CENTRALITY EVOLUTION OF pt AND yt SPECTRA FROM Au–Au COLLISIONS AT $\sqrt{s_{NN}} = 200\, {\rm GeV}$

Trainor, T. A.

doi:10.1142/s021830130801057x

Cited by 73 publications

(513 citation statements)

References 40 publications

(59 reference statements)

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“…Two-component model Soft+hard spectrum and correlation components representing non-single diffractive (NSD) N-N soft scattering and (longitudinal) fragmentation and pQCD semihard parton scattering and (transverse) fragmentation [13,28,35].…”

Section: Analysis Methodsmentioning

confidence: 99%

“…where ν = 2 n bin /n part is the participant-nucleon mean pathlength, S N N and H N N are reference per-participantpair soft and hard spectrum components respectively, and H AA is the hard component extracted from data [13]. Fig.…”

Section: B Plotting Formatsmentioning

confidence: 99%

“…Fig. 2 (left panel) shows ratio R AA for five centralities of Au-Au collisions (five bold curves of different line styles) plotted on transverse rapidity y t [13]. Also shown are five reference curves (light solid curves) with H AA replaced by reference H N N in Eq.…”

Section: B Plotting Formatsmentioning

confidence: 99%

“…Fig. 2 (right panel) shows alternative ratio r AA defined in terms of spectrum hard components from the same data as in the left panel [13]. Soft component S N N is eliminated from the ratio, and full access to hardcomponent centrality trends is thus achieved.…”

Section: B Plotting Formatsmentioning

confidence: 99%

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Examination of the relevance of hydrodynamics for data measured at the BNL relativistic heavy ion collider

Trainor¹

2010

J. Phys. G: Nucl. Part. Phys.

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The hydrodynamic (hydro) model applied to heavy ion data from the relativistic heavy ion collider (RHIC) in the form of single-particle spectra and correlations seems to indicate that a dense QCD medium nearly opaque to partons, a strongly-coupled quark-gluon plasma (sQGP), is formed in more-central Au-Au collisions, and that the sQGP may have a very small viscosity ("perfect liquid"). Measurements of radial and elliptic flows, with possible coalescence of "constituent quarks" to form hadrons, seem to support the conclusion. However, other measurements provide contradictory evidence. Unbiased angular correlations indicate that a large number of back-to-back jets from initial-state scattered partons with energies as low as 3 GeV survive as "minijet" hadron correlations even in central Au-Au collisions, suggesting near transparency. Two-component analysis of single-particle hadron spectra reveals a corresponding spectrum hard component (parton fragment distribution described by pQCD) which can masquerade as "radial flow" in some spectrum analysis. Reinterpretation of "elliptic flow" as a QCD scattering process resulting in fragmentation is also possible. In this paper I review analysis methods and results in the context of two paradigms: the conventional hydrodynamics/hard-probes paradigm and an alternative quadrupole/minijets paradigm. Based on re-interpretation of fiducial data I argue that hydrodynamics may not be relevant to RHIC collisions. Collision evolution may be dominated by parton scattering and fragmentation, albeit the fragmentation process is strongly modified in more-central A-A collisions.

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Section: Analysis Methodsmentioning

confidence: 99%

Section: B Plotting Formatsmentioning

confidence: 99%

Section: B Plotting Formatsmentioning

confidence: 99%

Section: B Plotting Formatsmentioning

confidence: 99%

See 2 more Smart Citations

Examination of the relevance of hydrodynamics for data measured at the BNL relativistic heavy ion collider

Trainor¹

2010

J. Phys. G: Nucl. Part. Phys.

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“…The basis for the jet assignments in p-p collisions and more-peripheral Au-Au collisions (below a "sharp transition" at about 50% of the total cross section [4]) is quantitative comparisons between correlation and spectrum data on the one hand [4,6,17,18,22] and measured jets, pQCD theory and QCD Monte Carlos on the other [4,5,7,23]. The SS 2D peak and AS 1D peak systematics agree quantitatively with predictions from a pQCD jet description.…”

Section: B Correlation Measuresmentioning

confidence: 99%

Challenging claims of nonjet “higher harmonic” components in 2D angular correlations from high-energy heavy-ion collisions

2012

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Background: Possible evidence for triangular flow and other "higher harmonic flows" in high energy nucleus-nucleus collisions has received much attention recently. It is conjectured that several higher harmonic flows vm may result from initial-state geometry fluctuations in A-A collisions coupled to a radially-expanding medium. But as with "elliptic flow" v2 measurements, nonhydrodynamic mechanisms such as jet production may contribute to other higher azimuth multipoles vm as biases. Purpose: Careful distinctions should be maintained between jet-related and nonjet (possibly hydrodynamic) contributions to vm (e.g., "nonflow" and "flow"). In this study we consider several questions: (a) To what extent do jet-like structures in two-dimensional (2D) angular correlations contribute to azimuth multipoles inferred from various vm methods? (b) If a multipole element is added to a 2D fit model is a nonzero amplitude indicative of a corresponding flow component? and (c) Can 2D correlations establish the necessity of nonjet contributions to some or all higher multipoles? Method: Model fits to 2D angular correlations are used to establish the origins of azimuth multipoles inferred from 1D projections onto azimuth or from nongraphical numerical methods. Results: We find that jet-like angular correlations, and specifically a 2D peak at the angular origin consistent with jet production, constitute the dominant contribution to inferred higher multipoles, and the data do not require higher multipoles in isolation from the jet-like 2D peak. Conclusions: Inference of "higher harmonic flows" results from identifying certain nominally jetlike structure as flow manifestations through unjustified application of 1D Fourier series analysis. Although the peak structure at the angular origin is strongly modified in more-central collisions some properties remain compatible with relevant pQCD theory expectations for jet production.

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STAR: Jet reconstruction, direct γ and multi-hadron correlations

Putschke

2011

Nuclear Physics A

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CENTRALITY EVOLUTION OF p_t AND y_t SPECTRA FROM Au–Au COLLISIONS AT $\sqrt{s_{NN}} = 200\, {\rm GeV}$

Cited by 73 publications

References 40 publications

Examination of the relevance of hydrodynamics for data measured at the BNL relativistic heavy ion collider

Examination of the relevance of hydrodynamics for data measured at the BNL relativistic heavy ion collider

Challenging claims of nonjet “higher harmonic” components in 2D angular correlations from high-energy heavy-ion collisions

STAR: Jet reconstruction, direct γ and multi-hadron correlations

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