118395281
NLO corrections to $\chi_{bJ}$ to two-$J/\psi$ exclusive decay processes
The next-to-leading order QCD corrections for $\chi_{bJ}$, the p-wave bottomonium, to $J/\psi$ pair decay processes are evaluated utilizing NRQCD factorization formalism. The scale dependence of $\chi_{b2}\rightarrow J/\psi J/\psi$ process is depressed with NLO corrections, and hence the uncertainties in the leading order results are greatly reduced. The total branch ratios are found to be the order of $10^{-5}$ for all three $\chi_{bJ}\rightarrow J/\psi J/\psi$ processes, indicating that they are observable in the LHC and super-B experiments.
119289860
P-wave quarkonium decays to meson pairs
A bstractThe processes of p-wave Quarkonium exclusive decays to two mesons are investigated, in which the final state vector mesons with various polarizations are considered separately. In the calculation, the initial heavy quarkonia are treated in the framework of non-relativistic quantum chromodynamics, whereas for light mesons, the light cone distribution amplitudes up to twist-3 are employed. It turns out that the higher twist contribution is significant and provides a possible explanation for the observation of the hadron helicity selection rule violated processes χc1→ φφ, ωω by the BESIII collaboration in recently. We also evaluate the χb1→ J/ψJ/ψ process and find that its branching ratio is big enough to be measured at the B-factories.
118532565
Higher order bulk characteristic parameters of asymmetric nuclear matter
The bulk parameters characterizing the energy of symmetric nuclear matter and the symmetry energy defined at normal nuclear density ρ0 provide important information on the equation of state (EOS) of isospin asymmetric nuclear matter. While significant progress has been made in determining some lower order bulk characteristic parameters, such as the energy E0(ρ0) and incompressibility K0 of symmetric nuclear matter as well as the symmetry energy Esym(ρ0) and its slope parameter L, yet the higher order bulk characteristic parameters are still poorly known. Here, we analyze the correlations between the lower and higher order bulk characteristic parameters within the framework of Skyrme Hartree-Fock energy density functional and then estimate the values of some higher order bulk characteristic parameters. In particular, we obtain J0 = (−355±95) MeV and I0 = (1473±680) MeV for the thirdorder and fourth-order derivative parameters of symmetric nuclear matter at ρ0 and Ksym = (−100 ± 165) MeV, Jsym = (224 ± 385) MeV, Isym = (−1309 ± 2025) MeV for the curvature parameter, third-order and fourth-order derivative parameters of the symmetry energy at ρ0, using the empirical constraints on E0(ρ0), K0, Esym(ρ0), L, and the isoscalar and isovector nucleon effective masses. Furthermore, our results indicate that the three parameters E0(ρ0), K0, and J0 can reasonably characterize the EOS of symmetric nuclear matter up to 2ρ0 while the symmetry energy up to 2ρ0 can be well described by Esym(ρ0), L, and Ksym.
119342398
Single and double π − / π + ratios in heavy-ion reactions as probes of the high-density behavior of the nuclear symmetry energy
Based on the isospin- and momentum-dependent hadronic transport model IBUU04, effects of the nuclear symmetry energy on the single and double ${\ensuremath{\pi}}^{\ensuremath{-}}/{\ensuremath{\pi}}^{+}$ ratios in central reactions of $^{132}\mathrm{Sn}+^{124}\mathrm{Sn}$ and $^{112}\mathrm{Sn}+^{112}\mathrm{Sn}$ at a beam energy of 400 MeV/nucleon are studied. It is found that around the Coulomb peak of the single ${\ensuremath{\pi}}^{\ensuremath{-}}/{\ensuremath{\pi}}^{+}$ ratio the double ${\ensuremath{\pi}}^{\ensuremath{-}}/{\ensuremath{\pi}}^{+}$ ratio taken from the two isotopic reactions retains about the same sensitivity to the density dependence of nuclear symmetry energy. Because the double ${\ensuremath{\pi}}^{\ensuremath{-}}/{\ensuremath{\pi}}^{+}$ ratio can significantly reduce the systematic errors, it is thus a more effective probe for the high-density behavior of the nuclear symmetry energy.
16543900
DETERMINING THE DENSITY DEPENDENCE OF THE NUCLEAR SYMMETRY ENERGY USING HEAVY-ION REACTIONS
We review recent progress in the determination of the subsaturation density behavior of the nuclear symmetry energy from heavy-ion collisions as well as the theoretical progress in probing the high density behavior of the symmetry energy in heavy-ion reactions induced by high energy radioactive beams. We further discuss the implications of these results for the nuclear effective interactions and the neutron skin thickness of heavy nuclei.
30546560
Circumstantial evidence for a soft nuclear symmetry energy at suprasaturation densities.
Within an isospin- and momentum-dependent hadronic transport model, it is shown that the recent FOPI data on the pi;{-}/pi;{+} ratio in central heavy-ion collisions at SIS/GSI energies [Willy Reisdorf, Nucl. Phys. A 781, 459 (2007)10.1016/j.nuclphysa.2006.10.085] provide circumstantial evidence suggesting a rather soft nuclear symmetry energy E_{sym}(rho) at rho> or =2rho_{0} compared to the Akmal-Pandharipande-Ravenhall prediction. Some astrophysical implications and the need for further experimental confirmations are discussed.
120276588
Recent Progress in Constraining the Equation of State of Dense Neutron-Rich Nuclear Matter with Heavy-Ion Reactions
Abstract The nuclear symmetry energy E s y m ( ρ ) is the most uncertain part of the Equation of State (EOS) of dense neutron-rich nuclear matter. In this talk, we discuss the underlying physics responsible for the uncertain E s y m ( ρ ) especially at supra-saturation densities, the circumstantial evidence for a super-soft E s y m ( ρ ) from analyzing π − / π + ratio in relativistic heavy-ion collisions and its impacts on astrophysics and cosmology.