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Search Results: 1 - 10 of 12262 matches for " Gavin George "
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Two Ridges, One Explanation
George Moschelli,Sean Gavin
Physics , 2009, DOI: 10.1016/j.nuclphysa.2009.10.058
Abstract: We attribute the phenomenon known as "the ridge" to long range initial state correlations from Color Glass Condensate flux tubes and later stage radial flow. We show that this description can explain the amplitude and azimuthal width of the soft ridge and nearly explain that of the hard ridge, suggesting that the two are essentially the same phenomenon.
Flow Fluctuations from Early-Time Correlations in Nuclear Collisions
Sean Gavin,George Moschelli
Physics , 2012, DOI: 10.1103/PhysRevC.86.034902
Abstract: We propose that flow fluctuations have the same origin as transverse momentum fluctuations. The common source of these fluctuations is the spatially inhomogeneous initial state that drives hydrodynamic flow. Longitudinal correlations from an early Glasma stage followed by hydrodynamic flow quantitatively account for many features of multiplicity and $p_t$ fluctuation data. We develop a framework for studying flow and its fluctuations in this picture. We then compute elliptic and triangular flow fluctuations, and study their connections to the ridge.
Viscosity and the Soft Ridge at RHIC
Sean Gavin,George Moschelli
Physics , 2008, DOI: 10.1088/0954-3899/35/10/104084
Abstract: Correlation studies exhibit a ridge-like feature in rapidity and azimuthal angle, with and without a jet trigger. We ask whether the feature in untriggered correlations can be a consequence of transverse flow and viscous diffusion.
Fluctuation Probes of Early-Time Correlations in Nuclear Collisions
Sean Gavin,George Moschelli
Physics , 2011, DOI: 10.1103/PhysRevC.85.014905
Abstract: Correlation measurements imply that anisotropic flow in nuclear collisions includes a novel triangular component along with the more familiar elliptic-flow contribution. Triangular flow has been attributed to event-wise fluctuations in the initial shape of the collision volume. We ask two questions: 1) How do these shape fluctuations impact other event-by-event observables? 2) Can we disentangle fundamental information on the early time fluctuations from the complex flow that results? We study correlation and fluctuation observables in a framework in which flux tubes in an early Glasma stage later produce hydrodynamic flow. Calculated multiplicity and transverse momentum fluctuations are in excellent agreement with data from 62.4 GeV Au+Au up to 2.76 TeV Pb+Pb.
The Glasma and the Hard Ridge
George Moschelli,Sean Gavin
Physics , 2009,
Abstract: Correlation measurements indicate that excess two particle correlations extend over causally disconnected rapidity ranges. Although, this enhancement is broad in relative rapidity $\eta=\eta_1 - \eta_2$, it is focused in a narrow region in relative azimuthal angle $\phi=\phi_1 - \phi_2$. The resulting structure looks like a ridge centered at $\eta = \phi=0$. Similar ridge structures are observed in correlations of particles associated with a jet trigger (the hard ridge) and in correlations without a trigger (the soft ridge). The long range rapidity behavior requires that the correlation originates in the earliest stage of the collision, and probes properties of the production mechanism. Glasma initial conditions as predicted by the theory of Color Glass Condensate and provide a and early stage correlation that naturally extends far in rapidity. We have previously shown that the soft ridge is a consequence of particles forming from an initial Glasma phase that experience a later stage transverse flow. We extend this work to study the ridge dependence on the $p_t$ of the correlated pairs. We then determine the soft contribution to the hard ridge.
Soft Contribution to the Hard Ridge in Relativistic Nuclear Collisions
George Moschelli,Sean Gavin
Physics , 2009, DOI: 10.1016/j.nuclphysa.2009.12.064
Abstract: Nuclear collisions exhibit long-range rapidity correlations not present in proton-proton collisions. Because the correlation structure is wide in relative pseudorapidity and narrow in relative azimuthal angle, it is known as the ridge. Similar ridge structures are observed in correlations of particles associated with a jet trigger (the hard ridge) as well as correlations without a trigger (the soft ridge). Earlier we argued that the soft ridge arises when particles formed in an early Glasma stage later manifest transverse flow. We extend this study to address new soft ridge measurements. We then determine the contribution of flow to the hard ridge.
Fluctuation and flow probes of early-time correlations in relativistic heavy ion collisions
Sean Gavin,George Moschelli
Physics , 2012, DOI: 10.1088/1742-6596/389/1/012038
Abstract: Fluctuation and correlation observables are often measured using multi-particle correlation methods and therefore mutually probe the origins of genuine correlations present in multi-particle distribution functions. We investigate the common influence of correlations arising from the spatially inhomogeneous initial state on multiplicity and momentum fluctuations as well as flow fluctuations. Although these observables reflect different aspects of the initial state, taken together, they can constrain a correlation scale set at the earliest moments of the collision. We calculate both the correlation scale in an initial stage Glasma flux tube picture and the modification to these correlations from later stage hydrodynamic flow and find quantitative agreement with experimental measurements over a range of collision systems and energies.
HIV/AIDS, growth and poverty in KwaZulu-Natal and South Africa: an integrated survey, demographic and economy-wide analysis
Thurlow James,Gow Jeff,George Gavin
Journal of the International AIDS Society , 2009, DOI: 10.1186/1758-2652-12-18
Abstract: Background This paper estimates the economic impact of HIV/AIDS on the KwaZulu-Natal province and the rest of South Africa. Methods We extended previous studies by employing: an integrated analytical framework that combined firm surveys of workers' HIV prevalence by sector and occupation; a demographic model that produced both population and workforce projections; and a regionalized economy-wide model linked to a survey-based micro-simulation module. This framework permits a full macro-microeconomic assessment. Results Results indicate that HIV/AIDS greatly reduces annual economic growth, mainly by lowering the long-run rate of technical change. However, impacts on income poverty are small, and inequality is reduced by HIV/AIDS. This is because high unemployment among low-income households minimises the economic costs of increased mortality. By contrast, slower economic growth hurts higher income households despite lower HIV prevalence. Conclusion We conclude that the increase in economic growth that results from addressing HIV/AIDS is sufficient to offset the population pressure placed on income poverty. Moreover, incentives to mitigate HIV/AIDS lie not only with poorer infected households, but also with uninfected higher income households. Our findings reveal the substantial burden that HIV/AIDS places on future economic development in KwaZulu-Natal and South Africa, and confirms the need for policies to curb the economic costs of the pandemic.
The APM Galaxy Survey:- V. Catalogues of Galaxy Clusters
Gavin Dalton,Steve Maddox,Will Sutherland,George Efstathiou
Physics , 1997, DOI: 10.1093/mnras/289.2.263
Abstract: We describe the construction of catalogues of galaxy clusters from the APM Galaxy survey using an automated algorithm based on Abell-like selection criteria. We investigate the effects of varying several parameters in our selection algorithm, including the magnitude range, and radius from the cluster centre used to estimate the cluster richnesses. We quantify the accuracy of the photometric distance estimates by comparing with measured redshifts, and we investigate the stability and completeness of the resulting catalogues. We find that the angular correlation functions for different cluster catalogues are in good agreement with one another, and are also consistent with the observed amplitude of the spatial correlation function of rich clusters.
Long Range Correlations and the Soft Ridge in Relativistic Nuclear Collisions
Sean Gavin,Larry McLerran,George Moschelli
Physics , 2008, DOI: 10.1103/PhysRevC.79.051902
Abstract: Relativistic Heavy Ion Collider experiments exhibit correlations peaked in relative azimuthal angle and extended in rapidity. Called the ridge, this peak occurs both with and without a jet trigger. We argue that the untriggered ridge arises when particles formed by flux tubes in an early glasma stage later manifest transverse flow. Combining a blast wave model of flow fixed by single-particle spectra with a simple description of the glasma, we find excellent agreement with current data.
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