123828193
Effective Λn potential from relativistic Brueckner-Hartree-Fock theory
67821379
Skyrme-Hartree-Fock plus Tensor Correction for Nuclear Matter
We study the equation of states of symmetric and pure neutron matter in the SkyrmeHartree-Fock (SHF) model with tensor corrections. We are aware now that the pion exchange interaction has a significant contribution to nuclear structure in light nuclei. The pion generates a strong tensor interaction between two nucleons, which cannot be treated within the Hartree-Fock framework for the spin-saturated system such as homogeneous nuclear matter. Therefore, we study the role of the tensor interaction based on the SHF model, in which we extend it by explicitly introducing two-particle-two-hole (2p-2h) excitations for the treatment of the tensor interaction in symmetric nuclear matter and pure neutron matter. We are able to describe infinite matter very well using the SHF model with tensor corrections. We also discuss the connection between the symmetry energy and the tensor interaction in this framework. Subject Index: 201
121460689
Relativistic Hartree-Fock model with bare nucleon-nucleon interaction for neutron-rich matter
Abstract We study neutron-rich matter in the relativistic Hartree–Fock model (RHF) with the bare nucleon–nucleon interaction. As an important ingredient, we take into account the short range correlation in terms of the unitary correlation operator method (UCOM). We calculate the equations of state (EOS) of neutron-rich matter with Bonn potential. Our results on neutron-rich matter compare very nicely with those in the Relativistic Brueckner–Hartree–Fock (RBHF) theory. On the other hand, when we apply the RHF model with the UCOM on symmetric nuclear matter, the EOS is largely different from the RBHF result particularly in the low density region. This is because the other important ingredient as the tensor interaction plays important role in symmetric nuclear matter. We also discuss the proton and neutron Dirac masses in neutron-rich matter and find that the proton Dirac mass is larger than the neutron mass in agreement with the RBHF theory using projection techniques.
121881392
Extended chiral Hartree-Fock model for nuclear matter
We study the properties of nuclear matter with extended chiral Hartree‐Fock model. The two‐particle‐two‐hole (2p‐2h) states are introduced in the nucleon ground wave function to take the tensor components of pion into account. We also consider the form factor effect of pion to regularize its high momentum behavior. We find that the pion contribution from 2p‐2h states plays a very important role in the saturation mechanism of nuclear matter. Furthermore, the saturation properties are also influenced by the cut‐off moment of form factor.
11077788
A GRB Follow-up System at the Xinglong Observatory and Detection of the High-Redshift GRB 060927 ⋆
A gamma-ray burst (GRB) optical photometric follow-up system at the Xinglong Observatory of National Astronomical Observatories of China (NAOC) has been constructed. It uses the 0.8-m Tsinghua-NAOC Telescope (TNT) and the 1-m EST telescope, and can automatically respond to GRB Coordinates Network (GCN) alerts. Both telescopes slew relatively fast, being able to point to a new target field within ~1 min upon a request. Whenever available, the 2.16-m NAOC telescope is also used. In 2006 the system responded to 15 GRBs and detected seven early afterglows. In 2007 six GRBs have been detected among 18 follow-up observations. TNT observations of the second most distant GRB 060927 (z = 5.5) are shown, which started as early as 91 s after the GRB trigger. The afterglow was detected in the combined image of the first 19×20 s unfiltered exposures. This GRB follow-up system has joined the East-Asia GRB Follow-up Observation Network (EAFON).
119772144
Microscopic study of the ground state properties of light nuclei
Ground state properties of light isotopes from helium to oxygen, such as binding energies, spin parities, rms radii, and halo phenomena are studied systematically by the Skyrme Hartree-Fock model with fit E{sub {sigma} } as the effective interaction. Since the particle number of the studied system is rather small, pairing interactions between identical nucleons are treated with the particle number conservation method. The results of the calculation show that most of the ground state properties can be well described. Some unsuccessful points of the calculation are pointed out. {copyright} {ital 1997} {ital The American Physical Society}
18113816
GRB follow-up observations in the East-Asian region
In 2004, we established a Japan-Taiwan-China collaboration for GRB study in the East-Asian region. This serves as a valuable addition to the world-wide optical and infrared follow-up network, because the East-Asia region would otherwise be blank. We have been carrying out imaging and spectroscopic follow-up observations at Lulin (Taiwan), Kiso (Japan), WIDGET (Japan) and Xinglong (China). From Xinglong and Kiso, we can locate candidates and obtain early time spectra for afterglows. While WIDGET provides early time observations before the burst, the high-time resolution for multi-band light curves can be obtained at Lulin. With the data from these sites, we can obtain detailed information about the light curve and redshift of GRBs, which are important to understand the mechanism of the afterglows. Up to March 2005, ten follow-up observations have been provided by this East-Asia cooperation. Two optical afterglows were detected, GRB 040924 and GRB 041006. The results of the two detected afterglows are reported in this article.
118584779
Reconstruction of the primordial power spectra with Planck and BICEP2 data
By using the cubic spline interpolation method, we reconstruct the shape of the primordial scalar and tensor power spectra from the recently released Planck temperature and BICEP2 polarization cosmic microwave background data. We find that the vanishing scalar index running (dn(s)= d ln k) model is strongly disfavored at more than 3 sigma confidence level on the k = 0.0002 Mpc(-1) scale. Furthermore, the power-law parametrization gives a blue-tilt tensor spectrum, no matter using only the first five bandpowers n(t) = 1.20(-0.64)(+0.56) (95% C.L.) or the full nine bandpowers nt 1.24(-0.58)(+0.51) (95% C.L.) of BICEP2 data sets. Unlike the large tensor-to-scalar ratio value (r similar to 0.20) under the scale-invariant tensor spectrum assumption, our interpolation approach gives r(0.002) < 0.060 (95% C.L.) by using the first five bandpowers of BICEP2 data. After comparing the results with/without BICEP2 data, we find that Planck temperature with small tensor amplitude signals and BICEP2 polarization data with large tensor amplitude signals dominate the tensor spectrum reconstruction on the large and small scales, respectively. Hence, the resulting blue tensor tilt actually reflects the tension between Planck and BICEP2 data.
120532642
Configuration dependence of moments of inertia in the odd-A nucleus from BCS theory
The moments of inertia (Mol) of odd-A and even-even rare-earth nuclei are calculated using the Nilsson + BCS method with and without the blocking effect taken into account. The calculated MoIs with blocking considered is smaller than that without blocking considered. The Mor of an odd-A nucleus depends strongly on which orbital is occupied by the odd nucleon. Although the calculated MoI's are systematically smaller than the data, the large fluctuations in the experimental odd-even differences in MoI's can be reproduced qualitatively. This is contrary to the common assertion that the MoI of an odd-A nucleus is some 15% larger than those of its neighboring even-even nuclei with the BCS theory and is helpful to understand the appearance of normally deformed identical bands in an odd-A nucleus and its even-even neighbors under the mean-field (BCS) approximation.