scholarly journals Open-Charm Hadron Measurements in Au+Au Collisions at √sNN = 200 GeV by the STAR Experiment

Universe ◽  
2019 ◽  
Vol 5 (9) ◽  
pp. 196
Author(s):  
Jan Vanek
Keyword(s):  
D Mesons ◽  
Heavy Ion ◽  
Gluon Plasma ◽  
Open Charm ◽  
Strong Interactions ◽  
Heavy Flavor ◽  
Directed Flow ◽  
Charm Quarks ◽  
Charm Hadron ◽  
200 Gev

Study of the open-charm hadron production in heavy-ion collisions is crucial for understanding the properties of the Quark-Gluon Plasma. In these papers, we report on a selection of recent STAR measurements of open-charm hadrons in Au+Au collisions at s NN = 200 GeV , using the Heavy-Flavor Tracker. In particular, the nuclear modification factors of D 0 and D ± mesons, elliptic and directed flow of D 0 mesons, D s /D 0 and Λ c / D 0 yield ratios are discussed. The observed suppression of D 0 and D ± mesons suggests strong interactions of the charm quarks with the QGP. The measured elliptic flow of D 0 mesons is large and follows the NCQ scaling, suggesting that charm quarks may be close to thermal equilibrium with the QGP medium. Both D s /D 0 and Λ c / D 0 yield ratios are found to be enhanced in Au+Au collisions. The enhancement can be explained by models incorporating coalescence hadronization of charm quarks. In addition, the directed flow of the D 0 mesons is measured to be negative and larger than that of light-flavor mesons which is in a qualitative agreement with hydrodynamic model predictions with a tilted QGP bulk.

scholarly journals Measurements of charm hadron production and anisotropic flow in Au+Au collisions at 200 GeV with the STAR experiment at RHIC

2018 ◽  
Vol 171 ◽  
pp. 18006 ◽  
Author(s):  
Sooraj Radhakrishnan
Keyword(s):  
Charm Quark ◽  
Heavy Ion ◽  
Gluon Plasma ◽  
Hadronic Decay ◽  
Heavy Flavor ◽  
Model Calculations ◽  
Anisotropic Flow ◽  
Ion Collisions ◽  
200 Gev ◽  
Heavy Flavor Quarks

Heavy flavor quarks, owing to their large masses, are predominantly produced through initial hard parton scatterings in heavy-ion collisions, and thus are excellent probes to study properties of the strongly coupled Quark Gluon Plasma (sQGP) medium produced in these collisions. Measurements of anisotropic flow harmonics of heavy flavor hadrons can provide information on the properties of the medium, including the heavy flavor transport coefficient. Charm quark hadronization mechanism in the sQGP medium can be studied through measurements of yields of different charm hadrons. In these proceedings we report on the measurements of elliptic and triangular flow harmonics of D0 mesons as well as the yield ratios of D±s/D0 and Λ±c/D0 in Au+Au collisions at [see formula in PDF] = 200 GeV at RHIC with the STAR detector. These measurements use the STAR Heavy Flavor Tracker (HFT) to reconstruct charm hadrons via their hadronic decay channels. Results are compared to model calculations and the implications on the understanding of charm quark dynamics in the medium are discussed.

scholarly journals Studies of Heavy Flavor Jets Using D0-Hadron Correlations in Azimuth and Pseudorapidity in Au Au Collisons at 200 GeV at the STAR Experiment

Proceedings ◽  
2019 ◽  
Vol 10 (1) ◽  
pp. 34
Author(s):  
Alexander Jentsch
Keyword(s):  
Early Stage ◽  
Heavy Ion ◽  
Azimuthal Anisotropy ◽  
Relativistic Heavy Ion Collisions ◽  
Strong Interactions ◽  
Heavy Flavor ◽  
Angular Correlations ◽  
Ion Collisions ◽  
200 Gev ◽  
Star Experiment

Heavy flavor (HF) quarks (charm, bottom) are important probes of the medium produced in relativistic heavy-ion collisions because they are formed in the early stage and propagate throughout the lifetime of the system. HF-meson spectra and azimuthal anisotropy ( v 2 ) measurements have been reported by experiments at RHIC and the LHC, and they suggest strong interactions of HF quarks with the medium. D 0 -hadron correlations on relative pseudorapidity and azimuth ( Δ η , Δ ϕ ) provide a method for disentangling correlation structures on ( Δ η , Δ ϕ )—allowing for separation of structures related to jets and bulk phenomena directly, with the D 0 serving as a proxy for a charm jet. In these proceedings, we present 2D D 0 -hadron angular correlations as a function of centrality in Au + Au collisions at s N N = 200 GeV. These data reveal a jet-like, peaked structure at ( Δ η , Δ ϕ ) = (0, 0) (near-side), and a Δ η -independent azimuthal harmonic modulation. Here, we focus on the evolution of the near-side peak’s yield and widths on ( Δ η , Δ ϕ ) as a function of centrality and compare them to results from light flavor correlations.

Understanding the unexpected suppression patterns at RHIC and LHC

2014 ◽  
Vol 29 (31) ◽  
pp. 1430035
Author(s):  
Magdalena Djordjevic ◽  
Marko Djordjevic
Keyword(s):  
Heavy Ion Collisions ◽  
D Mesons ◽  
Heavy Ion ◽  
Theoretical Framework ◽  
Relativistic Heavy Ion Collisions ◽  
Heavy Flavor ◽  
Major Goal ◽  
Neutral Pions ◽  
Single Electrons ◽  
Ion Collisions

Understanding properties of QCD matter created in ultra-relativistic heavy-ion collisions is a major goal of RHIC and LHC experiments. Suppression of light and heavy flavor observables is a powerful tool to understand these properties and the suppressions of underlying partons appear to suggest a clear hierarchy in the suppression of these observables. However, the measurements show significant qualitative differences between the observed and intuitively expected patterns, in particular for neutral pions and single electrons at RHIC and for charged hadrons and D mesons at LHC, which are denoted as heavy flavor puzzles at RHIC and LHC. In this review, we discuss these puzzles and also summarize evidence that they can be consistently explained within the same theoretical framework.

scholarly journals The signature of charge dependent directed flow observables by electromagnetic fields in heavy ion collisions

2021 ◽  
Vol 136 (7) ◽  
Author(s):  
Yifeng Sun ◽  
Vincenzo Greco ◽  
Salvatore Plumari
Keyword(s):  
Magnetic Field ◽  
Electromagnetic Fields ◽  
Complex Dynamics ◽  
Azimuthal Angle ◽  
Charged Particles ◽  
Heavy Ion ◽  
Strong Interactions ◽  
Directed Flow ◽  
The Difference ◽  
Freeze Out

AbstractWe discuss the generation of the directed flow $$v_1(p_T,y_z)$$ v 1 ( p T , y z ) induced by the electromagnetic field as a function of $$p_T$$ p T and $$y_z$$ y z . Despite the complex dynamics of charged particles due to strong interactions generating several anisotropies in the azimuthal angle, it is possible at $$p_T > m$$ p T > m to directly correlate the splitting in $$v_1$$ v 1 of heavy quarks with different charges to some main features of the magnetic field, and in particular its values at formation and freeze-out time. We further found that the slope of the splitting $$d\Delta v_1/dy_z|_{y_z=0}$$ d Δ v 1 / d y z | y z = 0 of positively and negatively charged particles at high $$p_T$$ p T can be formulated as $$d\Delta v_1/dy_z|_{y_z=0}=-\alpha \frac{\partial \ln f}{\partial p_T}+\frac{2\alpha -\beta }{p_T}$$ d Δ v 1 / d y z | y z = 0 = - α ∂ ln f ∂ p T + 2 α - β p T , where f is the $$p_T$$ p T spectra of the charged particles and the constants $$\alpha $$ α and $$\beta $$ β (order of MeV) are constrained by the y component of magnetic fields and the sign of $$\alpha $$ α is simply determined by the difference $$\Delta [tB_y(t)]$$ Δ [ t B y ( t ) ] in the center of colliding systems at the formation time of particles and at the time when particles leave the effective range of electromagnetic fields or freeze out. The formula is derived from general considerations and is confirmed by several related numerical simulations; it supplies a useful guide to quantify the effect of different magnetic field configurations and provides an evidence of why the measurement of $$\Delta v_1$$ Δ v 1 of charm, bottom and leptons from $$Z^0$$ Z 0 decay and their correlations are a powerful probe of the initial e.m. fields in ultra-relativistic collisions.

scholarly journals Data-driven extraction of heavy quark diffusion in quark-gluon plasma

2020 ◽  
Vol 80 (7) ◽  
Author(s):  
Shuang Li ◽  
Jinfeng Liao
Keyword(s):  
Diffusion Coefficient ◽  
Heavy Quark ◽  
Quark Gluon Plasma ◽  
Heavy Ion ◽  
Gluon Plasma ◽  
Data Driven ◽  
Strong Increase ◽  
Heavy Flavor ◽  
Modeling Framework ◽  
Wide Range

Abstract Heavy quark production provides a unique probe of the quark-gluon plasma transport properties in heavy ion collisions. Experimental observables like the nuclear modification factor $$R_\mathrm{AA}$$RAA and elliptic anisotropy $$v_\mathrm{2}$$v2 of heavy flavor mesons are sensitive to the heavy quark diffusion coefficient. There now exist an extensive set of such measurements, which allow a data-driven extraction of this coefficient. In this work, we make such an attempt within our recently developed heavy quark transport modeling framework (Langevin-transport with Gluon Radiation, LGR). A question of particular interest is the temperature dependence of the diffusion coefficient, for which we test a wide range of possibility and draw constraints by comparing relevant charm meson data with model results. We find that a relatively strong increase of diffusion coefficient from crossover temperature $$T_c$$Tc toward high temperature is preferred by data. We also make predictions for Bottom meson observables for further experimental tests.

scholarly journals Heavy-Flavor Measurements with the ALICE Experiment at the LHC

Universe ◽  
2019 ◽  
Vol 5 (5) ◽  
pp. 130 ◽  
Author(s):  
Róbert Vértesi
Keyword(s):  
Heavy Ion ◽  
Gluon Plasma ◽  
Heavy Quarks ◽  
Heavy Flavor ◽  
Successful Completion ◽  
Alice Experiment ◽  
Ion Collisions ◽  
State Of Matter ◽  
Heavy Flavor Quarks ◽  
Dense State

Heavy quarks (charm and beauty) are produced early in the nucleus–nucleus collisions, and heavy flavor survives throughout the later stages. Measurements of heavy-flavor quarks thus provide us with means to understand the properties of the Quark–Gluon Plasma, a hot and dense state of matter created in heavy-ion collisions. Production of heavy-flavor in small collision systems, on the other hand, can be used to test Quantum-chromodynamics models. After a successful completion of the Run-I data taking period, the increased luminosity from the LHC and an upgraded ALICE detector system in the Run-II data taking period allows for unprecedented precision in the study of heavy quarks. In this article we give an overview of selected recent results on heavy-flavor measurements with ALICE experiments at the LHC.

scholarly journals Open Heavy-Flavor Production in Heavy-Ion Collisions

2019 ◽  
Vol 69 (1) ◽  
pp. 417-445 ◽  
Author(s):  
Xin Dong ◽  
Yen-Jie Lee ◽  
Ralf Rapp
Keyword(s):  
Hadron Collider ◽  
Transport Coefficients ◽  
Diffusion Constant ◽  
Heavy Ion ◽  
Gluon Plasma ◽  
Radiative Energy ◽  
Heavy Flavor ◽  
Relativistic Heavy Ion Collider ◽  
Radiative Energy Loss ◽  
Ion Collisions

The ultrarelativistic heavy-ion programs at the Relativistic Heavy Ion Collider and the Large Hadron Collider have entered an era of quantitative analysis of quantum chromodynamics (QCD) at high temperatures. The remarkable discovery of the strongly coupled quark–gluon plasma (sQGP), as deduced from its hydrodynamic behavior at long wavelengths, calls for probes that can reveal its inner workings. Charm- and bottom-hadron spectra offer unique insights into the transport properties and the microscopic structure of the QCD medium created in these collisions. At low momentum the Brownian motion of heavy quarks in the sQGP gives access to their diffusion constant, at intermediate momentum these quarks give insight into hadronization mechanisms, and at high momentum they are expected to merge into a radiative-energy loss regime. We review recent experimental and theoretical achievements on measuring a variety of heavy-flavor observables, characterizing the different regimes in momentum and extracting pertinent transport coefficients to unravel the structure of the sQGP and its hadronization.

scholarly journals Production of Open-Charm Hadrons in AuAu Collisions at sNN=200GeV Mesured by the STAR Experiment +†

Proceedings ◽  
2019 ◽  
Vol 10 (1) ◽  
pp. 10 ◽  
Author(s):  
Jan Vanek
Keyword(s):  
Charm Quark ◽  
Heavy Ion ◽  
Open Charm ◽  
Hadronic Decay ◽  
Relativistic Heavy Ion Collisions ◽  
Supervised Machine Learning ◽  
Machine Learning Techniques ◽  
Heavy Flavor ◽  
Quark Interaction ◽  
Star Experiment

Charm quarks are primarily produced at the early stages of ultra-relativistic heavy-ion collisions and can therefore probe the quark-gluon plasma throughout its whole evolution. Final-state open-charm hadrons are commonly used to experimentally study the charm quark interaction with the medium. Thanks to the excellent secondary vertex resolution provided by the Heavy Flavor Tracker, STAR is able to directly reconstruct D ± , D 0 , D s , and Λ c ± via their hadronic decay channels. The topological cuts for signal extraction are optimized using supervised machine learning techniques. In these proceedings, we present an overview of recent open charm results from the STAR experiment. The nuclear modification factors of open-charm mesons and Λ c ± /D 0 ratio are shown as functions of transverse momentum and collision centrality.

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