arXiv 0812.47142008-12-26nucl-th

The Long Slow Death of the HBT Puzzle

Scott Pratt

备注：: Talk given at WPCF (Workshop on Particle Correlations and Femtoscopy) 2008, Krakow, Poland. Proceedings to be published in Acta Physica Polonica B
发表信息：: Acta Phys.Polon.B40:1249-1256,2009

英文摘要：

Femtoscopic measurements at RHIC have been hailed as a source of insight into the bulk properties of QCD matter. However, hydrodynamic models, which have been successful in reproducing other observables have failed to satisfactorily explain femtoscopic two-particle correlation measurements. This failure has been labeled the "HBT puzzle". In this talk, I present correlations using a hybrid model composed of a viscous hydrodynamic module and a hadronic cascade. After incorporating early acceleration, viscosity and a stiffer equation of state, the extracted source sizes come much closer to experiment.

机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。

阅读原文

阅读 PDF ↗

arXiv 页面 ↗HTML 原文 ↗

本文内容

英文摘要相关论文

机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。

继续探索

相关论文

Resolving the HBT Puzzle in Relativistic Heavy Ion Collision

Two particle correlation data from the Relativistic Heavy Ion Collider have provided detailed femtoscopic information describing the space-time structure of the emission of pions. This data had avoided description with hydrodynamic-based approaches, in contrast to the success of hydrodynamics in reproducing other classes of observables. This failure has inspired the term ``HBT puzzle'', where HBT refers to femtoscopic studies which were originally based on Hanbury-Brown Twiss interferometry. Here, the puzzle is shown to originate not from a single shortcoming of hydrodynamic models, but the co…

2008-11-20nucl-th

The Long Slow Death of the HBT Puzzle, Proceedings for QM 2009

At the onset of the RHIC era femtoscopic source sizes inferred from two-particle correlations at RHIC defied description with hydrodynamic models. This failure, which became known as the HBT puzzle, now appears to be solved. The source of the discrepancy appears to be a conspiracy of several factors, each of which contributed to making the evolution of RHIC collisions more explosive. These included pre-equilibrium flow, using a stiffer equation of state and adding viscosity.

2009-10-07nucl-th

The effect of "pre-formed" hadron potentials on the dynamics of heavy ion collisions and the HBT puzzle

The nuclear stopping, the elliptic flow, and the HBT interferometry are calculated by the UrQMD transport model, in which potentials for "pre-formed" particles (string fragments) from color fluxtube fragmentation as well as for confined particles are considered. This description provides stronger pressure at the early stage and describes these observables better than the default cascade mode (where the "pre-formed" particles from string fragmentation are treated to be free-streaming). It should be stressed that the inclusion of potential interactions pushes down the calculated HBT radius $R_O$…

2007-11-21nucl-th

Tsunamis, Viscosity and the HBT Puzzle

The equation of state and bulk and shear viscosities are shown to be able to affect the transverse dynamics of a central heavy ion collision. The net entropy, along with the femtoscopic radii are shown to be affected at the 10-20% level by both shear and bulk viscosity. The degree to which these effects help build a tsunami-like pulse is also discussed.

2007-11-13nucl-th

Early anisotropic hydrodynamics and the RHIC early-thermalization and HBT puzzles

We address the problem if the early thermalization and HBT puzzles in relativistic heavy-ion collisions may be solved by the assumption that the early dynamics of the produced matter is locally anisotropic. The hybrid model describing the purely transverse hydrodynamic evolution followed by the perfect-fluid hydrodynamic stage is constructed. The transition from the transverse to perfect-fluid hydrodynamics is described by the Landau matching conditions applied at a fixed proper time. The global fit to the RHIC data reproduces the soft hadronic observables (the pion, kaon, and the proton spect…

2010-09-14nucl-th

Comment on "Quantum Opacity, the RHIC HBT Puzzle, and the Chiral Phase Transition"

We are submitting a comment on the paper "Quantum Opacity, the RHIC HBT Puzzle, and the Chiral Phase Transition" by J.G. Cramer, G.A. Miller, J.M.S. Wu and J. Yoon, published in Phys. Rev. Lett. 94, 102302 (2005).

2005-06-05nucl-exnucl-th

更多相关论文收起更多论文

The early thermalization and HBT puzzles at RHIC

The early thermalization and HBT puzzles in relativistic heavy-ion collisions studied at RHIC are shortly reviewed. The results of recent hydrodynamic calculations that shed light on these two intriguing issues are presented. In particular, the role of the elliptic flow as a signature of early thermalization is critically examined.

2010-09-28hep-phnucl-th

Solution of the RHIC HBT puzzle with Gaussian initial conditions

It is argued that the consistent description of the transverse-momentum spectra, elliptic flow, and the HBT radii in the relativistic heavy-ion collisions studied at RHIC may be obtained within the hydrodynamic model if one uses the Gaussian profile for the initial energy density in the transverse plane. Moreover, we show that the results obtained in the scenario with an early start of hydrodynamics (at the proper time tau0 = 0.25 fm) are practically equivalent to the results obtained in the model where the hydrodynamics is preceded by the free-streaming stage of partons (in the proper time in…

2008-12-22nucl-th

Is HBT really puzzling?

Two-particle correlations from RHIC have provided a surprising snapshot of the final state at RHIC. In this talk I discuss the nature of the HBT puzzle and attempt to delineate several factors which might ultimately resolve the issue.

2005-11-02nucl-th

How the HBT-Puzzle at RHIC might dissipate

I compute the first-order corrections to two-particle Bose-Einstein correlations due to deviations from equilibrium. Based on that result I argue that for nearly perfect fluids, the HBT radii ``freeze out'' much later than the single-inclusive distribution. Therefore, to prevent a big longitudinal homogeneity length, the QGP presumably should hadronize not into a nearly perfect fluid of hadrons but rather into a very dissipative one. This could be achieved by a hadronization phase transition away from equilibrium.

2002-06-04hep-phnucl-exnucl-th

Quantum Opacity, the RHIC HBT Puzzle, and the Chiral Phase Transition

We present a relativistic quantum mechanical treatment of opacity and refractive effects that allows reproduction of observables measured in two-pion (HBT) interferometry and pion spectra at RHIC. The inferred emission duration is substantial. The results are consistent with the emission of pions from a system that has a restored chiral symmetry.

2004-12-07hep-phnucl-exnucl-th

A model comparison of resonance lifetime modifications, a soft equation of state and non-Gaussian effects on $π-π$ correlations at FAIR/AGS energies

HBT correlations of $π^--π^-$ pairs at FAIR/AGS energies are investigated by using the UrQMD transport model and the CRAB analyzing program. Three different possible sources (treatment of resonance lifetimes, a soft equation of state and non-Gaussian effects) to understand the HBT $R_O/R_S$ puzzle are investigated. Firstly, we find that different treatments of the resonance decay time can not resolve the HBT time-related puzzle, however it can modify the HBT radii at low transverse momenta to some extent to explain the data slightly. Secondly, with a soft equation of state with momentum depend…

2008-11-05nucl-th

Pion freeze-out through HBT correlation in HICs from AGS/FAIR to RHIC energies

In this talk we present the results of two-pion HBT correlation at freeze-out in heavy ion collisions (HICs) from AGS to RHIC energies. The UrQMD hadron-string transport model as well as the CRAB analyzing program are adopted. Based on the cascade mode, in general, the calculations are satisfying and well in line with the experimental data although discrepancies are not negligible. Such as: I), the HBT time-related puzzle exists at all energies. II), at low AGS energies, the calculated volume as well as the mean free path of pion source at freeze-out are lower than data. It implies that a bett…

2007-08-20nucl-th

Fitted HBT radii versus space-time variances in flow-dominated models

The inability of otherwise successful dynamical models to reproduce the ``HBT radii'' extracted from two-particle correlations measured at the Relativistic Heavy Ion Collider (RHIC) is known as the ``RHIC HBT Puzzle.'' Most comparisons between models and experiment exploit the fact that for Gaussian sources the HBT radii agree with certain combinations of the space-time widths of the source which can be directly computed from the emission function, without having to evaluate, at significant expense, the two-particle correlation function. We here study the validity of this approach for realisti…

2006-03-01nucl-th

Consistent hydrodynamic description of one- and two-particle observables in relativistic heavy-ion collisions at RHIC

We show that a consistent hydrodynamic description of soft-hadronic one- and two-particle observables (the HBT radii) studied in the relativistic heavy-ion collisions at RHIC may be obtained if one uses the Gaussian energy density profile as the initial condition. The transverse-momentum spectra, the elliptic flow coefficient $v_2$, and the pionic azimuthally sensitive HBT radii are successfully reproduced, which hints that the long standing HBT puzzle has been solved.

2009-01-09nucl-th

Anisotropic hydrodynamics and the early-thermalization puzzle

The framework of anisotropic hydrodynamics is used in 3+1 dimensions to analyze behavior of matter produced in ultra-relativistic heavy-ion collisions. The model predictions for the hadronic transverse-momentum spectra, directed and elliptic flows, and the HBT radii are presented. We show that the effects of the initial anisotropy of pressure may be compensated by appropriate adjustment of the initial energy density. In this way, the final hadronic observables become insensitive to the early stage dynamics and the early thermalization puzzle may be circumvented.

2012-07-25nucl-th

HBT interferometry and the parton-hadron phase transition

We discuss predictions for the pion and kaon interferometry measurements in relativistic heavy ion collisions at SPS and RHIC energies. In particular, we confront relativistic transport model calculations that include explicitly a first-order phase transition from a thermalized quark-gluon plasma to a hadron gas with recent data from the RHIC experiments. We critically examine the "HBT-puzzle" both from the theoretical as well as from the experimental point of view. Alternative scenarios are briefly explained.

2002-03-11hep-phnucl-exnucl-th

Hydrodynamics and perfect fluids: uniform description of soft observables in Au+Au collisions at RHIC

It is argued that the use of the initial Gaussian energy density profile for hydrodynamics leads to much better uniform description of the RHIC heavy-ion data than the use of the standard initial condition obtained from the Glauber model. With the modified Gaussian initial conditions we successfully reproduce the transverse-momentum spectra, v2, and the pionic HBT radii (including their azimuthal dependence). The emerging consistent picture of hadron production hints that a solution of the long standing RHIC HBT puzzle has been found.

2008-11-23nucl-th

Review of HBT or Bose-Einstein correlations in high energy heavy ion collisions

A brief review is given on the discovery and the first five decades of the Hanbury Brown - Twiss effect and its generalized applications in high energy nuclear and particle physics, that includes a meta-review. Interesting and inspiring new directions are also highlighted, including for example source imaging, lepton and photon interferometry, non-Gaussian shape analysis as well as many other new directions. Existing models are compared to two-particle correlation measurements and the so-called RHIC HBT puzzle is resolved. Evidence for a (directional) Hubble flow is presented and the conclusio…

2005-05-09astro-phhep-phnucl-ex

Describing transverse dynamics and space-time evolution at RHIC in a hydrodynamic model with statistical hadronization

A hydrodynamic model coupled to the statistical hadronization code Therminator is used to study a set of observables in the soft sector at RHIC. A satisfactory description of the pT-spectra and elliptic flow is obtained, similarly to other hydrodynamic models. With the Gaussian initial conditions the transverse femtoscopic radii are also reproduced, providing a possible solution of the RHIC HBT puzzle.

2009-09-15nucl-th

Transverse hydrodynamics and the early-thermalization problem at RHIC

The problem of early thermalization of matter produced in relativistic heavy-ion collisions at RHIC is discussed in the framework of a hybrid model that consists of the transverse-hydrodynamics stage followed by the standard perfect-fluid hydrodynamics stage and freeze-out. The two hydrodynamic regimes are connected with the help of Landau matching conditions. A satisfactory description of the soft hadronic observables is achieved. This indicates that the early-thermalization problem and also the HBT puzzle may be to large extent circumvented.

2010-07-27nucl-th

Hydrodynamic description of particle production in relativistic heavy-ion collisions

Our recently developed 2+1 (boost-invariant) hydrodynamic model has been presented and used to i) describe the soft hadronic data collected in the central region of the relativistic heavy-ion collisions at RHIC and ii) to make predictions for the heavy-ion collisions at the LHC energies. We have addressed both the one- and two-particle observables: the transverse momentum spectra, the elliptic flow coefficient v2, and the pion HBT radii. The realistic equation of state for strongly interacting matter has been constructed that interpolates between the hadron gas model and the results of the QCD…

2009-08-05nucl-th