Jet flavor conversions in the quark-gluon plasma

Ko, Che Ming; Liu, W.; Zhang, B.-W.

doi:10.1007/s00601-007-0188-0

Cited by 7 publications

(6 citation statements)

References 36 publications

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“…A heavy ion environment not only redistributes energies of energetic particles, it can also lead to significant changes in the relative abundances of hadrons. This can either happen through profound changes in the way hadronization works in high multiplicity environments [135], see also the discussion on quark recombination in the next section, or through the exchange of particles with the quark gluon plasma which leads to a phenomenon termed jet conversion [136,137,138,139]. Jet conversions would increase the number of protons and kaons relative to pions in nuclear collisions vs p + p collisions.…”

Section: Final State Effects: Other Developmentsmentioning

confidence: 99%

Evaluating results from the Relativistic Heavy Ion Collider with perturbative QCD and hydrodynamics

Fries

Nonaka

2011

Progress in Particle and Nuclear Physics

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We review the basic concepts of perturbative quantum chromodynamics (QCD) and relativistic hydrodynamics, and their applications to hadron production in high energy nuclear collisions. We discuss results from the Relativistic Heavy Ion Collider (RHIC) in light of these theoretical approaches. Perturbative QCD and hydrodynamics together explain a large amount of experimental data gathered during the first decade of RHIC running, although some questions remain open. We focus primarily on practical aspects of the calculations, covering basic topics like perturbation theory, initial state nuclear effects, jet quenching models, ideal hydrodynamics, dissipative corrections, freeze-out and initial conditions. We conclude by comparing key results from RHIC to calculations.

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Section: Final State Effects: Other Developmentsmentioning

confidence: 99%

Evaluating results from the Relativistic Heavy Ion Collider with perturbative QCD and hydrodynamics

Fries

Nonaka

2011

Progress in Particle and Nuclear Physics

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“…Flavor changing channels and conversions for gluons into quarks and vice versa, q + g ↔ g + q and q +q ↔ g + g, have been discussed by several authors [14,15,16] in the past. Recent interest in this process was fueled by the idea that partonic energy loss predicts a color factor 9/4 for the relative quenching strength of gluons and quarks.…”

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confidence: 99%

“…Flavor changing channels and conversions for gluons into quarks and vice versa, q + g ↔ g + q and q + q ↔ g + g, have been discussed by several authors [14,15,16] in the past. Recent interest in this process was fueled by the idea that partonic energy loss predicts a color factor 9/4 for the The nuclear modification factor R AA for direct photons with and without conversions switched on, calculated in the model introduced in [7] (preliminary PHENIX data from [17]).…”

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confidence: 99%

High Momentum Probes of Nuclear Matter

Fries¹

2010

Proceedings of 4th International Workshop High-pT Physics at LHC 09 — PoS(High-pT Physics09)

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We discuss how the chemical composition of QCD jets is altered by final state interactions in surrounding nuclear matter. We describe this process through conversions of leading jet particles. We find that conversions lead to an enhancement of kaons at high transverse momentum in Au+Au collisions at RHIC, while their azimuthal asymmetry v 2 is suppressed. 4th international workshop High-pT physics at LHC 09

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“…It was pointed out that a larger quenching for gluons could be reflected in more suppression of protons compared to pions given the preference of gluon to proton fragmentation in modern fragmentation functions [9]. Jet conversions should soften this effect and increase the proton to pion ration in central collisions [10,11]. Fig.…”

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confidence: 99%

High-PT Physics with Identified Particles

Fries

Liu

2009

Nuclear Physics A

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The suppression of high-P T particles in heavy ion collisions was one of the key discoveries at the Relativistic Heavy Ion Collider. This is usually parameterized by the average rate of momentumtransfer squared to this particle,q. Here we argue that measurements of identified particles at high P T can lead to complementary information about the medium. The leading particle of a jet can change its identity through interactions with the medium. Tracing such flavor conversions could allow us to constrain the mean free path. Here we review the basic concepts of flavor conversions and discuss applications to particle ratios and elliptic flow. We make a prediction that strangeness is enhanced at high P T at RHIC energies while its elliptic flow is suppressed.For the past decade high momentum particles and jets have been used to probe the quark gluon plasma (QGP) phase created at the Relativistic Heavy Ion Collider (RHIC). The energy loss of a fast parton suffered in the medium carries information about the typical momentum transfer µ along the path, more precisely about the transport coefficientq = µ 2 /λ [1, 2, 3, 4, 5, 6]. We have recently argued that the mean free path λ of a fast parton could be determined separately by measuring the change in hadro-chemistry induced by the medium [7,8].Here we discuss a model based on conversions of the leading particle of a jet. Just as partons can lose energy through collisions and induced radiation, they can scatter through channels in which the identity of the fastest parton in the initial and final state are not the same. Examples are binary collisions like q +q ↔ g + g or q + g ↔ g + q which can lead to conversions of quarks into gluons and vice versa. Here the first parton on each side has a large momentum (the leading jet parton) and the second parton in the initial state is a thermal parton from the quark gluon plasma. The rate of flavor conversions depends on the mean free path λ of fast partons.Conversions between quarks and gluons should obscure their different color factors coupling them to the medium. Instead of a relative factor 9/4 inq only an average color factor should be observable in a long enough medium. It was pointed out that a larger quenching for gluons could be reflected in more suppression of protons compared to pions given the preference of gluon to proton fragmentation in modern fragmentation functions [9]. Jet conversions should soften this effect and increase the proton to pion ration in central collisions [10,11]. Fig. 1 shows the ratio of nuclear modification factors R AA for protons and pions with and without conversions between quarks and gluons taken into account [7]. Clearly, flavor conversions lead to less proton suppression.Conversions had also been discussed before for photons and dileptons. Fast quarks and gluons can create real or virtual photons through Compton and annihilation processes with the medium, q + g → γ + q, q +q → γ + g. It has been realized over the years that this process can make a large contribution to the overall...

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Jet flavor conversions in the quark-gluon plasma

Cited by 7 publications

References 36 publications

Evaluating results from the Relativistic Heavy Ion Collider with perturbative QCD and hydrodynamics

Evaluating results from the Relativistic Heavy Ion Collider with perturbative QCD and hydrodynamics

High Momentum Probes of Nuclear Matter

High-PT Physics with Identified Particles

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