1,532 research outputs found
Forward-Backward Multiplicity Correlations in sqrt(s_NN) = 200 GeV Gold-Gold Collisions
Forward-backward correlations of charged-particle multiplicities in symmetric
bins in pseudorapidity are studied in order to gain insight into the underlying
correlation structure of particle production in Au+Au collisions. The PHOBOS
detector is used to measure integrated multiplicities in bins centered at eta,
defined within |eta|<3, and covering intervals Delta-eta. The variance
sigma^2_C of a suitably defined forward-backward asymmetry variable C is
calculated as a function of eta, Delta-eta, and centrality. It is found to be
sensitive to short range correlations, and the concept of "clustering'' is used
to interpret comparisons to phenomenological models.Comment: 5 Pages, 5 Figures, submitted to Physical Review C -- Rapid
Communication
Energy dependence of elliptic flow over a large pseudorapidity range in Au+Au collisions at RHIC
This paper describes the measurement of the energy dependence of elliptic
flow for charged particles in Au+Au collisions using the PHOBOS detector at the
Relativistic Heavy Ion Collider (RHIC). Data taken at collision energies of
19.6, 62.4, 130 and 200 GeV are shown over a wide range in
pseudorapidity. These results, when plotted as a function of
, scale with approximate linearity throughout ,
implying no sharp changes in the dynamics of particle production as a function
of pseudorapidity or increasing beam energy.Comment: 5 pages, 4 figure
Transverse Momentum and Rapidity Dependence of HBT Correlations in Au+Au Collisions at sqrt(s_NN) = 62.4 and 200 GeV
Two-particle correlations of identical charged pion pairs from Au+Au
collisions at sqrt(s_NN) = 62.4 and 200 GeV were measured by the PHOBOS
experiment at RHIC. Data for the 15% most central events were analyzed with
Bertsch-Pratt and Yano-Koonin-Podgoretskii parameterizations using pairs with
rapidities of 0.4 < y_{\pi\pi} < 1.3 and transverse momenta 0.1 < k_T < 1.4
GeV/c. The Bertsch-Pratt radii R_o and R_l decrease as a function of pair
transverse momentum, while R_s is consistent with a weaker dependence. R_o and
R_s are independent of collision energy, while R_l shows a slight increase. The
source rapidity y_{ykp} scales roughly with the pair rapidity y_{\pi\pi},
indicating strong dynamical correlations.Comment: 5 pages, 4 figures, 2 tables, submitted to Phys. Rev.
Phobos results on charged particle multiplicity and pseudorapidity distributions in Au+Au, Cu+Cu, d+Au, and p+p collisions at ultra-relativistic energies
Pseudorapidity distributions of charged particles emitted in ,
, , and collisions over a wide energy range have been
measured using the PHOBOS detector at RHIC. The centrality dependence of both
the charged particle distributions and the multiplicity at midrapidity were
measured. Pseudorapidity distributions of charged particles emitted with
, which account for between 95% and 99% of the total
charged-particle emission associated with collision participants, are presented
for different collision centralities. Both the midrapidity density,
, and the total charged-particle multiplicity, , are
found to factorize into a product of independent functions of collision energy,
, and centrality given in terms of the number of nucleons
participating in the collision, . The total charged particle
multiplicity, observed in these experiments and those at lower energies,
assumes a linear dependence of over the full range of
collision energy of =2.7-200 GeV.Comment: 25 pages, 29 figures, 8 table
The Landscape of Particle Production: Results from PHOBOS
Recent results from the PHOBOS experiment at RHIC are presented, both from
Au+Au collisions from the 2001 run and p+p and d+Au collisions from 2003. The
centrality dependence of the total charged particle multiplicity in p+p and
d+Au show features, such as Npart-scaling and limiting fragmentation, similar
to p+A collisions at lower energies. Multiparticle physics in Au+Au is found to
be local in (pseudo)rapidity, both when observed by HBT correlations and by
forward-backward pseudorapidity correlations. The shape of elliptic flow in
Au+Au, measured over the full range of pseudorapidity, appears to have a very
weak centrality dependence. Identified particle ratios in d+Au reactions show
little difference between the shape of proton and anti-proton spectra, while
the absolute yields show an approximate m_T scaling.Comment: 8 Pages, 11 Figures, Plenary talk at Quark Matter 2004, Oakland, CA,
January 11-18, 200
Measurement properties of tools used to assess depression in adults with and without Autism Spectrum Conditions: a systematic review
Depression is the most commonly experienced mental health condition in adults with Autism Spectrum Conditions (ASC). However, it is unclear what tools are currently being used to assess depression in ASC, or whether tools need to be adapted for this group. This systematic review therefore aimed to identify tools used to assess depression in adults with and without ASC, and then evaluate these tools for their appropriateness and measurement properties. Medline, PsychINFO and Web of Knowledge were searched for studies of depression in: a) adults with ASC, without co-morbid intellectual disability; and b) adults from the general population without co-morbid conditions. Articles examining the measurement properties of these tools were then searched for using a methodological filter in PubMed, and the quality of the evidence was evaluated using the COSMIN checklist. Twelve articles were identified which utilised three tools to assess depression in adults with ASC, but only one article which assessed the measurement properties of one of these tools was identified and thus evaluated. Sixty-five articles were identified which utilised five tools to assess depression in general population adults, and 14 articles had assessed the measurement properties of these tools. Overall, two tools were found to be robust in their measurement properties in the general population – the Beck Depression Inventory (BDI-II), and the Patient Health Questionnaire (PHQ-9). Crucially only one study was identified from the COSMIN search, which showed weak evidence in support of the measurement properties of the BDI-II in an ASC sample. Implications for effective measurement of depression in ASC are discussed
The twilight of the Liberal Social Contract? On the Reception of Rawlsian Political Liberalism
This chapter discusses the Rawlsian project of public reason, or public justification-based 'political' liberalism, and its reception. After a brief philosophical rather than philological reconstruction of the project, the chapter revolves around a distinction between idealist and realist responses to it. Focusing on political liberalism’s critical reception illuminates an overarching question: was Rawls’s revival of a contractualist approach to liberal legitimacy a fruitful move for liberalism and/or the social contract tradition? The last section contains a largely negative answer to that question. Nonetheless the chapter's conclusion shows that the research programme of political liberalism provided and continues to provide illuminating insights into the limitations of liberal contractualism, especially under conditions of persistent and radical diversity. The programme is, however, less receptive to challenges to do with the relative decline of the power of modern states
Measurement of the B0-anti-B0-Oscillation Frequency with Inclusive Dilepton Events
The - oscillation frequency has been measured with a sample of
23 million \B\bar B pairs collected with the BABAR detector at the PEP-II
asymmetric B Factory at SLAC. In this sample, we select events in which both B
mesons decay semileptonically and use the charge of the leptons to identify the
flavor of each B meson. A simultaneous fit to the decay time difference
distributions for opposite- and same-sign dilepton events gives ps.Comment: 7 pages, 1 figure, submitted to Physical Review Letter
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