1,037 research outputs found

    Event-by-event study of DCC-like fluctuation in ultra-relativistic nuclear collisions

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    A method based on sliding window scheme is developed to search for patches in the pseudorapidity-azimuth plane, on an event-by-event basis, having unusual fluctuation in the neutral pion fraction which may arise due to the formation of Disoriented Chrial Condensates (DCC) in high energy nuclear collisions. The efficiency of the method to extract the patches and the purity of the extracted sample are studied for possible experimental situations.Comment: 10 pages, 5 figure

    Surface Polymer Network Model and Effective Membrane Curvature Elasticity

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    A microscopic model of a surface polymer network - membrane system is introduced, with contact polymer surface interactions that can be either repulsive or attractive and sliplinks of functionality four randomly distributed over the supporting membrane surface anchoring the polymers to it. For the supporting surface perturbed from a planar configuration and a small relative number of surface sliplinks, we investigate an expansion of the free energy in terms of the local curvatures of the surface and the surface density of sliplinks, obtained through the application of the Balian - Bloch - Duplantier multiple surface scattering method. As a result, the dependence of the curvature elastic modulus, the Gaussian modulus as well as of the spontaneous curvature of the "dressed" membrane, ~{\sl i.e.} polymer network plus membrane matrix, is obtained on the mean polymer bulk end to end separation and the surface density of sliplinks.Comment: 15 pages with one included compressed uuencoded figure

    Slepton Oscillation at Large Hadron Collider

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    Measurement of Lepton-Flavor Violation (LFV) in the minimal SUSY Standard Model (MSSM) at Large Hadron Collider (LHC) is studied based on a realistic simulation. We consider the LFV decay of the second-lightest neutralino, χ~20l~lllχ~10\tilde{\chi}^0_2 \to \tilde{l} l' \to l l' \tilde{\chi}^0_1, in the case where the flavor mixing exists in the right-handed sleptons. We scan the parameter space of the minimal supergravity model (MSUGRA) and a more generic model in which we take the Higgsino mass μ\mu as a free parameter. We find that the possibility of observing LFV at LHC is higher if μ\mu is smaller than the MSUGRA prediction; the LFV search at LHC can cover the parameter range where the μeγ\mu \to e \gamma decay can be suppressed by the cancellation among the diagrams for this case.Comment: 29 pages, 10 figure

    Emotional valence and arousal affect reading in an interactive way: neuroimaging evidence for an approach-withdrawal framework

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    A growing body of literature shows that the emotional content of verbal material affects reading, wherein emotional words are given processing priority compared to neutral words. Human emotions can be conceptualised within a two-dimensional model comprised of emotional valence and arousal (intensity). These variables are at least in part distinct, but recent studies report interactive effects during implicit emotion processing and relate these to stimulus-evoked approach-withdrawal tendencies. The aim of the present study was to explore how valence and arousal interact at the neural level, during implicit emotion word processing. The emotional attributes of written word stimuli were orthogonally manipulated based on behavioural ratings from a corpus of emotion words. Stimuli were presented during an fMRI experiment while 16 participants performed a lexical decision task, which did not require explicit evaluation of a word's emotional content. Results showed greater neural activation within right insular cortex in response to stimuli evoking conflicting approach-withdrawal tendencies (i.e., positive high-arousal and negative low-arousal words) compared to stimuli evoking congruent approach vs. withdrawal tendencies (i.e., positive low-arousal and negative high-arousal words). Further, a significant cluster of activation in the left extra-striate cortex was found in response to emotional than neutral words, suggesting enhanced perceptual processing of emotionally salient stimuli. These findings support an interactive two-dimensional approach to the study of emotion word recognition and suggest that the integration of valence and arousal dimensions recruits a brain region associated with interoception, emotional awareness and sympathetic functions

    The Chiral Phase Transition in Dissipative Dynamics

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    Numerical simulations of the chiral phase transition in the (3+1)dimensional O(4)-model are presented. The evolutions of the chiral field follow purely dissipative dynamics, starting from random chirally symmetric initial configurations down to the true vacuum with spontaneously broken symmetry. The model stabilizes topological textures which are formed together with domains of disoriented chiral condensate (DCC) during the roll-down phase. The classically evolving field acts as source for the emission of pions and σ\sigma mesons. The exponents of power laws for the growth of angular correlations and for emission rates are extracted. Fluctuations in the abundance ratios for neutral and charged pions are compared with those for uncorrelated sources as potential signature for the chiral phase transition after heavy-ion collisions. It is found that the presence of stabilizing textures (baryons and antibaryons) prevents sufficiently rapid growth of DCC-domain size, so observability of anomalous tails in the abundance ratios is unlikely. However, the transient formation of growing DCC domains causes sizable broadening of the distributions as compared to the statistical widths of generic sources.Comment: 28 pages, 8 figure

    Event-by-Event Fluctuations in Particle Multiplicities and Transverse Energy Produced in 158.A GeV Pb+Pb collisions

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    Event-by-event fluctuations in the multiplicities of charged particles and photons, and the total transverse energy in 158A\cdot A GeV Pb+Pb collisions are studied for a wide range of centralities. For narrow centrality bins the multiplicity and transverse energy distributions are found to be near perfect Gaussians. The effect of detector acceptance on the multiplicity fluctuations has been studied and demonstrated to follow statistical considerations. The centrality dependence of the charged particle multiplicity fluctuations in the measured data has been found to agree reasonably well with those obtained from a participant model. However for photons the multiplicity fluctuations has been found to be lower compared to those obtained from a participant model. The multiplicity and transverse energy fluctuations have also been compared to those obtained from the VENUS event generator.Comment: To appear in Physical Review C; changes : more detailed discussion on errors and few figures modifie

    Search and study of Quark Gluon Plasma at the CERN-LHC

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    The major aim of nucleus-nucleus collisions at the LHC is to study the physics of strongly interacting matter and the quark gluon plasma (QGP), formed in extreme conditions of temperature and energy density. We give a brief overview of the experimental program and discuss the signatures and observables for a detailed study of QGP matter.Comment: 15 pages, Invited article for the volume on LHC physics to celebrate the Platinum Jubilee of the Indian National Science Academy, Edited by Amitava Datta, Biswarup Mukhopadhyaya and Amitava Raychaudhuri (Jan 2009

    Pneumocysterol [ (24Z) - ethylidenelanost - 8 - en -3 rare sterol detected in opportunistic pathogen Pneumocyctis carinii hominis : Structural identity and chemical synthesis

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    Edna S. Kaneshiro, Zunika Amit, Mardie M. Swonger, George P. Kreishman, Elwood E. Brooks, Mara Kreishman, Koka Jayasimhulu, Hang Sun, Stephen A. Kizito, David H. Beach, Edward J. Parish
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