Phase space constraints and statistical jet studies in heavy-ion collisions

The effect of the correlation induced by global momentum conservation on the two-particle distribution in nucleus-nucleus collisions is discussed, with a focus on the generic case of collisions with a non-vanishing impact parameter.Comment: 5 pages, invited talk at the RHIC & AGS Annual Users' Meeting, Brookhaven Nat. Lab. (USA) and at the EPS HEP 2007 Conference, Manchester (UK

Interdisciplinary Ontology Conference 2008 : Why I Am Not A Tropist

A major division among ontologists has always been the one between those who believe that all entities are particular, and those who believe that at least some entities are universal. I find myself with the latter, and in this paper I offer part of the reasons why this is so. More precisely, I offer a reason why we ought to reject tropism, due to the failure of this view to account for the similarities we experience among entities. In the paper, two tentative accounts are considered and rejected: one postulating the existence of a relation of primitive resemblance; the other denying the existence of any similarity

What Is a Recipe?

The ontology of recipes is by and large unexplored. In this paper, I offer a three-steps account. After introducing some key terminology, I distinguish four main options for a theory of recipes: realism, constructivism, existentialism, and the na < ve approach. Hence, I first argue that recipes are social entities whose identity depends (also) on a process of identification, typically performed by means of a performative utterance on the part of a cook (e.g. "This is fettuccine Alfredo," "This is falafel"); thus, the best theoretical framework for a theory of recipes is a constructivist. Secondly, I argue that the identity of recipes can be grasped only by being suitably acquainted with the dishes that instantiate them, because of the impossibility to spell out recipes in details that would match a full-fledged dish; hence, the authority to establish the identity of a recipe rests on a process of apprenticeship. Finally, I argue that the identity of recipes and-vicariously-of the dishes that instantiate them, rest on three factors: the expertise required on the part of the cook; authenticity (in turn based on the fit and approval rate of any purported rendering); and the open-ended character of recipes

Food and Foods : Toward a Definition

When I\u2019m hungry, I try to seek some food, namely an object that is edible and that can feed me and preferably it has to be tasty. It seems a very easy task to find it for there is an alleged natural boundary between what counts as food and what does not. I can naturally pinpoint that boundary. Nevertheless, at a closer inspection, such boundary turns out to be suspicious: a roasted human being is both edible and nutritious, and someone may even find it tasty, and yet it can be hardly considered as food. Likewise, a rotten food item is neither edible, nor nutritious and however it can be sometimes considered as food, such as marcescent cheese. Our aim in this paper is to nail down the different conceptions which regulate our conception of what is a food and then come up with a proper definition. We set forth four different stances: a biological one, i.e., food is what holds certain natural properties, an individual one, i.e., food is what can be eaten by at least one person, an authority one, i.e., food is what is considered so by an authority, and a social one. i.e., food is what is institutionally recognized as food

H2O and Cl in deep crustal melts: the message of melt inclusions in metamorphic rocks

The use of NanoSIMS on primary melt inclusions in partially melted rocks is a powerful approach to clarify the budget of volatiles at depth during crust formation and its reworking. Anatectic melt inclusions are indeed gateways to quantify H2O, halogens and other species (e.g. CO2, N) partitioned into the deep partial melts generated during metamorphism of the continental crust. Here we present new datasets of NanoSIMS measurements of H2O and Cl in preserved melt inclusions from metamorphic rocks with different protoliths – magmatic or sedimentary – which underwent partial melting at different pressure–temperature–fluid conditions. These new datasets are then compared with similar data on natural anatectic melts available in the literature to date. Our study provides novel, precise constraints for the H2O content in natural melts formed at high pressure, a field previously investigated mostly via experiments. We also show that H2O heterogeneities in partial melts at the microscale are common, regardless of the rock protolith. Correlations between H2O contents and P–T values can be identified merging new and old data on anatectic inclusions via NanoSIMS. Overall, the data acquired so far indicate that silicate melt generation in nature always requires H2O, even for the hottest melts found so far (&gt;1000 ∘C). Moreover, in agreement with previous work, preserved glassy inclusions always appear to be poorer in H2O than crystallized ones, regardless of their chemical system and/or P–T conditions of formation. Finally, this study reports the very first NanoSIMS data on Cl (often in amounts &gt;1000 ppm) acquired in situ on natural anatectic melts, showing how anatectic melt inclusions – additionally to magmatic ones – may become a powerful tool to clarify the role of halogens in many geological processes, not only in crustal evolution but also in ore deposit formation.</p

Anisotropic flow from Lee-Yang zeroes: a practical guide

We present a new method to analyze anisotropic flow from the genuine correlation among a large number of particles, focusing on the practical implementation of the method.Comment: 4 pages; contribution to Quark Matter 2004, Oakland, January 11-17, 200

Elliptic Flow Analysis at RHIC with the Lee-Yang Zeroes Method in a Relativistic Transport Approach

The Lee-Yang zeroes method is applied to study elliptic flow ($v_2$) in Au+Au collisions at $\sqrt{s}=200A$~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.Comment: 4 pages, 4 figure

Multiplicity distributions inside parton cascades developing in a medium

The explanation of the suppression of high-pT hadron yields at RHIC in terms of jet-quenching implies that the multiplicity distributions of particles inside a jet and jet-like particle correlations differ strongly in nucleus-nucleus collisions at RHIC or at the LHC from those observed at e+e- or hadron colliders. We present a framework for describing the medium-induced modification, which has a direct interpretation in terms of a probabilistic medium-modified parton cascade, and which treats leading and subleading partons on an equal footing. We show that our approach can account for the strong suppression of single inclusive hadron spectra measured in Au-Au collisions at RHIC, and that this implies a characteristic distortion of the single inclusive distribution of soft partons inside the jet. We determine, as a function of the jet energy, to what extent the soft fragments within a jet can be measured above some momentum cut.Comment: 5 pages, 4 eps-figures; talk given at Hot Quarks 2006, Villasimius (Sardinia, Italy), May 15-20, 200