We report the results on the open heavy-flavor production measured by the STAR experiment in Au+Au collisions at a center-of-mass energy per nucleon-nucleon pair of 200 GeV at RHIC, including the nuclear modification factors for $D^0$, $D^{pm}$, electrons from $B$ and $D$ hadron decays, and non-prompt $J/psi$ and $D^0$. We also present results on elliptic and triangular anisotropic flows for $D^0$ as well as the production ratios of $D^{pm}_s/D^0$ and $Lambda_c/D^0$. These results are compared to various theroretical predictions, providing us valuable information on the properties of the quark-gluon plasma.
{"title":"Overview of open heavy-flavor production from STAR","authors":"Y. Yi","doi":"10.22323/1.320.0030","DOIUrl":"https://doi.org/10.22323/1.320.0030","url":null,"abstract":"We report the results on the open heavy-flavor production measured by the STAR experiment in Au+Au collisions at a center-of-mass energy per nucleon-nucleon pair of 200 GeV at RHIC, including the nuclear modification factors for $D^0$, $D^{pm}$, electrons from $B$ and $D$ hadron decays, and non-prompt $J/psi$ and $D^0$. We also present results on elliptic and triangular anisotropic flows for $D^0$ as well as the production ratios of $D^{pm}_s/D^0$ and $Lambda_c/D^0$. These results are compared to various theroretical predictions, providing us valuable information on the properties of the quark-gluon plasma.","PeriodicalId":104537,"journal":{"name":"Proceedings of 12th International Workshop on High-pT Physics in the RHIC/LHC Era — PoS(High-pT2017)","volume":"99 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-01-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125703955","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 : 2018-10-10DOI: 10.1051/epjconf/201817205010
C. Nattrass
The Quark Gluon Plasma (QGP) is created in high energy heavy ion collisions at the Relativistic Heavy Ion Collider (RHIC) and the Large Hadron Collider (LHC). This medium is transparent to electromagnetic probes but nearly opaque to colored probes. Hard partons produced early in the collision fragment and hadronize into a collimated spray of particles called a jet. The partons lose energy as they traverse the medium, a process called jet quenching. Most of the lost energy is still correlated with the parent parton, contributing to particle production at larger angles and lower momenta relative to the parent parton than in proton-proton collisions. This partonic energy loss can be measured through several observables, each of which give different insights into the degree and mechanism of energy loss. The measurements to date are summarized and the path forward is discussed.
{"title":"Measurements of jets in heavy ion collisions","authors":"C. Nattrass","doi":"10.1051/epjconf/201817205010","DOIUrl":"https://doi.org/10.1051/epjconf/201817205010","url":null,"abstract":"The Quark Gluon Plasma (QGP) is created in high energy heavy ion collisions at the Relativistic Heavy Ion Collider (RHIC) and the Large Hadron Collider (LHC). This medium is transparent to electromagnetic probes but nearly opaque to colored probes. Hard partons produced early in the collision fragment and hadronize into a collimated spray of particles called a jet. The partons lose energy as they traverse the medium, a process called jet quenching. Most of the lost energy is still correlated with the parent parton, contributing to particle production at larger angles and lower momenta relative to the parent parton than in proton-proton collisions. This partonic energy loss can be measured through several observables, each of which give different insights into the degree and mechanism of energy loss. The measurements to date are summarized and the path forward is discussed.","PeriodicalId":104537,"journal":{"name":"Proceedings of 12th International Workshop on High-pT Physics in the RHIC/LHC Era — PoS(High-pT2017)","volume":"11 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-10-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128477961","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}
Measuring electroweak bosons in relativistic heavy ion collisions at high energy provide an opportunity to understand temporal evolution of the quark-gluon plasma created in such collisions by constraining the initial state of the interaction. Due to lack of colour charges the bosons and or particles produced in their leptonic decays are unaffected by the quark-gluon plasma and therefore preserve the information about the very early stage of the collision when they were born. This singles electroweak bosons as a unique and very interesting class of observables in heavy ion collisions. The ATLAS experiment at LHC measures production of electroweak bosons in $pp$, $p$+Pb and Pb+Pb collisions systems. A review of the existing results is given in this proceeding that includes studies made with isolated photons to constraint kinematic properties and flavour composition of associated jets, measurements of $W$ and $Z$ bosons used to estimate nuclear modification of parton distribution function and the production rates of the bosons used to verify geometric models implied to estimate event centrality. A novel analysis on measuring two particle correlations in pp collisions where the $Z$ boson is registered is also discussed in the proceeding. This is the first attempt to break into the initial geometry of the pp collisions by constraining the impact parameter with a hard scattering process. It shows that the strength of the two particle correlations in such collision is $1.08pm0.06$ above the inclusive. To make the measurement ATLAS solves the technical problem of measuring the underlying event in high pileup condition.
{"title":"Electroweak probes with ATLAS","authors":"A. Milov","doi":"10.22323/1.320.0016","DOIUrl":"https://doi.org/10.22323/1.320.0016","url":null,"abstract":"Measuring electroweak bosons in relativistic heavy ion collisions at high energy provide an opportunity to understand temporal evolution of the quark-gluon plasma created in such collisions by constraining the initial state of the interaction. Due to lack of colour charges the bosons and or particles produced in their leptonic decays are unaffected by the quark-gluon plasma and therefore preserve the information about the very early stage of the collision when they were born. This singles electroweak bosons as a unique and very interesting class of observables in heavy ion collisions. \u0000 \u0000The ATLAS experiment at LHC measures production of electroweak bosons in $pp$, $p$+Pb and Pb+Pb collisions systems. A review of the existing results is given in this proceeding that includes studies made with isolated photons to constraint kinematic properties and flavour composition of associated jets, measurements of $W$ and $Z$ bosons used to estimate nuclear modification of parton distribution function and the production rates of the bosons used to verify geometric models implied to estimate event centrality. A novel analysis on measuring two particle correlations in pp collisions where the $Z$ boson is registered is also discussed in the proceeding. This is the first attempt to break into the initial geometry of the pp collisions by constraining the impact parameter with a hard scattering process. It shows that the strength of the two particle correlations in such collision is $1.08pm0.06$ above the inclusive. To make the measurement ATLAS solves the technical problem of measuring the underlying event in high pileup condition.","PeriodicalId":104537,"journal":{"name":"Proceedings of 12th International Workshop on High-pT Physics in the RHIC/LHC Era — PoS(High-pT2017)","volume":"51 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-02-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130422234","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}
K. Eskola, Petja Paakkinen, H. Paukkunen, C. Salgado
We report on EPPS16, the first global analysis of nuclear parton distribution functions (nPDFs) to include LHC data. Also for the first time, a full flavour dependence of nPDFs is allowed. While the included Z and W data are found to have insufficient statistics to yield stringent constraints, the CMS 5.02 TeV proton-lead dijet data prove crucial in setting the shape of nuclear gluon modifications. With these and other observables being measured in proton-lead runs, we are experiencing a shift of nPDFs to the LHC precision era.
{"title":"EPPS16 – Bringing nuclear PDFs to the LHC era","authors":"K. Eskola, Petja Paakkinen, H. Paukkunen, C. Salgado","doi":"10.22323/1.320.0003","DOIUrl":"https://doi.org/10.22323/1.320.0003","url":null,"abstract":"We report on EPPS16, the first global analysis of nuclear parton distribution functions (nPDFs) to include LHC data. Also for the first time, a full flavour dependence of nPDFs is allowed. While the included Z and W data are found to have insufficient statistics to yield stringent constraints, the CMS 5.02 TeV proton-lead dijet data prove crucial in setting the shape of nuclear gluon modifications. With these and other observables being measured in proton-lead runs, we are experiencing a shift of nPDFs to the LHC precision era.","PeriodicalId":104537,"journal":{"name":"Proceedings of 12th International Workshop on High-pT Physics in the RHIC/LHC Era — PoS(High-pT2017)","volume":"71 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-02-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132147456","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}
In heavy-ion collisions, the quark-gluon plasma is expected to be produced, which is an almost perfect liquid that made up the Universe a few microseconds after the Big Bang. In these collisions, jets are also formed from hadronizing partons with high transverse momentum, and they traverse the hot and dense medium and interact with it. Their properties can be modified by these interactions, therefore these modifications, if present, can give insight into the properties of the plasma itself. Angular correlation measurements can be used to study jets in Pb-Pb collisions in a transverse momentum ($p_{rm T}$) regime where jets are not easily reconstructable above the fluctuating background. Small collision systems (e.g., pp or p-Pb) can be used as reference for these measurements; however, these collisions themselves are of interest. For example, particle production mechanisms and conservation laws can be tested in these systems. Results from Pb-Pb and pp collisions recorded by the ALICE detector are presented in this paper.
{"title":"Angular correlation results from ALICE","authors":"M. Varga-Kofarago","doi":"10.22323/1.320.0037","DOIUrl":"https://doi.org/10.22323/1.320.0037","url":null,"abstract":"In heavy-ion collisions, the quark-gluon plasma is expected to be produced, which is an almost perfect liquid that made up the Universe a few microseconds after the Big Bang. In these collisions, jets are also formed from hadronizing partons with high transverse momentum, and they traverse the hot and dense medium and interact with it. Their properties can be modified by these interactions, therefore these modifications, if present, can give insight into the properties of the plasma itself. Angular correlation measurements can be used to study jets in Pb-Pb collisions in a transverse momentum ($p_{rm T}$) regime where jets are not easily reconstructable above the fluctuating background. Small collision systems (e.g., pp or p-Pb) can be used as reference for these measurements; however, these collisions themselves are of interest. For example, particle production mechanisms and conservation laws can be tested in these systems. Results from Pb-Pb and pp collisions recorded by the ALICE detector are presented in this paper.","PeriodicalId":104537,"journal":{"name":"Proceedings of 12th International Workshop on High-pT Physics in the RHIC/LHC Era — PoS(High-pT2017)","volume":"29 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130809182","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}
For tomographic studies of relativistic nuclear collisions and of the quark-gluon plasma, photons (real and virtual) are unique. They are the only probes than can be both soft and penetrating. First we report on advances in modelling the hadron dynamics of heavy-ion collisions using a hybrid approach which consists of IP-Glasma, relativistic fluid dynamics, and hadronic cascade components. We briefly discuss the "photon flow puzzle", and then focus on a recent development in the theory of photon emission from a non-equilibrium, strongly interacting medium.
{"title":"Direct photon production in relativistic heavy-ion collisions - a theory update","authors":"C. Gale","doi":"10.22323/1.320.0023","DOIUrl":"https://doi.org/10.22323/1.320.0023","url":null,"abstract":"For tomographic studies of relativistic nuclear collisions and of the quark-gluon plasma, photons (real and virtual) are unique. They are the only probes than can be both soft and penetrating. First we report on advances in modelling the hadron dynamics of heavy-ion collisions using a hybrid approach which consists of IP-Glasma, relativistic fluid dynamics, and hadronic cascade components. We briefly discuss the \"photon flow puzzle\", and then focus on a recent development in the theory of photon emission from a non-equilibrium, strongly interacting medium.","PeriodicalId":104537,"journal":{"name":"Proceedings of 12th International Workshop on High-pT Physics in the RHIC/LHC Era — PoS(High-pT2017)","volume":"60 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132487277","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}
In the BDMPSZ model, the energy loss of an outgoing parton in a medium $-dE/dx$ is the transport coefficient $hat{q}$ times $L$ the length traveled. This results in jet quenching, which is well established. However BDMPSZ also predicts an azimuthal broadening of di-jets also proportional to $hat{q}L$ which has so far not been observed. The broadening should produce a larger $k_T$ in A$+$A than in p$+$p collisions. This presentation introduces the observation that the $k_T$ measured in p$+$p collisions for di-hadrons with $p_{Tt}$ and $p_{Ta}$ must be reduced to compensate for the energy loss of both the trigger and away parent partons when comparing to the $k_T$ measured with the same di-hadron $p_{Tt}$ and $p_{Ta}$ in A$+$A collisions. This idea is applied to a recent STAR di-hadron measurement in Au$+$Au at $sqrt{s_{NN}}$=200 GeV, [Phys. Lett. B760 (2016) 689], with result $ =2.1pm 0.6$ GeV$^2$. This is more precise but in agreement with a theoretical calculation of $ =14^{+42}_{-14}$ GeV$^2$ using the same data. Assuming a length $ approx 7$ fm for central Au$+$Au collisions the present result gives $hat{q}approx 0.30pm 0.09$ GeV$^2$/fm, in fair agreement with the JET collaboration result from single hadron suppression of $hat{q}approx 1.2pm 0.3$ GeV$^2$/fm at an initial time $tau_0=0.6$ fm/c in Au$+$Au collisions at $sqrt{s_{NN}}=200$ GeV. There are several interesting details to be discussed: for a given $p_{Tt}$ the $ $ seems to decrease then vanish with increasing $p_{Ta}$; the di-jet spends a much longer time in the medium ($approx 7$ fm/c) then $tau_0=0.6$ fm/c which likely affects the value of $hat{q}$ that would be observed.
{"title":"Measurement of $hat{q}$ in RHI collisions using di-hadron correlations","authors":"M. Tannenbaum","doi":"10.22323/1.320.0036","DOIUrl":"https://doi.org/10.22323/1.320.0036","url":null,"abstract":"In the BDMPSZ model, the energy loss of an outgoing parton in a medium $-dE/dx$ is the transport coefficient $hat{q}$ times $L$ the length traveled. This results in jet quenching, which is well established. However BDMPSZ also predicts an azimuthal broadening of di-jets also proportional to $hat{q}L$ which has so far not been observed. The broadening should produce a larger $k_T$ in A$+$A than in p$+$p collisions. This presentation introduces the observation that the $k_T$ measured in p$+$p collisions for di-hadrons with $p_{Tt}$ and $p_{Ta}$ must be reduced to compensate for the energy loss of both the trigger and away parent partons when comparing to the $k_T$ measured with the same di-hadron $p_{Tt}$ and $p_{Ta}$ in A$+$A collisions. This idea is applied to a recent STAR di-hadron measurement in Au$+$Au at $sqrt{s_{NN}}$=200 GeV, [Phys. Lett. B760 (2016) 689], with result $ =2.1pm 0.6$ GeV$^2$. This is more precise but in agreement with a theoretical calculation of $ =14^{+42}_{-14}$ GeV$^2$ using the same data. Assuming a length $ approx 7$ fm for central Au$+$Au collisions the present result gives $hat{q}approx 0.30pm 0.09$ GeV$^2$/fm, in fair agreement with the JET collaboration result from single hadron suppression of $hat{q}approx 1.2pm 0.3$ GeV$^2$/fm at an initial time $tau_0=0.6$ fm/c in Au$+$Au collisions at $sqrt{s_{NN}}=200$ GeV. There are several interesting details to be discussed: for a given $p_{Tt}$ the $ $ seems to decrease then vanish with increasing $p_{Ta}$; the di-jet spends a much longer time in the medium ($approx 7$ fm/c) then $tau_0=0.6$ fm/c which likely affects the value of $hat{q}$ that would be observed.","PeriodicalId":104537,"journal":{"name":"Proceedings of 12th International Workshop on High-pT Physics in the RHIC/LHC Era — PoS(High-pT2017)","volume":"58 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-01-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132793828","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}
{"title":"Recent Heavy Flavor Results from PHENIX","authors":"Xiaochun He","doi":"10.22323/1.320.0033","DOIUrl":"https://doi.org/10.22323/1.320.0033","url":null,"abstract":"","PeriodicalId":104537,"journal":{"name":"Proceedings of 12th International Workshop on High-pT Physics in the RHIC/LHC Era — PoS(High-pT2017)","volume":"11 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123771919","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}
E. Zabrodin, L. Bravina, G. Eyyubova, I. Lokhtin, L. Malinina, S. Petrushanko, A. Snigirev
The Monte Carlo event generator HYDJET++ (HYDrodynamics with JETs) contains the description of both soft and hard processes in relativistic heavy-ion collisions by combining the parametrized hydrodynamics with the treatment of jets. The interplay of hard and soft processes describes the violation of the mass hierarchy of meson and baryon elliptic $(v_2)$ and triangular $(v_3)$ flows at intermediate transverse momenta, the fall-off of the flow harmonics after the certain $p_T$ threshold, and the worsening of the number-of-constituent-quark (NCQ) scaling of $v_2$ and $v_3$ at LHC energies compared to that at RHIC ones. The role of this interplay in di-hadron correlations and in production of open and hidden charm in heavy-ion collisions at RHIC and LHC energies is also discussed.
{"title":"Interplay between hard and soft processes in HYDJET++ model","authors":"E. Zabrodin, L. Bravina, G. Eyyubova, I. Lokhtin, L. Malinina, S. Petrushanko, A. Snigirev","doi":"10.22323/1.320.0040","DOIUrl":"https://doi.org/10.22323/1.320.0040","url":null,"abstract":"The Monte Carlo event generator HYDJET++ (HYDrodynamics with JETs) \u0000contains the description of both soft and hard processes in relativistic \u0000heavy-ion collisions by combining the parametrized hydrodynamics with \u0000the treatment of jets. The interplay of hard and soft processes \u0000describes the violation of the mass hierarchy of meson and baryon \u0000elliptic $(v_2)$ and triangular $(v_3)$ flows at intermediate transverse \u0000momenta, the fall-off of the flow harmonics after the certain $p_T$ \u0000threshold, and the worsening of the number-of-constituent-quark (NCQ) \u0000scaling of $v_2$ and $v_3$ at LHC energies compared to that at RHIC \u0000ones. The role of this interplay in di-hadron correlations and in \u0000production of open and hidden charm in heavy-ion collisions at RHIC and \u0000LHC energies is also discussed.","PeriodicalId":104537,"journal":{"name":"Proceedings of 12th International Workshop on High-pT Physics in the RHIC/LHC Era — PoS(High-pT2017)","volume":"20 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2017-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123893216","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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