Bulletin of the American Physical Society
3rd Joint Meeting of the APS Division of Nuclear Physics and the Physical Society of Japan
Volume 54, Number 10
Tuesday–Saturday, October 13–17, 2009; Waikoloa, Hawaii
Session LE: Mini-Symposium on Strangeness in Stellar Systems |
Hide Abstracts |
Chair: Benjamin Gibson, LANL Room: Kohala 2 |
Saturday, October 17, 2009 2:00PM - 2:30PM |
LE.00001: Strangeness in compact stars Invited Speaker: Neutron stars have long been suspected to contain some form of strangeness in their interiors. Matter containing hyperons, or kaons or deconfined quark matter can have lower energy than neutron-rich matter at supranuclear density. I will briefly review models of dense matter where a phase transition to matter strangeness is favored. If strangeness were to occur inside neutron stars it can dramatically change both the structure, cooling and transport properties of the compact object. These changes influence observable aspects of neutron stars. I will review observable phenomena that have the potential to directly probe the composition of the interior. While these observations can provide insights about the existence of new forms of matter inside neutron stars, we need to improve theoretical models of dense matter ad neutron star evolution to properly interpret the current suite of neutron star observations. I will outline a few areas where we can anticipate progress in the near future. [Preview Abstract] |
Saturday, October 17, 2009 2:30PM - 2:45PM |
LE.00002: Kaon condensation from lattice QCD William Detmold, Kostas Orginos, Martin Savage, Andre Walker-Loud Kaon condensation may play an important role in the structure of hadronic matter at densities greater than that of nuclear matter, as exist in the interior of neutron stars. We present the results of the first lattice QCD investigation of kaon condensation obtained by studying systems containing up to twelve negatively charged kaons. Surprisingly, the properties of the condensate that we calculate are remarkably well reproduced by leading order chiral perturbation theory. In our analysis, we also determine the three-kaon interaction from the multi-kaon systems. [Preview Abstract] |
Saturday, October 17, 2009 2:45PM - 3:00PM |
LE.00003: Effects of $\Lambda$(1405) on the Structure of Multi-Antikaonic Nuclei Takumi Muto, Toshiki Maruyama, Toshitaka Tatsumi Multi-strangeness system in hadronic matter has received much attention toward understanding high-density QCD.Recently deeply bound antikaonic nuclear states have been studied extensively. We have investigated multi-antikaonic nuclei (MKN), where several $K^-$ mesons are bound in the nucleus. In this paper, we extend our framework to take into account the $\Lambda$(1405) ($\Lambda^{\ast}$) and consider its effects on the structure of the MKN. We base our study on the relativistic mean-field theory (RMF), coupled with $\bar K$-nucleon ($N$) and $\bar K-\bar K$ interactions which respect chiral symmetry. The $\Lambda^{\ast}$ is introduced as a pole contribution to the energy together with the range effects as the second-order perturbation with respect to the relevant axial-vector current. The density profiles of the nucleons and $K^-$ for the MKN are obtained. It is shown that the $I$=0 $\bar KN$ attraction is enhanced as a result of avoiding the $\Lambda^{\ast}$ pole. Therefore both protons and $K^-$ mesons become denser around the center of the MKN as compared with the previous result without the range terms and $\Lambda^{\ast}$. We also discuss behavior of the binding energy of the MKN by systematically changing the number of the embedded $K^-$, $|S|$. [Preview Abstract] |
Saturday, October 17, 2009 3:00PM - 3:15PM |
LE.00004: Impact of strange quark matter nuggets on pycnonuclear reaction rates in the crusts of neutron stars Fridolin Weber, Barbara Golf, Joe Hellmers This paper presents an investigation into the pycnonuclear reaction rates in dense crustal matter of neutron stars contaminated with strange quark matter nuggets. The presence of such nuggets in the crustal matter of neutron stars would be a natural consequence if Witten's strange quark matter hypothesis is correct. The methodology presented in this paper is a recreation of a recent representation of nuclear force interactions embedded within pycnonuclear reaction processes. The study then extends the methodology to incorporate distinctive theoretical characteristics of strange quark matter nuggets, like their low charge-per-baryon ratio, and then assesses their effects on the pycnonuclear reaction rates. Particular emphasis is put on the impact of color superconductivity on the reaction rates. Depending on whether or not quark nuggets are in this novel state of matter, their electric charge properties vary drastically which turns out to have a dramatic effect on the pycnonuclear reaction rates. Future nuclear fusion network calculations may thus have the potential to shed light on the existence of strange quark matter nuggets and on whether or not they are in a color superconducting state, as suggested by QCD. [Preview Abstract] |
Saturday, October 17, 2009 3:15PM - 3:30PM |
LE.00005: Hot hadron-quark mixed phase including hyperons Nobutoshi Yasutake, Toshiki Maruyama, Toshitaka Tatsumi We study the hadron-quark phase transition with the finite size effects at finite temperature. For the hadron phase, we adopt the nuclear equation of state in the framework of the Bruekner-Hartree-Fock theory including hyperons. The properties of the mixed phase are clarified by considering the finite size effects under the Gibbs conditions. We find that the equation of state becomes similar that given by the Maxwell construction. Moreover, the number of hyperons is suppressed by the presence of quarks. These are characteristic features of the hadron-quark mixed phase, and should be important for many astrophysical phenomena such as collisions of neutron star-neutron star binaries. [Preview Abstract] |
Saturday, October 17, 2009 3:30PM - 3:45PM |
LE.00006: Hadonic Star Matter in an RMF Model with a SCL Chiral Potential Kohsuke Tsubakihara, Akira Ohnishi In constructing the dense matter equation of state (EOS), it is desired to respect both chiral symmetry and hypernuclear physics. In dense matter, strangeness is expected to play a decisive role and the partial restoration of chiral symmetry would modify the hadrons' properties. From the point of view of chiral symmetry, we have developed a chiral SU(2) symmetric RMF model with a logarithmic sigma potential, which is derived in the strong coupling limit (SCL) of the lattice QCD in zero temperature. In order to investigate hypernuclear systems, we have introduced an extended chiral SU(3) RMF model which includes both chiral symmetry and hypernuclear physics information. We determine hyperon-meson coupling constants in this chiral SU(3) RMF model by fitting existing data. The EOS of symmetric matter is found to be more softened than SCL model by the scalar meson with hidden strangeness, $\zeta = s\bar{s}$ and to be consistent with the EOS in a variational calculation at around $\rho_0$. At higher $\rho_B$, however, EOS is so soft that the calculated neutron star mass underestimates the observed value. In order to cure this problem, we have examined arcsinh type chiral potential which is derived in the finite temperature treatment of SCL. In this presentation, we discuss how to construct this chiral SU(3) RMF models and show an effect to nuclear star maximum mass by introducing this potential. [Preview Abstract] |
Saturday, October 17, 2009 3:45PM - 4:00PM |
LE.00007: EOS table with hyperons and emergence of hyperons in core-collapse processes Akira Ohnishi, C. Ishizuka, K. Tsubakihara, K. Sumiyoshi, S. Yamada, H. Suzuki We discuss the roles of hyperons in dense matter formed during core-collapse supernovae. We have recently presented several nuclear matter EOS tables including hyperons using an $\mathrm{SU}_f(3)$ extended RMF model~[1]. $\Sigma$ and $\Xi$ potential in nuclear matter are chosen to be $U_\Sigma(\rho_0)\simeq+30~\mathrm{MeV}$ and $U_\Xi(\rho_0)=-15~\mathrm{MeV}$, based on recent hypernuclear physics information. Hyperons do not play important roles in the collapse and bounce stages, but they are found to populate at 0.5-0.7 s after the core bounce and to trigger the re-collapse to a black hole in failed supernovae~[2]. Hyperons start to show up off center owing to high temperatures caused by the shock-accretion interaction, and later prevail at center when the central density becomes high enough. The neutrino emission stops much earlier with the hyperonic EOS, while the average energies and luminosities are not affected much. In the presentation, we discuss the EOS with hyperons at high temperatures, and its dependence on hyperon potentials. \\\noindent [1] C. Ishizuka, A. Ohnishi, K. Tsubakihara, K. Sumiyoshi, S. Yamada, J. Phys. G {\bf 35} (2008), 085201. \\\noindent [2] K.~Sumiyoshi, C.~Ishizuka, A.~Ohnishi, S.~Yamada and H.~Suzuki, Astrophys. J. {\bf 690} (2009), L43. [Preview Abstract] |
Saturday, October 17, 2009 4:00PM - 4:15PM |
LE.00008: YN interaction with Lattice QCD Assumpta Parreno Lattice QCD simulation of hadronic interactions in the non perturbative regime has been pointed out as a powerful and useful technique to obtain information of relevance in Nuclear Physics, in special in those sectors where experiments are ellusive or difficult to perform. This would be the case of the hyperon-nucleon interaction, crucial for the correct understanding of hypernuclear processes, as well as for a better knowledge of astrophysical phenomena related to the evolution of compact stellar systems. I will discuss recent efforts driven by the {\sl Nuclear Physics Lattice QCD (NPLQCD)} Collaboration to formulate and simulate the interaction between two baryons in the strange sector with Lattice QCD. After outlining the techniques that are used to extract the relevant physics parameters in the low energy regime, I will present the latest results we have produced. [Preview Abstract] |
Saturday, October 17, 2009 4:15PM - 4:30PM |
LE.00009: ABSTRACT WITHDRAWN |
Follow Us |
Engage
Become an APS Member |
My APS
Renew Membership |
Information for |
About APSThe American Physical Society (APS) is a non-profit membership organization working to advance the knowledge of physics. |
© 2024 American Physical Society
| All rights reserved | Terms of Use
| Contact Us
Headquarters
1 Physics Ellipse, College Park, MD 20740-3844
(301) 209-3200
Editorial Office
100 Motor Pkwy, Suite 110, Hauppauge, NY 11788
(631) 591-4000
Office of Public Affairs
529 14th St NW, Suite 1050, Washington, D.C. 20045-2001
(202) 662-8700