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Der Workshop "Nationale Spezifika und internationale Aspekte in der Wissenschaftsentwicklung – unter besonderer Berücksichtigung der Narratologie" soll, so die Organisatoren in ihrer Einladung – "Gelegenheit bieten, Bedingungen und Möglichkeiten integrativer Ansätze zur Untersuchung von Wissenschaftsprozessen zu diskutieren und wichtige Faktoren der Wissenschaftsentwicklung zu benennen und kritisch zu beleuchten." Die Produktion, Distribution und Rezeption von Wissenssystemen vollziehe sich, schreiben die Organisatoren, "in unterschiedlichen nationalen und internationalen sozialen Räumen, die sowohl die Form als auch den kognitiven Gehalt von Theorien mitunter stark mitstrukturieren, ihre Durchsetzung begünstigen oder behindern. Das wird besonders deutlich, wenn man Transferprozesse von Theorien verfolgt." Den Begriff des Wissenstransfers, der hier in Anschlag gebracht wird, möchte ich in meinem Beitrag einer terminologischen Klärung zuführen. Dazu möchte ich zunächst einige terminologische Überlegungen über den Status der Teilbegriffe anstellen, aus denen der Begriff zusammengesetzt ist (I.), dann die Verwendung des Begriffs in verschiedenen disziplinären Kontexten beobachten (II.) und schließlich einen Vorschlag für eine differenzierte Verwendung des Begriffs als Analysekategorie der Wissenschaftsentwicklung machen (III).
At present, there are no quantitative, objective methods for diagnosing the Parkinson disease. Existing methods of quantitative analysis by myograms suffer by inaccuracy and patient strain; electronic tablet analysis is limited to the visible drawing, not including the writing forces and hand movements. In our paper we show how handwriting analysis can be obtained by a new electronic pen and new features of the recorded signals. This gives good results for diagnostics. Keywords: Parkinson diagnosis, electronic pen, automatic handwriting analysis
Von der welt louff vnd gestallt (3b) [Anm. 1] - vom Lauf der Welt und ihrem Zustand - handelt ein Werk, das im Zentrum der nachfolgenden Überlegungen stehen soll: die Reimchronik zum Schwaben- bzw. Schweizerkrieg des Hans Lenz vom Jahr 1499. In Form eines fiktiven Gesprächs, einer disputatz (62b) zwischen dem Autor und einem Waldbruder, werden die historische Zeitgeschichte und die damalige politisch-gesellschaftliche Situation gesichtet, geordnet, diskutiert, gedeutet und in größere, insbesondere heilsgeschichtliche Zusammenhänge gebracht. Text und Kontext stehen in diesem Beispiel (wie in der Historiographie ganz allgemein) in besonders offensichtlicher Beziehung zueinander - es leuchtet unmittelbar ein, daß ein solcher Text ohne den geschichtlichen Hintergrund nicht angemessen beurteilt werden kann. Dabei darf allerdings nicht allein danach gefragt werden, wie der Historiograph mit den geschichtlichen Fakten (soweit diese überhaupt objektiv rekonstruiert werden können!) umgeht, es muß auch dem Umfeld des Verfassers selbst und seiner Rezipienten sowie dem Zweck und der Funktion seiner Dichtung Rechnung getragen werden, den literarischen und außerliterarischen Einflüssen und Vorbildern, den Denk- und Argumentationsmustern, kurz: die "Lebenswelt" [Anm. 2] des Textes sollte zu seinem Verständnis im gesellschaftlich-kulturellen Kontext soweit als möglich erschlossen werden.
Die Driften der Wörter in öffentlichen Räumen sind vielfältig. Neue Wortentwicklungen belegen unterschiedliche Interessen, "chillen" und "dissen" andere als das in der konservativen Züricher Zeitung zuerst erschienene "share-holder-value". Im Folgenden soll eine sinnbezoge Verallgemeinerung unternommen werden, die die Handlungen der Akteure mit der strukturellen Ebene verbindet. Die Veränderungen in den Verwendungen sollen zu strukturellen sozialen und sprachlichen Rahmenbedingungen in Bezug gesetzt werden. Wie werden Neuerungen und Änderungen der Anwendungsbedingungen von Wörtern vor dem Hintergrund des Wissens um die traditionelle Standardsprache und deren soziale Funktion wahrgenommen? Welche Funktionen haben Neologismen in Abgrenzung zu diesem Standard?
Eine Reihe von nicht in Kodifikationen des Standards aufgenommenen sprachlichen Mustern wird im Blick auf ihre Karrieren in verschiedenen mündlichen und schriftlichen Texten in einer Flut von Veröffentlichungen thematisiert, meist in der Hoffnung hier grammatische Entwicklungen und die Basis für eine Orientierung der Grammatikschreibung an der Pragmatik zu entdecken. Im Folgenden soll Sprache nicht „konzeptuell schriftlich“ gedacht und „sozusagen literal idealisiert“ werden. Es soll argumentiert werden für eine einheitliche, mit Sprachgeschichte, ontogenetischem Spracherwerb und Variantenbildung verträgliche Erklärung nicht-standardisierter sprachlicher Muster im Rahmen einer Grammatikalisierungstheorie.
Bern, bis ins 18. Jh. Zentrum der regionalen Großmacht, heute mit nicht ganz 130.000 Einwohnern die viertgrößte Stadt der Schweiz und seit 1848 die Hauptstadt der Schweiz. Auf Grund dieser Ausgangslage würde man erwarten, dass Bern wie andere Städte eine sprachliche Strahlungskraft in die unmittelbare Umgebung aufweist. Entgegen der allgemeinen Vorstellung zeigt sich jedoch in den Karten des Sprachatlas der deutschen Schweiz (SDS) kaum eine der für die Umgebung von Städten typischen sprachgeographische Verbreitungsbilder. So finden sich viele Isoglossen in unmittelbarer Nähe der Stadt Bern: trichter-, keil- oder gar kreisförmige Bündelungen von Isoglossen, die auf eine sprachliche Wirkung der Stadt hindeuten würde, lassen sich kaum nachweisen.
Wenn Deutsch geschrieben wird, wird im Allgemeinen die standardsprachliche Form gewählt. King: nei nei nöd eso Häx ..... verschtasch mi wieder falsch :-( *sniff (bluewin.ch, #flirt60plus, 1.10.2004) Elle: HeinEr: öhm jez versteh ich gar nix mehr (Antenne Bayern #flirten40, 16.9.2005) Big: Mu auch niemand verstehen (IRCnet, #mannheim,9.2.2003) Tezo: verstehe (IRCnet, #linux, 7.1.2003) In Büchern, Zeitungen, Zeitschriften und auch im Internet ist die deutsche Standardsprache Standard. Sie ist die für die Schriftlichkeit normierte Varietät, die überregional verständlich sein soll. Diese Standardsprache ist zwar überall ähnlich, aber nicht gleich. So zeigen sich Besonderheiten im Lexikon, in der Wortbildung und vereinzelt in der Grammatik, welche in einer Region üblich sind, in der anderen jedoch nicht, oder die da eine andere Bedeutung tragen. Diese Besonderheiten sind aber nicht an einem Ort einfach falsch, sondern sie stellen regionale Ausprägungen des Standards dar (vgl. dazu das Variantenwörterbuch; Ammon u. a. 2004). ...
Die 15. Arbeitstagung zur alemannischen Dialektologie, zu der die Vorarlberger Landesregierung vom 18.–21.Septemer auf Schloss Hofen im vorarlbergischen Lochau bei Bregenz eingeladen hatte, hat wiederum einen Einblick in unterschiedliche aktuelle Forschungsaspekte der Dialektologie im Südwesten des deutschen Sprachgebiets geboten. Im dicht gedrängten Programm mit einer öffentlichen Präsentation des VALTS und des Tonarchivs der Mundarten Vorarlbergs von EUGEN GABRIEL und ARNO RUOF folgen sich an drei Tagen insgesamt 18 Vorträge, 10 Kurzvorträge, 14 Arbeitsberichte und ein dialektologischer Ausflug in den Bregenzer Wald. Im Folgenden werden die Vorträge in der präsentierten Reihenfolge referiert, während die zahlreichen Arbeitsberichte von Sprachatlanten, Wörter- und Namenbüchern sowie Tondokumentationsstellen nur pauschal erwähnt werden, welche einerseits einen Blick in die laufenden großen und größeren Projekte der alemannischen Dialektologie öffnen und andererseits die Finanzknappheit als übergreifendes Element der Dialektologie offenbaren.
Der folgende Text betrachtet die Varietätenverwendung von Schweizer ChatterInnen und rückt dabei altersspezifische Fragen in den Vordergrund. Im Gegensatz zu vielen Versuchen, an die Sprache Jugendlicher heranzugehen, kommt hier ein quantitativer Ansatz zur Anwendung, der die Sprache der jugendlichen ChatterInnen mit der Sprache von ChatterInnen anderer Generationen vergleicht.
In the past, a divide could be seen between ’deep’ parsers on the one hand, which construct a semantic representation out of their input, but usually have significant coverage problems, and more robust parsers on the other hand, which are usually based on a (statistical) model derived from a treebank and have larger coverage, but leave the problem of semantic interpretation to the user. More recently, approaches have emerged that combine the robustness of datadriven (statistical) models with more detailed linguistic interpretation such that the output could be used for deeper semantic analysis. Cahill et al. (2002) use a PCFG-based parsing model in combination with a set of principles and heuristics to derive functional (f-)structures of Lexical-Functional Grammar (LFG). They show that the derived functional structures have a better quality than those generated by a parser based on a state-of-the-art hand-crafted LFG grammar. Advocates of Dependency Grammar usually point out that dependencies already are a semantically meaningful representation (cf. Menzel, 2003). However, parsers based on dependency grammar normally create underspecified representations with respect to certain phenomena such as coordination, apposition and control structures. In these areas they are too "shallow" to be directly used for semantic interpretation. In this paper, we adopt a similar approach to Cahill et al. (2002) using a dependency-based analysis to derive functional structure, and demonstrate the feasibility of this approach using German data. A major focus of our discussion is on the treatment of coordination and other potentially underspecified structures of the dependency data input. F-structure is one of the two core levels of syntactic representation in LFG (Bresnan, 2001). Independently of surface order, it encodes abstract syntactic functions that constitute predicate argument structure and other dependency relations such as subject, predicate, adjunct, but also further semantic information such as the semantic type of an adjunct (e.g. directional). Normally f-structure is captured as a recursive attribute value matrix, which is isomorphic to a directed graph representation. Figure 5 depicts an example target f-structure. As mentioned earlier, these deeper-level dependency relations can be used to construct logical forms as in the approaches of van Genabith and Crouch (1996), who construct underspecified discourse representations (UDRSs), and Spreyer and Frank (2005), who have robust minimal recursion semantics (RMRS) as their target representation. We therefore think that f-structures are a suitable target representation for automatic syntactic analysis in a larger pipeline of mapping text to interpretation. In this paper, we report on the conversion from dependency structures to fstructure. Firstly, we evaluate the f-structure conversion in isolation, starting from hand-corrected dependencies based on the TüBa-D/Z treebank and Versley (2005)´s conversion. Secondly, we start from tokenized text to evaluate the combined process of automatic parsing (using Foth and Menzel (2006)´s parser) and f-structure conversion. As a test set, we randomly selected 100 sentences from TüBa-D/Z which we annotated using a scheme very close to that of the TiGer Dependency Bank (Forst et al., 2004). In the next section, we sketch dependency analysis, the underlying theory of our input representations, and introduce four different representations of coordination. We also describe Weighted Constraint Dependency Grammar (WCDG), the dependency parsing formalism that we use in our experiments. Section 3 characterises the conversion of dependencies to f-structures. Our evaluation is presented in section 4, and finally, section 5 summarises our results and gives an overview of problems remaining to be solved.
Using a qualitative analysis of disagreements from a referentially annotated newspaper corpus, we show that, in coreference annotation, vague referents are prone to greater disagreement. We show how potentially problematic cases can be dealt with in a way that is practical even for larger-scale annotation, considering a real-world example from newspaper text.
In this paper, we investigate the usefulness of a wide range of features for their usefulness in the resolution of nominal coreference, both as hard constraints (i.e. completely removing elements from the list of possible candidates) as well as soft constraints (where a cumulation of violations of soft constraints will make it less likely that a candidate is chosen as the antecedent). We present a state of the art system based on such constraints and weights estimated with a maximum entropy model, using lexical information to resolve cases of coreferent bridging.
In recent years, research in parsing has extended in several new directions. One of these directions is concerned with parsing languages other than English. Treebanks have become available for many European languages, but also for Arabic, Chinese, or Japanese. However, it was shown that parsing results on these treebanks depend on the types of treebank annotations used. Another direction in parsing research is the development of dependency parsers. Dependency parsing profits from the non-hierarchical nature of dependency relations, thus lexical information can be included in the parsing process in a much more natural way. Especially machine learning based approaches are very successful (cf. e.g.). The results achieved by these dependency parsers are very competitive although comparisons are difficult because of the differences in annotation. For English, the Penn Treebank has been converted to dependencies. For this version, Nivre et al. report an accuracy rate of 86.3%, as compared to an F-score of 92.1 for Charniaks parser. The Penn Chinese Treebank is also available in a constituent and a dependency representations. The best results reported for parsing experiments with this treebank give an F-score of 81.8 for the constituent version and 79.8% accuracy for the dependency version. The general trend in comparisons between constituent and dependency parsers is that the dependency parser performs slightly worse than the constituent parser. The only exception occurs for German, where F-scores for constituent plus grammatical function parses range between 51.4 and 75.3, depending on the treebank, NEGRA or TüBa-D/Z. The dependency parser based on a converted version of Tüba-D/Z, in contrast, reached an accuracy of 83.4%, i.e. 12 percent points better than the best constituent analysis including grammatical functions.
This paper presents an approach to the question whether it is possible to construct a parser based on ideas from case-based reasoning. Such a parser would employ a partial analysis of the input sentence to select a (nearly) complete syntax tree and then adapt this tree to the input sentence. The experiments performed on German data from the Tüba-D/Z treebank and the KaRoPars partial parser show that a wide range of levels of generality can be reached, depending on which types of information are used to determine the similarity between input sentence and training sentences. The results are such that it is possible to construct a case-based parser. The optimal setting out of those presented here need to be determined empirically.
This paper presents a comparative study of probabilistic treebank parsing of German, using the Negra and TüBa-D/Z treebanks. Experiments with the Stanford parser, which uses a factored PCFG and dependency model, show that, contrary to previous claims for other parsers, lexicalization of PCFG models boosts parsing performance for both treebanks. The experiments also show that there is a big difference in parsing performance, when trained on the Negra and on the TüBa-D/Z treebanks. Parser performance for the models trained on TüBa-D/Z are comparable to parsing results for English with the Stanford parser, when trained on the Penn treebank. This comparison at least suggests that German is not harder to parse than its West-Germanic neighbor language English.
Relative quantifier scope in German depends, in contrast to English, very much on word order. The scope possibilities of a quantifier are determined by its surface position, its base position and the type of the quantifier. In this paper we propose a multicomponent analysis for German quantifiers computing the scope of the quantifier, in particular its minimal nuclear scope, depending on the syntactic configuration it occurs in.
Our paper aims at capturing the distribution of negative polarity items (NPIs) within lexicalized Tree Adjoining Grammar (LTAG). The condition under which an NPI can occur in a sentence is for it to be in the scope of a negation with no quantifiers scopally intervening. We model this restriction within a recent framework for LTAG semantics based on semantic unification. The proposed analysis provides features that signal the presence of a negation in the semantics and that specify its scope. We extend our analysis to modelling the interaction of NPI licensing and neg raising constructions.
This paper compares two approaches to computational semantics, namely semantic unification in Lexicalized Tree Adjoining Grammars (LTAG) and Lexical Resource Semantics (LRS) in HPSG. There are striking similarities between the frameworks that make them comparable in many respects. We will exemplify the differences and similarities by looking at several phenomena. We will show, first of all, that many intuitions about the mechanisms of semantic computations can be implemented in similar ways in both frameworks. Secondly, we will identify some aspects in which the frameworks intrinsically differ due to more general differences between the approaches to formal grammar adopted by LTAG and HPSG.
The work presented here addresses the question of how to determine whether a grammar formalism is powerful enough to describe natural languages. The expressive power of a formalism can be characterized in terms of i) the string languages it generates (weak generative capacity (WGC)) or ii) the tree languages it generates (strong generative capacity (SGC)). The notion of WGC is not enough to determine whether a formalism is adequate for natural languages. We argue that even SGC is problematic since the sets of trees a grammar formalism for natural languages should be able to generate is difficult to determine. The concrete syntactic structures assumed for natural languages depend very much on theoretical stipulations and empirical evidence for syntactic structures is rather hard to obtain. Therefore, for lexicalized formalisms, we propose to consider the ability to generate certain strings together with specific predicate argument dependencies as a criterion for adequacy for natural languages.
In the recent literature there is growing interest in the morpho-syntactic encoding of hierarchical effects. The paper investigates one domain where such effects are attested: ergative splits conditioned by person. This type of splits is then compared to hierarchical effects in direct-inverse alternations. On the basis of two case studies (Lummi instantiating an ergative split person language and Passamaquoddy an inverse language) we offer an account that makes no use of hierarchies as a primitive. We propose that the two language types differ as far as the location of person features is concerned. In inverse systems person features are located exclusively in T, while in ergative systems, they are located in T and a particular type of v. A consequence of our analysis is that Case checking in split and inverse systems is guided by the presence/absence of specific phi-features. This in turn provides evidence for a close connection between Case and phi-features, reminiscent of Chomsky’s (2000, 2001) Agree.
The causative/anticausative alternation has been the topic of much typological and theoretical discussion in the linguistic literature. This alternation is characterized by verbs with transitive and intransitive uses, such that the transitive use of a verb V means roughly "cause to Vintransitive" (see Levin 1993). The discussion revolves around two issues: the first one concerns the similarities and differences between the anticausative and the passive, and the second one concerns the derivational relationship, if any, between the transitive and intransitive variant. With respect to the second issue, a number of approaches have been developed. Judging the approach conceptually unsatisfactory, according to which each variant is assigned an independent lexical entry, it was concluded that the two variants have to be derivationally related. The question then is which one of the two is basic and where this derivation takes place in the grammar. Our contribution to this discussion is to argue against derivational approaches to the causative / anticausative alternation. We focus on the distribution of PPs related to external arguments (agent, causer, instrument, causing event) in passives and anticausatives of English, German and Greek and the set of verbs undergoing the causative/anticausative alternation in these languages. We argue that the crosslinguistic differences in these two domains provide evidence against both causativization and detransitivization analyses of the causative / anticausative alternation. We offer an approach to this alternation which builds on a syntactic decomposition of change of state verbs into a Voice and a CAUS component. Crosslinguistic variation in passives and anticausatives depends on properties of Voice and its combinations with CAUS and various types of roots.
The globalized Western culture of innovation, as propagated by major aid institutions, does not necessarily lead to empowerment or improvement of the well-being of the stakeholders. On the contrary, it often blocks viable indigenous innovation cultures. In African societies and African Diasporas in Latin America, cultures of innovation largely accrue from the informal, not the formal sector. Crucial for their proper understanding is a threefold structural differentiation: between the formal and informal sector, within the informal sector, according to class, gender or religion, and between different transnational social spaces. Different innovation cultures may be complementary, mutually reinforcing, or conflicting, leading in extreme cases even to a ‘clash of cultures’ at the local level. The repercussions of competing, even antagonistic agencies of innovative strategic groups are demonstrated, analyzing the case of the African poor in Benin and the African Diasporas of Brazil and Haiti.
The article provides a critical discussion of the literature on “patrimonialism” and "neopatrimonialism” as far as the use in Development Studies in general or African Studies in particular is concerned. To overcome the catch-all use of the concept the authors present their own definition of “neopatrimonialism” based on Max Weber’s concept of patrimonialism and legal-rational bureaucracy. However, in order to make the concept more useful for comparative empirical research, they argue, it needs a thorough operationalisation (qualitatively and quantitatively) and the creation of possible subtypes which, in combination, might contribute to a theory of neopatrimonial action.
The properties of the outer crust of non-accreting cold neutron stars are studied by using modern nuclear data and theoretical mass tables updating in particular the classic work of Baym, Pethick and Sutherland. Experimental data from the atomic mass table from Audi, Wapstra, and Thibault of 2003 is used and a thorough comparison of many modern theoretical nuclear models, relativistic and non-relativistic ones, is performed for the first time. In addition, the influences of pairing and deformation are investigated. State-of-the-art theoretical nuclear mass tables are compared in order to check their differences concerning the neutron dripline, magic neutron numbers, the equation of state, and the sequence of neutron-rich nuclei up to the dripline in the outer crust of non-accreting cold neutron stars.
We study the effect of neutrino trapping on the phase diagram of dense, locally neutral three-flavor quark matter within the framework of a Nambu--Jona-Lasinio model. In the analysis, dynamically generated quark masses are taken into account self-consistently. The phase diagrams in the plane of temperature and quark chemical potential, as well as in the plane of temperature and lepton-number chemical potential are presented. We show that neutrino trapping favors two-flavor color superconductivity and disfavors the color-flavor-locked phase at intermediate densities of matter. At the same time, the location of the critical line separating the two-flavor color-superconducting phase and the normal phase of quark matter is little affected by the presence of neutrinos. The implications of these results for the evolution of protoneutron stars are briefly discussed. PACS numbers: 12.39.-x 12.38.Aw 26.60.+c
We discuss the phase diagram of moderately dense, locally neutral three-flavor quark matter using the framework of an effective model of quantum chromodynamics with a local interaction. The phase diagrams in the plane of temperature and quark chemical potential as well as in the plane of temperature and lepton-number chemical potential are discussed.
Event-by-event fluctuations of the net baryon number and electric charge in nucleus-nucleus collisions are studied in Pb+Pb at SPS energies within the HSD transport model. We reveal an important role of the fluctuations in the number of target nucleon participants. They strongly influence all measured fluctuations even in the samples of events with rather rigid centrality trigger. This fact can be used to check different scenarios of nucleus-nucleus collisions by measuring the multiplicity fluctuations as a function of collision centrality in fixed kinematical regions of the projectile and target hemispheres. The HSD results for the event-by-event fluctuations of electric charge in central Pb+Pb collisions at 20, 30, 40, 80 and 158 A GeV are in a good agreement with the NA49 experimental data and considerably larger than expected in a quark-gluon plasma. This demonstrate that the distortions of the initial fluctuations by the hadronization phase and, in particular, by the final resonance decays dominate the observable fluctuations.
Based on the UrQMD transport model, the transverse momentum and the rapidity dependence of the Hanbury-Brown-Twiss (HBT) radii R_L, R_O, R_S as well as the cross term R_OL at SPS energies are investigated and compared with the experimental NA49 and CERES data. The rapidity dependence of the R_L, R_O, R_S is weak while the R_OL is significantly increased at large rapidities and small transverse momenta. The HBT "life-time" issue (the phenomenon that the calculated sqrt R_O^2-R_S^2 value is larger than the correspondingly extracted experimental data) is also present at SPS energies.
We obtain the D-meson spectral density at finite temperature for the conditions of density and temperature expected at FAIR. We perform a self-consistent coupled-channel calculation taking, as a bare interaction, a separable potential model. The Lambda_c (2593) resonance is generated dynamically. We observe that the D-meson spectral density develops a sizeable width while the quasiparticle peak stays close to the free position. The consequences for the D-meson production at FAIR are discussed.
We examine experimental signatures of TeV-mass black hole formation in heavy ion collisions at the LHC. We find that the black hole production results in a complete disappearance of all very high p_T (> 500 GeV) back-to-back correlated di-jets of total mass M > M_f ~ 1 TeV. We show that the subsequent Hawking-decay produces multiple hard mono-jets and discuss their detection. We study the possibility of cold black hole remnant (BHR) formation of mass ~ M_f and the experimental distinguishability of scenarios with BHRs and those with complete black hole decay. Finally we point out that a Heckler-Kapusta-Hawking plasma may form from the emitted mono-jets. In this context we present new simulation data of Mach shocks and of the evolution of initial conditions until the freeze-out.
We propose to measure azimuthal correlations of heavy-flavor hadrons to address the status of thermalization at the partonic stage of light quarks and gluons in high-energy nuclear collisions. In particular, we show that hadronic interactions at the late stage cannot significantly disturb the initial back-to-back azimuthal correlations of DDbar pairs. Thus, a decrease or the complete absence of these initial correlations does indicate frequent interactions of heavy-flavor quarks and also light partons in the partonic stage, which are essential for the early thermalization of light partons.
The experimental signatures of TeV-mass black hole (BH) formation in heavy ion collisions at the LHC is examined. We find that the black hole production results in a complete disappearance of all very high p_T (> 500 GeV) back-to-back correlated di-jets of total mass M > M_f ~ 1 TeV. We show that the subsequent Hawking-decay produces multiple hard mono-jets and discuss their detection. We study the possibility of cold black hole remnant (BHR) formation of mass ~ M_f and the experimental distinguishability of scenarios with BHRs and those with complete black hole decay. Due to the rather moderate luminosity in the first year of LHC running the least chance for the observation of BHs or BHRs at this early stage will be by ionizing tracks in the ALICE TPC. Finally we point out that stable BHRs would be interesting candidates for energy production by conversion of mass to Hawking radiation.
The concept of Large Extra Dimensions (LED) provides a way of solving the Hierarchy Problem which concerns the weakness of gravity compared with the strong and electro-weak forces. A consequence of LED is that miniature Black Holes (mini-BHs) may be produced at the Large Hadron Collider in p+p collisions. The present work uses the CHARYBDIS mini-BH generator code to simulate the hadronic signal which might be expected in a mid-rapidity particle tracking detector from the decay of these exotic objects if indeed they are produced. An estimate is also given for Pb+Pb collisions.
We develop a 1+1 dimensional hydrodynamical model for central heavy-ion collisions at ultrarelativistic energies. Deviations from Bjorken's scaling are taken into account by implementing finite-size profiles for the initial energy density. The calculated rapidity distributions of pions, kaons and antiprotons in central Au+Au collisions at the c.m. energy 200 AGeV are compared with experimental data of the BRAHMS Collaboration. The sensitivity of the results to the choice of the equation of state, the parameters of initial state and the freeze-out conditions is investigated. The best fit of experimental data is obtained for a soft equation of state and Gaussian-like initial profiles of the energy density.
We propose to use the hadron number fluctuations in the limited momentum regions to study the evolution of initial flows in high energy nuclear collisions. In this method by a proper preparation of a collision sample the projectile and target initial flows are marked in fluctuations in the number of colliding nucleons. We discuss three limiting cases of the evolution of flows, transparency, mixing and reflection, and present for them quantitative predictions obtained within several models. Finally, we apply the method to the NA49 results on fluctuations of the negatively charged hadron multiplicity in Pb+Pb interactions at 158A GeV and conclude that the data favor a hydrodynamical model with a significant degree of mixing of the initial flows at the early stage of collisions.
We study forward-backward charge fluctuations to probe the correlations among produced particles in ultra relativistic heavy ion collisions. We develop a model that describes the forward-backward dynamical fluctuations and apply it to interpret the recent PHOBOS data. Within the present model, the dynamical fluctuations are related to the particle production mechanism via cluster decay and to long range correlations between the forward and backward rapidity hemispheres. We argue that with a tight centrality cut, PHOBOS may see a strong decrease of the dynamical fluctuations. Within the present model, this deterioration of the correlation among the produced hadrons can be interpreted as a sign for the production of a hot, dense and interacting medium.
We have calculated the D-meson spectral density at finite temperature within a self-consistent coupled-channel approach that generates dynamically the Lambda_c (2593) resonance. We find a small mass shift for the D-meson in this hot and dense medium while the spectral density develops a sizeable width. The reduced attraction felt by the D-meson in hot and dense matter together with the large width observed have important consequences for the D-meson production in the future CBM experiment at FAIR.
The production of Large Extra Dimension (LXD) Black Holes (BHs), with a new, fundamental mass scale of M_f = 1 TeV, has been predicted to occur at the Large Hadron Collider, LHC, with the formidable rate of 10^8 per year in p-p collisions at full energy, 14 TeV, and at full luminosity. We show that such LXD-BH formation will be experimentally observable at the LHC by the complete disappearance of all very high p_t (> 500 GeV) back-to-back correlated Di-Jets of total mass M > M_f = 1 TeV. We suggest to complement this clear cut-off signal at M > 2*500 GeV in the di-jet-correlation function by detecting the subsequent, Hawking-decay products of the LXD-BHs, namely either multiple high energy (> 100 GeV) SM Mono-Jets (i.e. away-side jet missing), sprayed off the evaporating BHs isentropically into all directions or the thermalization of the multiple overlapping Hawking-radiation in a eckler-Kapusta-Plasma. Microcanonical quantum statistical calculations of the Hawking evaporation process for these LXD-BHs show that cold black hole remnants (BHRs) of Mass sim M_f remain leftover as the ashes of these spectacular Di-Jet-suppressed events. Strong Di-Jet suppression is also expected with Heavy Ion beams at the LHC, due to Quark-Gluon-Plasma induced jet attenuation at medium to low jet energies, p_t < 200 GeV. The (Mono-)Jets in these events can be used to trigger for Tsunami-emission of secondary compressed QCD-matter at well defined Mach-angles, both at the trigger side and at the awayside (missing) jet. The Machshock-angles allow for a direct measurement of both the equation of state EoS and the speed of sound c_s via supersonic bang in the "big bang" matter. We discuss the importance of the underlying strong collective flow - the gluon storm - of the QCD- matter for the formation and evolution of these Machshock cones. We predict a significant deformation of Mach shocks from the gluon storm in central Au+Au collisions at RHIC and LHC energies, as compared to the case of weakly coupled jets propagating through a static medium. A possible complete stopping of pt > 50 GeV jets at the LHC in 2-3 fm yields nonlinear high density Mach shocks in he quark gluon plasma, which can be studied in the complex emission and disintegration pattern of the possibly supercooled matter. We report on first full 3-dimensional fluid dynamical studies of the strong effects of a first order phase transition on the evolution and the Tsunami-like Mach shock emission of the QCD matter.
The rapidity dependence of the single- and double- neutron to proton ratios of nucleon emission from isospin-asymmetric but mass-symmetric reactions Zr+Ru and Ru+Zr at energy range 100 ~ 800 A MeV and impact parameter range 0 ~ 8 fm is investigated. The reaction system with isospin-asymmetry and mass-symmetry has the advantage of simultaneously showing up the dependence on the symmetry energy and the degree of the isospin equilibrium. We find that the beam energy- and the impact parameter dependence of the slope parameter of the double neutron to proton ratio (F_D) as function of rapidity are quite sensitive to the density dependence of symmetry energy, especially at energies E_b ~ 400 A MeV and reduced impact parameters around 0.5. Here the symmetry energy effect on the F_D is enhanced, as compared to the single neutron to proton ratio. The degree of the equilibrium with respect to isospin (isospin mixing) in terms of the F_D is addressed and its dependence on the symmetry energy is also discussed.
We demonstrate the occurrence of canonical suppression associated with the conservation of an U(1)-charge in current transport models. For this study a pion gas is simulated within two different transport approaches by incorporating inelastic and volume-limited collisions pi pi leftrightarrow K bar-K for the production of kaon pairs. Both descriptions can dynamically account for the suppression in the yields of rare strange particles in a limited box, being in full accordance with a canonical statistical description.
The transverse momentum dependence of the anisotropic flow v_2 for pi, K, nucleon, Lambda, Xi and Omega is studied for Au+Au collisions at sqrt s_NN = 200 GeV within two independent string-hadron transport approaches (RQMD and UrQMD). Although both models reach only 60% of the absolute magnitude of the measured v_2, they both predict the particle type dependence of v_2, as observed by the RHIC experiments: v_2 exhibits a hadron-mass hierarchy (HMH) in the low p_T region and a number-of-constituent-quark (NCQ) dependence in the intermediate p_T region. The failure of the hadronic models to reproduce the absolute magnitude of the observed v_2 indicates that transport calculations of heavy ion collisions at RHIC must incorporate interactions among quarks and gluons in the early, hot and dense phase. The presence of an NCQ scaling in the string-hadron model results suggests that the particle-type dependencies observed in heavy-ion collisions at intermediate p_T are related to the hadronic cross sections in vacuum rather than to the hadronization process itself, as suggested by quark recombination models.
Several observables of unbound nucleons which are to some extent sensitive to the medium modifications of nucleon-nucleon elastic cross sections in neutron-rich intermediate energy heavy ion collisions are investigated. The splitting effect of neutron and proton effective masses on cross sections is discussed. It is found that the transverse flow as a function of rapidity, the Q_zz as a function of momentum, and the ratio of halfwidths of the transverse to that of longitudinal rapidity distribution R_t/l are very sensitive to the medium modifications of the cross sections. The transverse momentum distribution of correlation functions of two-nucleons does not yield information on the in-medium cross section.
Elliptic flow analysis at RHIC with the Lee-Yang Zeroes method in a relativistic transport approach
(2006)
The Lee-Yang zeroes method is applied to study elliptic flow (v_2) in Au+Au collisions at sqrt s =200 A GeV, with the UrQMD model. In this transport approach, the true event plane is known and both the nonflow effects and event-by-event v_2 fluctuations exist. Although the low resolutions prohibit the application of the method for most central and peripheral collisions, the integral and differential elliptic flow from the Lee-Yang zeroes method agrees with the exact v_2 values very well for semi-central collisions.
We propose to measure correlations of heavy-flavor hadrons to address the status of thermalization at the partonic stage of light quarks and gluons in high-energy nuclear collisions, shown on the example of azimuthal correlations of D-Dbar pairs. We show that hadronic interactions at the late stage can not disturb these correlations significantly. Thus, a decrease or the complete absence of these initial correlations indicates frequent interactions of heavy-flavor quarks in the partonic stage. Therefore, early thermalization of light quarks is likely to be reached. PACS numbers: 25.75.-q
The pion source as seen through HBT correlations at RHIC energies is investigated within the UrQMD approach. We find that the calculated transverse momentum, centrality, and system size dependence of the Pratt-HBT radii R_L and R_S are reasonably well in line with experimental data. The predicted R_O values in central heavy ion collisions are larger as compared to experimental data. The corresponding quantity sqrt R_O^2-R_S^2 of the pion emission source is somewhat larger than experimental estimates.
Gravitational radiation from ultra high energy cosmic rays in models with large extra dimensions
(2006)
The effects of classical gravitational radiation in models with large extra dimensions are investigated for ultra high energy cosmic rays (CRs). The cross sections are implemented into a simulation package (SENECA) for high energy hadron induced CR air showers. We predict that gravitational radiation from quasi-elastic scattering could be observed at incident CR energies above 10^9 GeV for a setting with more than two extra dimensions. It is further shown that this gravitational energy loss can alter the energy reconstruction for CR energies E_CR > 5 10^9 GeV.
No black holes at IceCube
(2006)