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Search Results: 1 - 10 of 19877 matches for " Heng-Tong Ding "
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In-medium hadron properties from lattice QCD
Ding Heng-Tong
EPJ Web of Conferences , 2012, DOI: 10.1051/epjconf/20123600008
Abstract: I review recent results from lattice QCD calculations on the in-medium hadron properties. I discuss the thermal dilepton rates, heavy quarkonium properties as well as the chiral and U(1)A symmetries at finite temperature.
Exploring QCD phase diagram at vanishing baryon density on the lattice
Heng-Tong Ding
Physics , 2013, DOI: 10.1088/1742-6596/432/1/012027
Abstract: I report on the current status of QCD phase diagram at vanishing baryon density. I focus on the QCD phase diagram with three degenerate quark flavor using Highly Improved Staggered Quarks on $N_{\tau}=6$ lattices. No evidence of a first order phase transition in the pion mass window of $80\lesssim m_{\pi} \lesssim 230 $MeV is found. The pion mass at the critical point where the chiral first order phase transition ends is estimated to be $m^c_{\pi} \lesssim 45$ MeV.
Recent lattice QCD results and phase diagram of strongly interacting matter
Heng-Tong Ding
Physics , 2014, DOI: 10.1016/j.nuclphysa.2014.09.053
Abstract: I review recent lattice QCD results on a few selected topics which are relevant to the heavy ion physics community. Special emphasis is put on the QCD equation of state at vanishing and nonzero baryon chemical potential, the onset of deconfinement of open strange and charmed hadrons, the contribution from experimentally not yet observed hadrons to the thermodynamics of the hadronic gas and their influence on freeze-out conditions of strange and light-quark hadrons.
Momentum dependences of charmonium properties from lattice QCD
Heng-Tong Ding
Physics , 2012, DOI: 10.1016/j.nuclphysa.2013.02.092
Abstract: Charmonia produced in initial hard parton scatterings during heavy ion collisions move with respect to the medium rather than flow with the medium. Lattice studies suggest that charmonium bound states at the rest are dissociated at $T\gtrsim 1.5 T_c$. We present results on momentum dependences of charmonium properties in a hot medium from lattice QCD Monte Carlo simulations. The dispersion relation of the screening mass and the change of correlation and spectral functions at various temperatures and momenta are discussed.
Hard and thermal probes of QGP from the perspective of Lattice QCD
Heng-Tong Ding
Physics , 2014, DOI: 10.1016/j.nuclphysa.2014.08.066
Abstract: In this talk I review the current status of lattice QCD results on the hard and thermal probes of QGP, including jet quenching parameters, the melting of quarkonia and open heavy flavours, thermal photon/dilepton rates, electrical conductivity as well as heavy quark diffusion coefficients.
Thermodynamics of heavy-light hadrons
Heng-Tong Ding,for the BNL-Bielefeld-CCNU collaboration
Physics , 2014,
Abstract: Ratios of cumulants of conserved net charge fluctuations are sensitive to the degrees of freedom that are carriers of the corresponding quantum numbers in different phases of strong interaction matter. We calculate second and fourth order cumulants of net charm and strange fluctuations and their correlations with other conserved charges such as net baryon number and electric charge. Simulation are performed on $N_\tau$=6 and 8 lattices using the Highly Improved Staggered Quark (HISQ) action with a light to strange quark mass ratio of 1/20 and having charm quarks treated in the quenched approximation. Analysing appropriate ratios of these cumulants we observe that both open strange and charm hadrons start to get dissociated in the chiral crossover region. We provide indirect evidence for the existence of additional, experimentally yet unobserved open charm and strange hadrons from QCD thermodynamics. This is done by comparing lattice QCD results to Hadron Resonance Gas (HRG) model calculations performed with a hadron spectrum as listed in the Particle Data Tables as well as with a spectrum predicted in the relativistic quark model and observed in lattice QCD calculations. We also discuss the influence of these experimentally yet unobserved states on the determination of freeze-out temperature and chemical potentials from heavy ion collision experiments. We found that including these additional states in the HRG model leads to a systematic 5-8 MeV decrease in the freeze-out temperature of strange hadrons.
Vector spectral functions and transport properties in quenched QCD
Heng-Tong Ding,Olaf Kaczmarek,Florian Meyer
Physics , 2014,
Abstract: We present new results on the reconstruction of mesonic spectral functions for three temperatures $1.1T_c$, $1.2T_c$ and $1.4T_c$ in quenched QCD. Making use of non-perturbatively improved clover Wilson valence quarks allows for a clean extrapolation of correlator data to the continuum limit. For the case of vanishing momentum the spectral function is obtained by fitting the data to a well motivated ansatz, using the full covariance matrix of the continuum extrapolated data in the fit. We found that vector correlation function is almost temperature independent in the current temperature window. The electrical conductivity of the hot medium, related to the origin of the vector spectral function at zero momentum, is computed from the resulting parameters at all three temperatures, leading to an estimate of $0.2C_{em}\lesssim \sigma/T\lesssim0.4C_{em}$. The dilepton rates resulting from the obtained spectral functions show no significant temperature dependence.
Thermodynamics of strong-interaction matter from Lattice QCD
Heng-Tong Ding,Frithjof Karsch,Swagato Mukherjee
Physics , 2015,
Abstract: We review results from lattice QCD calculations on the thermodynamics of strong-interaction matter with emphasis on input these calculations can provide to the exploration of the phase diagram and properties of hot and dense matter created in heavy ion experiments. This review is organized as follows: 1) Introduction, 2) QCD thermodynamics on the lattice, 3) QCD phase diagram at high temperature, 4) Bulk thermodynamics, 5) Fluctuations of conserved charges, 6) Transport properties, 7) Open heavy flavors and heavy quarkonia, 8) QCD in external magnetic fields, 9) Summary.
A stochastic approach to the reconstruction of spectral functions in lattice QCD
Hai-Tao Shu,Heng-Tong Ding,Olaf Kaczmarek,Swagato Mukherjee,Hiroshi Ohno
Physics , 2015,
Abstract: We present a Stochastic Optimization Method (SOM) for the reconstruction of the spectral functions (SPFs) from Euclidean correlation functions. In this approach the SPF is parameterized as a sum of randomly distributed boxes. By varying the width, location and height of the boxes stochastically an optimal SPF can be obtained. Using this approach we reproduce mock SPFs fairly well, which contain sharp resonance peaks, transport peaks and continuum spectra. We also analyzed the charmonium correlators obtained from $N_{\tau}$=96, 48, 32 lattices using SOM and found similar conclusion on the dissociation temperatures of charmonium ground states as that obtained using the Maximum Entropy Method.
Chiral phase transition of $N_f$=2+1 and 3 QCD at vanishing baryon chemical potential
Heng-Tong Ding,Prasad Hegde,for the Bielefeld-BNL-CCNU collaboration
Physics , 2015,
Abstract: We present updated results on chiral phase structure in (2+1)-flavor ($N_f$=2+1) and 3-flavor ($N_f=3$) QCD based on the simulations using Highly Improved Staggered Quarks on lattices with temporal extent $N_\tau$ =6 at vanishing baryon chemical potential. In $N_f$=2+1 QCD we have performed simulations with a strange quark fixed to its physical value and two degenerate light quarks whose values are adjusted to have 5 values of Goldstone pion masses in the region of 160 - 80 MeV in the continuum limit. The universal scaling behavior of chiral condensates as well as chiral susceptibilities is discussed and the tri-critical point is suggested to be located below the physical point, i.e. at smaller than physical strange quark mass. In $N_f$=3 QCD simulations with 6 different masses of 3 degenerate quarks corresponding to the Goldstone pion masses in the region of 230 - 80 MeV have also been performed. Our results suggest that the QCD transition with these values of quark masses is of crossover type and an upper bound of the critical pion mass where the first order phase transition starts is estimated to be about 50 MeV.
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