of log(L([OIII])/[erg/s])=42.7+-0.15. We show that the ENLR sizes are least a factor of 2 larger than determined with HST, but are consistent with those of recently reported type 2 QSOs at matching [OIII] luminosities. The ENLR of type 1 and type 2 QSOs appear to follow the same size-luminosity relation. Furthermore, we show for the first time that the ENLR size is much better correlated with the QSO continuum luminosity than with the total/nuclear [OIII] luminosity. We show that ENLR luminosity and radio luminosity are correlated, and argue that radio jets even in radio-quiet QSOs are important for shaping the properties of the ENLR. Strikingly, the kinematics of the ionised gas is quiescent and likely gravitationally driven in the majority of cases and we find only 3 objects with radial gas velocities exceeding 400km/s in specific regions of the EELR that can be associate with radio jets. In general, these are significantly lower outflow velocities and detection rates compared to starburst galaxies or radio-loud QSOs.Comment: 34 page, 22 figures (slightly degraded in resolution), 10 tables, accepted for publication in A&A, minor corrections to match with the publisher versio

Investigating subject-specific writing skills and historical reasoning in historical explanations: a study of 7th- and 8th-grade comprehensive school students in North Rhine-Westphalia, Germany

The purpose of this study was to examine the writing skills of 7th- and 8th-grade students with a high proportion of migration background in North Rhine-Westphalia, Germany. The study was part of the SchriFT project (2017–20), funded by the Federal Ministry of Education and Research. A writing task was given on the topic: Why can we only make assumptions about many past events? As an answer to the task, the students had to write a historical explanation that took into account the epistemological principles of historical reasoning. The students’ writing was analysed using a category system, and their historical knowledge was assessed through a knowledge test. The results showed that the students possess diverse levels of writing skills, with few producing elaborate explanations, and most struggling with the subject-specific language and reasoning skills. The study also highlights the potential for genre-based writing approaches in history education. The results suggest that many students perceive history as an image of the past and have limited understanding of historical reasoning. Further research is needed to investigate the influence of motivation and interest on language learning