123272027
Extension of Hartree–Fock theory including tensor correlation in nuclear matter
Extension of Hartree–Fock theory including tensor correlation in nuclear matter Jinniu Hu1,2,∗,†, Hiroshi Toki1,∗,†, and Yoko Ogawa1,∗,† 1Research Center for Nuclear Physics (RCNP), Osaka University, Ibaraki, Osaka 567-0047, Japan 2State Key Laboratory of Nuclear Physics and Technology, School of Physics, Peking University, Beijing 100871, China ∗E-mail: jinniuhu@rcnp.osaka-u.ac.jp (JH), toki@rcnp.osaka-u.ac.jp (HT), ogaway@rcnp.osaka-u.ac.jp (YO)
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.
123828193
Effective Λn potential from relativistic Brueckner-Hartree-Fock theory
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.
17422276
1RXS J232953.9+062814: a New SU UMa Dwarf Nova below the Period Minimum
1RXS J232953.9+062814 was identified as a cataclysmic variable by Wei et al. (1999). Four low-resolution spectra of 1RXS J232953.9+062814 were obtained with the 2.16-m telescope of the National Astronomical Observatories, of which two were at outburst, and two were at quiescence. The system is about 16.8 B and 16.5 V at quiescence, and 12.6 B and 12.6 V at outburst. The quiescent spectra were dominated by double-peaked Balmer emissions, which indicates a hydrogen-rich system with a high-inclination accretion disc. MgH and TiO absorption bands appeared in the quiescent spectrum which implies a companion with a spectral type of early M dwarf. If we take it as an M0 dwarf, then the system is located at a distance of 350 pc with a proper motion velocity 150 km s -1 . The superhump period of 0.046311 days was confirmed by our V photometry. The short period and the hydrogen-rich nature reveal that this system is another SU Ursae Majoris-type dwarf nova below the period minimum after V485 Centauri. 1RXS J232953.9+062814 is one of the most important systems for studying the evolutionary scenario of cataclysmic variables since it is much brighter than V485 Cen.
17626951
Time expansion chamber system for characterization of TWIST low energy muon beams
A low-mass time expansion chamber (TEC) has been developed to measure distributions of position and angle of the TRIUMF low-energy surface muon beam used for the TRIUMF Weak Interaction Symmetry Test (TWIST) experiment. The experiment is a high-precision measurement of muon decay and is dominated by systematic uncertainties, including the stability, reproducibility, and characterization of the beam. The distributions measured by two TEC modules are one essential ingredient of an accurate simulation of TWIST. The uncertainties, which are extracted through comparisons of data and simulation, must be known to assess potential systematic uncertainties of the TWIST results. The design criteria, construction, alignment, calibration, and operation of the TEC system are discussed, including experiences from initial beam studies. A brief description of the use of TEC data in the TWIST simulation is also included.
119172921
Inflation coupled to a Gauss-Bonnet term
The newly released Planck cosmic microwave background data place tight constraints on slow-roll inflationary models. Some commonly discussed inflationary potentials are disfavored due mainly to the large tensor-to-scalar ratio. In this paper we show that these potentials may be in good agreement with the Planck data when the inflaton has a nonminimal coupling to the Gauss-Bonnet term. Moreover, such a coupling violates the consistency relation between the tensor spectral index and tensor-to-scalar ratio. If the tensor spectral index is allowed to vary freely, the Planck constraints on the tensor-to-scalar ratio are slightly improved.
13913450
Ten Overdensities and an Arc Structure in the Galactic Halo
Aims. We use Sloan Digital Sky Survey (SDSS) DR5 photometric data to explore the structure of the Galaxy halo and hope to discover new companions or substructures which may reveal the forming history of the halo. Methods. We study overdensities in a sky area where � = 120 ◦ � 270 ◦ and � = 25 ◦ � 70 ◦ and pick out ten overdensity areas by comparing color-magnitude diagrams with known globular clusters or dwarf spheroidal galaxies. An automatic template matching method is developed to fit the color-magnitude diagram for ea ch overdensities with a suitable stellar evolution isochro nic line so that distance module and metalicity are roughly estimated. The performance test of the method indicates that our estimates on distance is acceptable. Results. The 10 overdensities and three known objects, UMa I, UMa II and Willman 1 are found to be connected with a long arc substructure starts from � 8kpc above the disk and spread to � 150kpc into north galactic cap. Evidence also shows a relationship between metalicities and distance modules of the overdensities. Conclusions. C7, one of the 10 overdensities is most likely a dwarf spheroidal galaxy according to radial density profile study and its absolute magnitude. Other overdensties are not classifi ed for poor information. The arc structure may either be a long tidal stream or be an intrinsic substructure of the halo. Follow-up study need to be done to clarify this problem.
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.