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Register a new userGluon emission from heavy quarks in dense nuclear matter
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We study the medium-induced gluon emission process experienced by a hard jet parton propagating through the dense nuclear matter in the framework of deep inelastic scattering off a large nucleus. We work beyond the collinear rescattering expansion and the soft gluon emission limit, and derive a closed formula for the medium-induced single gluon emission spectrum from a heavy or light quark jet interacting with the dense nuclear medium via transverse and longitudinal scatterings. Without performing the collinear rescattering expansion, the medium-induced gluon emission spectrum is controlled by the full distribution of the differential elastic scattering rates between the propagating partons and the medium constituents. We further show that if one utilizes heavy static scattering centers for the traversed nuclear matter and takes the soft gluon emission limit, our result can reduce to the first order in opacity Djordjevic-Gyulassy-Levai-Vitev formula.
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We develop a new heavy quark transport model, QLBT, to simulate the dynamical propagation of heavy quarks inside the quark-gluon plasma (QGP) created in relativistic heavy-ion collisions. Our QLBT model is based on the linear Boltzmann transport (LBT) model with the ideal QGP replaced by a collection of quasi-particles to account for the non-perturbative interactions among quarks and gluons of the hot QGP. The thermal masses of quasi-particles are fitted to the equation of state from lattice QCD simulations using the Bayesian statistical analysis method. Combining QLBT with our advanced hybrid fragmentation-coalescence hadronization approach, we calculate the nuclear modification factor $R_mathrm{AA}$ and the elliptic flow $v_2$ of $D$ mesons at the Relativistic Heavy-Ion Collider and the Large Hadron Collider. By comparing our QLBT calculation to the experimental data on the $D$ meson $R_mathrm{AA}$ and $v_2$, we extract the heavy quark transport parameter $hat{q}$ and diffusion coefficient $D_mathrm{s}$ in the temperature range of $1-4~T_mathrm{c}$, and compare them with the lattice QCD results and other phenomenological studies.
A three-dimensional effective lattice theory of Polyakov loops is derived from QCD by expansions in the fundamental character of the gauge action, u, and the hopping parameter, kappa, whose action is correct to kappa^n u^m with n+m=4. At finite baryon density, the effective theory has a sign problem which meets all criteria to be simulated by complex Langevin as well as by Monte Carlo on small volumes. The theory is valid for the thermodynamics of heavy quarks, where its predictions agree with simulations of full QCD at zero and imaginary chemical potential. In its region of convergence, it is moreover amenable to perturbative calculations in the small effective couplings. In this work we study the challenging cold and dense regime. We find unambiguous evidence for the nuclear liquid gas transition once the baryon chemical potential approaches the baryon mass, and calculate the nuclear equation of state. In particular, we find a negative binding energy per nucleon causing the condensation, whose absolute value decreases exponentially as mesons get heavier. For decreasing meson mass, we observe a first order liquid gas transition with an endpoint at some finite temperature, as well as gap between the onset of isospin and baryon condensation.
We evaluate heavy-quark (HQ) transport properties in a Quark-Gluon Plasma (QGP) employing interaction potentials extracted from thermal lattice QCD. Within a Brueckner many-body scheme we calculate in-medium T-matrices for charm- and bottom-quark scattering off light quarks in the QGP. The interactions are dominated by attractive meson and diquark channels which support bound and resonance states up to temperatures of ~1.5 T_c. We apply pertinent drag and diffusion coefficients (supplemented by perturbative scattering off gluons) in Langevin simulations in an expanding fireball to compute HQ spectra and elliptic flow in sqrt{s_{NN}}=200 GeV Au-Au collisions. We find good agreement with semileptonic electron-decay spectra which supports our nonperturbative computation of the HQ diffusion coefficient, suggestive for a strongly coupled QGP.
Lattice QCD at finite density suffers from a severe sign problem, which has so far prohibited simulations of the cold and dense regime. Here we study the onset of nuclear matter employing a three-dimensional effective theory derived by combined strong coupling and hopping expansions, which is valid for heavy but dynamical quarks and has a mild sign problem only. Its numerical evaluations agree between a standard Metropolis and complex Langevin algorithm, where the latter is free of the sign problem. Our continuum extrapolated data clearly show a first order phase transition building up at $mu_B approx m_B$ as the temperature approaches zero. An excellent description of the data is achieved by an analytic solution in the strong coupling limit.
The three-dimensional pion and kaon emission source functions are extracted from the HKM model simulations of the central Au+Au collisions at the top RHIC energy $sqrt{s_{NN}}=200$ GeV. The model describes well the experimental data, previously obtained by the PHENIX and STAR collaborations using the imaging technique. In particular, the HKM reproduces the non-Gaussian heavy tails of the source function in the pair transverse momentum (out) and beam (long) directions, observed in the pion case and practically absent for kaons. The role of the rescatterings and long-lived resonances decays in forming of the mentioned long range tails is investigated. The particle rescatterings contribution to the out tail seems to be dominating. The model calculations also show the substantial relative emission times between pions (with mean value 14.5 fm/c in LCMS), including those coming from resonance decays and rescatterings. The prediction is made for the source functions in the LHC Pb+Pb collisions at $sqrt{s_{NN}}=2.76$ TeV, which are still not extracted from the measured correlation functions.
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