Relativistic Transport Theory for Systems Containing Bound States

Using a Lagrangian which contains quarks as elementary degrees of freedom and mesons as bound states, a transport formalism is developed, which allows for a dynamical transition from a quark plasma to a state, where quarks are bound into hadrons. Simultaneous transport equations for both particle species are derived in a systematic and consistent fashion. For the mesons a formalism is used which introduces off-shell corrections to the off-diagonal Green functions. It is shown that these off-shell corrections lead to the appearance of elastic quark scattering processes in the collision integral. The interference of the processes $q\bar q\to\pi$ and $q\bar q\to\pi\to q\bar q$ leads to a modification of the $s$-channel amplitude of quark-antiquark scattering

Expansion and Hadronization of a Chirally Symmetric Quark--Meson Plasma

Using a chirally symmetric Lagrangian, which contains quarks as elementary degrees of freedom and mesons as bound states, we investigate the expansion and hadronization of a fireball, which initially contains only quarks and produces mesons by collisions. For this model, we study the time scales of expansion and thermal and chemical equilibration. We find that the expansion progresses relatively fast, leaving not necessarily enough time to establish thermal and chemical equilibrium. Mesons are produced in the bulk of the fireball rather than at a surface, at a temperature below the Mott temperature. Initial density fluctuations become amplified during the expansion. These observations challenge the applicability of hydrodynamical approaches to the expansion of a quark-gluon plasma

A Numerical Slow Manifold Approach to Model Reduction for Optimal Control of Multiple Time Scale ODE

Time scale separation is a natural property of many control systems that can be ex- ploited, theoretically and numerically. We present a numerical scheme to solve optimal control problems with considerable time scale separation that is based on a model reduction approach that does not need the system to be explicitly stated in singularly perturbed form. We present examples that highlight the advantages and disadvantages of the method

One Loop Integrals at Finite Temperature and Density

The technique of decomposing Feynman diagrams at the one loop level into elementary integrals is generalized to the imaginary time Matsubara formalism. The three lowest integrals, containing one, two and three fermion lines, are provided in a form that separates out the real and imaginary parts of these complex functions, according to the input arguments, in a fashion that is suitable for numerical evaluation. The forms given can be evaluated for arbitrary values of temperature, particle mass, particle momenta and chemical potential.Comment: 32 Pages REVTeX, 9 Figures available as separate fil

An Analysis of Temperate Deciduous Shrub Phenology in Downer Woods, University of Wisconsin-Milwaukee, Wisconsin, USA

Shrub species, both native and non-native, are an important component of temperate deciduous forest ecosystems but are an often-overlooked and under-studied functional group. Shrubs tend to leaf-out earlier than trees in spring and retain their leaves later in autumn thus extending the overall growing season and the carbon uptake period of the forest ecosystem. In this study, a range of 5- native and 3- non-native shrub species were identified in a deciduous urban woodlot, and the phenology was monitored over a 3-year period on the University of Wisconsin-Milwaukee campus. The aim of this work was to determine any variation in the timing (DOY) and duration (days) of key spring (bud-open, leaf-out, full-leaf unfolded) and autumn (leaf color, leaf fall) phenophases between native and non-native species. Preliminary results revealed interesting findings with buckthorn Rhamnus cathartica (an alien invasive/non-native species) consistently leafing out later than most native species and taking longer to reach full-leaf unfolded. Additionally, non-native species such as European privet Lingustrum vulgare have a longer growing season than native species ranging from 14 days to 35 days longer in non-native species than native species across the three-year period. This shows how non-native species can lengthen the fall season compared to native species. These results could add to the understanding of how non-native shrub species may gain a competitive advantage over native shrubs and may help inform future conservation management plans

Altruistic Individualists: Motivations for International Volunteering Among Young Adults in Switzerland

Modernization theory posits a change from traditional or "collective” forms to modern or "reflective” forms of volunteering. In a research project using a combined qualitative-quantitative approach, the motivation of 118 young Swiss adults who showed an interest in international volunteering was investigated. Qualitative analysis revealed 12 different motives which could be categorized into three different groups: A first group called "Achieving something positive for others,” a second group named "Quest for the new,” and a third group of motives labeled "Quest for oneself.” Motivations of young Swiss adults for international volunteering clearly show the characteristics of "reflexive” volunteers. Most respondents displayed a combination of motives while for only 11% of them altruism ("Achieving something positive for others”) was the one and only driving force behind their interest in international volunteering. The inductively constructed typology of motives can be a useful planning device for organizations that run or intend to set up an international volunteering program for young adult

A criterion for a two-dimensional domain to be Lipschitzian

We prove that a two-dimensional domain is already Lipschitzian if only its boundary admits locally a one-dimensional, bi-Lipschitzian parametrization

Pruned Inside-Out Polytopes, Combinatorial Reciprocity Theorems and Generalized Permutahedra

Generalized permutahedra are a class of polytopes with many interesting combinatorial subclasses. We introduce pruned inside-out polytopes, a generalization of inside-out polytopes introduced by Beck-Zaslavsky (2006), which have many applications such as recovering the famous reciprocity result for graph colorings by Stanley. We show (quasi-)polynomiality and reciprocity results for the integer point count of pruned inside-out polytopes by applying classical Ehrhart polynomials and Ehrhart-Macdonald reciprocity. This yields a geometric perspective on and a generalization of a combinatorial reciprocity theorem for generalized permutahedra by Aguiar-Ardila (2017), Billera-Jia-Reiner (2009), and Karaboghossian (2022). Applying this reciprocity theorem to hypergraphic polytopes allows to give a geometric proof of a combinatorial reciprocity theorem for hypergraph colorings by Aval-Karaboghossian-Tanasa (2020). This proof relies, aside from the reciprocity for generalized permutahedra, only on elementary geometric and combinatorial properties of hypergraphs and their associated polytopes