Baryon production from cluster hadronization

We present an extension to the colour reconnection model in the Monte-Carlo event generator Herwig to account for the production of baryons and compare it to a series of observables for soft physics. The new model is able to improve the description of charged-particle mutliplicities and hadron flavour observables in pp collisionsComment: 13 pages; v3: updated to match journal versio

O(a)\mathcal{O}(a) improved quark mass renormalization for a non-perturbative matching of HQET to three-flavor QCD

The use of Heavy Quark Effective Theory (HQET) on the lattice as an approach to B-physics phenomenology is based on a non-perturbative matching of HQET to QCD in finite volume. As a first step to apply the underlying strategy in the three-flavor ($N_f = 2+1$) theory, we determine the renormalization constant and improvement coefficients relating the renormalized current and subtracted quark mass of (quenched) valence quarks in $\mathcal{O}(a)$ improved $N_f=3$ lattice QCD. We present our strategy and first results for the relevant parameter region towards weak couplings along a line of constant physics, which corresponds to lattice resolutions $a\leq 0.02\,$fm and fixes the physical extent of the matching volume to $L\approx 0.5\,$fm.Comment: 7 pages including 7 figures, latex2e; Proceedings of the 36th International Symposium on Lattice Field Theory (Lattice 2018), 22-28 July 2018, Michigan State University, East Lansing, Michigan, US

Scale dependence of galaxy biasing investigated by weak gravitational lensing: An assessment using semi-analytic galaxies and simulated lensing data

Galaxies are biased tracers of the matter density on cosmological scales. For future tests of galaxy models, we refine and assess a method to measure galaxy biasing as function of physical scale $k$ with weak gravitational lensing. This method enables us to reconstruct the galaxy bias factor $b(k)$ as well as the galaxy-matter correlation $r(k)$ on spatial scales between $0.01\,h\,{\rm Mpc^{-1}}\lesssim k\lesssim10\,h\,{\rm Mpc^{-1}}$ for redshift-binned lens galaxies below redshift $z\lesssim0.6$. In the refinement, we account for an intrinsic alignment of source ellipticities, and we correct for the magnification bias of the lens galaxies, relevant for the galaxy-galaxy lensing signal, to improve the accuracy of the reconstructed $r(k)$. For simulated data, the reconstructions achieve an accuracy of $3-7\%$ (68\% confidence level) over the above $k$-range for a survey area and a typical depth of contemporary ground-based surveys. Realistically the accuracy is, however, probably reduced to about $10-15\%$, mainly by systematic uncertainties in the assumed intrinsic source alignment, the fiducial cosmology, and the redshift distributions of lens and source galaxies (in that order). Furthermore, our reconstruction technique employs physical templates for $b(k)$ and $r(k)$ that elucidate the impact of central galaxies and the halo-occupation statistics of satellite galaxies on the scale-dependence of galaxy bias, which we discuss in the paper. In a first demonstration, we apply this method to previous measurements in the Garching-Bonn-Deep Survey and give a physical interpretation of the lens population.Comment: 31 pages, 16 figures; corrected typos in Eqs. (31), (34), and (36

A New Generation of Cool White Dwarf Atmosphere Models Using Ab Initio Calculations

Due to their high photospheric density, cool helium-rich white dwarfs (particularly DZ, DQpec and ultracool) are often poorly described by current atmosphere models. As part of our ongoing efforts to design atmosphere models suitable for all cool white dwarfs, we investigate how the ionization ratio of heavy elements and the H$_2$-He collision-induced absorption (CIA) spectrum are altered under fluid-like densities. For the conditions encountered at the photosphere of cool helium-rich white dwarfs, our ab initio calculations show that the ionization of most metals is inhibited and that the H$_2$-He CIA spectrum is significantly distorted for densities higher than 0.1 g/cm$^3$.Comment: 4 pages, 2 figures, submitted for publication in the proceedings of the 20th European Workshop on White Dwarf

Pressure Distortion of the H2_2-He Collision-Induced Absorption at the Photosphere of Cool White Dwarf Stars

Collision-induced absorption (CIA) from molecular hydrogen is a dominant opacity source in the atmosphere of cool white dwarfs. It results in a significant flux depletion in the near-IR and IR parts of their spectra. Because of the extreme conditions of helium-rich atmospheres (where the density can be as high as a few g/cm$^3$), this opacity source is expected to undergo strong pressure distortion and the currently used opacities have not been validated at such extreme conditions. To check the distortion of the CIA opacity we applied state-of-the-art ab initio methods of computational quantum chemistry to simulate the CIA opacity at high densities. The results show that the CIA profiles are significantly distorted above densities of $0.1\,{\rm g/cm}^3$ in a way that is not captured by the existing models. The roto-translational band is enhanced and shifted to higher frequencies as an effect of the decrease of the interatomic separation of the H$_2$ molecule. The vibrational band is blueward shifted and split into $Q_R$ and $Q_P$ branches, separated by a pronounced interference dip. Its intensity is also substantially reduced. The distortions result in a shift of the maximum of the absorption from $2.3\,\mu{\rm m}$ to $3-7 \mu{\rm m}$, which could potentially explain the spectra of some very cool, helium-rich white dwarfs.Comment: 12 pages, 13 figures. Accepted for publication in The Astrophysical Journa

Colour Reconnection from Soft Gluon Evolution

We consider soft gluon evolution at the amplitude level to expose the structure of colour reconnection from a perturbative point of view. Considering the cluster hadronization model and an universal Ansatz for the soft anomalous dimension we find strong support for geometric models considered earlier. We also show how reconnection into baryonic systems arises, and how larger cluster systems evolve. Our results provide the dynamic basis for a new class of colour reconnection models for cluster hadronization.Comment: 24 pages, 15 figure

Still Waiting for Mister Right? Asymmetric Information, Abortion Laws and the Timing of Marriage

Previous studies have suggested that more liberal abortion laws should lead to a decrease in marriage rates among young women as 'shotgun weddings' are no longer necessary. Empirical evidence from the United States lends support to that hypothesis. This paper presents an alternative theory of abortion access and marriage based on asymmetric information, which suggests that more liberal abortion laws may actually promote young marriage. An empirical examination of marriage data from Eastern Europe shows that countries that liberalized their abortion laws saw an increase in marriage rates among non-teenage women.abortion, marriage asymmetric information

Confronting semi-analytic galaxy models with galaxy-matter correlations observed by CFHTLenS

Testing predictions of semi-analytic models of galaxy evolution against observations help to understand the complex processes that shape galaxies. We compare predictions from the Garching and Durham models implemented on the Millennium Run with observations of galaxy-galaxy lensing (GGL) and galaxy-galaxy-galaxy lensing (G3L) for various galaxy samples with stellar masses in the range 0.5 < (M_* / 10^10 M_Sun) < 32 and photometric redshift range 0.2 < z < 0.6 in the Canada-France-Hawaii Telescope Lensing Survey (CFHTLenS). We find that the predicted GGL and G3L signals are in qualitative agreement with CFHTLenS data. Quantitatively, the models succeed in reproducing the observed signals in the highest stellar mass bin (16 < ( M_* / 10^10 M_Sun) < 32) but show different degrees of tension for the other stellar mass samples. The Durham models are strongly excluded at the 95% confidence level by the observations as they largely over-predict the amplitudes of the GGL and G3L signals, probably because they predict too many satellite galaxies in massive halos.Comment: 9 pages, 8 figures, submitted to A&A. Comments welcom