125427818
Anisotropic flows and dihadron correlations in heavy ion collisions
Using a multiphase transport model that includes both initial partonic and final hadronic scatterings, we have studied anisotropic flows and dihadron correla tions as functions of pseudorapidity and azimuthal angular differences between trigger and associated particles in heavy ion collisions at LHC. With parameters in the model determined from fitting t he measured multiplicity density of mid-pseudorapidity charged particles in central collis ions and their elliptic flow in mid-central collisions, the calculated higher-order anisotropic flows from the two-particle cumulant method reproduce approximately those measured in experiments. Similar to experimental results, the two-dimensional dihadron correlations at most central collisions show a ridge structure at the near side and a broad structure at the away side. The short- and long-range dihadron azimuthal correlations, corresponding to small and large pseudorapidity differences, respectively, are studied for triggering particles with different transverse mom enta and are found to be qualitatively consistent with experimental results.
119023494
Shear viscosity of nuclear matter
In this talk I report my recent study on the shear viscosity of neutron-rich nuclear matter from a relaxation time approach. An isospinand momentum-dependent interaction is used in the study. Effects of density, temperature, and isospin asymmetry of nuclear matter on its shear viscosity have been discussed. Similar to the symmetry energy, the symmetry shear viscosity is defined and its density and temperature dependence are studied.
125427818
Anisotropic flows and dihadron correlations in heavy ion collisions
Using a multiphase transport model that includes both initial partonic and final hadronic scatterings, we have studied anisotropic flows and dihadron correla tions as functions of pseudorapidity and azimuthal angular differences between trigger and associated particles in heavy ion collisions at LHC. With parameters in the model determined from fitting t he measured multiplicity density of mid-pseudorapidity charged particles in central collis ions and their elliptic flow in mid-central collisions, the calculated higher-order anisotropic flows from the two-particle cumulant method reproduce approximately those measured in experiments. Similar to experimental results, the two-dimensional dihadron correlations at most central collisions show a ridge structure at the near side and a broad structure at the away side. The short- and long-range dihadron azimuthal correlations, corresponding to small and large pseudorapidity differences, respectively, are studied for triggering particles with different transverse mom enta and are found to be qualitatively consistent with experimental results.
119095770
Temperature effects on the nuclear symmetry energy and symmetry free energy with an isospin and momentum dependent interaction
Within a self-consistent thermal model using an isospin and momentum dependent interaction (MDI) constrained by the isospin diffusion data in heavy-ion collisions, we investigate the temperature dependence of the symmetry energy ${E}_{\mathrm{sym}}(\ensuremath{\rho},T)$ and symmetry free energy ${F}_{\mathrm{sym}}(\ensuremath{\rho},T)$ for hot, isospin asymmetric nuclear matter. It is shown that the symmetry energy ${E}_{\mathrm{sym}}(\ensuremath{\rho},T)$ generally decreases with increasing temperature while the symmetry free energy ${F}_{\mathrm{sym}}(\ensuremath{\rho},T)$ exhibits opposite temperature dependence. The decrement of the symmetry energy with temperature is essentially due to the decrement of the potential energy part of the symmetry energy with temperature. The difference between the symmetry energy and symmetry free energy is found to be quite small around the saturation density of nuclear matter. While at very low densities, they differ significantly from each other. In comparison with the experimental data of temperature dependent symmetry energy extracted from the isotopic scaling analysis of intermediate mass fragments (IMF's) in heavy-ion collisions, the resulting density and temperature dependent symmetry energy ${E}_{\mathrm{sym}}(\ensuremath{\rho},T)$ is then used to estimate the average freeze-out density of the IMF's.
119225572
Density slope of the nuclear symmetry energy from the neutron skin thickness of heavy nuclei
Expressing explicitly the parameters of the standard Skyrme interaction in terms of the macroscopic properties of asymmetric nuclear matter, we show in the Skyrme-Hartree-Fock approach that unambiguous correlations exist between observables of finite nuclei and nuclear matter properties. We find that existing data on neutron skin thickness $\ensuremath{\Delta}{r}_{\mathit{np}}$ of Sn isotopes give an important constraint on the symmetry energy ${E}_{\mathrm{sym}}({\ensuremath{\rho}}_{0})$ and its density slope $L$ at saturation density ${\ensuremath{\rho}}_{0}$. Combining these constraints with those from recent analyses of isospin diffusion and the double neutron/proton ratio in heavy-ion collisions at intermediate energies leads to a more stringent limit on $L$ approximately independent of ${E}_{\mathrm{sym}}({\ensuremath{\rho}}_{0})$. The implication of these new constraints on the $\ensuremath{\Delta}{r}_{\mathit{np}}$ of $^{208}\mathrm{Pb}$ as well as the core-crust transition density and pressure in neutron stars is discussed.
119288462
Non-Newtonian gravity in finite nuclei
In this talk, we report our recent study of constraining the non-Newtonian gravity at femtometer scale. We incorporate the Yukawa-type non-Newtonian gravitational potential consistently to the Skyrme functional form using the exact treatment for the direct contribution and density-matrix expansion method for the exchange contribution. The effects from the non-Newtonian potential on finite nuclei properties are then studied together with a well-tested Skyrme force. Assuming that the framework without non-Newtonian gravity can explain the binding energies and charge radii of medium to heavy nuclei within 2% error, we set an upper limit for the strength of the non-Newtonian gravitational potential at femtometer scale.
121568193
Energy determination at BEPC-II
The BEPC-II collider beam energy calibration system is discussed. The system is based on the Compton backscattering method. The expected precision of the electron and positron beam energy e determination is δ e / e ≈ 3 ⋅ 10 − 5 .
124654178
Extracting the jet transport coefficient from jet quenching in high-energy heavy-ion collisions
Within five different approaches to parton propagation and energy loss in dense matter, a phenomenological study of experimental data on suppression of large $p_T$ single inclusive hadrons in heavy-ion collisions at both RHIC and LHC was carried out. The evolution of bulk medium used in the study for parton propagation was given by 2+1D or 3+1D hydrodynamic models which are also constrained by experimental data on bulk hadron spectra. Values for the jet transport parameter $\hat q$ at the center of the most central heavy-ion collisions are extracted or calculated within each model, with parameters for the medium properties that are constrained by experimental data on the hadron suppression factor $R_{AA}$. For a quark with initial energy of 10 GeV we find that $\hat q\approx 1.2 \pm 0.3$ GeV$^2$/fm at an initial time $\tau_0=0.6$ fm/$c$ in Au+Au collisions at $\sqrt{s}=200$ GeV/n and $\hat q\approx 1.9 \pm 0.7 $ GeV$^2$/fm in Pb+Pb collisions at $\sqrt{s}=2.76 $ TeV/n. Compared to earlier studies, these represent significant convergence on values of the extracted jet transport parameter, reflecting recent advances in theory and the availability of new experiment data from the LHC.
119117591
PROPERTIES AND KEPLERIAN ROTATION OF THE HOT CORE IRAS 20126+4104
We present Submillimeter Array (SMA) observations of the massive star-forming region IRAS 20126+4104 in the millimeter continuum and in several molecular line transitions. With the SMA data, we have detected nine molecular transitions, including deuterated hydrogen cyanide, CH{sub 3}OH, H{sub 2}CO, and HC{sub 3}N molecules, and imaged each molecular line. From the 1.3 mm continuum emission a compact millimeter source is revealed, which is also associated with H{sub 2}O, OH, and CH{sub 3}OH masers. Using a rotation temperature diagram, we derive that the rotational temperature and the column density of CH{sub 3}OH are 200 K and 3.7 Multiplication-Sign 10{sup 17} cm{sup -2}, respectively. The calculated results and analysis further indicate that a hot core coincides with IRAS 20126+4104. The position-velocity diagrams of H{sub 2}CO (3{sub 0,3}-2{sub 0,2}) and HC{sub 3}N (25-24) clearly present Keplerian rotation. Moreover, H{sub 2}CO (3{sub 0,3}-2{sub 0,2}) is found to trace the disk rotation for the first time.
119284289
The tricky azimuthal dependence of jet quenching at RHIC and LHC via CUJET2.0
Abstract High transverse momentum neutral pion and charged hadron suppression pattern with respect to reaction plane at RHIC and LHC energies in central and semi-peripheral AA collisions are studied in a perturbative QCD based model, CUJET2.0. CUJET2.0 has dynamical DGLV radiation kernel and Thoma–Gyulassy elastic energy loss, with both being generalized to including multi-scale running strong coupling as well as energy loss probability fluctuations, and the full jet path integration is performed in a low p T flow data constrained medium which has 2+1D viscous hydrodynamical expanding profile. We find that in CUJET2.0, with only one control parameter, α max , the maximum coupling strength, fixed to be 0.26, the computed nuclear modification factor R AA in central and semi-peripheral AA collisions are consistent with RHIC and LHC data at average χ 2 / d.o.f. 1.5 level. Simultaneous agreements with high p T azimuthal anisotropy v 2 data are acquired given average α max over in-plane and out-of-plane paths varying as little as 10%, suggesting a non-trivial dependence of the high p T single particle v 2 on the azimuthally varied strong coupling.
119114895
The open cluster NGC 6823 and possible triggered star formation associated with SNR G59.5+0.1
Aims. We investigate the environment in the vicinity of the supernova remnant (SNR) G59.5+0.1 and identify all the young stellar objects (YSOs) around the SNR, to derive the physical properties, obtain insight into the star-formation history, and determine whether SNR G59.5+0.1 can trigger star formation in this region. Methods. We perform the submillimeter/millimeter observations in CO lines toward the southeast of SNR G59.5+0.1 with the KOSMA 3 m Telescope. High values of the integrated CO line-intensity ratio RICO(3−2)/ICO(2−1) is identified as one good signature of the SNR-MC (molecular cloud) interacting system. To investigate the impact of SNR G59.5+0.1 on the process of star formation, we use GLIMPSE I catalog to select YSOs (including Class I and Class II sources). Results. The CO emission forming an arc-like shape and mid-infrared 8.28 μm emission are coincident with SNR G59.5+0.1, which ‐ ‐