Pub Date : 2005-10-28DOI: 10.1556/APH.27.2006.2-3.36
M. Kitazawa, T. Kunihiro, Y. Nemoto
We study how the quasiparticle picture of the quark can be modified near but above the critical temperature (Tc) of the chiral phase transition; we incorporate into the quark self-energy the effects of the precursory soft modes of the phase transition, i.e. ‘para-σ(π) meson’. It is found that the quark spectrum has a three-peak structure near Tc: We show that the additional new spectra originate from the mixing between a quark (antiquark) and an antiquark-hole (quark-hole) caused by a “resonant scattering” of the quasi-fermions with the thermally-excited soft modes.
{"title":"Quasiparticle picture of quarks near chiral phase transition","authors":"M. Kitazawa, T. Kunihiro, Y. Nemoto","doi":"10.1556/APH.27.2006.2-3.36","DOIUrl":"https://doi.org/10.1556/APH.27.2006.2-3.36","url":null,"abstract":"We study how the quasiparticle picture of the quark can be modified near but above the critical temperature (Tc) of the chiral phase transition; we incorporate into the quark self-energy the effects of the precursory soft modes of the phase transition, i.e. ‘para-σ(π) meson’. It is found that the quark spectrum has a three-peak structure near Tc: We show that the additional new spectra originate from the mixing between a quark (antiquark) and an antiquark-hole (quark-hole) caused by a “resonant scattering” of the quasi-fermions with the thermally-excited soft modes.","PeriodicalId":201208,"journal":{"name":"Acta Physica Hungarica A) Heavy Ion Physics","volume":"78 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2005-10-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132350131","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2005-10-28DOI: 10.1556/APH.27.2006.2-3.20
J. Ruppert
We calculate the wake induced in a hot, dense QCD medium by a fast parton in the framework of linear response theory. We discuss two different scenarios: i) a weakly coupled quark gluon plasma (pQGP) described by hardthermal loop (HTL) perturbation theory and ii) a scenario where the plasma has the properties of a quantum liquid. We show that a Mach cone can appear in the second scenario, but not in the first one.
{"title":"Jet-medium interactions: Wakes in the QCD medium","authors":"J. Ruppert","doi":"10.1556/APH.27.2006.2-3.20","DOIUrl":"https://doi.org/10.1556/APH.27.2006.2-3.20","url":null,"abstract":"We calculate the wake induced in a hot, dense QCD medium by a fast parton in the framework of linear response theory. We discuss two different scenarios: i) a weakly coupled quark gluon plasma (pQGP) described by hardthermal loop (HTL) perturbation theory and ii) a scenario where the plasma has the properties of a quantum liquid. We show that a Mach cone can appear in the second scenario, but not in the first one.","PeriodicalId":201208,"journal":{"name":"Acta Physica Hungarica A) Heavy Ion Physics","volume":"57 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2005-10-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126672694","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2005-10-28DOI: 10.1556/APH.27.2006.2-3.27
K. Tywoniuk, I. Arsene, L. Bravina, A. Kaidalov, E. Zabrodin
New data from HERA experiment on deep inelastic scattering have been used to parametrize nucleon and Pomeron structure functions. Within the Gribov theory, the parameterizations were employed to calculate gluon shadowing for various heavy ions. The latter was compared with predictions from other models. Calculations of multiplicity reduction due to gluon shadowing for d+Au collisions at forward rapidities at √sNN=200 GeV are in good agreement with BRAHMS data on the nuclear modification factor.
{"title":"Gluon shadowing and unitarity effects","authors":"K. Tywoniuk, I. Arsene, L. Bravina, A. Kaidalov, E. Zabrodin","doi":"10.1556/APH.27.2006.2-3.27","DOIUrl":"https://doi.org/10.1556/APH.27.2006.2-3.27","url":null,"abstract":"New data from HERA experiment on deep inelastic scattering have been used to parametrize nucleon and Pomeron structure functions. Within the Gribov theory, the parameterizations were employed to calculate gluon shadowing for various heavy ions. The latter was compared with predictions from other models. Calculations of multiplicity reduction due to gluon shadowing for d+Au collisions at forward rapidities at √sNN=200 GeV are in good agreement with BRAHMS data on the nuclear modification factor.","PeriodicalId":201208,"journal":{"name":"Acta Physica Hungarica A) Heavy Ion Physics","volume":"193 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2005-10-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122179519","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2005-10-27DOI: 10.1556/APH.27.2006.2-3.18
Star Collaboration, R. Ray, M. Daugherity
Two-particle correlations and event-wise fluctuations in transverse momentum p tare reported for Au−Au collisions at √s NN =62 and 200 GeV on pseudorapidity η and azimuth ϕ. Distributions of all pairs of particles (no leading trigger particle) reveal jet-like correlations, or peaks at pair-wise opening angles of order 1 radian or less. The width of this same-side correlation peak increases dramatically on pseudorapidity and decreases on azimuth for increasing collision centrality. Evolution of the same-side peak with centrality suggests dissipation of low-Q 2 partons via strong couplign to an expanding bulk medium. p t correlations, which provide access to temperature and/or velocity distributions in the colliding system, are also presented.
在伪快度η和方位φ上报道了√s NN =62和200gev下Au - Au碰撞的两粒子相关和横向动量p的事件方向波动。所有粒子对的分布(没有领先的触发粒子)显示出类似喷流的相关性，或者在1阶弧度或更小的成对开放角处达到峰值。该同侧相关峰的宽度随着伪快度的增大而显著增大，而随着方位角的增大而减小，以增加碰撞中心性。具有中心性的同侧峰的演化表明低q2部分通过与膨胀体介质的强耦合而耗散。本文还介绍了P - t相关关系，它提供了对碰撞系统中温度和/或速度分布的访问。
{"title":"Dissipation and fragmentation of low- Q 2 scattered partons in Au−Au collisions at RHIC","authors":"Star Collaboration, R. Ray, M. Daugherity","doi":"10.1556/APH.27.2006.2-3.18","DOIUrl":"https://doi.org/10.1556/APH.27.2006.2-3.18","url":null,"abstract":"Two-particle correlations and event-wise fluctuations in transverse momentum p\u0000 tare reported for Au−Au collisions at √s\u0000 NN\u0000 =62 and 200 GeV on pseudorapidity η and azimuth ϕ. Distributions of all pairs of particles (no leading trigger particle) reveal jet-like correlations, or peaks at pair-wise opening angles of order 1 radian or less. The width of this same-side correlation peak increases dramatically on pseudorapidity and decreases on azimuth for increasing collision centrality. Evolution of the same-side peak with centrality suggests dissipation of low-Q\u0000 2 partons via strong couplign to an expanding bulk medium. p\u0000 t correlations, which provide access to temperature and/or velocity distributions in the colliding system, are also presented.","PeriodicalId":201208,"journal":{"name":"Acta Physica Hungarica A) Heavy Ion Physics","volume":"43 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2005-10-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123148135","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2005-10-27DOI: 10.1556/APH.27.2006.2-3.35
Jean-Sébastien Gagnon, F. Fillion-Gourdeau, Sangyong Jeon
We use the full multiple scattering expansion of the retarded self-energy to obtain the gain and loss rates present in the Kadanoff-Baym relativistic transport equation. The rates we obtain include processes with any number of particles. As a first approximation, we only consider central cuts in the self-energies, but otherwise our results are general. We specialize to the case of scalar field theory to compare with lowest order results. The main application of this work is relativistic transport theory of very dense systems, such as the quark-gluon plasma or the early universe, where multi-particle interactions are important.
{"title":"All Orders Transport Theory from the Multiple Scattering Expansion of the Self-Energy: The Central Cuts","authors":"Jean-Sébastien Gagnon, F. Fillion-Gourdeau, Sangyong Jeon","doi":"10.1556/APH.27.2006.2-3.35","DOIUrl":"https://doi.org/10.1556/APH.27.2006.2-3.35","url":null,"abstract":"We use the full multiple scattering expansion of the retarded self-energy to obtain the gain and loss rates present in the Kadanoff-Baym relativistic transport equation. The rates we obtain include processes with any number of particles. As a first approximation, we only consider central cuts in the self-energies, but otherwise our results are general. We specialize to the case of scalar field theory to compare with lowest order results. The main application of this work is relativistic transport theory of very dense systems, such as the quark-gluon plasma or the early universe, where multi-particle interactions are important.","PeriodicalId":201208,"journal":{"name":"Acta Physica Hungarica A) Heavy Ion Physics","volume":"72 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2005-10-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114948456","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2005-10-27DOI: 10.1556/APH.27.2006.2-3.31
A. Baltz
The heavy ion cross section for continuum e+e− pair production has been calculated to all orders in Zα. Comparison is made with available CERN SPS and RHIC STAR data. Computed cross sections are found to be reduced from perturbation theory with increasing charge of the colliding heavy ions and for all energy and momentum regions investigated. Au or Pb total cross sections are reduced by 28% (SPS), 17% (RHIC) and 11% (LHC). For very high energy (E e +, E e −>3 GeV) forward pairs at LHC the reduction from perturbation theory is a bit larger (17%). Use of zero degree calorimeter triggering (and thus small impact parameter weighting) makes impact parameter representation of exact pair production useful. Preliminary exact calculations in the zero impact parameter limit show a much larger reduction from perturbation theory (about 40%) at both RHIC and LHC.
计算了连续体e+e -对产生的重离子截面在Zα中的所有阶数。并与现有CERN SPS和RHIC STAR数据进行了比较。根据摄动理论计算出的截面随着碰撞重离子电荷的增加而减小，对于所研究的所有能量和动量区域都是如此。Au或Pb总横截面分别减少28% (SPS)、17% (RHIC)和11% (LHC)。对于高能(E E +， E E−> 3gev)正激对，微扰理论的减少幅度更大(17%)。使用零度量热计触发(因此小的冲击参数权重)使精确成对生产的冲击参数表示有用。在零冲击参数极限下的初步精确计算表明，在RHIC和LHC上，从摄动理论(约40%)减少得更大。
{"title":"Heavy Ion e + e - Pairs to All Orders in Z α","authors":"A. Baltz","doi":"10.1556/APH.27.2006.2-3.31","DOIUrl":"https://doi.org/10.1556/APH.27.2006.2-3.31","url":null,"abstract":"The heavy ion cross section for continuum e+e− pair production has been calculated to all orders in Zα. Comparison is made with available CERN SPS and RHIC STAR data. Computed cross sections are found to be reduced from perturbation theory with increasing charge of the colliding heavy ions and for all energy and momentum regions investigated. Au or Pb total cross sections are reduced by 28% (SPS), 17% (RHIC) and 11% (LHC). For very high energy (E e +, E e −>3 GeV) forward pairs at LHC the reduction from perturbation theory is a bit larger (17%). Use of zero degree calorimeter triggering (and thus small impact parameter weighting) makes impact parameter representation of exact pair production useful. Preliminary exact calculations in the zero impact parameter limit show a much larger reduction from perturbation theory (about 40%) at both RHIC and LHC.","PeriodicalId":201208,"journal":{"name":"Acta Physica Hungarica A) Heavy Ion Physics","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2005-10-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123834991","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2005-10-20DOI: 10.1556/APH.27.2006.2-3.38
V. Magas, L. Csernai, Etele Molnár
The freeze-out of particles from a layer of finite thickness is discussed in a phenomenological kinetic model. The proposed model, based on the Modified Boltzman Transport Equation, is Lorentz invariant and can be applied equally well for the freeze-out layers with space-like and time-like normal vectors. It leads to non-equilibrated post freeze-out distributions. The dependence of the resulting distribution on the thickness of the layer is presented and discussed for a space-like freeze-out scenario.
{"title":"Freeze-out in narrow and wide layers","authors":"V. Magas, L. Csernai, Etele Molnár","doi":"10.1556/APH.27.2006.2-3.38","DOIUrl":"https://doi.org/10.1556/APH.27.2006.2-3.38","url":null,"abstract":"The freeze-out of particles from a layer of finite thickness is discussed in a phenomenological kinetic model. The proposed model, based on the Modified Boltzman Transport Equation, is Lorentz invariant and can be applied equally well for the freeze-out layers with space-like and time-like normal vectors. It leads to non-equilibrated post freeze-out distributions. The dependence of the resulting distribution on the thickness of the layer is presented and discussed for a space-like freeze-out scenario.","PeriodicalId":201208,"journal":{"name":"Acta Physica Hungarica A) Heavy Ion Physics","volume":"18 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2005-10-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126952425","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2005-10-20DOI: 10.1556/APH.27.2006.2-3.12
J. Jia
PHENIX has measured the two-particle azimuth correlation in Au+Au at √s=200 GeV. Jet shape and yield at the away side are found to be strongly modified at intermediate and low p T, and the modifications vary dramatically with p T and centrality. At high p T, away side jet peak reappears but the yield is suppressed. Similar jet strength is found for Au+Au and Cu+Cu collisions with similar number of participant nucleons.
{"title":"Di-jet correlation in Au+Au and Cu+Cu Collisions from PHENIX","authors":"J. Jia","doi":"10.1556/APH.27.2006.2-3.12","DOIUrl":"https://doi.org/10.1556/APH.27.2006.2-3.12","url":null,"abstract":"PHENIX has measured the two-particle azimuth correlation in Au+Au at √s=200 GeV. Jet shape and yield at the away side are found to be strongly modified at intermediate and low p T, and the modifications vary dramatically with p T and centrality. At high p T, away side jet peak reappears but the yield is suppressed. Similar jet strength is found for Au+Au and Cu+Cu collisions with similar number of participant nucleons.","PeriodicalId":201208,"journal":{"name":"Acta Physica Hungarica A) Heavy Ion Physics","volume":"27 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2005-10-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129864381","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2005-10-19DOI: 10.1556/APH.27.2006.2-3.40
E. Molnár, L. Csernai, V. Magas
The problem of freeze-out (FO) in high energy heavy ion reactions is addressed. We develop and analyze a covariant FO description valid for a finite space-time layer.
研究了高能重离子反应中的冻结问题。我们发展并分析了有限时空层有效的协变FO描述。
{"title":"Covariant kinetic freeze-out description through a finite space-time layer","authors":"E. Molnár, L. Csernai, V. Magas","doi":"10.1556/APH.27.2006.2-3.40","DOIUrl":"https://doi.org/10.1556/APH.27.2006.2-3.40","url":null,"abstract":"The problem of freeze-out (FO) in high energy heavy ion reactions is addressed. We develop and analyze a covariant FO description valid for a finite space-time layer.","PeriodicalId":201208,"journal":{"name":"Acta Physica Hungarica A) Heavy Ion Physics","volume":"18 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2005-10-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134543427","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2005-10-14DOI: 10.1556/APH.27.2006.2-3.19
T. Renk
The flow pattern and evolution of the medium created in ultrarelativistic heavy ion collisions can have significant influence on the energy loss of hard partons traversing the medium. We demonstrate that within a range of assumptions for longitudinal and transverse flow which are all compatible with the measured hadronic single particle distributions, the quenching power of the medium can vary within a factor five. Thus, the choice of the medium evolution is one of the biggest uncertainties in jet quenching calculations and needs to be addressed with some care.
{"title":"The influence of flow on the jet quenching power in heavy-ion collisions","authors":"T. Renk","doi":"10.1556/APH.27.2006.2-3.19","DOIUrl":"https://doi.org/10.1556/APH.27.2006.2-3.19","url":null,"abstract":"The flow pattern and evolution of the medium created in ultrarelativistic heavy ion collisions can have significant influence on the energy loss of hard partons traversing the medium. We demonstrate that within a range of assumptions for longitudinal and transverse flow which are all compatible with the measured hadronic single particle distributions, the quenching power of the medium can vary within a factor five. Thus, the choice of the medium evolution is one of the biggest uncertainties in jet quenching calculations and needs to be addressed with some care.","PeriodicalId":201208,"journal":{"name":"Acta Physica Hungarica A) Heavy Ion Physics","volume":"7 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2005-10-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132165783","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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